texts: How can true altitude be calculated from pressure altitude, temperature and altimeter setting?

texts:
The manual that came with my Jeppensen E6B has the following sample...

  If an aircraft is flying at 12,500 feet with an outside air
  temperature of -20C and the altimeter is set on 30.42 inches of
  mercury, what is the true altitude?

The explanation goes on to find a pressure altitude of 12,000 feet.  After placing -20C over 12,000 we find 12,500 (12.5) on the B scale and read the true altitude of 12,000 (12.0) on the outer ring.

Looking closely at the outer ring, I see that the true altitude is actually just slightly below 12,000.  Now for practical purposes I realize we don't worry about differences like this and round the result.  But I'm working on a project in which I need to calculate the true altitude precisely.  I'm having a difficult time finding the formula.  The closest thing I have found says the correction is 4 feet per thousand feet indicated per degree off of ISA.

When I attempt to apply that formula to our sample problem I get 4 * 12.5 * -35 = -1750.   Applying that correction gives a value far below expected so obviously I'm doing something wrong.  Can someone straighten me out here?  References to documentation with educational value are especially welcome.


texts: What is the first recorded instance of simulating weightlessness in an airplane?

texts: I wonder what the first instance ever has been of a controlled creation of weightlessness onboard an aircraft, like during a parabola or flying nose-down ~90 degrees. Do we have a record of the first controlled 0-gravity flight ever? Or a record of 0-gravity experiments being performed the first time on such a flight? When it took place and how long the weightlessness lasted, who performed it and something. Thank you.


texts: When can a taxi clearance allow me to cross multiple runways?

texts:
I was just reading the FAA instrument procedures handbook and saw the paragraph below in Ch 1. I'm puzzled by this, because I routinely get "Cross runways XX right and XX left on Alpha" as part of my taxi clearance. How do I square that with the statement here?

  Instructions to cross a runway are issued one at a
  time. Instructions to cross multiple runways are not
  issued. An aircraft or vehicle must have crossed the
  previous runway before another runway crossing
  is issued. This applies to any runway, including
  inactive or closed runways.

(Top of 1-8.)


texts:
Why are aircraft turbine blades made of nickel alloys? What is the advantage of using them? Why did they replace steel alloys for turbine blades?

How to overcome failure cases of turbine blades?


texts: How do the cockpit controls of a tiltrotor aircraft work?

texts:
I'm having trouble trying to imagine the primary flight controls in the cockpit of a tiltrotor aircraft - how would one design it?

In an airplane, turning the wheel to the left would always deflect the ailerons (even when the plane is stationary!), while in a helicopter moving the stick to the left would always tilt the rotor disc. However in a tiltrotor neither is true - not to mention, we need to control the aircraft when it is transitioning between hover and cruising state!

So, just exactly how does one pilot a tiltrotor aircraft?


texts: Is it possible to "take a bullet [missile]" for another plane as shown in the movie Air Force One?

texts:
In Air Force One a fighter jet maneuvers between a missile and the president's plane, as shown in this clip.

Is such a maneuver possible?
If not, what could be done in that situation?


texts: How high are you when you are three miles away from the threshold of the landing RWY and get 3 white and 1 red on PAPI?

texts:
Let's say you were shooting a visual approach and you were precisely on a three mile final. You gave a glance at the PAPI, you find it giving three white and one red. How high you are from the 3 degree glide path at the moment?

Anybody can do math for me?


texts: What is the teardrop-shaped appendage on the T-6 Texan?

texts: Can anyone explain what is the teardrop-shaped item behind the cockpit?


texts: Does a decreasing shape factor correspond to greater or reduced probability of separation?

texts: The shape factor ($H=\frac{\delta^*}{\theta}$) is the ratio of displacement thickness, a measure of the thickness of the boundary layer, to the momentum thickness, a measure of the shear stress. I think that a larger shape factor indicates that the boundary layer is larger and there is less shear stress, so it seems like a larger shape factor should be associated with a greater likelihood of separation. Is that right? If not, why?


texts: What is the procedure to fill/send/approve a flight plan to the ATS network from outside?

texts:
We are planning to develop an app that allows general pilots to fill/send a flight plan to the ATS. We're wondering to know if it is needed to have a regular access (register access or account) to the ATS network (thru AMHS or other way).

The idea is to automate the process through an app for general pilots.

For example, Garmin Pilot's app works and offers same solution., among many other related solutions for pilots.


texts:
The B-52 was introduced in 1955, and is still used by the US Airforce, and is expected to remain in use till the 2040s.

On the other hand, the A-4 Skyhawk was introduced in 1956 and retired in 1998/2003.

Now granted these are completely different aircraft. What I'm wondering, is why one aircraft can remain so useful for so long, while others quickly become obsolete.


texts: Will the new Part 23 changes reduce the cost of avionics for existing aircraft?

texts: Will the part 23 changes coming in August help to reduce the cost of IFR GPS avionics? I'm looking to upgrade the IFR avionics in a 1978 Cessna 182.


texts: Why don't aircraft have DME that can automatically convert the slant range to ground range?

texts:
Knowing that $a^2 = b^2 + c^2$ where $a = \text{slant range},\ b= \text{ground range},\ c = \text{height}$.

Why can't the DME equipment which calculates the slant range then just convert it to the ground range? Surely for navigation and position fixing knowing the actual ground range would be more useful? Is there a practical reason why the slant range has stuck?


texts: Is it possible that meteor could strike a commercial airliner?

texts: Is it possible? Are there some such accidents in human history? Is there any rules or systems design to protect airplanes?


texts: What is the difference between ICAO, JAA, FAA, EASA, and CAA?

texts: There seems to be many regulation bodies across the globe, how are they different and how are they alike? Specifically, how is ICAO different from the rest?


texts:
Screen burn-in can be a problem for older and cheaper monitors.  It can be caused by fixed-width text, fixed-size graphics, and operating for long durations, which are things that are common in aircraft displays.

So is burn-in a problem for aircraft? Have there been hardware or software improvements to minimize burn-in?


texts: Are there any missile systems as of 2019 capable of shooting down aircraft in excess of mach 6?

texts:
Are there any missile systems, ground based, or air to air, as of 2019 that are capable of shooting down aircraft in excess of mach 6, such as the X-15?

For simplicity I'm ignoring the fact that the X-15 may be considered a spacecraft or "space plane".


texts: Can a super land without flaps/spoilers?

texts: Can the Airbus A380 or Boeing 787 land safely without flaps/slats/spoilers or thrust reversers?


texts: What uses for flight did early aviation pioneers envision?

texts:
Between 1903 and 1914, what did the aviation pioneers think flight would be used for, besides military purposes? Did they envision anything like crop dusting, commercial transportation, charting terrain in the wilderness, scientific study of the atmosphere, etc.? Even just pure entertainment flights?

I did read this little article about the Wright Bros thinking it would actually deter war, but it didn't mention if they had thought of some alternative use to warfare.

There are of course many aviation pioneers from those days. Did any of them envision uses besides war? It would be really interesting to see what they came up with and if it turned out that way.


texts: What type of hydraulic oil is used in the aviation industry?

texts: Among the three different types of hydraulic fluid types (mineral based/petroleum based, synthetic esters, naturally occurring vegetable oils) which one is used in the aviation industry and why?


texts: Why should jet engine throttles be moved smoothly?

texts:
On the only jet engined aircraft I'm trained on, the Bell 206B (Allison 250 engine), I was taught to move the throttle slowly and smoothly, especially when opening.  I've also see this done with Rolls Royce testing RB211s and early Trents.

I've realised I don't actually know why this is.  Is it to prevent possible flame out with a sudden increase in fuel with no corresponding increase in air mass since the engine will spool up much more slowly?

Do modern engines need this handling?  In this video at about 0:17, the pilot commences the roll by more or less slamming the throttle open. My guess is that like all other computer controlled controls, the FADEC interprets this as "as much fuel as possible without flaming out".


texts: Why were there passengers allowed on Concorde's route proving flights?

texts: Based on this site, Concorde needed to fly 750 hours to prove its airworthiness and be used in regular service. Air France and British Airways flew two Concords (F-BTSC and G-BOAC respectively) on a total of 254 flights, with... 11180 passengers combined! How come there were passengers allowed to be on the plane when it was doing flights to get its airworthiness certificate?


texts: Why do some U.S. airlines require passenger headrests to be lowered during takeoff?

texts:
I've experienced a few times recently where cabin crew have asked passengers to lower their adjustable headrests during takeoff and landing and, in at least one case, it was even part of the pre-recorded safety briefing.

I'm wondering what on Earth would be the reason for this?

I completely understand needing to keep seatbacks and tray tables upright and aisle armrests lowered, but having headrests lowered makes no sense to me. As a tall person, having the headrest lowered is uncomfortable. For extended durations (e.g. a long wait to takeoff, etc.,) it becomes extremely uncomfortable.

Even more concerningly, though, it seems like this would significantly reduce safety in the event of a crash, due to forcing a tall passenger's spine into an unnaturally-forward position and having neither most of the spine nor the head supported. It seems like this would be much more likely to cause head/neck/spine injuries to the passenger during a crash than would allowing passengers to adjust their headrests to properly support their heads and necks (and not push their shoulders forward.)

I see that 14 CFR 121.311(e) requires seatbacks to be in the upright position during takeoff and landing, but I see nothing in the FARs about requiring adjustable headrests to be lowered for takeoff and landing during Part 121 operations, though I may have missed something.

So, my question is what is the reason for this requirement for headrests to be lowered? Is there some regulatory requirement for this or is it an airline-specific thing?


texts: Are a gyrodyne and a compound helicopter the same thing?

texts: Both the gyrodyne and the compound helicopter are typically rotorcraft with driven rotor, additional stub wings and thrust provision. Are they two terms for the same thing or do they differ in some way?


texts: Can the divergence Mach be greater than 1?

texts:
I know that by decreasing t/c and increasing the sweep angle it is possible to increase the divergence Mach, but what is the limit?

I am calculating the Mach for a wing with a quarter chord sweep angle $\Lambda_{1/4}=54 ^\circ$. According to Denish Howe (Aircraft Conceptual Design) the “two-dimensional” divergence Mach can be found with Korn equation and then converted in a "three-dimensional" Mach considering the sweep with the following equation:

$$ \frac{M_{3d}}{M_{2d}}=\frac{1}{(\cos\Lambda_{1/4})^{0.6}} $$
 This led me to a divergence Mach of 1.19 which doesn't seem reasonable at all.

However, if the assumption that only Mach perpendicular flow affects the shock is maintained, this might be possible with very high sweep angles. What is the limit of this assumption?


texts: Airplane generations - how does it work?

texts:
I was reading about Atlas B763 that was involved in an accident on Feb 23rd, 2019. Based on what I read plane was 25 years or so old.

As a person who has no relationship about aviation industry except occasional flying as a passenger, I'm curious to find out if these planes also have generations or models like car manufacturers do e.g. Honda civic, 2015, 2016 or 2017 models where there are small but distinct changes.

Based on Wikipedia pictures, cockpit photos are different for various generations as technology is improving/changing.

Are pilots rated on particular generation of the plane or once you are rated on B763, you can fly any one of them whether it was built 25 years back or yesterday?


texts: I need to know how to calculate drift with a Jeppessen CR-3. Can someone help?

texts:
In my exams we are not allowed to use E-6B, just a CR-3 jeppessen flight computer and I'm having serious issues calculating W/V from other parameters like TAS/GS and HDG/TRACK.
Example:
Q : Given:
True HDG = 035°, TAS = 245 kt, Track (T) = 046°, GS = 220 kt.
Calculate the W/V?
A: 340/50kt
I need to know how to calculate Track HDG and Drift Can someone help ?
HDG-001degree TR-? Drift-05degree
What should be the Track? and what will be the Steps to solve !


texts: Do transoceanic airliners monitor marine VHF emergency frequencies?

texts:
I know that modern jetliners often have a multitude of radio equipment on board, including VHF, HF, satellite, etc.

From what I've read (such as here), it's customary for jetliners to monitor 121.5 MHz for aircraft emergency traffic.

Do commercial airliners traveling transoceanic routes also monitor marine VHF channel 16 (156.8 MHz), a common frequency used by ships in distress?

If so, is this a fairly customary, routine matter (like monitoring 121.5 MHz) or is it simply up to the crew of each aircraft?


texts: When is the use of reverse thrust recommended in airline operations?

texts:
I know the answer largely depends on each airline's FOM but I still wonder what the FOMs generally recommend with regard to the use of reverse thrust after landing. For example, I guess its use would be generally recommended for the accelerate-stop maneuver and also for landing on short runways.

So once again, what're their general recommendations on the use of reverse thrust after landing, if any?


texts: Can an aircraft be controlled after an ejection?

texts:
What kind of damage does the ejection process do to the inside of a cockpit or to the aircraft in general?

If ejection were accidentally triggered on the ground (i.e. the ejection wouldn't be followed by a hull damaging/destroying crash), would the damage be minimal enough that it could be flown again by simply installing a new seat and canopy, or would it have to go through a major inspection to ensure no additional damage was done to instruments, wiring, etc?


texts: Why are the leading edges on the Boeing 787 made from aluminum?

texts: Why are the leading edges of the wings, horizontal stabiliser and vertical stabiliser and the engine's inlets made from Aluminium?


texts: How much water is produced in jet exhaust?

texts:
If a jet has typical combustion efficiency, what equivilent amount of liquid water will be created per gallon of jet or kerosene fuel. An acceptable answer can be a ratio in weight or volume to the original unburned fuel. For example an answer might be 1 part in 50 by volume or 1/4oz per pound is converted to water.

An answer in "water vapor" volume should be avoided because gas volume changes dramatically with altitude (pressure) and temperature.

If you are also able to show a comparison for gasoline, that would be even better.


texts:
So I was looking for the Miami In in SkyVector and I saw this.

Apparently a stadium game has the power to block runways in (At least in US).

What is really going on there? I am not well acquinted with charts.


texts:
If you paid attention to NEXRAD training, you know that the colors of pixels show the maximum activity at any altitude in that air column. (It’s a “composite” view.)

NEXRAD itself samples in three dimensions, so that integration into the composite is being done on the ground before being sent back out on SiriusXM or ADS-B.

Given ADS-B’s bandwidth constraints, it makes sense that you only get maximums—it’s the thing that most pilots will care about. The bandwidth constraints are the same reason pixel granularity falls off with distance—the stations can’t send nationwide data in the bandwidth allotted.

But could SiriusXM give you the raw 3D data in addition to the composite view? They have the bandwidth where you could dial in a given altitude and get a 2D slice rather than just maximums. And you can get other data like wind on an altitude basis, so the capability seems to be there.

I don’t know if it’s a case of cost (considering how SiriusXM charges for subscriptions, I imagine they’d be happy to offer this to pilots as an additional tier), a worry that some pilots could take on even more risk around storms by trying to do 3D rather than just 2D daisy-clipping, or something else (like a technical issue with NEXRAD—as far as I can tell, none of the weather sites offering NEXRAD give the ability to dial in altitudes).

Given how many accident studies (even into incidents where the PIC’s were instrument-rated private pilots) have shown that pilots who flew into unexpected IMC or icing could have survived had they made a different decision about what altitude to seek for safety, it feels like it could be an improvement in situational awareness and safety, and usually we seem to accept those technologies in aviation, even if they may also present greater risk of recklessness.


texts: Is lowering V1/VR (and runway length required) the only reason for flaps at take off?

texts:
I've read that some aircraft (examples include the Saab 340 and the Fokker 100) can perform flapless take offs, provided there is enough runway available. It's also my understanding that, in terms of lifting off the ground, any aircraft would be theoretically capable of that, as long as there were a long enough runway (which isn't the case in practice).

However, I was wondering why aircraft such as the ATR-42/72 or the Dash-8 still lower their flaps for take off, even from runways that are over 3000m/10000ft long. At least those I've flown with always did that.

Is there some other reason for non-flapless take offs, even with very long runways, for some models? For instance, anything related to pitch/roll stability?


texts: Why don't we see diverging nozzles or diffusers?

texts:
When it comes to fully subsonic propulsion, all outlets are converging nozzles (I did say fully subsonic so no converging diverging). From what I understand, they are flow regulating devices (changing the exit diameter allows to control the mass flow through the propulsion system, be it a turbofan or ducted electric fan).

Why don't we ever use diverging outlets, i.e. diffusers? Is it due to the back pressure? Wouldn't such a shape increase the pressure recovery, i.e. more thrust.


texts: Is the compressibility of air the reason high aspect ratio wings are more effecient

texts:
As stated many times here 1, 2, 3 wings generate lift by moving air downwards. This downward air creates an equal and opposite force pushing the aircraft up.

High aspect ratio wings have a greater lift/drag ratio because they are moving large amounts of air a little bit, vs lower aspect ratio wings which move a little bit of air a lot.

Now my question is why does this matter?

When using "solid" objects to generate "lift" this doesn't matter as long as the solid object is strong enough not to break. For example the image below shows 2 different sized poles (different aspect ratios) resisting the same amount of force.

Air is not a solid, and so when high pressure is exerted against it, air will compress absorbing some of that pressure and converting it into heat and potential energy.

There is also pockets of low pressure that will form which can try to "suck" the aircaft back into it creating drag. In some cases these low pressure pockets cause the water vapor in the air to even evaporate:

Is this the reason it's more effective to move a lot of air slowly, vs a little bit of air a lot? To prevent the energy from being lost to heat conversion/ storing potential energy that your aircraft will not beneficent from as you already flew out of the area of the release?

If that is true would the same apply to water which is a non compressible liquid? Is this why we don't often see boats with "high aspect ratio" displacements of water?


texts: Can a seaplane make a long distance sea voyage on the sea?

texts:
In general, if a seaplane can fly X distance, can it travel that distance on the surface of the water as if it was a boat or ship? In other words, this would be equivalent to taxiing all the way to a destination. E.g. if a seaplane has the range to fly from New York to Amsterdam, could a pilot simply choose to taxi all the way across the Atlantic Ocean and casually slip into the harbor?

If this is not generally possible, what rules define what sort of sea journeys a seaplane could undertake? Is there a coefficient of inefficiency (e.g. if a seaplane can fly X miles, it can taxi X/2 miles due to increased drag from the water)? Are the vast majority of seaplanes not set up to handle the stresses of a long-distance sea trip, making them likely to result in a shipwreck (er, seaplanewreck)?

This is not the same question as Is it possible to sail a seaplane? . That question is asking about sailing a seaplane using sails without any engines. I am asking about "sailing" a seaplane using the engines and whatever other tools are available for taxiing.

This question is about the physics and engineering issues - not about licensing. I am fully aware that taxiing a seaplane across a body of water might make the trip fall under boat regulations and require a sea captain's license, but I'm not asking about that.


texts: Which are some planes shaped like an inverted wing?

texts:
To understand my question better, let's consider the priciple behind the lift generated by the wing - The upper surface of the air-foil is curved to deflect the air downwards using the Coanda effect. According to Newton's 3rd Law, an equal reaction is produced by the downwards deflection of air in the form of lift.

So here's my question - Why aren't some planes designed to look like a massive cross-section of a wing from the side? e.g. A Cessna C172 looks like an inverted wing (with the curved side on the bottom, which might create 'inverse lift' by pulling it down. From that aspect, is the Cirrus SR22 and the Cessna TTx more lift-friendly? Their upper part of the fuselage is relatively more curved than their lower part when viewed from the side. Or am I making a mistake - is it due to high-wing low-wing design philosophies?


texts: Can the ball on a turn coordinator be to the full right/left while the wings are level?

texts: Can it ever happen in a wings level flight that the Turn and Slip indicator ball is to the full right/left? If so then when and what will be the flight path of such an aircraft? Thanks in advance.


texts: Is an alternate airport always required when flying internationally?

texts:
When flying a domestic US flight, an alternate airport is not required unless the weather is below specific minimums at the destination.

What are the rules when on an international flight plan and leaving or returning to the US?

In larger airplanes, carrying the extra fuel required to fly to an alternate (which costs money) is a little silly when there isn't a cloud in the sky and there are multiple airports in the vicinity of your destination that can be easily reached with your already required 45 minute IFR reserve.  We should always have a plan for when things go wrong, but if it can be done safely, is it legal to file an international flight plan without an alternate?


texts: What makes the swooping noise when a jet flies overhead?

texts:
I've lived near several airports and have grown accustomed to a certain noise a jet plane makes when passing overhead: a swooping sound, very bass-heavy, that dives rapidly in pitch, maybe 1.5 seconds in duration. It happens toward the very beginning of the plane's audibility and is followed by the normal sound of the jet passing above.

Is it simply the Doppler effect as the plane passes overhead and its noise rapidly changes?

Or is there a mechanism on the airframe whose actuation on an approach might make this sound? Sometimes the same plane makes this sound more than once, which makes me think it isn't simply the Doppler effect.


texts: Saw the video of the helicopter chopping off its own refueling probe. That made me wonder what the stall speed of the tanker is, and how difficult it is to fly slow enough for the helis to keep up.


texts: With power off, is it possible to maintain constant altitude for some period of time, until the stall speed is reached?

texts:
With power off, is it possible to maintain constant altitude for some period of time, until the 1-G stall speed is reached, i.e. until the stall angle-of-attack is reached?

Implicit in the question is the assumption that the initial airspeed is above the 1-G stall speed.


texts: Why do helicopters have such limited range?

texts: Why do rotorcraft like helicopters have such limited range, rarely exceeding 1000 km on a full tank? For example, the range of the Apache is close to 425 km, and MI-26's is 800 km.


texts: Why do we use pylons to mount the engines on jetliners?

texts:
This question focus on jet airliners.

The De Havilland Comet's engine were mounted inside the wing, the Concorde's engines were mounted underwing (as many jet engines) but without pylon. It seems jet airliners' engines are now mounted on pylon. That assumption goes wherever the engine is mounted (underwing or at the rear of the aircraft).

What are the advantages of doing so (aerodynamic, maintenance, safety,...)? Is there some drawback (must be minimal as this design is dominant)?

Note: I don't want discussion about where to mount engine (underwing as for the B747, overwing as for the VFW-Fokker 614, at the rear as for the MD-80, ...), I'm curious about why we use pylons for all this designs.


texts: What is the purpose of the hole in the Cirrus SR22's parachute?

texts:
Watching this video I notice there is a big hole in the middle of the parachute, at its top when deployed. This feature seems to exist in other smaller parachutes.

For me, it seems that air can escape the parachute by this hole and thus the parachute is less efficient than a same-sized parachute without this hole. But it must serve in a way I don't imagine. What is its purpose?


texts: Can TS-1 fuel be used in an aircraft that takes Jet A?

texts: Reading up on some airports in Russia I noticed that some only supply TS-1 jet fuel (see point 7) instead of Jet A. I tried to find out more about this fuel, but only saw that it has a lower freezing point and a higher flash point. What I couldn't figure out was if this fuel is "compatible" with Jet A. Could a plane that usually flies with Jet A operate with TS-1 instead, or vice versa? My guess is yes, but I couldn't find anything authoritative about this.


texts: Which AFDX connections are used in Airbus A380?

texts: AFDX is defined by ARINC 664 Part 7 and used in Airbus A380, I would like to know in which connections on the aircraft is used and for which purposes? Does anyone knows the answer or good documentation from which to start a research about?


texts: What liability does an aviation inspector have for errors & omissions?

texts:
In reading online, I've come across the term "pencil-whipping". The actual term is new to me but I'm familiar with the practice; it's when someone fills out the paperwork that attests something is true, without actually verifying it himself (at least not to the standards required). Technically that's fraud, but it's also usually a "who'll watch the watchmen" situation; if you don't know what the guy is required to do and watch him do it, or else call in a second opinion, you won't know anything's been skipped.

I purchased a home a few years ago, and the home inspector did a good job of finding the things we'd have to get fixed. If he hadn't though, State of Texas requires these inspectors to have "errors and omissions insurance" on top of a "general liability" policy. If the inspector said he has checked something though he didn't; or he made a mistake checking it; or he didn't check something he was supposed to, he and his insurer are liable for any damages resulting from the new homeowner trusting that report. This generally discourages pencil-whipping in the home buying industry, as after the first instance of the insurer having to pay out for an electrical fire caused by an outlet the inspector attested to be fine, the guy's likely out of a job.

The question here is, do A&Ps in the United States carry a similar liability? If I were to hire a guy and pay him thousands of dollars for a pre-purchase inspection of an aircraft, get the all-clear, buy it and then find out the aircraft actually isn't airworthy because of something he missed, what recourse do I personally have against the inspector? How would I report this misfeasance and to whom? Assuming nobody was hurt and I just have a loan payment on a museum piece (or a fat unexpected repair bill), what damages can I claim?


texts: Is it practical to use ground effect to extend range in an emergency?

texts:
Imagine a piston engine airplane (let's say a DC-3) flying at cruise speed and altitude over a calm sea, trying to reach an unreachable airstrip straight ahead, just above sea level. Fuel is very low and ditching may occur at some point even if highest lift to drag to consumption ratio is achieved.

Would a ground effect low horizontal flight increase the range? That could mean ditching closer to the shore, and getting help sooner (or even landing safely).

If yes, is it also the case for a modern jet airliner usually cruising faster and in a much thinner air, and are there some emergency procedures or regulations about that?


texts: What accidents of chance have played a part in the design evolution of aircraft?

texts:
I asked a question, Have we seen the last significant experiments in the configuration of jet airliners?, and then by chance while reading something else came across a link to How the 747 Got Its Hump, an article describing various key developments of aircraft design that can be attributed to unpredictable events and causes.

If we consider only airliners, there are some obvious drivers of design in aviation: economy, safety, performance, passenger comfort, reliability, ease of maintenance and so on.

There are some though that appear to be on-off or wholly unexpected factors that nonetheless have left a permanent mark on design - significant random mutations, if you want a biological metaphor:

  Today’s 747 has a large upstairs cabin because Trippe thought it would be a freighter, because a round hump produced too much drag, because Pan Am bosses had fond memories of the Stratocruiser’s bar (and all-night parties held by the light of the Pratt & Whitney R-4360s’ flaming exhausts), and because fuel prices went through the roof. Nobody set out to design the airplane with an upper deck. It came about because it was possible and because it adapted the 747 to a changing environment. It evolved. (How the 747 Got Its Hump)

What other notable accidents of chance have had enduring effects on aircraft design?


texts:
Full size: http://155.178.201.160/d-tpp/1710/06656ILD5.PDF

So for the plate, if we were approaching from the southwest on the ILS or the LOC/DME, would we have to conduct that holding pattern if we were cleared for the approach before reaching the IAF (not a straight in, not vectored, not timed, etc.)? Also, the MAP would be TFD 7.5 DME correct? How do I confirm that is the MAP?


texts:
(airplane-pictures.net) Airbus A330 no engine option.

Why are empty pylons weighed down?

The plausible answer is to maintain the correct center of gravity. But why not just load ballast pallets in the forward cargo compartment, like those used on tail heavy planes on ferry flights?
On airliners.net there is a theory (plus debate) that states another reason is to relieve the load on the wingbox, which I would imagine would also decompress the landing gear (I don't see how).
Lastly, I remember on a TV documentary it was stated that the reason is so the wing would not deform upwards (again I don't see how).


texts: What is the purpose of the fuel shutoff valve?

texts:
Most GA planes have a fuel shutoff valve which I don't quite understand the purpose of. Does it cut the fuel flow with the mixture.
My theory is to prevent fuel flow at earlier stage for safety reasons?


texts: where are filed flight plans / routing stored? or: where does flightaware get route data?

texts:
One of my favorite new distractions is to look at the routing information that flightaware.com makes available.  If we pull this one, for example:  http://flightaware.com/live/flight/UAL98/history/20170123/0635Z/KLAX/YMML we can see the route is described as:

PRCH2 DINTY R576 DIALO R576 DENNS BARKR B474 ADOWA B474 ARTOP B474 SON BODEG 2300S/16000E HARVS SCOTT Y32 CG Q53 ISKIM Q94 CANTY H119 ARBEY

Which I can plug into ForeFlight or other flight planners or whatever.  My question is: where does flightaware get this data?  I have to assume that it's created by some combination of the airline dispatch groups and filed with the FAA, and lives in "some database" that the FAA/ATC uses.  But what mechanism does flightaware.com use to get this information?  And is there a way (preferably programmatically) that I can get access to the routing filed for a particular flight or tail number?


texts:
Ok, we had a few beer.

Imaging a plane with two cockpits back to back. One Pilot flies to the destination and the other returns without turning the plane.

The question is, whether there is a profile for a wing that would create lift in both directions. Our idea was a wave form.

Is there a profile for a wing with a reverse gear?


texts: Two- and three-wheel undercarriage in the same airplane?

texts: Are there any airplane types which have the capacity to land in a tricycle configuration and a tail dragger configuration in consecutive landings? I have one example in mind but wonder whether there are more. Different versions of the same type don't count; it should be the same airplane without structural changes between landings.


texts: Why would a pilot want to land with less than full flaps?

texts:
So for example if I am flying the Boeing 737-800, the FMC gives me three flap settings and approach speeds.

Why would a pilot want to fly with anything less than full flaps where possible?


texts: Why Do They Continue To Abbreviate Weather Products? Can We As A Community Change This?

texts: Why are area forecasts, METARs, and TAFs written in an abbreviated manner? I understand that in the beginning, each digit or symbol costs money. However, that is no longer the situation. Why not make an area forecast as clear as possible? Aviators kill themselves because they do not understand the weather. Is there a reason the FAA continues to do this? Can the community of aviators change this?


texts:
I saw this question on Google Plus and it seems to be a good question to put here.

  Is there a flash pattern for the strobe lights?
  I think I've read that Airbus has ~2 flashes/sec and Boeing has ~1 flash/sec. I've seen both patterns in the air but I didn't know the aircraft type.


texts: Why do some T-tail aircraft have a protrusion on the top front of the tail?

texts:
Aircraft like the Tu-154 and VC-10 have a "point" on the T-tail, while others like the 727 do not. Is this structure a shock body, or otherwise related to the tail's aerodynamics? And why is it only found on some designs?

Tu-154

VC-10

727


texts: Why is True Altitude calculated using the difference from the QNH to 1013hPa?

texts:
I have an example for true altitude calculation.
The given Information is
QNH: 983hPa, cruise in FL 85, ISA -10°C in this Alt.

The math and calculations are not hard and i also get to the correct result, but my Question lies in understanding the principles.

So to get the height difference from my QNH (MSL) and 1013hPa i simply take the difference of 30hPa x 30ft. and get 900ft. of seperation.

Now to the Question: Why is it correct to calculate the difference from the QNH, so actually a "virtual pressure", to a true temperature corrected pressure level of 1013hPa?
Wouldn't i need to calculate it from the actual temperature corrected pressure at MSL?


texts: Whenever I hear a plane throttling down quickly, what is happening visually?

texts:
I am completely blind and have heard this several times when I was at air shows. Then my friend sent me this recording of a crop duster spraying the fields, and I heard the same type of sound.
It starts out by slowly ascending, and then the plane's engine rapidly decreases its speed.
I know that because of the Doppler effect, sounds can sometimes be deceiving, so I wondered what I would hear if I were inside the plane.
Here's the recording. It's audio, unfortunately, but hopefully someone with experience will be able to provide clarification.


texts: Is there any System to warn of Runway Incusion?

texts:
From what I learn, in large towered airports, the control of who enters and leaves the runways belong to the Control Tower Operators.

And that got me thinking:

Is there any Equipment or System in large airports to warn the tower of something/someone entered or is crossing the runway?


texts: What classifies as an ultralight vehicle?

texts:
I am looking into the possibly of getting my pilots license and I noticed that it says you don't need a license for "ultralight vehicles".

What are ultralight vehicles?

I am located in the USA, and I am particularly interested in details for the states Utah and Washington.


texts: How can I go from a CPL to an A320 Rating?

texts: For example, I completed my CPL multi and have 300 flight hours, can I do a A320 type rating and work for an airline if they allowed my to work with 300 hours?


texts: Do (did) powered airplanes exist where pilots are not in a seated position?

texts:
Well... all is said in the title. I mean "traditional" powered airplane, with a cockpit and long flight capable, not a paraglider.

Upright pilot or prone pilot would qualify.
Likely experimental or military.

Source

The concept was once studied with the XF-90, but didn't get to reality.


texts: Why do most biplanes have their top wing slightly forward of the lower wing?

texts: In most of the biplanes, the top wing is located a little forward of the lower wing. What is the use of this? Also, how does this affect stability of the aircraft.


texts: Received ADS-B TC=31 message with non-existent version 3?

texts:
On several dates, my ground station received some airborne operational status ADS-B messages (TC=31) where the version number was reported as 3. As far as I know, the only valid versions are 0, 1, and 2.

I don't think it was just a garbled reception because

I received more than 500 messages of the same type, all reporting 3 as the version number.
The messages came from three USAF aircraft of the same type, KC-10A Extenders.

Here is a sample message, in raw form: 8DAE022EF8000000206143635C24

The dates on which I saw the messages:

2018-04-13
2019-02-16

The aircraft associated with the messages:

ICAO AE020E, registration 79-1948
ICAO AE0212, registration 82-0193
ICAO AE022E, registration 86-0037

What's the most likely reason behind these messages having this (AFAIK non-existent) version number? A test? A misconfigured piece of equipment (it strikes me as unlikely that the version number can be set to 3, but maybe I'm wrong). Is it a bug in the decoder I'm using?

[Edited 2019-02-16 to include other aircraft I've received the anomalous messages from.]


texts: Do some aircraft windshields contain gold particles?

texts: I've heard that the windshields of some aircraft have gold particles, but I don't know why?


texts: Could flywheel type gyros stablize a plane?

texts: An aircraft carrier has massive spinning gyros to keep the ship upright against waves. Do planes of any type have gyros like those used in satellites? Not instrument gyros. In the picture below spinning this one when suddenly stopped could move the plane in flight significantly allowing it to correct from a flat spin? It would spin in the event of a flat spin and stop suddenly to correct it, but it would not spin in normal flight. Or it can be used to shoot backwards momentarily. Can they be used this way for more control of the plane with the fins?


texts: Why aren't thermal analysis of propeller done?

texts: I have searched for articles on Thermal Analysis of Propeller but couldn't find one. Can I assume the aircraft company don't perform heat transfer simulation and analysis of high speed propeller? Isn't that important? What kind of simulation can be done of propeller besides the flow simulation of propeller obtaining drag, thrust and efficiency of it? Thank you.


texts: How long are the nacelle strakes on a GE-90?

texts: For my school project, I'm doing something where I create a nacelle strake on a model plane and I want to make it to scale. Could you please let me know the dimensions of a nacelle strake? I would greatly appreciate it!!


texts: How does the less dense air affect the reciprocating aircraft engine performance?

texts: How does the less dense air can affect the reciprocating engine performance ? For an example " rotax engine "


texts: Why use turbofan engines for high altitude flight?

texts:
I noticed that a lot of high altitude aircraft have turbofans for engines. So I researched and figured out that turboprop engines are more efficient. But most high altitude aircraft like the Global Hawk and U-2 have turbofan engines, with some exceptions like crazy long-endurance solar-powered aircrafts.

Is this because the low density is a problem for turboprops? or why?


texts:
A little background: I am a senior software engineer with over 14 years of experience. I will turn 30 soon. I live in the UK but I'm neither a British citizen nor from EU member country. BSc in software engineering (abroad) and MSc in Advanced Computer Science (UK).

If I decide to pursue a career as a pilot, would I be eligible?

I'm not just asking this randomly, I genuinely want to know and seriously thinking of it. Aviation's been my dream for so long now I can't even remember the beginning of it. Not studying to become a pilot has been my biggest regret so far, and feels like this is one of those last moments I can do something about it. Not counting the satisfaction I can't get from my industry anymore - been doing this for some time now!

I hope this type of question is not against the rules of this community, but I don't know where else I can this. Also, if you were in my position, would you risk everything and do it?


texts: What FAA rules govern tethered, outdoor UAV flight?

texts:
This question is concerning the possibility of operating an Unmanned Aerial Vehicle (UAV) outdoors—a commercially available quadcopter, for example—but with the distinction of operating the UAV while tethered.

In this letter of legal interpretation, the FAA states, that:

  The FAA has repeatedly affirmed it's position that any vehicle
  designed for tethered operations only, and not for "free flight",
  should be considered a kite.

An applicable kite (over 5 lbs., etc) would be subject to 14 CFR 101.

However, any UAVs which were originally designed for free flight would clearly not meet the "kite" definition—even if operated tethered, since the original design was for "free flight" and not tethered operations only.

This is my primary question: If an UAV were attached to a tether and so operated, would that UAV remain subject to all legal requirements regarding the operation of UAVs?

Additionally, I would be interested in the following:

Is there a letter of legal interpretation from the FAA on this matter, or any other regulatory or guidance material that I am not aware of?

Are there any rules governing tethered aircraft flight, in general, apart from 14 CFR 101?


texts: What is the significance of a clover-shaped flight track?

texts:
These are portions of two flights by a Cessna T206H on separate days:

The cloverleaf portion of the track was flown at around 8200 feet altitude. This plane is typically seen over the Los Angeles basin flying "lawnmower" patterns similar to those that might be used for sterile insect technique flights or aerial imagery collection flights.

What is the significance of this pattern?  Could it be for radio direction finding?

Edit: The aircraft is N915WC, which is registered to a company that specializes in supporting the intelligence community and law enforcement.  I didn't mention that initially because I didn't want to bias people's answers, and I was curious if the pattern was distinctive enough to identify without that information.


texts: Can training for an Instrument Rating be applied towards a commercial pilot certificate?

texts:
Per 14 CFR 61.129, a person who applies for a commercial pilot certificate for airplanes (both single and multiengine) must log at least ten hours of instrument training.

Assuming a pilot obtains their instrument rating prior to training for their commercial pilot certificate, can the instrument time logged during training for an instrument rating be used to satisfy this requirement (assuming class of aircraft requirements are met)?


texts: Is there a benefit to representing a SID/STAR in 3D?

texts:
There are several examples of 2D representations of SIDs and STARs on the web.  I have yet to encounter a 3D representation of one.

Does one currently exist?  Are there any benefits of representing a SID/STAR in 3D as opposed to 2D?


texts: What's the thrust coefficient for a convergent nozzle?

texts:
As you know, the Ideal Thrust Coefficient of convergent-divergent nozzle is calculated using this equation:

But what about a convegent nozzle? Is there any equation to calculate the Ideal Thrust Coefficient for a convergent nozzle?

Image from: this link


texts: How does aircraft maintain precise speed, e.g. in formation flying or refueling?

texts:
I understand ailerons, elevators and rudders can be controlled to a very fine degree, and in precise flight, like formation flying, they can be used for very fine course adjustments to maintain the relative distance from another wingman.

But the throttle lever can regulate the thrust in range from near zero to several hundred kilonewtons by pushing it maybe 15cm forward. There's very little fine control to it and especially jet engines are sluggish to react to the changes.

How do pilots precisely fine-tune relative speed when traveling at high airspeed then? Are they using other tools - flaps, airbrakes maybe? Or am I underestimating the precision of the throttle, or missing some other mechanisms?


texts: Can an APU exhaust make a contrail in flight?

texts:
I saw this picture in a local newspaper.

My thoughts were, silly artists, that's the APU exhaust, it won't ever produce a trail like that during takeoff (or ever).
Of course, the picture is clearly photoshopped, as can be seen by the planes' outlines. But somebody didn't do the research :)

Just to be sure, were my thoughts correct?


texts:
I understand that most larger jets have a Ram Air Turbine (RAT) in case of total electrical failure (for instance, when you run out of fuel) in order to at least have some hydraulics and a couple of instruments. The RAT gets deployed automatically at the loss of electrical systems.

But how does it get deployed? I'm interested in the triggering mechanism, as, during a complete electrical failure, there can be no electrical trigger (computer or otherwise). So it must be something mechanical. Or are they relying on batteries?

I figured it'd have to be some failsafe mechanism, like stored (hydraulic or otherwise) pressure held back by something like an electromagnet or hydraulic pressure, cut the power and presto, the RAT deploys. However, I've never seen one deployed on an aircraft sitting on the ground with the power off, so that kind of shot down that idea.


texts: Does TC holder of aircraft need to be notified by the PART 21 DOH that they are making a major mod STC to their product?

texts:
Can someone confirm if a part 21 design organizations has to inform the TC holder or not? This is because I am on a part 66 course at the moment and the text is as follows in one of the books, but I'm not sure if It is true.
“The Supplemental Type Certificate will not be issued unless the type certificate holder has been informed and has expressed no technical objections to the proposal and has agreed to collaborate with the STC holder in matters affecting continuing airworthiness".

Thanks


texts: What is the proper procedure for a piston engine fire on the ground (e.g. during engine starting)?

texts:
I am wondering what is the correct sequence of action if there is a fire e.g. during engine starting. Of course I know that there are emergency procedures in each AFM and every single plane is different etc. but I am thinking about "general" set of actions.
Let's say that an aircraft has a fuel shut off valve and mixture control - like a little Cessna. What should we do if an engine catches fire during start-up - shut off the fuel valve and mixture to idle cutoff, or remain mixture and cut off fuel valve (and still try to start the engine)?
Please help me out what are the correct steps.


texts: How do pilots manage the speed during the approach?

texts:
Once the initial approach fix is reached, what are the different "speed stages" to the runway?

I often read about landing speed and approach speed. For example on this chart, Boeing indicates various approach speeds.

I don't understand from what point an aircraft is supposed to be at the approach speed. Is there a specific distance threshold that you cannot cross above the approach speed? What about for the landing speed?
Are there other key speeds than those two ones between the IAF and the runway?


texts: How to calculate the best climb rate and glide rate?

texts:
Considering the lift equation

$$L = C_L \frac{1}{2}\rho v^2 s$$

Given $P$ is 1,000 ft, $\rho$ is 0.002308, and $V$ is the cruise speed of a Piper Archer or 126 knots, we get

$$L = (0.4) (0.002308) (\frac{1}{2}) (126)^2 (160)$$

or 1,172.5 Newtons.

What are the pencil-and-paper formulae for calculating the best-climb and best-glide rates?


texts: Why is there a compressor in an air cycle machine?

texts: I'm a curious high school student. Why is there a compressor after the first heat exchanger in an air cycle machine? I've read that compressing the cold air is for the cause of efficiency because compressing hot air uses much more work than cold air, and the effect of this is that the compressed air temperature increases. But if so, why compress at all when the air itself is going to be cooled again in the second heat exchanger?  Why not leave the compressor and place the turbine as it is from the ACM?


texts:
How does the MiG-29 fuel system work? Like, where does it store around 300 cubic feet of fuel?

Also, which fuel does it use? Is JP4 preferable?


texts: What are the rules of thumb for intercepting and tracking VOR and LOC courses?

texts: Pilots training to become instrument rated must learn to intercept and track VOR and LOC courses. What are the basic rules of thumb all pilots should learn regarding picking a course for intercept and making corrections to maintain the course? How do they vary between VOR and LOC courses?


texts: Is aerodynamics study compulsory for building a plane?

texts: I want to make a plane like a trike. I have a design and some knowledge about plane requirements.


texts: Is there any order of loading containers into aircraft instead of weight balance?

texts:
Assuming there is some container which have to load into the airliners.

All of them are stored into same size ULD and same weight.

The difference is that some are exclusively passenger luggage, while some are cargo, in which some are more dangerous (eg: more flammable) or less durable.

So, in practice, is there any order of loading those containers into airliners?


texts: Does the MD-80 seat layout affect the balance of the aircraft?

texts:
The MD-80 family has a 2-3 seat layout as seen in this image:

Does the layout have any influence on the balance of the aircraft and if so what is used to balance out the weight?

Image from seatguru.com


texts: Why isn't testing fuel flow from both tanks a run-up checklist item?

texts:
On most single engine GA aircraft, testing both mags is always on the checklist. For a plane (like a Mooney M20) that doesn't have a "both" selector, it would seem prudent to throw the switch to verify there is not a flow issue from either tank.

Is there any good reason why not to run this test, or is it just not considered worth the effort?


texts: Can I count PIC time when regaining night currency with an instructor?

texts:
Let's say I want to get night current again, but I haven't flown at night recently so I hire an instructor to fly with me. If I don't count PIC time I don't see a problem, I would just log it as dual instruction. But if I log PIC time, is the instructor considered a passenger? If so I wouldn't be able to have the instructor with me since I am not night current.

Is there an exception for flying with an instructor?


texts: What are these large yellow circles painted across the runway?

texts:
There are not many yellow markings on a runway. This row of six is painted about 400m from the threshold at both ends:

Montgomery Airport (Alabama) - Source: Google Maps

What does it mean for a pilot? Why yellow?


texts: Are STOL kits that use leading edge slats available for 'typical' GA aircraft?

texts:
Has anyone tried fitting leading edge slats to any of the 'typical' general aviation aircraft? If so, are the benefits worthwhile? I know they're available for the Piper Super Cub, but I haven't been able to find any for tricycle gear aircraft like a Cessna 182 or Piper Comanche. I know that having a  high wing or low wing will also be a factor.

The Helio Courier, a well known STOL aircraft, has a speed range from 25 knots to 147 knots. I assume that other aircraft may benefit for using leading edge slats or other devices to lower the stall speed to 25 knots or so, leading to slower, safer landings and emergency landings. All the advantages of the Helio, but in a different form that some people may prefer, for example the low wing aircraft configuration.

The only disadvantages I can think of are the limits of the tricycle landing gear in achieving a high enough angle of attack when landing due to the possibility of tail strikes, and the better protection from debris
in soft field takeoffs and landings.

And what would happen if someone fixed a Helio wing on a Piper Commanche, assuming cost no object?


texts: Why do heavy departures wait 5-10 minutes on the runway at ZRH?

texts:
I'm frequently travelling to Zürich for business and I usually make my schedule so that I have at least an hour to do some planespotting and photographing at the ZRH airport.

Whenever I came to the airport, the runway usage was the same: RWY14 for all the landings, RWY28 for almost all the takeoffs, while RWY16 was used by heavies for takeoffs (usually the flights to Asia or to the USA). I noticed that once a heavy aircraft lines up at RWY16, it waits for some 5-10 minutes before it starts rolling (although it is already way behind its scheduled departure time). The only possible explanation that I could think of was that its engines would cause severe turbulence for the airplanes which are landing at RWY14 and that it has to wait for a significant gap between the landings.

Am I right? Or if not, does anyone know the real reason for these delays?


texts: Is there any good database for aircraft technical specifications?

texts: Due to using them in my application, I am looking for a database(or guide) of aircraft technical specifications. Is there any source for it(preferably free).


texts: Could you help me identify this plane (miniature model)?

texts:
please help me identify this model.
Thank you


texts: Why would an airplane pilot choose to intentionally use more runway than required for a takeoff?

texts: An assumed temperature takeoff intentionally requires a pilot to use more runway than would be normally required.  Why would someone want to do that instead of getting off the runway in the minimum distance possible?


texts: What are typical ratios of galley carts to passengers?

texts: What are typical ratios for the number of galley carts to passengers on a two meal long haul flight for First, Business, Premium Economy and Economy? This is for cabin layout planning. I found one a/c lessor using 1.0 for First, 0.41 for Business, 0.13 for Premium Economy and 0.1 for Economy. Is that about right?


texts: Do pilots ever intentionally land a monowheel glider on the main wheel and a wingtip wheel in crosswind conditions?

texts:
Do pilots ever intentionally strike a wingtip when landing a mono wheel glider in gusty crosswind conditions?

I understand the Lazair changed from a mono wheel to a standard tail dragger layout for better cross wind ground handling. What about gliders?

Is doing a two-point high-speed ground roll/landing ever done intentionally, with the mono wheel and wing tip wheels (intentional wing strike), instead of slowing down then dropping the wing just before coming to a stop? Say 10 mph crosswind, gusting to 15mph/max crosswind component.


texts: What are the advantages and disadvantages of the MiG-29's horizontal stabilizers (not what do they do)?

texts: The MiG-29's tail axes are located fairly close to the leading edge, and rotate along an axis oblique to the chord. What are the possible consequences to this arrangement (e.g. actuator torque, flutter potential)?


texts: How do airplanes act as corner reflectors despite lacking significant flat surfaces in one of the three necessary mutually-perpendicular planes?

texts:
One feature common to virtually all stealth aircraft is that they have vertical tails that are tilted away from actually being vertical (or lack them entirely).  This is said to be because the 90° angles formed by, on the one hand, the vertical tail of a typical aircraft, and, on the other, its wing or horizontal stabiliser, act as corner reflectors, reflecting incoming radar signals back towards their source and giving other people a nice bright return from the aircraft; having a non-vertical vertical tail, or no vertical tail at all, eliminates this effect, scattering radio waves away from their source and drastically reducing the aircraft’s radar cross-section.
However, a corner reflector, in order to function as such, needs three mutually-perpendicular flat surfaces (shaped like the inside of a corner of a hollow cube, hence the name) in order to reverse an incoming photon’s motion in the x, y, and z axes and send it back towards its source.  A reflector consisting of two perpendicular flat surfaces would reverse our photon’s motion in only two of the three spatial axes, sending it out on a track deflected 90° from its incoming trajectory, rather than the 180° necessary to return it to sender.
If we take an aircraft’s longitudinal axis (its roll axis, running from nose to tail) as its x axis, its vertical axis (its yaw axis, where you would stick a mounting pin through its fuselage1) as its y axis, and its lateral axis (its pitch axis, running from wingtip to wingtip2) as its z axis, aircraft, even non-stealth ones, generally only have flat surfaces in (or near) the xy (vertical tail[s], opened landing-gear and bomb-bay doors) and xz (wings, horizontal tails, canards) planes, or in other planes at least reasonably close to parallel with the aircraft’s x axis; aircraft tend to avoid having large flat surfaces in the yz plane, as these would create impressive amounts of drag.
So where does the corner-reflector effect of a typical airplane come from?

1: Think of the airplane as a giant butterfly being mounted in a display box.
2: For aircraft with highly-swept wings (displacing the wingtips forward or aft), or where the amount of lift produced by the secondary horizontal surface (horizontal tail or canard) is a large fraction of that produced by the main wing (requiring the wings to be displaced away from the aircraft’s center of mass in order to keep its overall center of lift close to the center of mass), the lateral axis may not actually pass through the wingtips, but this serves as a pretty good approximation.


texts: Where does the Garmin G1000 Nav ID come from?

texts:
If you tune in a NAV frequency into your G1000 the ID of the Nav Aid will be shown next to the frequency after some time. In this example SEA:

Source: http://krepelka.com

How does this work? Because we know that there is the possibility that two VORs could have the same frequency, so the frequency is not uniquely bound to an identifier.

I have two assumptions:

The Garmin is listening to the morse code, transfers it into the letters and shows it in the display.
The Garmin is checking the Nav database and searches for the frequency and takes the identifier of the closest, based on the GPS position.

Which one is right, or is there even another way Garmin does it?


texts: Where is a missed approach point for circling while flying ILS?

texts:
In my company we have a problem that we cannot understand completely, because we  cannot find the answer.

If I don't have the runway in sight at the circle minimum (MDA) on an ILS
approach, I must immediately execute a missed approach or can I level off and maintain the circle minimum (MDA) and continue inbound until reach the MAPt by DME or timing block (don't have DME) and missed approach?
If a RVR is published in the chart, normally it is RVR at MAPt right? For ILS (precision approach) it is clear that MAP is at the DA. LOC (Non-precision approach) uses MDA at MAPt by DME or timing but for circling where is a MAPt? Use same Non-precision or use circle minimum (MDA) on glide?
If we fly ILS for circling, is it a precision or non precision approach?


texts: How can a helicopter be designed without a tail rotor?

texts: How will the main rotor torque be balanced if a helicopter doesn't have a tail rotor?


texts: Is flying as a post-retirement occupation possible?

texts: Is it possible for a non-professional pilot to pursue a post-retirement career as a professional pilot? Of course I'm not talking about airline jobs but what about bush piloting or missionary/non-profit work?


texts: Can I use an expired IFR-certified GPS with an out of date database in lieu of DME?

texts: I know I should update the database in my GPS, but nevertheless I'm wondering if i can use an expired IFR-certified GPS with an out-of-date database in lieu of DME


texts:
I got a question from PPL oral checker, but I was not able to answer. The question:

  One pilot is practicing an instrument approach in VMC, can you be a safety pilot?


texts: Could a turbofan have two adjacent fans?

texts:
Is there any a point where it becomes possible/ideal to run two large front fans (side by side) powered from a 'single' core? Otherwise shoot this to pieces and explain the ways this is a bad idea.

This inspiration for this question is from the design of some rocket motors which utilize a single turbine driving both pumps on a single shaft to feed multiple combustion chambers and nozzles.  Example would be the RD-180.


texts: What is the relation between airspeed and rate of turn?

texts:
I am reading about aircraft maneuvering and the end of section check contains this question:

  During a turn, if you reduce the airspeed and maintain the angle of bank, the result is a _____________ rate of turn.

The correct answer is "higher" which is confusing me.

If I reduce the airspeed, won't it take longer to complete the turn, thus "lower" rate of turn?
I can understand that the turn might be smoother and more coordinated if I reduce the airspeed, but how can the rate of turn be higher?
What am I missing here?


texts: What are the FAA regs regarding landing a helicopter off airport?

texts:
I have been mulling over getting a Mosquito helicopter, the experimental version with the uprated gas or turbine engine and larger fuel capacity. It's unwise to try to fly any of the Mosquitos without at least a rotary wing solo ticket, and if you have that, you may as well get the better version so you can log the time, and take advantage of the greater range and power. This leads to an interesting question:

What are the regulations regarding where a helicopter can be landed? Obviously, it can be landed in a lot of places, but what does officialdom have to say about where a helicopter can and cannot be landed?


texts: What is the average aerodynamic load on a control surface of a commuter-sized airplane?

texts:
I'm doing a study about aircraft hydraulic pump sizing. In order to do that, I need to know the size of a flight control actuator, then determine the maximum flow and pressure that the actuator needs.

Therefore, I need to know how much force that the flight control surface needs to be moved.

What is the average aerodynamic load on a flight control surface of a commuter-sized airplane (10-20 passengers)?


texts: How does the training for an EASA license from the US compare to that from Europe?

texts:
My plan is to work as a commercial pilot in Europe. But, I heard that the training in Europe might be more expensive and harder than in the US.

For example, to get your PPL you have to face some 1000 theoretical questions before even getting on the plane.

A friend of mine who got his licenses in the US told me that there are academies that offer EASA licenses but in a more affordable and "inviting" kind of training.

Is applying for EASA licenses in the US really a better option? (Cost and training.)


texts: How do services like Flightradar24 and FlightAware track flights?

texts: Do they use the same data sources/aviation services? If so, how do they differ?


texts: How can pressure pattern navigation be applied to light airplanes?

texts:
I want to attempt max range flights in a single engine piston airplane using pressure pattern navigation.  My goal is to achieve greater efficiency than what is published in the POH while still using common cruise settings (ex. 65% at a LOP setting or as published in the POH, usually ROP).  I know pressure pattern flying is employed by GA pilots on long range ferry flights (to Hawaii, for example) but I cannot find practical guidance on how to plan such a flight.  There is plenty of theory and anecdotal information online, and I've read most of it, but very little in the way of practical instruction or calculations.

How would one go about applying PP principles to an actual flight?  My objective is to build a front end user interface using live weather data to plan flights using PP principles.

Hypothetical flight:
Tucson, AZ to McCook, NE at or below 12,500' in an unpressurized 155 KTAS single engine plane with a ~700nm range.  I chose cities that were near the hypothetical plane's max range...could be any city pair.

GA - little piston plane
LOP - lean of peak EGT
ROP - rich of peak EGT


texts: What could cause an engine shutdown on a Q400 with CDS codes 732, 907, 915 and 938?

texts:
A Bombardier Q400 displays error code 938 on the Central Diagnostics System(CDS), which is attributed to turbomachinery chip detector. An examination shows debris in the detector hitch which is collected and sent for further analysis.

Meanwhile, while on a flight the crew experiences an automatic engine shutdown with the following codes and their corresponding explanations showing on the CDS:

  732-NH Speed Sensing (Connectors Eng. controls Harness  NH sensor A EEC (Freq In))
  907- Engine Flameout
  915-Replace Main Oil Filter
  938-Turbo-machinery Chip Detected

Has anyone experienced similar problems or have any lead on the same?


texts: How are individual rotor/stator blades identified during engine inspection for the CFM56?

texts:
During the inspection of fan, compressor and turbine blades, what is the method of identification?
For example during borescope inspection, what is the mode of identification of stator and rotor stages? Is there any form of labeling on these blades?


texts: Why would the outer tanks fuel on the A320 be colder than the inner tanks?

texts:
I have noticed in a number of instances during long flights typically over 5 hours the fuel in the outer tanks on the A320 are colder than the fuel in the inner tanks. This goes against the system logic as warm fuel gets first recirculated to the outer tanks then the inner tanks.

However in the FCOM it's mentioned in a note if the outer tanks are full, fuel spills over into the inner tank, does this mean that the warm fuel is now going directly into the inner tanks? Also can any other variables play a factor like fuel temperature on ground?


texts: What are the rules for PIC change during flight?

texts: Per the FAA FARs - Are there any rules governing a "change of who is the PIC during flight, and thus who can log hours? Say a friend and I go flying together - can we switch as PIC half way through and each log half the time? Also, would the time not spent as PIC (if it is possible to switch) be logged as total flight time in addition to the time spent as PIC?


texts: Why are swept wings better for breaking the sound barrier?

texts: I'm told that swept wings perform better when an aircraft is trying to break the sound barrier.  I was wondering why that would be?


texts: How do ATCs choose between Tower, Approach, and Enroute facilities?

texts:
Under the FAA system, regarding the allocation to different streams for ATCs, how is this decision made? Do trainees decide early on during training which stream they'd like to work for and participate in respective training? Or do they receive a general/abstract training and are then separated among different streams for further training?

I'd like to become an ATC in the US, but can't seem to find this information anywhere. I'm wondering if tower ATCs get to finish their entire careers in towers? Or do they have to obtain radar licenses at some point and transfer/relocate to radar facilities?


texts: How can you identify an Airbus or Boeing from the inside?

texts: How can you recognize a plane from the inside, when you are already sitting as passenger? In particular, is there a way to understand if you are inside a Boeing or an Airbus?


texts: Does training adolescents require a different approach with regard to the level of neurological development?

texts:
There is some evidence of brain under development in adolescents, those from 13 through as high as 23 or 24, that is linked to judgment, decision making, risk appetite, etc., mostly in an unfavourable way as it relates to properly evaluating a flight.

See:  http://www.nimh.nih.gov/health/publications/the-teen-brain-still-under-construction/index.shtml

Does this suggest that CFIs training an adolescent should approach the training differently than how they train adults?  Are additional training and scrutiny indicated in order to minimize the effects of an under developed brain in this population group?  Or does doing so somehow cause some level of unwarranted discriminating practices to an adolescent training for his pilot certificates?


texts: How are fan and compressor discs balanced?

texts:
@curious-cat brought up an interesting question on another thread. How are the fan discs, compressor spools and turbines balanced on a jet engine. As they wear they surely get out of balance. Do they add weights as is done on your car tires?

And what method do they use to determine where the balance point is?
I'm imagining a giant version of this


texts: How can you find AGL if the altimeter is set to MSL?

texts: Without doing the math, how do you know your true altitude AGL when your altimeter is set to MSL


texts: Is airport's magnetic variation value used for terminal procedure design?

texts:
I am studying how instrument flight procedures are coded to ARINC-424 format, and since I was curious about the method used to determine the outbound/inbound magnetic courses, I checked the section describing the magnetic variation field.

  ARINC-424 Version 18, Page 75, section 5.39: […] the government authority has
  established the value as valid for everything associated
  with a given location. For example, if a Magnetic Variation
  of Record is established for an airport location, everything
  referenced to that airport will use the same value. This is of
  interest as it means that Terminal Procedure design is also
  based on that value.

Does this imply that an officially published chart will depict each leg's magnetic azimuth based on the magnetic declination value of the associated airport, rather than the magnetic declination corresponding to the first point of the particular leg of the procedure?

In other words, if I want to find the true azimuth of an aircraft's heading, while it follows a specific terminal procedure, do I substract from the magnetic azimuth depicted on chart the magnetic variation value of the associated airport?


texts:
I have an FAA Commercial License and my instrument checkride was completed 8 months ago. Now I am in Canada and trying to convert my license. Problem is the currency of the instrument rating. Transport Canada said they require an IPC check and I want to know if there are any FAA CFIIs here in Canada who I can do the IPC with. I don't want to go back to the US just to do that.

I was reading the other similar post by a user who says he signed an IPC for FAA pilots in Canada. If you are that user and are reading this post please let me know where I can do my FAA IPC in Canada.


texts: What is the Runway Design Code (RDC) for San Francisco airport (KSFO)?

texts: I need the Runway Design Code (RDC) for the SFO airport. Can anyone provide a link for this and possibly other airports? I have checked the SFO Master Plan/Development Plan and found nothing.


texts: How is rotor pitch best managed in helicopter autorotation?

texts:
In a recent stack exchange question writers were comparing autorotation to an aircraft engine out rotation prop when something rather startling occured to me:

In an engine out the airflow will continue to rotate the prop on the same direction as with power.  When helicopter loses power, WRT to rotor, it falls "backwards", creating force AGAINST the powered direction of rotation.

The thought is to go negative pitch and allow the rotor to build up angular momentum in the same direction as powered rotation, then switch to positive pitch to use that energy to flare and land.

Is this how it is done?


texts: Can leaning provide more power when running at full throttle?

texts:
Looking at this graph I see that a piston engine provides less than best power when the mixture is richer than best power, and this is expected indeed.

I know that at full throttle, more than the required fuel is provided to the engine in order to achieve better cooling.
Also, I know that - especially on supercharged engines - the amount of "cooling" fuel is quite high, that is, the engine is not surely providing its best power when at full throttle.

If an engine is rated 300hp when at 29 inches of manifold pressure (MAP) and 2700RPM at full throttle, does it mean that it is actually capable of providing more power if leaned to the best power mixture? It seems to be that it should be able to provide around 8-9% more power. Of course, I would expect it to suffer some serious damage.


texts: What is the IATA code for the A320neo family?

texts:
I was looking for A319neo, A320neo and A321neo IATA code all over the net but I could't find it, can someone help me with this.

(As of 9 March, 2018, the answer with the highest up-vote count (from April 2016) states "will likely be the same as". A more definitive answer should be available now.)


texts: With larger wings comes more drag. So why don't large planes have 4 smaller wings instead of 2 very long ones?


texts: What can a new commercial pilot do to build flight time?

texts:
Most new commercial pilots don't have a lot of flight time, so won't be hired by the airlines or corporate operators.

A lot of operations require an air carrier certificate (even though they are a "commercial" pilot, they can't just start flying people around)!

What can they do to build time while (hopefully) getting paid to fly?


texts: Will I fail a skills test for doing a constant-aspect climb-out?

texts:
The climb-out for one of the runways at my local aerodrome is over a residential area, with fields to the left. My instructor has had a bee in his bonnet lately about engine failure after take-off if the take-off run is longer than it should be (e.g. after a touch-and-go). He's started encouraging all of us to perform constant-aspect climb-out into the circuit, where we start the turn onto the crosswind leg at the aerodrome boundary regardless of height, and keep the runway end at the same declination in our field of view as the turn progresses. This means we point towards the fields much earlier on, but it hurts the climb performance to do it.

Although I can see the wisdom of being ready for EFATO, I'm concerned about practising a non-standard circuit which contravenes the Noise Abatement Procedure. (The NAP forbids turns below 500 ft, although it is overridden by measures to ensure flight safety.) When I come to do my PPL skills test, would this unusual circuit be acceptable, or will I have to fly a standard circuit with a straight climb-out, turning onto base at 500 ft? I'm in the UK and studying towards an EASA PPL(A).


texts: Why doesn't the Tu-154's center engine have a thrust reverser?

texts:
In this gorgeous photo of a landing Tu-154, one can clearly see that the lateral engines are equipped with thrust reversers, but the center engine is not.

Why?


texts: What is it like flying in class B airspace?

texts:
I'm a student pilot at a class C airport in the USA. Last weekend I did pattern work. Mostly touch and goes, but it was busy and my approaches were less than perfect so there were some go arounds and some 360s for traffic.

Being in the pattern on a busy day was a little stressful. I was constantly reading things back, changing traffic direction, switching runways R/L, etc.

I am curious to know what it's like flying in class B airspace. Are traffic patterns different from class C? Are there additional skills that pilots must have? For example, I know that I'm not even allowed to be in class B airspace as a student without a class B endorsement.


texts: What is the possibility of a depressurization emergency during a commercial flight where all or some of the oxygen masks fail?

texts: Can we calculate this? Or is it almost impossible?


texts: Why do many fighter jets have double vertical stabilizers?

texts:
Many fighter jets have double vertical stabilizers, e.g. F-14, F-15, F/A-18, F-22:

On the contrary, most general aviation planes and commercial airliners do not. While there are certainly exceptions in both categories, I think it is fair to say that this design is, comparatively, far more common in fighter jets.

What is the advantage of double vertical stabilizers? Why is it common in fighter jets?


texts: What does it mean for a ATC to say a flight's callsign followed by "in disguise"?

texts:
So I'm just a aviation fan without industrial background.

I'm listening to Kennedy Steve's ATC communication and he said more than once like "American 600 in disguise."

What does it mean "in disguise" in this context?

Thank you.


texts: In the old days, why didn't aircraft use simpler systems to land on a Carrier?

texts:
In the old days (during and before WW2), Carriers used arresting wires to help aircraft land. In fact this is still used today for jet-based carriers, but I want to ask about the old days with piston-prop aircraft because they go slower and generally make this easier.

I'm pretty sure even back in WW2, most carrier aircraft had tailhooks that grabbed the wire. This is so you "brake in the back", not the front. If you braked in the front, you are much more likely to nose forward or spin around.

Well, I've seen plenty of footage where that happens because something in the front of the aircraft, the nose or front wheels, gets tangled up in those wires, causing bad accidents. Here's a good compilation that has all sorts of landing accidents, including with the wire. What tends to happen is the wire is snagged wrong and the aircraft nose dives into the deck, wrecking the propeller, and/or the aircraft goes spinning around.

I can think of several alternatives to an arresting wire:

Reverse Pitch Propellers (reverse thrust)
Powerful Brakes in the rear wheel, or all wheels
Drag Chute
Air Brake

To me the simplest solution seems to be the last one, an Air Brake. I've seen this on modern jets like the Su-27 (@ 5:06). It's basically a big flat panel that swings out and creates enormous drag. In the Su-27 they keep it near the center of mass so it doesn't induce large torques, but you can put it in the rear half of the aircraft too. That will "brake in the back" and I think it won't require any more airframe strengthening than a tailhook, since that brakes in the back too.

So why not use this simpler solution? For reference, an Essex Class Carrier has a runway of about 260 m. I actually could not find normal "landing distance" that a small aircraft (bf 109, spitfire, etc.) needs once it touches down. If someone can find that, we would be closer to an answer.


texts: What is (are) the accidental cause(s) most feared by the flight crew?

texts:
As the question says, which is the accidental cause most feared (in general) by the flight crews and what's the reason of it?

Apart from hijacking, pilot incapacity or that kind of issues, I am referring to causes like aircraft systems failure, fire on cabin, etc.

Observation: I'm not asking this question to be an opinion question, since I want to know in general, what is this cause and reason(s) to be the most feared accidental cause.


texts: Is there something like a table of aircraft required runway lengths?

texts:
I'm looking for a chart showing the minimum length a runway can be for various aircraft to land and take off.

Does something like this exist?


texts: What material is used to make engine covers for passenger airliners?

texts: What material is used to make the engine shrouds for passenger airliners?


texts: Why are the tails always painted, but not the fuselage, in test and delivery flights?

texts:
Granted some airlines prefer to paint their own planes, but we always see planes like the one below, protective coating everywhere but the tail.

Why's that?

(Source)


texts: Is precipitation static a concern for small drones?

texts:
I read a bit about Precipitation Static buildup on the outside of aircraft flying through dust, rain, or snow.  Can this also happen on a small drone and if so, could it interfere with controlling it?

The FAA has a question on their drone certification test that addresses this and I'm curious if a small/medium size drone would be affected by this.


texts: How to calculate the induced drag coefficient?

texts:
In an exercice of Flight mechanic, I have to compute the drag coefficient at zero lift: $C_{D0}$.We saw in class two ways to find it :

$$
C_{D0} = \frac{\pi AR e}{4E_{max}^2}
$$

With $AR$ the aspect ratio, $e$ the Oswald number and $E_{max}$ the maximal Lift-to-drag ratio. I don't have the value for the two last ones in my exercice so I can't use this formula.

We saw another way, by using the polar definiton: $C_D = C_{D0} + kC_L^2$ with $C_D$ the drag coefficient, $C_L$ the lift coefficient and $k$ the induced drag coefficient. In order to use it I just need to find the value of $k$ but the only formula that I have is:

$$
k = \frac{1}{\pi e AR}
$$

And I still need the value of $e$ the Oswald number. Is there a way to compute $e$ ? I didn't found any on Internet. If not, is there another way to compute $k$ without $e$ ?

Thanks for your help and sorry if I don't have the proper english vocabulary.


texts: Can Navy WSO use autopilot to fly to safety?

texts: If pilot becomes incapacitated, can Navy WSO use autopilot to fly to a safe place to eject?


texts: How are pitch angle and pitch rate measured in an airplane?

texts:
What equipment or method is used to obtain measurements of the pitch angle (θ) and pitch rate (q) during flight?

Edit: I am asking about how the aircraft systems sense these quantities


texts:
So I don't have my pilots licence, but I was part of the Australian Air Force Cadets for nearly 8 years (wonderful organisation). During this time I went on a number of flights in Cessna 172's and Cessna 152's. I always noticed that as part of the pre-flight check, the pilot checked both magneto's and this corresponded to a slight RPM drop on the engine.

Why does the lack of a magneto affect engine RPM?


texts: What are the forces acting on an air particle along curved streamline(wing upper surface)?

texts:
What forces act at air particle at curved streamline (at first 1/4 upper wing surface) , looking from inertial and non-inertial frame of reference? (show free body diagram)

Pressure gradient normal to the local flow direction balance the centrifugal force associated with the curvature of flow..
Which Centrifugal force,inertial or reactive?


texts: How can adverse maneuverability due to a fuel tank behind the rear pressure bulkhead be mitigated in Airbus ZeroE hydrogen plane?

texts:
Airbus recently announced three concept aircraft for commercial use, powered by liquid hydrogen, with an ambition to have the plane in operation by 2035.
https://www.airbus.com/innovation/zero-emission/hydrogen/zeroe.html
https://www.airbus.com/newsroom/stories/these-new-Airbus-concept-aircraft-have-one-thing-in-common.html
From what I can tell, the turbofan variant is in the same segment as the current A320, albeit with somewhat reduced range.
Considering hydrogen powered planes, the challenge is to carry enough fuel to make it compete with kerosene.
There are several options, and from this question it seems 3 options stand out:

Cryogenic: storing the fuel as a liquid
Compressed: requiring heavy and strong fuel tanks
Hydrides: bind hydrogen with another substance and release upon heating

Airbus intends to go with option number 1, that is storing the fuel liquid and cryogenically behind the rear pressure bulkhead.
The unbalanced weight distribution storing not only the fuel, but assuming also heavy tanks and cooling equipment in the far rear of the plane seems like a maneuverability issue to me, with a pitch-up moment from the shifted weight balance.
What measures can be taken to mitigate the (assumed) adverse handling this creates?


texts: I'm wondering if the Cessna 152 has a name? There's the Cessna Skyhawk 172 and the Cessna Skylane 182.


texts: Can thrust vectoring be used to enable the use of flaps on tailless delta-winged aircraft?

texts:
I'm considering flying wings as well as airplanes with only vertical stabilizer for their compact size, efficiency and high speed.

As I can't find a working example of such scheme, theoretical explanation is very welcome.
To compensate for rear end additional lift, thrust output will probably be placed at the nose.

Possible options by propulsion types:

Propeller

tilted prop rotor (fixed / variable pitch)
propwash forwarding - canard fins
collective pitch thrust vectoring (swashplate driven)

Jet

additional small engine at the front (electric ducted fan)
ducts from the main engine
fan driven by the front shaft of the engine (as in Harrier Jump Jet)
tractor placement (as in ekranoplan)

Problems

(summary from answers and comments, thanks for valuable input)

Stability.
Change of angle of attack either intentional or by air conditions changes wing lengthwise distribution of lift.
Is it manageable for human to safely maintain stability in such conditions and if not - for a computer?

Thrust availability.
Approaching landing the forward thrust is minimized, so there should be close to 90° downward thrust line deflection.

Thrust agility.
Combustion jets are sluggish. There should be a nozzle limiting the output.
Partial reverser?

Safety.
Engine out below unpowered stall-speed at landing sounds like a nose down crash.
Redundancy should help.

So, is it viable to add enough nose-up moment and stability by vectoring thrust to counter the nose-down moment produced by flap extension, thus allowing STOL capabilities with flaps at acceptable angle of attack?


texts: Do airline pilots ever risk not hearing communication directed to them specifically, from traffic controllers?

texts:
I gather pilots communicate regularly with air traffic controllers within air traffic controllers' jurisdiction or airspace as they enter the space, during their time in that space and as they leave.  In some or most instances, they will not land in that air space, they are simply passing through and may encounter lots and lots of regional and international air traffic.

They are routinely directed by air traffic controllers to fly at a certain direction, increase or decrease altitude for safety in order to avoid collisions and accidents.  In most instances, auto pilot is engaged and I assume the headphones come off, for flights longer than say 2 hours or even 1 hour.

Speaker phone may be on but pilots can read a book or watch a movie on their laptop or revise their reading on knowledge of their ever changing craft.  At a certain frequency.

I gather lots of communication to planes occurs and listening to all of them can become tedious and may require too much concentration.  In this light, do airline pilots ever risk not hearing communication directed to them specifically, from traffic controllers of space they are flying past on cruise?

Does a light or sound or siren switch on when a message is directed at them and I assume they differentiate communication directed at them by their call sign, e.g., American Airlines Flight 200.

Is there a risk they might not hear it and how is that risk mitigated?


texts: What are the differences between PC and professional simulators?

texts:
It looks like there are a differences between the models used in the schools and the simulators you can run in a PC .

I'm curious to know the differences and price of both type of simulators.

I thought that the one in the schools were just simple PC simulators.

What simulator can I use to practice basic helicopter stuff?


texts: just a completely random question that I suddenly thought - doesn't straight and level flight prove that the earth's surface is not a globe? Once cruising altitude is reached, the plane remains at the same altitude for the entire flight until it starts to descend for landing. If earth was a globe, we would need to drop the nose of the plane every couple of minutes to compensate for the curve of the earth. Is this correct? Because on my most recent flight, we reached 2000ft altitude and my instructor told me to maintain this altitude for 30 minutes (which I managed to do). I asked why we don't need to compensate for the curve of the earth and he couldn't answer me. Sorry for the random question but it's been bothering me.


texts: How much force are large aircraft brakes able to exert?

texts:
In a comment left on my answer here Jan Hudec says:

  Note that usually on dry surface the brakes exert much less force than the tires could handle.

This got me wondering how much force large aircraft brakes can provide.

The limiting factor in brake force for a vehicle is the friction between the tire and the surface. On my car, even on dry pavement, the brake force available is always greater than the tire/ground friction, so I can always lock the brakes and set off the ABS. I may be misunderstanding it, but Jan’s comment makes me think that maybe large aircraft don’t have that much brake force available. If you commanded maximum braking on a dry runway would the brakes try to lock? Is the ABS really only necessary on a contaminated runway?


texts: How are pilots prepared for a go around on a simultaneous converging approach when the "converging chart" is not published?

texts:
Source: adsbexchange.com

Today I learned that at KPHL (Philadelphia) simultaneous converging approaches are used. (Note that AAL is faster, which narrowed down the time gap by the time it landed.)
Those planes are approaching to runways 35 and 27R.
But, those two runways do not have "converging" approach plates (red paths below). The published ones are for 09R and 17 – ILS V RWY 09R (CONVERGING) and ILS V RWY 17 (CONVERGING) – with missed approach paths that diverge like so (blue paths):

Source: skyvector.com; modified

By checking JO 7210.3BB - Facility Operation and Administration:

SIMULTANEOUS CONVERGING INSTRUMENT APPROACHES
(...)
The requirements for conducting SCIA operations to converging runways are:
(...)
SIAP specifically titled "Converging" and is published in parenthesis after the title of the procedure, for example, ILS V Rwy 17 (Converging).

With those charts not available, how would the pilots anticipate and plan where to go? Are they available but not public, or are the pilots notified by radio on what to expect? How does it work?


texts: Why close isolation valve and APU bleed air for engine fire?

texts: For engine fire, the reason to close the packs (affected side) is to prevent smoke from filling up the cabin? But why the Isolation Valve and APU Bleed Air need to be closed too?


texts: How can I calculate the minimum thrust to weight ratio required for a given takeoff distance?

texts: I am building a plane and I have a take-off distance of 50ft, is there a way for me to estimate the thrust-to-weight ratio required for this constraint (even if it was in terms of say wing loading)?


texts: Do commercial flights continue with an engine out?

texts: Do commercial flights continue with an engine failure? If you look closely at the attached picture it seems that one of the engines has a much smaller contrail than the other three. This seems to suggest that the aircraft is flying on three engines with the one at reduced (idle?) power. Is this normal?


texts: Who can perform different maintenance checks?

texts:
The different types of check (A-check to D-check) require different types of competence and certification.

If I understand correctly, D-checks require special equipment and certification and some airlines developed whole subsidiaries to take care of this task (LHT, AFI,...) in which they send their aircraft to perform a D-check.

Given the existence of those subsidiaries, I assume that a D-check cannot be performed by the airline's employee and must be performed by a company specialized in aircraft maintenance.

A-checks and daily maintenance do not require the same amount of qualifications, certification and equipment and may thus be performed by the airline without sending the aircraft to a specialized place.

For each check (A-check, B-check, C-check and D-check), who is qualified to perform those checks? Can these checks be performed by the airline itself or must a specialized company take responsibility for the aircraft?


texts: Why do some airlines not use containers for luggage?

texts:
Many planes allow the use of ULD containers to store hold luggage: such luggage is placed into the containers, then the containers are stored in the hold of the plane.

There are many advantages to this, as explained here: Why is luggage required to be loaded in containers?

However, some airlines do not use ULD containers even when that is possible. I have in mind Easyjet on their A320-family planes, which don't use containers, at least on some flights, even though the planes definitely can handle them.

What could be the possible reasons for this? Given the high emphasis on saving every single penny they can, I suppose they have tried both approaches and come to the conclusion that not using ULDs is actually somehow cheaper than using them, which seems counter-intuitive:

it should take longer to load and unload luggage one by one than just move containers in
more manipulations increases the risk of damage to the luggage

Possible reasons I can guess at (but not verify) are:

loading the containers is actually not so much faster, with containers possibly getting stuck or some similar problem?
loading containers requires more equipment, and turns out to be more expensive for this reason
it depends on the amount of luggage being carried?

Does anyone have any insights on this?


texts: Did the FAA order the installation of "Cooper vanes?"

texts:
On November 24, 1971, a man hijacked a Boeing 727 and parachuted away, never to be found.

According to Wikipedia, this prompted (together with 2 other hijackings) the installation of "Cooper vanes" devices that prevented the opening of the 727 ventral airstair in flight.

  In the United States, following three hijackings in 1972, the Federal Aviation Administration ordered that Boeing 727 aircraft be fitted with Cooper vanes.

Wikipedia cites "Beyond Fear: Thinking Sensibly About Security in an Uncertain World," which I don't have access to. I can find the same claim here and here.

I couldn't find any Federal Aviation Regulations specifically mentioning "727." I also couldn't find any Airworthiness Directives specifically mentioning "727" relevant to the situation. There is this one. Furthermore, the policy change isn't mentioned here.

Did the FAA order the installation of "Cooper vanes" on Boeing 727 aircraft?
Was the "order" in 1972?

I am asking this question because of a recent April 2 answer on Aviation.SE:

  Boeing did have a small regional jet called the Boeing 727. This plane was designed to operate at smaller airports, with independence from ground facilities as a selling feature. The best example is that the 727 had built-in stairs in the rear underbelly of the aircraft. This could be opened in flight until some hijacker known as DB Cooper jumped out to make his escape.

Apologies if the background research is poorly conducted and irrelevant. I am not familiar with the best way to research historic and current FAA "orders."