texts: HEPA filters, airliner HVAC and COVID 19

texts:
There is this report that says the risk of aerosol spreading on a commercial liner is low due to HEPA filters.
But it is not considering the cases when A/C is OFF. This seems to be quite common when the plane is on the tarmac but away from the gates. At the gate the air is supplied by the airport. There are numerous reports of planes being delayed for hours in hot weather and passengers suffering. I have been in that situation myself a few times.
This is explained on quora:

It's kind of a double-edged sword. Simply put, cabin air in flight comes from intakes just behind the engine compressors. In flight, you're getting fresh, clean air that is inducted, mixed and filtered. It circulates through the cabin and eventually, lots of the circulated air gets sucked out by air blowing past the plane at nearly the speed of sound. However, its a different story when you're sitting on the tarmac. Engines at idle are still producing fumes, and these can get inducted along with fresh air because there's no air thrusting the fumes away from the plane as there is when you're moving at 500 knots. That mix can be filtered to a degree and is safe to breathe, but it's still going to smell awful, and even burn your throat. If you fly often, you'll often notice an awful smell of fuel when you get on the plane that clears up after takeoff. Granted, some of that smell at idle also comes from open passenger doors, but you get the idea. Also, due to changes resulting from in-flight fires, and 9/11, the pilots are isolated, and can often be unaware of how uncomfortable it is getting in the passenger cabin. Someone has got to bring it to their attention. Its not like a thermostat in your house, where you just set it and forget it. The crew has to control the cabin air on a more or less manual basis. Ever been to a restaurant that's freezing cold? Lots of times, the thermostat is controlled by people working in the hot kitchen, and the kitchen crew may not be aware (or even care) that their comfort is turning your fingers into icicles. Same principle.

So if the AC is OFF on the tarmac due to fumes, would it not make sense to use 100% recirculation in this instance and switch to fresh air whilst airborne? Can the pilot control this from the cockpit?


texts: Why are the intakes of some fighters not attached to the fuselage?

texts:
Look at the photo below. As you can see the intake isn't attached to the fuselage. Why? Other examples include the F-16, F-22, and F/A-18 Hornet.

(F/A-18E Super Hornet Walk Around)


texts: Why is air accelerating over the wing surface?

texts: I know that there are dozens of questions about lift generation here but after reading them I still don't understand everything. My question is: why does air accelerate over the (upper side) wing? I know that it accelerates because there is pressure differential etc. but why wouldn't the air just flow over both sides of the wing with equal speed?


texts:
This aircraft flew overhead at less than 1000 ft a little while ago. We think it's a C-17. We can't figure out what it was doing...

(Click here for full image)

We're in Culver City, between LAX and Santa Monica. It was traveling south to north, about 4:50 this afternoon.

Scared the neighborhood...


texts: Which type of chevrons is applied on the B787?

texts: Which type of chevron nozzle was applied on the B787? I'm really confused about whether if it's sawtooth or sine wave.


texts: How does the spoiler actuation mechanism work on the Airbus A340?

texts: How does the servo control spoiler actuation mechanism on the Airbus A340 work?


texts: Why do glider licences have fewer restrictions than powered aircraft?

texts:
Under FAA rules a license for gliders doesn't require a medical certification and you can get your license at 16 rather than 17 for powered aircraft. You can get your student license two years sooner at age 14.

It appears to me that gliding would require MORE skill and experience than a powered aircraft. It looks very unforgiving. You only have one shot at landing, there is no go-around. If you lose too much altitude you could end up not being able to reach the airport. You have to know how to find thermals, etc to gain altitude. While being towed you will be flying in closer proximity to another aircraft than you normally would in a powered airplane.

Why are the restrictions less for a glider?


texts: What forward airspeed produces maximum rate-of-climb in helicopters?

texts:
Lift in a helicopter increases with airspeed (from zero IAS up to some Vmax).  But in contrast to fixed-wing aircraft a helicopter can generate lift at zero airspeed.
Is there a formula for the airspeed at which a helicopter achieves it maximum rate of climb?


texts: How to calculate Equivalent Airspeed immediately from Calibrated Airspeed?

texts:
I want to calculate each step like IAS -> CAS -> EAS -> TAS
as a chain. Each chain step should depend on the previous step.

IAS is clear. This is a function of pressures. With the Bernoulli equation, IAS = f(p_total - p_static)

CAS is not clear. But I know that static error is taken into account, CAS = f(IAS,static error)

EAS is not clear. I know that EAS takes compressiblity effects into account.

TAS is again clear, dependent on density it is easy to calculate with TAS = f(EAS, rho, rho_0)

How to calculate EAS from CAS immediately
with EAS = f(CAS)?

I know that one can calculate EAS with
EAS = f(Mach, a_0), also by taking in account of
the compressibility of air.

Thank you very much!


texts: Are tiltrotor planes less safe than conventional propellor planes?

texts:
I got interested in Tiltrotor type of airplanes and was reading up about some specific models, the AgustaWestland AW609 and the Bell Boeing V-22 Osprey. Both planes have a history of quite a few crashes.

That's where my question comes from: Are tiltrotor planes generally less safe than conventional propellor planes of similar size?


texts: Would better location tracking for airliners improve safety?

texts:
Once in a while an airliner just up and disappears -- typically over ocean -- and lengthy and expensive search efforts have to be launched in order to find it. The most famous cases in recent years were of course AF447 and MH370.

It is hard for the bemused public to understand how something as large and technologically advanced as a wide-body jet can just go missing. Some people end up on websites like this one, asking why we can't just do such-and-such to make sure planes can always be found. The answers typically center around how such-and-such would actually be very expensive, and probably not 100% effective anyway. This doesn't really seem to convince most questioners, who wonder how important a bit of cash ought to be when there are lives at stake.

The purpose of this question is to clarify whether lives are actually at stake.

Suppose we had a magical technology which at negligible cost could give us reliable access to the exact flight path of an airliner in trouble anywhere on Earth. How much safer would that make flying?

For definiteness, let's assume that the magical technology gives us position samples at 1-minute intervals at a one-hour delay, so it won't be useful for real-time purposes such as ATC.


texts: How much do elevators deflect on takeoff?

texts:
Do elevators create immediate lift off on the big airplanes? E.g., on a 737, 747, or an Airbus, I don't see elevators moving up when I see airplanes lifting off in videos. Is it just a slight up movement that is hard to see then?

In other words—for airliners—how big of an elevator deflection is required for takeoff?


texts: Is a holding pattern required on the Twentynine Palms VOR for RWY 26?

texts: I am an instrument student and confused about whether or not you have to fly the holding pattern charted on the VOR RWY 26 at Twentynine Palms. At Jehli (Intermediate Fix), it says "No PT".


texts: Is excess lift or excess power needed for a climb?

texts:
As answered in this question, aircraft need excess power - not excess lift - to climb. This is plausible when the aircraft's thrust vector has a vertical component (its nose and engine points upwards), but I challenge the requirement of excess power for every case.

Please take a look at the following cart. The thrust gets delivered by a propeller at the rear and the thrust vector is always horizontal. A wing attached to a vertical beam is free to move up and down.

When the cart gets accelerated and reaches a certain speed, the lift acting onto the wing gets greater than the wing's weight, leading to a climb of the wing. Please notice that - because thrust is horizontal - the chemical energy burned goes into kinetic energy of the cart and/or heat energy (due to overcoming drag). No power invested by the propeller goes into potential energy of the wing; the climb of the wing is done purely by lift.

Did I miss something?


texts: What exactly causes pitch moment in the Phugoid mode?

texts:
I am trying to figure out exactly what causes the pitching moment for the Phugoid mode? We know that alpha remains mostly constant, so what is causing the pitching moment? I thought maybe it is the trim point of the aircraft, but if trim was exactly neutral then how would the phugoid mode still proceed, since alpha is zero and at the design condition there would be zero tail load?
I guess my question then becomes what derivatives are responsible for causing the Phugoid mode or am I missing somehow that is just the dynamic response to the derivatives as a whole?


texts: Can a certified mechanic ground my airplane?

texts: The courtesy (under-wing) lighting and the rear seat overhead map light were on the same switch. I didn't like having the bright outside light on while my passenger read his magazine, so I separated the lights to two different switches.  What will happen when this is discovered during my next annual? And can a certified mechanic ground my airplane for it?


texts: What is the physical meaning of Mean Aerodynamic Chord?

texts:
I have not been able to find a consistent definition of what it really is.

I have come across definitions such as: "Physically, MAC is the chord of a rectangular wing, which has the same area, full aerodynamic force and position of the center of pressure at a given angle of attack as the given wing has." which is contradictory with this one "The mean aerodynamic chord is (loosely) the chord of a rectangular wing with the span, (not area) that has the same aerodynamic properties with regarding the pitch-moment characteristics as the original wing."

I am very confused and I wonder if you could please give me a precise definition (maybe in relation to an equivalent rectangular wing, as those two definitions I found), that shows intuitively what it is


texts: Is it practical to use wires to stiffen rotor arms?

texts:
(Related to my last question on ducting.)

Wires have been used in the past to stabilize wings with a very low weight cost. Could something similar be use to stabilize the arms for a UAV's rotors?

Assuming I don't have enough money to build a custom 8 arm (based on previous advice) carbon fiber frame, could the wiring approach be applied to UAVs? I ask because for a V1 prototype PVC is cheap and relatively strong, but I could enhance it with a bit of aluminum plate in the center and small aircraft cable in tension.


texts: How do pitch attitude, airspeed and sink rate come into play in a rapid descent or a dive?

texts:
So, I have a hypothetical aircraft that needs to get from FL350 to 10,000' as quickly as possible.

What is the difference in sink rate between a 'standard' airliner rapid descent (idle thrust, extended spoilers, and nose slightly down) vs. having the flight crew simply point the nose down below the horizon as far as they care to?
How does the airspeed build-up over time differ between a 'standard' rapid descent vs. a dive?
For a rapid descent, what nose-down pitch would be typical?


texts: Why don't all wind tunnels use magnets to suspend models?

texts:
NASA and the French aerospace agency have conducted research into magnetic suspension and balancing systems (MSBS) to suspend models during wind tunnel tests, like this system in South Korea.

Where did the NASA and ONERA research lead?
If MSBS reduces interference from the springs and arms that usually hold models, why don't all wind tunnels use this technology? What are the disadvantages?

Also, can somebody create a wind-tunnel or wind-tunnel-testing tag?


texts: So, as most of you know, Airbus has adopted fly-by-wire (fbw) technology. Pretty much every single plane made by Airbus is a fbw plane. So I was wondering, before computers were everywhere, did Airbus implement fbw systems?


texts: Can 80hp Rotax 912s be upgraded to 100hp?

texts: The more recent Rotax 912's are 100 hp engines. Can the earlier 80 hp models be upgraded to 100hp - without a complete engine swap?


texts: How do humanitarian flights arrange special permissions to fly when ATC isn't available?

texts:
In natural disasters, transportation infrastructure is often among the first and most critical of public services to be disrupted. Not coincidentally, it's also a time that tends to see small airports become vital intake for international support.

If aircraft acting on humanitarian concerns, say a commercial airliner loaded with doctors and medicine, wants to land in a major city affected by a natural disaster where radar is destroyed, ATC is non-functional, and runways are... surprisingly clear, what is the procedure for arranging landing?

In practice, do humanitarian support just approach, land, and deal with the consequences later?


texts: What would the reason be for this helicopter maneuver?

texts:
At 4:30 in this YouTube video, a Chinook traverses the runway on its rear wheels. The text on the video lists "Emergency landing and take-off". Is there any reason for the pilot to do this other than "because I can and it's an airshow"?

The pilot then proceeds to back down the runway on the rear wheels, a maneuver that I can only imagine is showing off, but again, is there a legitimate flying need to do this?


texts: Why is Bombardier selling off all of its airliner series?

texts:
Bombardier’s product lineup formerly had three separate families of airliners (in addition to its side business with the Challenger, Learjet, and Global business-jet series):

The DHC-8 (Dash 8, Q-Series1) line of 39-to-90-seat regional turboprops, acquired with Bombardier’s 1992 assimilation of de Havilland Canada (hence the “DHC” in the name); the DHC-8 itself had originally entered service back in 1984.
The CRJ (Canadair Regional Jet) line of (surprise!) regional jets, which entered service later in 1992 as a stretched airliner version of the Challenger 600 business jet (which was originally produced by Canadair, and was acquired, along with its parent company, by Bombardier in 1987, thus explaining the “Canadair” in the CRJs’ long-form name); the original version was the 40-to-50-seat CRJ100/200 series, produced until 2006, but this was later superseded by the 50-to-104-seat CRJ700 series, which entered service in 2001.
The CSeries line of 108-to-160-seat midrange jets, a homegrown Bombardier design which entered service in late 2016.

Recently, however, Bombardier has been selling off their airliner lines seemingly as quickly as they can find buyers to take them off their hands:

In mid-2018, Bombardier sold a majority stake in the CSeries to Airbus (who renamed it the Airbus A220), and sold off its remaining stake in the project in February 20202 (although Bombardier does continue to build them at its Montréal factory, albeit merely as an Airbus contractor).
In mid-2019, the DHC-8 was sold to Longview Aviation Capital, which resurrected the De Havilland Canada name for a company it established to build the aircraft.
Finally, Bombardier is currently (as of mid-2020) finalising a deal to sell the CRJ series to Mitsubishi Heavy Industries, which would drive Bombardier out of the airliner market completely.

These sales are allegedly to improve the company’s profit margin; however, divesting oneself of one’s flagship products seems completely self-defeating (in a boiling-the-seed-potatoes kind of way) as a strategy for making more money, as it eliminates their ability to sell more of these aircraft in the future.  (Moving out of the airliner business to focus solely on business jets is looking especially stupid right now, given that business aviation, unlike commercial aviation, is unlikely to recover more than partially from the current state of affairs.)

What is Bombardier trying to get at here?

1: Technically, the Q-Series moniker only refers to the later DHC-8s equipped with active-noise-suppression equipment; however, with the exception of the DHC-8-100 (which was never equipped with the system, and which left production in 2005), all DHC-8s delivered since mid-1996 are so equipped, including all DHC-8-400s.

2: Thanx to @JZYL for pointing this out.


texts: How are batteries cooled in passenger aircraft?

texts:
What sort of systems are used to cool batteries in the air? Liquid cooled? Air cooled?

I am interested in lithium chemistry batteries in the form of either pouch cells or 18650 batteries inside of boxes placed in the fuselage or wing.


texts: Do flaps have a maximum speed limit but spoilers don't? Why?

texts:
This related question on Aviation SE describes how in most aircraft spoilers (flight spoiler mode not ground spoilers) are deploy-able at any speed But flaps on the other hand mostly have a V_FE above which they cannot be deployed.

I assume the speed limit imposed on using flaps is due to structural reasons? I am just wondering why spoilers do not have a similar limit? Looking at a spoiler photo in the deployed position it looks like the spoiler mechanism ought to be under a lot more stress than the flaps. Am I wrong here?

Or are spoilers reinforced to a degree out of need that is not felt necessary for flaps? i.e. There can be a legitimate need to deploy flight-spoilers at a speed higher than for flaps.


texts: Why are APU engine generators rated in kVA and not kW?

texts: Auxiliary Power Unit (APU) generators seem to be rated in kilo-volts-amperes (kVA) and not kilo-watts (kW). Are kVA not the same as kW? Is there a reason why the generator is rated in terms of kVA instead of kW?


texts: Why don't black boxes send a signal when above water?

texts:
Cockpit Voice Recorder and Flight Data Recorder's "Underwater locator beacons" only send their position when underwater.

Why don't they do so when not underwater?


texts: Do the cabin announcements follow a common protocol?

texts:
Until recently, my local airline made all their pre-flight and pre-landing announcements in Swedish and using an informal language. A few months ago they changed this and are now using all the standard phrases (Cabin crew ten minutes to landing, Arm slides, cross check and report, etc.)
Is such a change dictated by some authority or is it the choice of the company? Are the actual phrases defined somewhere, or is it convention?


texts: What indication will appear in case of one of A320 LGCIU is inoperative?

texts: What indication and where it will appear in case of one of LGCIU (landing gear control and interface unit) is inoperative?


texts: Can fuel sloshing in the tanks cause a stall?

texts: Cargo planes secure their load meticulously and if it breaks loose, the result is sometimes catastrophic. However, how do you prevent fuel sloshing inside the tanks and causing the same problems as loose cargo?


texts: Do windows on the side of the fuselage increase drag?

texts: I wonder this because I'm not too sure glass is easier for air to travel over than metal.


texts: Is c.g rear or fore of wing leading edge?

texts: This video states that the c.g of most non tapered airplane is 25%-30% of wing chord REAR of the leading edge.The aerodynamic center(a.c) of most wing is 25% rear of the leading edge ....Does this mean the a.c can coincide with the c.g in a tailplane?


texts: How is the flight of a tricopter controlled?

texts:
For a quadcopter, diagonally opposite rotors have the same speed and direction which causes it to hover, and adjusting the speed of the rotors give the three basic movements of a flying object, i.e. pitch, roll, yaw.

Similarly, what is the physics behind the tricopter flight control?


texts:
What does the horizontal flag on the G1000 flight plan page mean?

Thanks


texts: What should a pilot do upon reaching a Missed Approach Fix when holding instructions are not given?

texts:
Typically, Missed Approach Procedures end with a hold at the Missed Approach Fix. This is written in the textual procedures as something like "direct ABC VOR and hold." The graphical section also depicts the Missed Approach Fix, and the holding pattern relative to that fix, including the inbound course, inbound radial, and outbound course.

However, the ILS 20R approach at John Wayne Airport (KSNA) has only a fix as the last element of the Missed Approach Procedures. The textual procedures say:

  Climb to 3000 on I-SNA LOC south course (196°) to MINOE INT/I-SNA 10.9 DME

The graphical representation of the Missed Approach Fix only shows the radials and DME used to identify the fix. It does not have a depicted holding pattern.

What should a pilot do upon reaching MINOE, in absence of other ATC instructions?


texts: What instruments were "standard" in WWI aircraft?

texts:
What instruments made up a typical panel of a WWI airplane?

Did any country regulate the required cockpit instruments prior to the United States "Air Commerce Act" of 1926?


texts: What are the major non-pilot causes of GA accidents?

texts:
I'm considering getting a private pilot license. From what I've read, pilot error is the leading cause of major airline crashes -- such as on this page, but that's for major commercial carriers. As the pilot, pilot error is something that I can address myself. One of the things that concerns me is the chance for an accident due to circumstances beyond my control.

What's the cause breakdown for general aviation accidents? What are the most common mechanical failures?


texts:
Is there an airplane that never crashed?

Or more specifically, without any crash history on any database. By crash, let's say any accident / incident which resulted in damage to the airplane and/or injuries to the people on board.

Not including military airplanes, only commercial or general aviation aircraft. Obviously I'm asking about a plane that had multiple flights and maybe is even still flying, not an experimental built that only flew a few times.


texts: Why is the trailing edge sweep angle smaller at the wing root?

texts:
Many airliners have a distinct unswept part at the wing root at the trailing edge. See for example this image from Wikimedia of a B737-400.

Other examples include the B777, A320, Embrear 145, and many more. Virtually all airliners have at least some degree of less sweep at the wing root.

Why is there a part of less sweep at the wing root (to facilitate engine mount; Aerodynamic reasons)? Why does a completely unswept part seem to be a preferred choice for this part of less sweep, as opposed to any other sweep angle than zero?


texts: If I'm on a IFR flight plan with appropriate IFR reserves, and I'm given a lower altitude which will consume more fuel, what should I do?

texts:
Let's say I'm on a long-range flight at my requested altitude of FL250, and I am handed off into a very busy sector where the controller tells me "Descend and maintain FL210, for traffic."

At FL250, my fuel burn and capacity is sufficient to make the flight with better than IFR reserves.

But if I have to descend to a lower altitude, my fuel burn will increase and my true airspeed decrease to the point where I would have to stop en route for fuel.

How can I describe my situation to ATC in such as way as they will allow me to stay at 250?  Controllers do have some obligation to get you to your intended point of landing, and if giving you an altitude, airspeed, or vector that will adversely affect your flight, shouldn't there be some way to describe that?

What about saying, "if you give us 210, we're going to have to declare minimum fuel"


texts: Why can't model aircraft be used to discover spin and stall behavior of manned aircraft designs?

texts:
I was reading some literature on stalls and spins (which are almost always preceded by a stall) of aircraft when a thought hit me. Why can't a model aircraft (1/4 scale of manned aircraft) be used to inexpensively explore the stall and spin behavior of manned aircraft?

(One disclaimer for this, I know this can't be done at ALL speed ranges or all scales. Airliners are too big to make inexpensive 1/4 scale R/C aircraft, and aircraft that cruise at transsonic speeds will not benefit from this since the effects seen there only happen at that particular reynolds and mach number combination)

However, I was thinking more for aircraft that spend a lot of time at fairly low speed (below Mach 0.3) such as ultralight or light sport aircraft. Here the air is effectively incompressible, meaning flow physics wise, the reynolds number is dominant in determining flow separation. And because of that, all a 1/4 scale model has to do is fly four times faster to get the same flow separation characteristics as the full scale aircraft.

So for an ultralight aircraft, which is speed capped at 30 m/s, a 1/4 scale model would have to fly at 120 m/s to see similar stall behavior, which is at the bottom end of where the flow starts to become compressible, meaning most of the flow structures seen at full scale will be seen at the model scale. Accounting for the lower moment of inertia of the model, the spin behavior of the model should predictably scale to reveal the behavior of the full scale aircraft.

My question is, what am I getting wrong in my reasoning? Why can't this work?


texts: I'm having troubling understanding where the relative wind is coming from for a propeller. The relative wind that I do know is the one that comes right in front of the aircraft which flows over the wings which is an airfoil. The propeller is also an airfoil, which leads me to believe the relative wind would come from the opposite direction of the propeller, but where?


texts: Can a quadcopter fly stable while its all 4 motors from different manufacturers?

texts: What if we used 4 motors which all are from different manufacturers? Will it fly/hover ? All 4 brushless motors have same kv and dimensions. Like 2204 2300kv .


texts: What follow-up actions, if any, does the FAA take when a pilot declares an emergency in flight?

texts:
This question focuses on what the FAA is required to do when pilot declares an emergency, as opposed to what a pilot is required to do. (The answer to this question is not covered in typical pilot training).

Example: Pilot loses situational awareness and becomes lost. Pilot is low on fuel and declares emergency and ATC provides vectors; pilot turns towards nearest airport. Pilot arrives at airport and makes an uneventful landing at small airport. No other traffic was diverted, aircraft and passengers fine, pilot did not deviate from any Part 91 FARs.

After the emergency is over, what legal, administrative, or investigative actions will the FAA or other official bodies take?

I understand that when a pilot declares an emergency the pilot gets priority from air traffic control, and may take reasonable actions for the safety of the flight even if it means deviating from part 91 regulations.

It would appear that, so long as there was no incident or accident, no one is injured, and no regulation is broken that FAA will take a "no harm, no foul" approach.

I'm curious if any one has source information as to what should the pilot expect: a call from ATC, an investigation, nothing, etc.? (Assume no FAA deviations, no injuries or accidents, etc.)


texts: Light aircraft elevator/aileron/direction not working

texts:
What is the correct procedure if a light aircraft (under1000kg) elevator/aileron/direction stop working? Is it alright to use the ballistic parachute(if the aircraft is equipped with one)?
If not, then in what situation ballistic parachute is used?


texts: Can cellular towers be used to correct INS drift?

texts: At a high enough altitude a line-of-sight can be established with multiple cellular towers. Can such information be used to accurately correct INS drift (assuming GNSS is not available)?


texts:
Are weather balloon launches NOTAM'ed?

Related, how frequent (periodically and spatially) are they for gathering data on wind-aloft, etc.?


texts: Do military tactical transport flights provide seatbelts for all occupants?

texts:
In several movies I have watched recently, the temporary bench style seats of tactical transport aircraft such as the C-130 do not show seat-belts. I would not be surprised that some instances of seat belts would be ignored during times of war but let's limit this question to standard operations.

So, is it standard practice for transport aircraft such as the C-130 or Chinook helicopter during large personnel missions to provide all occupants with seat belts?


texts: Is there a universal departure recovery procedure?

texts: Let us say you're in a non-fly-by-wire tactical aircraft (say a F-15 or an A-4) doing maneuvers in the local MOA, and you manage to depart the jet in some non-spin fashion.  Is there a standard procedure for recovering the jet to controlled flight, analogous to how there are standard spin recovery procedures, or is the first step on the checklist "eject"?


texts: Is there a database of European surveillance radar installations?

texts: Does anybody know a link to a database or appropriate webpage where I can find the locations of surveillance radar installations in Europe?


texts: Runway landing with a front skid instead of wheel - how does steering happen? (Dreamchaser)

texts:
The Spaceflight Now article Sierra Nevada’s Dream Chaser performs critical glide test flight shows the Dreamchaser performing a runway landing using a front skid and two wheels.

The skid extends backwards from the point where it connects to the aircraft. I am guessing that it can turn for steering once in contact with the runway during landing. Are front skids an established method for runway landings? Can they be used to steer by rotating? If so, is there a simple way to understand how this works - how would rotating the skid actually change the direction of the aircraft; how does the frictional force from forward motion produce a lateral force that changes the direction of the aircraft's motion?

Screen shot cropped from Dream Chaser Spacecraft Extended Free Flight

Images (cropped from originals) from here.


texts: Why is a clock required to be mounted on the instrument panel for IFR flights?

texts: A clock is required for IFR flights in the US but any clock doesn't do; the clock should be the one mounted on the instrument panel. What's the idea behind this requirement? Is it because random clocks the pilots might carry with them for their flights cannot be trusted?


texts: How many US airports have 4 or more parallel runways?

texts:
Which airports in the US have four or more parallel runways?

How many are planning additions in the next 5 years?

A few years back, 10 years, Charlotte opened their 3rd parallel runway and it was said to be only one in seven in the country. Just wondered if there is an updated number for 4+ runways. I have searched and some sites have great information but I am not sure it is up to date. Not trying to offput just looking for information that might not be posted to the public.


texts:
In class D and E airspace, there is no separation between IFR and VFR traffic. However, most airspace in the United States below 18,500 feet MSL is class E airspace, which is exactly where non-pressurized aircraft cruise when flying IFR.

My question is not about regulation (that's perfectly clear: no separation between IFR/VFR) but I'm curious to learn how safe it actually is when cruising at 10,000 feet in VMC on an IFR flight plan while in class E airspace. I'm pretty sure many pilots will be on autopilot without taking too much notice of what's happening outside but according to the regulations the pilot is still responsible for seeing and avoiding other VFR traffic.

Are there any accident statistics on this? I have read hundreds of accident reports over the last few years and I can't remember ever seeing a report on a midair collision between IFR and VFR aircraft in class E.


texts: Is there a public database for annual flights by aircraft type?

texts:
I am doing research about the number of flights and distance flown performed by aircraft types, in a given year. For example:

There were X A320-200 flights, flying an average distance of Y nautical miles, in the year Z.

I know that these records are kept for all registered flights, so I am wondering if there is a database where one can find such info?

I am looking for data of as many regional flight airliners as possible.


texts: What is the purpose of the extremely high cabin altitudes in military aircraft?

texts:
The Lockheed SR-71 and the (old) Lockheed U-2 were engineered to maintain cabin altitudes in excess of 25000 feet AMSL at an altitude of more than 70000 feet AMSL.

However, in both airplanes, pilots are required to wear space suits which maintain the safe pressurisation and oxygen content anyway. If the space suit develops a pressurisation leak, I think it's unlikely that the very high cabin altitude in these airplanes would buy the pilots any more time to descent to a safe altitude safely as the time of useful consciousness at 25000 feet AMSL is the order of a few minutes. Furthermore, it seems strange that aerospace engineers would install a pressurisation system on the Lockheed U2, an airplane already struggling to be as light as possible.

So why is this pressurisation maintained at such a high altitude in the airplanes?


texts: How attitude, speed, and altitude vary when increasing pitch?

texts:
I have been struggling with the following question for a while, would greatly appreciate some help and explanation why.
Scenario:

I'm cruising in my Cessna- cruise attitude 2300 RPM trimmed for 95.

I pitch up, say 1 inch of back pressure, and hold it.

Initially the plane starts climbing and slows down, but what happens next?
How will the plane look in say 5 minutes with me still holding that 1 inch pitch up, what attitude, speed, and altitude will it have?


texts: Can manoeuvres like overbanking and high G braking be used in a single propeller aircraft?

texts:
While watching this very interesting short movie:

I noticed that for some turns pilot uses overbanking like at 1:25. Basically in a turns more than 90 of bank is used.

Can you explain how it works and how to use it and what is the advantage compared with regular steep turns?

I have CPL but I was never thought such maneuvering. Can it be used in SEP aircraft or glider with just a couple of G?

At the end of the movie looks like 5G is used for slowing airplane for landing. 5G is pulled and jet instantly slows from 300 to 260. I don't know if brakes are extended though. Can it be used in SEP as well? Like dive to the runway pull some G, slowdown and land?


texts: Are the student solo endorsements a “package deal” with that one specific instructor?

texts:
If someone receives a student who’s completed his old instructor’s pre written solo exam and received an endorsement, do I need to give him my solo test and endorsement?
Or go ahead and complete the flight training/proficiency and 90 day endorsement?
My understanding is that it’s a "package deal", one instructor must do it all. Except the XC pre-flight planning preparation endorsement, and this one can be given by any instructor.
Can someone confirm this? With possible quotes from FAR, ACs or interpretations.


texts: Why is the end of the F-35's jet nozzle 'spiky'?

texts: Why is the end of the F-35's jet nozzle 'spiky', is it like that to increase performance or some other factor?


texts: Why do the 737-100/200’s thrust reversers blow fully open if hydraulic pressure is removed while the reversers are partly open?

texts:
If the thrust reversers on an Original-series 737 (the 737-100 and -200) are 2 inches or more from the stowed position, and hydraulic pressure is removed from the reverser actuators, the reversers will travel to the fully-extended position under aerodynamic loads at airspeeds down to below 130 KEAS (knots equivalent airspeed), as was discovered during the investigation into the crash of Pacific Western Airlines Flight 314.  To quote the official accident report:

... It was found that the air loads on the reversers were insufficient to deploy them further if they were freed with the leading edges 1 inch out from the closed position. If the initial deflection was increased to 2 inches, they invariably deployed fully under the air loads. At intermediate settings, deployments only occasionally occurred. ...  [p. 17-18 of the report; p. 23-24 of its PDF file]
... The ground runs showed that partially opened thrust reversers deployed at various speeds during taxi tests with manually controlled airlground logic. The rate of deployment varied with the amount of the initial open condition of the reverser doors and also varied with speed. In all cases partially opened doors deployed fully before 130 Kts.  [p. 18/24]

However, the 737 Originals use target-type reversers (you know, the kind with the two buckets that close behind the engine’s tailpipe, the ones that everyone immediately thinks of when they hear the phrase “thrust reverser”); I can easily see how they would be blown to the full-open position if the engine(s) aren’t operating, but, if they are running, then, without hydraulic pressure holding the reverser buckets in position, shouldn’t the engine(s)’ jet blast force the buckets apart and open a path between them for the engine efflux to exit?


texts: Were my airplane's wheels under-inflated?

texts:
I recently took a flight on a (Lufthansa) Bombardier CRJ900 aircraft. As I was about to embark, my eyes caught this image:

And the aircraft wasn't even loaded with the passengers yet. If I saw this in a car, I would assume a flat tire or other loss of air pressure...were these wheels under-inflated?


texts: What happens aerodynamically when we trim an aircraft?

texts:
I'm trying to understand stability & control. Please correct me if I'm mistaken.
An aircraft will have longitudinal stability if the aerodynamic center (AC) is behind the center of gravity (CG). The AC is a point, where all the changes in the magnitude of the lift effectively take place.
The aircraft will be trimmed if the sum of the moments equals zero.

Question: is the center of pressure (CP) of the total aircraft (wing's lift and tailplane's aerodynamic force) or the AC, that must be positioned to coincide with the CG in order to trim the aircraft?
Do we change the location of the AC when we deflect the elevator?


texts: What aerodynamic phenomenae can decrease the pressure gradient in Boundary Layer Ingestion?

texts:
I'm exploring a question concerning whether or not boundary layer airflow presents physical limitations that are too great for current technologies to overcome (I'm holding the position that it is in fact doable) but I've seem to only be able to find one main method of active flow control in the inlet of an embedded engine.

Specifically, pulsating air jets for active manipulation of the air ingested into the engine. As to create uniformity along any modeling 3D or otherwise for future flow sims I am using the basic frame of the Boeing BWB 450-1U concept with the proposed GE58 F2/B1 UEET turbofans.

I would like to know if there are any aerodynamic phenomena that would decrease or eliminate a pressure gradient that would naturally build up on the face of a Boundary Layer Ingestion.

As previously noted, I am aware of active control measures, but I would prefer a passive solution like vortex generators (as they present a minimal detriment in aerodynamic quality yet a significant advantage in efficient solution to the given lift problem)

P.S. I have checked all related posts/answers and none are either recent enough nor complete enough for my question in particular, so please don't disregard it as such.


texts: What is the cause of this roll oscillation during BA492 go-around?

texts:
Earlier today, BA492 aborted a landing at Gibraltar due to a strong tailwind, according to this article. Videos of the go-around show the Airbus A320 undergoing pronounced oscillation in the roll axis:

[Content warning: both videos contain profanities]

What is the cause of such large magnitude oscillations?


texts: On which axis do we measure angle of attack and airspeed?

texts:
The lift value depends on the relative airspeed of the plane. That's what every website says without anymore explainations.

But as we are talking about lift, are we talking about the relative speed ONLY on the axis of the chord line of the airfoil ? Or the relative speed, not related to any particular axis ?

Now about angle of attack (AOA ):

Is the AOA measured on a specific axis ? Or is it the absolue angle between the airspeed Vector and the chord Line ?
Or with other words : does AOA = 20° when the plane is on a 20° side slip ?? That's seems wrong to me but if we relate to the words of wikipedia for example thats what is being said.


texts: How do changes in flight affect L/D max and the speed at which I must travel to maintain it?

texts:
I have an plane flying at L/D max and I want to maintain L/D max.

Firstly, if this plane burns through a portion of fuel and becomes lighter, how would I have to change the speed to maintain it?
My thoughts are that because the plane is ligher, less lift is required to keep it level and therefore Cl decreases, decreasing L/D and therefore I'd have to increase speed?

Also, how would an altitude drop affect L/D max?
I assume because of the higher density of air, you'd get more drag and therefore, lower L/D as such, would need to speed up to maintain?

Also, extending speed breaks during landing - again i assume because this increases drag you would need to speed up to get back to max ratio.

I'm quite confused with this concept and what parameters affect what.


texts: Does the downwash created by induced drag increase or decrease lift?

texts:
According to the theory I know, lift is produced by accelerating air downwards at the trailing edge (downwash). Hence, as downwash increases so does lift. Induced drag is due to vortices at the wing tips and they also create downwash. So according to the above theory induced drag should also increase lift.

But, the books say that induced drag increases downwash and reduces the effective AOA, which subsequently reduces the lift. Does the downwash from induced drag increase or decrease lift?


texts: How is the amount of time for an A check or daily maintenance determined?

texts:
How can the time for daily maintenance or A Check be calculated for different aircraft types?

Is there any exact formulation depending on the aircraft specifications?
 P.S.,I'm very new to the aviation field.


texts: How did the AAIB assist in locating MH370?

texts:
I saw on news that the AAIB helped to locate the missing MH370 flight, saying that it ended up in Indian Ocean, with the help of a whole new technology.

I was wondering what kind of "new technology" it was?


texts: Why is Russian super-maneuverable thrust vectoring more prevalent than American?

texts:
Based on the sheer number of super-manouverable thrust vectoring Russian fighter jets, it seems that Russia has put more effort into developing thrust vectoring for enhanced maneuverability than the US has.  Why is this?

Examples of American thrust vectoring aircraft:

F-22 Raptor

Russian thrust vectoring aircraft:

Su-30 MKI
Su-35
PAK FA
Su-37
Mig-35

Of course you could include the MV-22 Osprey, Harrier, and F-35B as thrust vectoring, but I'm talking about thrust vectoring for enhanced maneuverability, not for STOVL.


texts: Who is legally responsible for tiedown ropes?

texts: When an airport has tie downs listed on their official FAA record, who is responsible for the ropes/chains. Is there any federal regulation or legal precedent for this or is it a case-by-case determination based on the FBO policy?


texts: DA40 fuselage static ports / G1000 not in AFM

texts:
I’m a flight instructor who just switched from instructing in 172’s to flying the Diamond DA40 and am confused about a few things. Our DA40 has two static ports, one on either side of the fuselage. This doesn’t make sense to me because the AFM in the airplane says the static ports are on the left wing along with the pitot probe. I haven’t been able to find anything online about these static ports, and I’ve only seen one DA40 AFM.

My second confusion is, the airplane is equipped with a G1000; however, the AFM in the airplane doesn’t say anything about the G1000, there is only a cockpit reference guide for it. Would this indicate an upgrade from original avionics? Would it be in the maintenance records? (Mx records was my next stop)


texts: If an approach chart says "GPS required", do I need GNSS capability to fly it?

texts:
If an aircraft is /Y, /C, or /I (RNAV no GNSS), can they fly an approach chart that says "DME/DME/IRU or GPS required"? GPS in my mind is a GNSS. If you don't have DME/DME/IRU and are RNAV (non-GNSS) capable, can you legally fly the approach?

An example of a chart that has the "DME/DME/IRU or GPS required" notation is here.


texts: Did the Stuka Ju-87 really have a radio altimeter? If so, when?

texts:
This is what Wikipedia says near the end of its radio altimeter article:

  The radio altimeter first showed up in the German Junkers Ju-87 "Stuka" dive bomber which was equipped with one for automatic pullouts in the dive bomb run which usually consisted of an 80-90 degree dive. The Stuka pilot would set the radio altimeter to 750m which was connected to the bomb release and automatic pull out. The radio altimeter would drop the bombs and pull the Stuka out of the dive at the set altitude to a level flight. This was invented because the pilots would black out on the pull out, usually for 2 to 5 seconds.

No citation, and I would be skeptical anyway. I know the Stuka had an autopilot that pulled out of a dive, but I thought it was activated manually by the pilot dropping his bomb. I figured he would just drop his bomb at whatever altitude he judged by his own eyes, rather than watching some altimeter instead of the target.

I'll also note that Wikipedia is not self-consistent here. If you scroll up just a few paragraphs, it says:

  In 1924, American engineer Lloyd Espenschied invented the radio altimeter. In 1938, Bell Labs put Espenschied's device in a form that was adaptable for aircraft use.[13] In 1938 in co-operation with Bell Labs, United Air Lines fitted a radar type device to some of its airliners as a terrain avoidance device.[14]

Two citations there. So I don't know what the author means exactly when saying it "first showed up" in the Stuka.

I would have thought such a radio altimeter would have been very difficult without the cavity magnetron, invented in Britain and sent to America in the Tizzard Mission of 1940 September.

On the other hand, I have come across some night fighter radars that Germany had, such as the Lichtenstein Radar that did not need cavity magnetrons. That was not used until 1942, though.

So did the Stuka really have some radio altimeter? If so, when? Was it really the B version that saw action in 1939? What frequency and power did it use? How big was it?


texts: What could cause instant nausea when entering larger passenger planes?

texts:
This may not be the right forum for this question, but I almost always experience temporary nausea when entering the cabin of a larger passenger plane (e.g. A320). It hits me as soon as I enter the cabin and can be quite debilitating. Strangely enough it tends to dissipate almost completely after about 5 minutes inside the cabin.

Does anyone know what might be causing this? My only thought is that is has to do with the air inside the cabin as even the smell of the cabin when boarding (but still on the boarding ramp) causes the nausea to occur.

Additionally, I'm open to any suggestions for how to reduce this effect... I fly quite often and have learned to put it up with this sensation but I would greatly appreciate not having to go through this anymore.


texts: Is there an online source of active flight plans?

texts: Is there a way I can look up flight plans filed in the United States? I tracked an aircraft on Flightradar24 and I would like to be able to find it's flight plan in some sort of database.


texts: Do pilots need special training to land Lockheed U-2 reconnaissance aircraft?

texts: Do pilots need special training to land Lockheed U-2 reconnaissance aircraft as its body is too shallow and is a wide wing aircraft?


texts: In airline operations, what are the typical ramifications for pilots for breaking items on the flight deck?

texts: Knowing that equipment on the aircraft breaks like any other stuff do pilots get into trouble for breaking (small) equipment etc. on the aircraft or in the cockpit if they are behaving carelessly?


texts: Can active flight plan be sent for the aircraft in the air?

texts:
We are processing some aviation data and I wonder if it is possible that flight plan message can be sent for an active flight (aircraft in the air)?

In the documentation we have the sentence:
"Active flight plan, aircraft is in the air. For ARTS III indicates an overflight"


texts: What is the material and font used on the panels of most cockpits?

texts: I am working on a project for one of my aerospace engineering classes and was curious to see if anyone knew what type of material is used to make the panels of a cockpit (preferably a 737) as well as the font used for the lettering?


texts:
What are the different structural weight limitations that have to be considered when loading large aircraft? Is there a difference in complexity as to whether it's a passenger aircraft or a freighter being loaded?

I think I know the answers, but it's precisely because I have to say "I think" rather than just "I know" that I'm asking the question. I'm hoping those here more technically oriented than I will be able to add to what I know.


texts: In an articulated hub rotor craft, what could cause the blade to flap negatively?

texts: For example in forward flight what could cause the blade to flap lower than parallel to the CF at the front of the aircraft ?


texts: Can pilots wear glasses/corrective lenses inside the cockpit?

texts: I was wondering If I could wear corrective lenses/glasses inside the cockpit If I have a certified class 2 medical certificate?


texts: What do these numbers and symbols on the ICAO SIGMET chart represent?

texts: Anybody who can identify the numbers and alphabets in the red, green, and purple circles on the chart above?


texts: How is the change of moment handled in a Weight and Balance calculation with a swept wing aircraft?

texts:
I'm writing a weight and balance calculator for a charter operation.

Every aircraft I've ever flight planned for has all the tanks on the same moment arm, so I don't know how you calculate the W&B for an aircraft that has swept wings. Do they have one tank on each wing whose moment changes as it drains, or do they have multiple tanks? And if they have multiple tanks, so you have to calculate for 'drain the forward tanks first' and 'drain the rearward tanks first' and plot both of those on envelope?


texts: Why are there curved blades on jet engines?

texts: On the fan and comssorssor and turbine for that matter there are blades and they are also curved. Im already confused beucase the fan has blades but wouldn't it blow out air not suck in air? Why are there blades even on the compressor and turbine and why are they curved?


texts: Why do (or did, until very recently) aircraft transponders wait to be interrogated before broadcasting beacon signals?

texts:
An aircraft’s transponder transmits signals that announce (at the very least) the aircraft’s identity, altitude, and direction of motion (plus, for most newer aircraft, a whole slew of other useful information); this is what allows secondary surveillance radar (SSR), the backbone of modern air traffic control, to function,1 and what makes it possible for aircraft’s TCAS to see other nearby aircraft and (if necessary) warn their pilots not to collide with them.2

For a long time, I thought that this worked by having the transponders broadcast this information in the blind, in case there was a radar or TCAS within range who might want to know about the aircraft attached to the transponder.  I’ve recently learned, however, that most aircraft transponders “speak only when spoken to”, not transmitting their information until they hear a radar or TCAS shouting “Anyone there?” into the deep blue sky (although ADS-B, which works essentially how I thought all transponders worked, is being rolled out, and will soon become mandatory in the U.S. for many aircraft) - and that this transmission is sent only to the shouter, and not to anybody else who might have an interest in the matter.3

I don’t get why most (or, until very recently, all) transponders don’t broadcast unbidden; it’s obviously feasible (otherwise we wouldn’t be able to have ADS-B), and would eliminate the need for those big, expensive SSR transmitters (ATC would just need a small, cheap receiver, plus a primary surveillance radar4 dish for detecting birds, weather, detached aircraft parts, aircraft with broken-or-otherwise-nonfunctioning transponders, and aircraft without transponders [such as most balloons and gliders], and as a backup in case the aforementioned receiver blew up/contracted malware/got stolen by space aliens).  So why do, or, at least, did, aircraft transponders have to be interrogated by a radar or TCAS before they spill the peanuts?5

1: Which, in turn, enables controllers (for instance) to stack multiple aircraft at different altitudes in close horizontal proximity to one another without risking a mid-air collision (whereas most primary radars can’t determine the altitudes of their targets - since they can measure the azimuth and slant distance of a target, but not its elevation angle - and, thus, can’t be used for vertical separation of targets), to warn aircraft if they sink dangerously low (same reason), to immediately identify new targets appearing on their screens, and to associate said targets with radio transmissions from said aircraft without having to ask the transmitter to make a 360º turn for identification purposes.

2: I’m sure there are a lot of other things transponders are useful for as well, but that I’ve forgotten to include.

3: For instance, this means that an aircraft has to have an operational transponder in order for its TCAS to work - it can’t just sniff out transponder signals sent by nearby aircraft in response to interrogation by other radars and/or TCASses.

4: Radars that detect targets by physically bouncing radio waves off them and listening for the echoes.

5: Like spilling the beans, except that aircraft serve (and spill) peanuts instead.


texts:
I'd like to ask if the DC-3 has a prop sync.
I found nothing about prop sync in the DC-3 operations manual, in the running specs, design features, or in the chapters about its engine and propeller. I've read the Wikipedia article about prop sync (which  didn't mention it) and this What is propeller / engine sync and how does it work? (which was great, but didn't speak of the DC-3). I've used this last link (which highlights the instrument) to check pictures of the cockpit and didn't see anything that looked exactly the same, but I don't think the instruments would look exactly the same in aircraft of different manufacturers (Junkers and Douglas). I assumed it didn't, but being that it's a twin-engine (which qualifies as a multi-engine) turboprop aircraft I'd have thought it'd make sense to have one. Can anyone help?
Thanks


texts: What was this helicopter photographed on a Chinese aircraft carrier?

texts:
I've read this twit

Chinese carrier got photographed by a satellite.

On the nose you can find a helicopter and several people around it.

What helicopter is that?


texts: How is the TCAS negotation information encoded?

texts:
As I understand, according to this FAA booklet on TCAS, transponders will engage in cycles of interrogations and responses to establish if a collision may occur.

The next step is for both TCAS systems to negotiate respective resolution advisories. My question is how the negotiation takes place in the TCAS system internally, and in particular what communication protocol takes place for the negotiation.

To elaborate, as an example, a browser can make an HTTP request to a server (like this site) which follows protocols as to what information should be provided and how it should be encoded.

Along the same vein, how is information encoded for TCAS systems to negotiate? Since I don't know of any open source TCAS used in commercial aviation, I can't inspect code.


texts: Why do forward-swept winged fighters have the main wings in the back?

texts:
These are the only 2 fighter jets I know of with forward-swept wings. (Su-47 and X-29, they're both still experimental). As you can see, they both have their wings in the back, not the middle.

Why is this? To me it seems like those wings in the far rear place the center of lift very aft, meaning a constant nose-down torque.

Is there something precluding a conventional-tailed aircraft with forward-swept wings?


texts: Where does this integral for a 'aerospike nozzle' come from?

texts:
Today I was reading about the aerospike nozzle and found this image:

(from section 10.3.1 of this lecture)

This image tells us how to measure the thrust of this kind of nozzle. I can understand all of it except this part:

Where does this integral come from? How do they derive it?


texts: What is the difference between a pressure switch, high-pressure control, and low-pressure control in a landing gear hydraulic system?

texts:
This is an Arrow II landing gear diagram.

In the diagram, the high and low pressure controls look like check valves.  The pressure switch is unclear.

What are these three items, and what purpose does each one serve?


texts: Could a tail rotor serve as a spin breaker for winged aircraft?

texts:
It seems that yaw, more than pitch or roll, creates the greatest wing asymmetry in a spin.
If the spin progresses to the point where it cannot be broken, some aircraft are equipped with parachutes to try to stop rotation and to get the nose pointed down. Some cannot be saved.

Tail rotors work well in helicopters, and are part of the design to control the (spinning wing) rotor yaw, and, such as the 180 knot MH-65 Dolphin, have the rotor built into the tail to save drag.

Could this work as a safety feature for GA aircraft?


texts: Does an airport need to have at least one instrument approach that I can use in order to fly IFR to it?

texts:
Half Moon Bay (KHAF) does not have any instrument approaches into the airport that I can use. All the approaches require RNAV but my aircraft is not RNAV-capable. Can I fly IFR to it?

I'm thinking that if weather is good, ATC can clear me for the visual approach.

If weather is bad, I'm thinking that they wouldn't be able to clear me and would ask me for an alternate airport to land at?


texts: How do head- and tailwinds affect airspeed?

texts:
I'm sure this was asked somewhere, I just can't find it. So if it's a dupe, let me know.

Anyway, I'm one of those guys that actually looks at the flight information when I'm flying. I fly transatlantic 3-4 times a year and they show it on the personal screens.

They display the groundspeed, headwind/tailwind, temperature etc. I'm wondering how to calculate the actual speed based on that. Is it the groundspeed plus/minus the headwind/tailwind? Meaning, if groundspeed is 500mph, and the headwind is 200mph, does that mean we're only traveling 300mph? Meaning it will take us 10 hours to travel 3000 miles? Or are there more factors involved and more math calculations?


texts: How much radiation is an airline pilot exposed to in a year?

texts:
Flying exposes us to more radiation since we are closer to the sun, and there is less atmosphere to protect us.

Consider an airline pilot flying on a routine and frequent basis. How much radiation is absorbed per flight hour, and per year?


texts: When can a tower's callsign differ from the airfield name, and how do I find the proper callsign?

texts:
It seems like a lot of air traffic control towers use callsigns that are much different from the name of the airfield.  For example, Lehigh Valley International (ABE) has "Allentown Tower."

"Allentown Tower" doesn't appear anywhere I can see on the sectional chart.  (The control frequencies tab even lists it as "Lehigh Valley Intl.")  You might be able to figure it out through other hints, such as the presence of the "Allentown Class C," but that doesn't seem like something that can be relied upon in general.

I doubt pilots are expected to have airport diagrams handy for every airfield in the vicinity just for this.

If, say, I had to divert to an unfamiliar airfield, how would I find the proper callsign for its tower?


texts: I just flew into class B airspace without a clearance, what should I do now?

texts:
Hypothetical: Let's say (for whatever reason) a pilot became distracted or disorientated, and found themselves in class B airspace.

What steps should they take immediately and after landing to be safe and avoid any backlash from authorities?


texts: Do pilots have their own in-flight entertainment?

texts:
Besides flying the plane and talking to the person in the other seat, what other forms of entertainment are (also legally) available to pilots while on the job?

I'm thinking of 'activities' like reading, listening to music, watching a movie, or... playing a flight simulator game on a laptop.


texts:
The downwash is caused due to higher pressure below the wing than above it (for a positive lift generating wing that is). What I am not able to understand is how would the flow be in a gross sense? Will the flow move bottom to up around the wing tips and move top to bottom along leading and trailing edge? I thought of this because it is the only way I am able to justify that downwash induces a negative velocity component which decreases the angle of attack that the wing sees at the leading edge.

But can’t the air also move bottom to up along leading or trailing edge? To me, at leading edge it seems unlikely based on intuition because of the air upstream constantly trying to direct the air ahead but at trailing edge it seems more likely.

So what is the correct visualisation of downwash over a finite wing?


texts: What are typical stability analysis dampening values?

texts:
I'm not an aerospace engineer, so don't know if I'm asking this correctly. I've been using the new XFLR5 with stability analysis. Just don't know what values are good.

What are typical stability analysis dampening values for GA aircraft
for:

Lateral modes:

roll control
dutch 1
dutch 2
spin

Longitudinal modes:

short period 1
short period 2
phugoid 1
phugoid 2


texts: How can I reduce the responsivness of my homebrew brake system?

texts:
I have a hydraulically actuated aircraft brake system.
Each main landing gear are equipped with brake disk hydraulically operated. The actuation is realized independently for each wheels by means of the correspondent control valve which controls pressure delivery to the brakes. Each brake control valve is connected to each pedal brake. When the pedal brake is depressed, the control valve will open and deliver a variable pressure to the brake adjusted by the pedal angel.
The problem is the Brake is too responsive. When the pedal is depressed slightly, the aircraft suddenly stop.

What is the main problem? Is it the hydraulic flow to the brake disk too high?
Can I install a "restrictor valve" from the brake valve to disk to restrict the flow and make the brake smoother?
if so, how can i determine the size of the restrictor valve?

or the pressure to disk brake is too high?

the function of accumulator is for emergency


texts:
I used to simply think It was the speed where any attempt to pitch up to maintain an equilibrium between lift and weight would result in flow separation, But Wikipedia says;

But I noticed in a Sim I play, The stall buzzer plays whenever the airspeed gets under a certain point, No matter what angle of attack?
I first thought this was a bug or flaw in my simulator, But why on earth would there be a stall? As said before, stalling is not dependent on speed, so what exactly is "Stall speed"?


texts: Why are W, S, N, E highlighted on a flight management computer?

texts:
Why are W, S, N, E highlighted on a flight management computer (FMC)? My assumption that they represent West, South, North, and East.

Here is a Boeing FMC:

And here is one from Airbus:


texts: How unusual were MH370's final ATC exchanges?

texts:
There are 2 noteworthy occurrences in the ATC radio transcript within just minutes of a 3rd noteworthy, quite unprecedented occurrence in aviation history:

At 01:07:55 MH370 unnecessarily reported maintaining FL350 a second time
At 01:19:29 MH370 famously only replied "Good Night, Malaysian 370" without reading back the frequency for the handover, although this is an ATC instruction that should be repeated (see below)
At 01:20:33 MH370 "goes dark" (losing XPNDR, ACARS and SDU).

This temporal proximity caught my attention and left me wondering if the 2 ATC transmissions cited above are out of the ordinary (and thus a possible precursor of what was to come).

background information:

  What are some important things controllers usually expect you to read back?
  • Clearances: headings, vectors, altitudes, transponder codes, and radio
  frequencies. (a288)

  « The last radio transmission “Good Night Malaysian Three Seven Zero”
  was spoken by the PIC. However, he did not readback the assigned
  frequency, which was inconsistent with radio-telephony procedures. »
  (safety investigation report, p.431)

questions

Please cite what (if any) ATC rules have not been followed.
From your experience as flight controllers or pilots, how unusual is that ? Is this rather unheard of or occurring fairly regularly ?
Is the handoff procedure described below by the 767 Captain technically correct and does the missing step 3 permit the conclusion that step 2 was not executed either ?

  @Edward_767, a 767 captain, has closely studied the audio recordings
  of the MH370 radio transmissions. He is convinced that the second
  altitude call at 01:07:55 was NOT made by the Captain, but by the
  First Officer, possibly because the captain was not in the cockpit at
  that time. His theory is that the first officer made the call because
  he was not sure whether the captain had made the previous altitude
  call at 01:01:14.

  He makes another interesting observation regarding the final exchange
  where MH370 is handed off to HCM. He states that the typical radio
  procedure would be to

  receive the new frequency (in this case, 120.9 MHz)
  dial it into the radio as the standby frequency
  read back what frequency was dialed in as part of the confirmation of the handoff
  listen for the final transmission
  hit the radio switch which swaps the active and standby frequencies
  and call ATC on the new frequency.

  In the transmission that acknowledged the handoff to HCM, the captain
  did not read back the frequency. Ed believes this is because the new
  frequency was never dialed into the radio, as the captain never
  anticipated making a call to HCM ATC. Ed believes the missing
  frequency during the acknowledgement of the handoff is yet another red
  flag.

  The time between the 2 transmissions would be less than 15 seconds. It
  was 13 seconds at MH370’s previous controller handoff, where the new
  frequency was read back. At the handoff between Kuala Lumpur and Ho Chi
  Minh, the pilot acknowledged the handoff, but never read back the new
  frequency, and the call to Ho Chi Minh was not made. That leaves a window
  of only about 15 seconds for the abnormal event that caused the turn back.

ATC transmission log (full transcript incl. taxiing here)


texts: Which country has the lowest flight time requirement for the issuance of a pilot certificate?

texts: Which country requires the fewest number of flight hours for pilot certification?


texts: Do coaxial rotors provide twice the amount of lift?

texts: Do coaxial rotors provide twice the amount of lift given same diameter and RPM?


texts: How are ADS-B surface position frames decoded?

texts:
I am developing C# code that reads 1090ES Automatic Dependent Surveillance - Broadcast  (ADS-B).

The ADS-B position messages broadcast by the aircraft's ADS-B transmitter have a different encoding depending on whether the aircraft is airborne or on the ground.

When I decode Airborne Position frames as Compact Position Reporting (CPR) encoded positions, I get realistic results. However, when I decode the CPR for Surface Position frames, the positions I get are far (geographically) from what I should get.

How is the CPR in Surface position messages different from airborne position messages and how are they decoded properly?


texts: What is the purpose of the translucent tube and dial on JU 52 engine nacelle?

texts:
Mounted on top of each JU 52 engine is a translucent tube and a dial (see images).

What is the purpose of the tube and what does it measure?
Does the dial measure (oil or fuel) flow or quantity?
Are these indicators visible at night?


texts: Were RCS tests performed on the ATF YF-22/YF-23 prototypes?

texts:
I know that radar cross-section (RCS) tests were performed on geometric models of both the YF-22 and YF-23 prototype submitted for the Advanced Tactical Fighter (ATF) competition, but were the same tests performed on the actual YF-22 and YF-23 prototypes when they were in flight?

Both designs had the correct shaping to their outer machine lines in order to minimize radar cross-section, but there is a noticeable difference between those prototypes and, say, the production F 22 in terms of very small details i.e. RAM inlays, putties, tapes around doors etc.  A similar phenomenon was observed with the X-35 JSF when compared with the F-35 Lightning II development aircraft. That makes me wonder if such an RCS test was part of the ATF competition.


texts:
My questions are:

According to the article ''H''; what about the other runway/runways when I want to add extra info other runway/runways too; there is just one runway in here?
According  to the article ''J''  it is indicated that critical snowbanks; but it is again just 1 runway I think so.
According to the article ''P'' 15 is the meter of this taxiway snowbank but in which direction is 15 mt.?

I did not fill any SNOWTAM format so; I want to ask in advance..


texts: Could the Boeing 757 replace the Boeing 737 Max 8/9/10?

texts:
The "Baby Boeing" 737 started life in the 1960s with roughly half the thrust and around 60% of the weight as the 757. In stages the 737 grew into a capacity squarely in the range of the 757. Originally, it prospered as a smaller regional jet. The Max 10 essentially will be a 757.

Is it possible the longer 757 airframe is a better match for the LEAP engines? Does the older, more forgiving AR 8 wing make it a safer aircraft?

Seems (forgive me) like comparing the graceful look of a thoroughbred, built for what it does best, compared to an overloaded old quarterhorse. Is the 757 worth another run?


texts:
This aircraft is at Dodson International in Rantoul, KS. I've boiled it down to Convair. Looks most similar to a C-240. And does anyone recognize the livery?

It has USAF painted in the top of the right wing, as can be seen from satellite at 38.541248,-95.103554


texts: Is it possible to determine if winds were high without groundspeed, wind speed, AoA or AoS?

texts: I have a data set that includes TAS, IAS, GPS Lat/Lon, Inertial Lat/Lon, ENU speed,  inertial speeds, attitude, and accelerations. I don't need to know the exact wind speed, and I don't think that's even possible to calculate at this point, but I would like to determine whether or not wind speeds were significant at a certain point in the flight. Is this possible?


texts: What is this abandoned airplane parked in Tegel airport?

texts: This airplane is parked in Tegel airport. Probably something extremely common, but can you please help to identify it?


texts: Can I take my Canadian PPL with flight hours logged in the US?

texts: I was wondering if I can combine my flight training hours in the US with my Canadian ones if I want to take my PPL in Canada?


texts: Aircraft which have been in service for a long time often have a lot of entries in their logbooks for Airworthiness Directives (ADs). What are they, and why are they important?


texts:
How do I find pressure altitude?

Find pressure altitude using rule of thumb for 1498 feet when the altimeter setting is 27.83" Hg.

I did (29.92-27.83)*1000+1498=3588

Did I do this correctly?


texts: Did Pacific Southwest Airlines ever operate flights under VFR?

texts:
Does anyone know if Pacific Southwest Airlines (PSA) ever flew certain routes under VFR?

I've read this question and I understand that Part 121 does allow for VFR flight, but my question is specific to PSA. I've heard they routinely flew low altitude VFR flights on shorter routes throughout California.


texts: Center of Gravity and Center of Lift stability

texts:
I have recently been reading about the center of gravity and center of lift. On the German Wikipedia there are many different graphics about the relation between the center of gravity and the center of lift. The one that struck me the most is the one where the description is the one where the center of gravity is the same as the center of lift:

Image according to: https://en.wikipedia.org/wiki/Wikipedia:Image_use_policy
The article in Wikipedia mentions that having a center of gravity (theoretically) coincide with the center of lift constitutes for a very unstable aircraft. It says that even the slightest turbulence will cause very bad nose attitude changes as the airplane becomes very unstable along the lateral axis.
I am having a really hard time understanding how this is any different from any other CG/CL configuration. Why is the airplane more laterally stable if the center of gravity is in front of the center of lift and the elevator is compensating the ensuing torque around the center between center of lift and gravity?


texts: What additional airspace will be off-limits to an a/c w/ no elect. system or xponder under 91.225 (ADS-B) compared to under 91.215?

texts: Under FAR 91.225 (requirement for ADS-B-out), what additional airspace over the 48 contiguous states in the U.S. will be off-limits to an aircraft w/ no electrical system or transponder, compared to the current situation under FAR 91.215 (requirement for Mode C transponder)?


texts: Could a plane land on specialized vehicles if its landing gear failed?

texts:
This (fake) video has stirred up a lot of questions online about whether such a scenario would be possible in reality - and the answer to those questions appears to be a resounding "No, that's very implausible."

But most of those answers seem to focus on the specifics of the Nissan truck - it would exceed its rated weight tolerance, it probably wouldn't be able to match the plane's speed...

What if an airport had specialized vehicles for this sort of thing, Thunderbirds-style? Could such vehicles be built, or would the engineering challenges just be too great to overcome?


texts: Can TRACON increase plane speed on approach?

texts:
I was listening to Norcal yesterday and heard a controller request an airplane increase speed to 210 knots "if able". The plane was previously at ~180 knots. The pilot responded he had flaps 2 and politely declined.

Can TRACON demand a plane increase speed if the controller already assigned a slower speed?
And if yes, what would be the phraseology? "Maintain 210 knots or greater until DUMBA"? (I don't think I've ever heard that when a plane was slower.)


texts: How much fuel does an A380 hold and where?

texts: How much fuel does an A380 usually carry (in litres) and what is the maximum? How much is in each wing? How much is in other fuel tanks and where are they?


texts: Why are passengers not given the option of shoulder harnesses?

texts:
From this question:

  In airliners, shoulder harnesses are not installed for passengers because:

  it is not mandated by law
  it is too much for average passengers to deal with
  it requires money to install
  it is superfluous in a crash when compared to the same safety from a lap belt

  Flight crew is required to use the shoulder harness (when installed) as it is the law (14 CFR 91.105): [...]

How is 4 true? Why would shoulder harnesses be obligated for flight attendants in their jump seats, but not for passengers?

Against 1 and 2, should shoulder harnesses be installed, at least to enable passengers to decide to use them or not?

Against 3, do the safety benefits not outweigh the costs?


texts: What is the available range for DME, and why do we need EFC?

texts: How far from the station can a DME signal be picked up, and why do we need EFC?


texts: Is there any requirement that airports have distinct names?

texts:
Is there any requirement that airports have reasonably distinct names from each other?

I've known about SYD versus YQY for a while, but I've just read that there's two airports mentioning Genghis Khan: ULN in Mongolia and NZL in Inner Mongolia in the PRC.


texts: What are the 40 hours requirements for a PPL?

texts:
According to 14 CFR 61.109, a private pilot applicant must log 40 hours of flight time.

  (...) that includes at least 20 hours of flight training from an authorized instructor and 10 hours of solo flight training (...)

What are the requirements for the remaining 10 hours?


texts: What official government document should a pilot check to determine what magnetic north a VOR was set to when it was commissioned?

texts:
Today I learned that VOR stations are all set to magnetic north at the time of commission, and since magnetic north moves, the VOR is not necessarily in-line with magnetic north in the present.

Where can a pilot look to read numerically what the VOR is set to as its magnetic north?  I understand a sectional chart could be measured, but I want to know where I can read the setting in a manual.

For example, is it contained in chart supplements?


texts: How does a Secondary Surveilliance Radar send data?

texts:
When aircraft are detected by radar and their transponders 'ping' back to the radar site, this data is passed over data network cables to the air traffic controllers.

Is there typically any specialist equipment (high safety certification?) to send the data from the radar site on to the data network? Or is it something as simple as a server/PC with a network card?


texts: How to obtain transformation parameters between the Vertical Reference System EGM-96 and a Local Geoid Model?

texts:
Dear Mr/Mrs Geodesy Engineer, Cartographers and AIS Specialists

I have a quite deep question here,
AIP data locations are determined by geographic coordinates /X & Y axis/ and vertical values /Z axis/ via Geodesy science.

ICAO adopted EGM-96 standard for Vertical Reference System.

Question is raised regarding to Annex-15, 1.2.2.3:

  ....When a geoid model other than the EGM-96 model is used, a
  description of the model used, including the parameters required for
  height transformation between the model and EGM-96, shall be provided
  in the Aeronautical Information Publication (AIP).

In Mongolia, we are not using EGM-96 for Vertical Reference System. Instead, wWe are using the Baltic sea level value /1940-1970/ in Air Navigation.

My question is: How to figure out the parameters required for height transformation between any model and EGM-96 for AIP publication?
In my thinking, the parameters must contain following values: ∆X, ∆ Y, ∆ Z, X rotation, Y rotation, Z rotation, Scale... etc. Is this correct?


texts: Is it necessary to strengthen the airframe of an aircraft that is used for sustained low level flight?

texts:
I was looking at the image of the A 10 and saw that its air frame looks far more stronger than the air frame of the F 15 or the F-16.

I realized that the A 10 is used for undertaking low-level flights for deep interdiction. Apart from the A 10, the French Rafale fighter is also used for low level flights.

So is it necessary to strengthen the air frame of such aircraft or are they built from scratch with a material that is different from the ones used to design aircraft like F 15 and F 16?

I've heard of designers strengthening high stress areas of air frames with fiberglass,Coffee filters etc. However, increased weight will translate into higher wing loading which means more landing and flying stresses.

EDIT:

Sustained low level flights are associated with more structural failures in fighter aircraft. This is why a number of Air Force the world over have mission specific aircraft. Basically what I need to know is whether the airframe  of a fighter aircraft that is generally used for low level flight(A 10, Rafale, Su 34) any different from the airframe of other fighters like F 15, F 16 or Typhoon?

To be sure, I got the answer from the posts below, but just wanted to clarify as this question is on hold.


texts: Can crews hand-fly an RNP AR approach in IMC?

texts:
Required Navigation Performance (Authorization Required) approaches require multi-crew with special training and strict equipment, similar to ILS CAT II/III.

Typically, the aircraft must have at least the following equipment: dual GNSS sensors, dual flight management systems (FMS), dual air data systems (ADS), dual autopilots, and a single IRU. (Source: FAA AC No: 90-101A.)

In IMC, can such approaches—which may include radius-to-fix segments (RF)—be flown by hand following the Flight Director cues, or must the autopilot be engaged? Such approaches usually have very small tolerances for navigational errors especially in mountainous areas.

(airnav.com) KGUC RNAV (RNP) RWY 06.

Related: What is a SAAAR instrument approach?


texts: What are the following documents about aircraft maintenance?

texts:
What is a service bulletin? How does it originate?
What is a rapid revision in aircraft maintenance?
What is a non-conformation report?

What is the difference between these 3 documents?


texts: What makes the Antonov An-2 have no stall speed?

texts:
The Antonov An-2 is notable for being able to fly at a very low speed. However, what confuses me is that it has no stall speed:

  The An-2 has no stall speed, a fact which is quoted in the operating handbook. A note from the pilot's handbook reads: "If the engine quits in instrument conditions or at night, the pilot should pull the control column full aft and keep the wings level. The leading-edge slats will snap out at about 64 km/h (40 mph) and when the airplane slows to a forward speed of about 40 km/h (25 mph), the airplane will sink at about a parachute descent rate until the aircraft hits the ground."

(From Wikipedia article on An-2)

How is this possible? What makes the airplane have no stall speed?


texts: What were the J47's turbine blades made of?

texts: What materials were used to make the General Electric J47 turbine blades in the 1960's?


texts: Is is possible to use non-hydraulic fluids in a hydraulic system in an emergency?

texts:
In this answer, Ralph wrote:

Spare fluid is common enough to have on-board to replenish the resevoirs.

After reading that, I recalled an incident I was told about nearly twenty years ago about a hydraulic failure on an Aeroflot flight, where Lemonade (a Russian soft drink of sorts) was used in a pinch. I've always wondered about the authenticity of this story.

Is it true? Is it plausible? Have there been other times where some non-ideal fluid was used in place of hydraulic fluid?


texts: What does mean PPM unit and why it is the unit of flow rate for the ASU(Air start unit)?

texts:
I was seeing the specifications of several ASU(Air start unit)s and found out that makers of such machines provide the flow rate of the ASU in PPM. Why? why not Volumetric flow rate?

Example:

TS200 Air Start Unit


texts: Why does a helicopter need cyclic control rather than just tilting the whole main rotor?

texts: Helicopters use a cyclic control to tilt each blade differently through the rotor's revolution. This is quite a complex mechanism. What is the advantage of this vs tilting the whole rotor plane? This seems to be a much more simple solution.


texts: Is it permitted to load a full cargo container onto an aircraft without a roller track loading/locking system?

texts: Aircraft with roller track cargo loading systems transport containers/pallets in the cargo compartments. When an aircraft doesn't consist of a certain system but just a flat floor (so for example a small bulk cargo aircraft), is it allowed (regulation wise), and if the dimensions are no problem, to place one or more (loaded) containers in the aircraft?


texts: What does rudder input control in normal law in an A320?

texts:
I understand form documentation that in normal law, pedal input is not necessary to keep coordinated flight. It is merely said that using the pedals is not necessary. Later in the documentation it is said that the law for the yaw axis is either normal, alternate or direct (depending on the condition). For the normal law, automatic functions are implemented (yaw damping, coordinated flight). What happens when the pilot provides a non-neutral command on the pedals? Such information is well documented for pitch an roll control (command of load factor and roll rate), but not for yaw.

On the A380, the documentation states that, "A pedal deflection results in a proportional sideslip and bank angle". I found no such precision for the A320, but it seems reasonable to assume the pedals command a sideslip angle.

In normal and alternate law on a A320, do the pedals command a sideslip? If not, what do they command?


texts: What types of data can be extracted from a non-motion flight simulator?

texts:
What are the types of data that can be extracted from a non-motion flight simulator?

Based on the type of data I want to do:

A comparison study between flight simulator data and ground-based systems data
To know if it's possible to calculate the fuel consumed by an aircraft while following certain ATC procedures, so that further improvements in fuel consumption can be explored by altering those procedures


texts: How many turns of a 737 trim wheel equal 2.5 degrees stabilizer deflection?

texts: After the well known crashes I looked at the question of stabilizer trimming. In case of trim runaway the pilot is supposed to "grasp and hold" the wheel manually steering the stabilizer. Hence my question: how many turns of the wheel to achieve a 2.5 degrees deflection of the stabilizer?


texts: Why is a urine test performed during pilot medical examinations?

texts:
I've wondered this for a long time (every six months while getting my latest first class medical), but what are the doctors checking for when they perform the urine test?

Maybe Drugs?  Medical conditions (which ones)?  Both?  Other things?


texts: How often do commercial flights go-around?

texts:
I've seen many references here to a flight going around, and YouTube is filled with videos of it happening, but I don't recall ever having been on a commercial flight that had an aborted landing. It might have happened when I flew as a small child, but, having been really, really excited to fly, I think I'd have remembered that.

How often do commercial flights actually abort a landing and have to make another attempt?

I'm primarily curious about US statistics, but non-US would be interesting as well.


texts: The NASA X-57 uses 12 electric motors for takeoff. Does it need 12 control levers or just one?

texts:
If the NASA X-57 uses 12 motors for takeoff, does it need 12 controllers (like throttle levers), or just one?

The traditional way of engine throttle design was 1 throttle per engine, but what if you have 12 engines? Twelve levers would be unmanageable, pushing a quadrant of 12 levers forward on takeoff.

I suppose that on initial setup, you would need a small dial for each prop to sync rpms. More sophisticated electronics could have a feedback loop to do this automatically.

So... what about just 1 controller, and 2 or 3 backup controllers for redundancy as they are electronic and could easily be blown. I'm thinking of a 3 or 4 position selector switch to choose the active throttle, sort of like choosing between magneto 1 and magneto 2 in a typical GA aircraft.

Yes, you could wire the motors up in banks of 4 and have a quadrant of 3 levers, but my specific question is:

Would having just one active controllers for 12 motors be acceptable?


texts: Can a sonic boom arrive before the source?

texts:
I'm on the ground, a fast jet flies from very near to the ground, I hear the sonic boom soon, but after the plane passes my point, right?

The real question I'm trying to solve is this:

I just heard an explosion-like sound, and then heard a jet pass. So this means there was an explosion. Am I correct?

One thing I doubt is that the "normal" sounds I heard after could also be "lagged", so it might have confused me about the timing, but I think that wouldn't make a big difference.


texts: Why do we commonly use a "/" in acronyms in aviation world?

texts:
In non-aviation world, separation between letters in acronyms is either nothing (e.g. URL) or a point (e.g. A.M.). But in the aviation world, the "/" is common (e.g. G/S, V/S).

I'm puzzled as:

some acronyms never use "/" (e.g. ATC)
some acronyms almost always use the "/" (e.g. V/S")
some abbreviation use this separator but are not acronyms (e.g. A/THR, THR containing more than one letter)

Why is this separator so spread in this worlds ?
Why some acronyms does not use this separator ?


texts: How and why would one call the cockpit of an A330 inside its nose gear bay?

texts:
According to this A330 call panel diagram,

there is an option to call the nose gear bay with the MECH button. Where is the connection for this in the nose gear bay, and what would it be used for? The closest I can find is in this video, where some connections to call the cockpit of a Boeing 777 are shown in the forward avionics bay, presumably to help with communication among maintenance personnel. Whether these jacks are similar to the MECH channel on the A330 I do not know.


texts: Why did Cessna use a new design for the C162, instead of updating the C150 design?

texts:
As I stare at the ceiling unable to fall asleep, airplanes are on my mind.  Failed airplanes.  Specifically: the Cessna 162.

I understand that Cessna perceived a need for a two seat trainer.  The CEO himself called that out: "The need for a modern, cost-effective two-seat trainer aircraft has never been greater, and we believe we are well positioned to meet that need."  I also understand that the light-sport aircraft (LSA) market was thought to be a significant driver for aircraft sales.  That turned out to be a gross miscalculation.  Cessna ended up selling 192 Skycatchers (versus a planned run of 600 per year) due to quality and price misses.  About 80 were not sold and retained as parts donors.  A fleet of ready-made LSA aircraft already existed (Champs, Chiefs, Cubs, T-Crafts, etc) so the value proposition of a new $150,000 LSA runabout was not compelling...or so it seems.

The following question assumes that there are folks on SE.av that have some industry knowledge of the GA manufacturing scene...

Why did Cessna not just resuscitate the proven 150 line (~24,000 built) and forego the LSA segment, given that the objective was to capture the two-seat training market and a good number of very cheap LSA airplanes already existed?

I recognize that there may be no good answer for this.  Maybe it was just one of those plausible-at-the-time business moves that didn't pan out.


texts: How do the airlines allot the passengers seats to make sure the balance is maintained?

texts:
How do the airlines allot the seats for the passengers?
Is there any procedure, like first front seats has to be filled next middle and at last the end seats?

Any algorithm works during the ticket booking to distribute the passengers according to their weight?


texts: Is it the engines or the fuselage that limits service ceiling?

texts: Reading this article about the Northrop Grumman E8 it says the the aircraft will be able to fly higher after engine upgrades. Wouldn't the max service ceiling be limited by the fuselage design too?


texts: What do the levels stand for in French Air Traffic Service Levels?

texts:
I am planning a flight to Le Touquet (LFAT) in France next week, I've been told that ATC is not open all days so I've checked the NOTAMS. This seems applicable but I'm not sure I'm interpreting it correctly:

  LFFA-B3753/14  A) LFAT  LE TOUQUET PARIS PLAGE B) 2014 Aug 01  07:00
  C) 2014 Aug 31  23:59 E) FIRE AND RESCUE HOURS OF SERVICE:
  0700-0900 1500-1800    : LEVEL 2
  0900-1500              : LEVEL 4
  SAUF 15,16,22,23,26-29 : LEVEL 2 ATS HOURS OF SERVICE LEVEL 5 O/R, PPR 24H
  TO OPR  PHONE: +33(0)3 21 05 03 99  FAX: +33(0)3 21 05 59 34 LEVEL 1
  OUTSIDE ATS HOURS OF SERVICE.

I think what this is saying is that it is operating at level 2 ATC hours of service except  (Sauf) on the 15,16,22,23,and 26-29th of August, but level 1 all other hours. I think what this means is that next week on weekdays it will be operating at level 2 hours of service. I also think that level 2 means 07-09:00Z and 15-18:00Z, and during this service level 5 will be offered, but all other times level 1 will be offered.

So I think that if I go on those days listed and times listed the tower will be open, otherwise it will be closed (I'm assuming that's what level 1 means), and that I will need to use French non-towered procedures, including French calls.

I'd like to know if I've made the right interpretation, and if there's a source of information about ATC levels in France. I've scoured the web for a couple of hours with no result.

So what are level 2 hours of service, and what service is provided? What is provided with level 1 ATS?


texts: Is it unprecedented for an F-16 to get hit by its own bullet(s)?

texts:
According to Dutch state broadcaster NOS, an F-16 was hit by its own bullet(s) in a training exercise:

  De F-16 die in januari aanzienlijke schade opliep tijdens een oefening boven Vlieland blijkt geraakt te zijn door zijn eigen munitie.

My translation:

  The F-16 that in January suffered considerable damage during a training exercise above Vlieland turns out to have been hit by its own ammunition.

They also added a picture of the damage:

Image attribution: originally by Inspectie Veiligheid Defensie, taken from nos.nl.

Comparing that picture with the following stock photo, it looks to me like the bullet that caused the damage entered from the front. Of course it could also be due to the aircraft flying at a high velocity.

Image attribution: "F-16 Cockpit (J-513)" by Gerard van der Schaaf // CC BY 2.0

Is this unprecedented? Or are there any records of other F-16 jets getting hit by or collide with their own bullets?


texts: What are the design parameters for airliner safety?

texts:
Airliners designed to carry multiple airfare paying passengers are regulated by CFR 14 Part 25, and by EASA CS-25. The design regulations are such that the probability of a catastrophic failure with multiple deaths is extremely remote or extremely improbable.

How is that defined? Can it be quantified at all?


texts: Why is fuel usage discussed per time, not per distance?

texts:
I don't understand why sometimes the fuel used for a flight is discussed in terms of fuel used per time.
I think I have seen it a couple of times here - not sure whether it was in some common context.

I would think that it's much more relevant how much fuel is used per distance in almost every respect, except designing engines.

As an example, this answer to the recent question How do you compare private jet and commercial jet efficiency? uses "x/hr USD" as in "Hourly fuel costs for a private jet can run from 800-2000/hr USD." I'm sure I noticed similar cases a couple of times.
It's fuel cost per time, instead of fuel weight or volume, but that does not make a difference in regards to the question.

Maybe there is a reason based on some "tradition"?


texts: MH370 blackbox - is it still possible to retrieve data from it?

texts:
If the blackbox of MH370 were to be found today, would it actually still provide any information, assuming that it was in 5km deep water or so for some 5 years now?
If not, why would you still be looking for the missing aircraft and especially the blackbox, if there was nothing to find out about the reason that caused the 777 to disappear?


texts: Is it allowed to scatter human cremains (ashes) from an aircraft?

texts: A serious question, here: There's gotta be a pilot out there somewhere who has done a memorial request to spray someone's ashes over a city street. I'm gonna do it out of spite for a lousy little mill town in Central Pa. There seems to be no laws against it on the books. 500' fly-overs are okay, spreading ashes falls under no FAA rule that I can find. When I go (soon, I'm an AO affected Vietnam Vet), I plan to have a contract with a crop-duster or acrobatic pilot for a decent show. Aside from (moral) advice, can someone comment, please? I wish to know of any known regulations governing this, especially any against.


texts: Can an aircraft operate IFR without ground-based navigation?

texts:
If I were to redo my avionics to only include a WAAS GPS unit and two comm radios, would anything prevent me from operating IFR? 14 CFR 91.205(d) only states that my airplane must have:

  (2) Two-way radio communication and navigation equipment suitable for the route to be flown.

I'm aware that this is not the most bulletproof way to fly hard IFR. In this case, assume that the aircraft is primarily used for currency/proficiency and the occasional light IFR flight.