texts: What happens to en route flights when a major earthquake etc. destroys facilities?

texts:
Suppose you're flying a big plane in to an airport like Mexico City, already in final descent, when an earthquake strikes.  Large cracks appear in the paved infrastructure catching some vehicles by surprise.  The airport suspends operations.  Planes planning to take off are stuck on the tarmac for at least several hours.
Planes planning to come in from farther away are told not to, maybe from an external seismic monitoring service if communications are out.  Those already in the air but far enough away to be able to divert can land at other airports.

Yesterday, the main infrastructure was inspected and found to be OK, and the airport reopened several hours later.  But what would have happened if the earthquake had been strong enough to destroy the runway or other landing-critical infrastructure at this airport and at the nearest alternative, so that neither "rack & stack holding patterns" nor "just go to the alternate" (as in e.g. a terrorist takeover at one airport) are viable options?  Are there special rules/considerations in place to help protect safety in such a rare region-affecting event?

Continuing the distinguishing analogy from the terrorist takeover question, this situation is more like a widespread cyber-attack, solar flare, or electromagnetic pulse that knocks out ground facilities and prevents landing at multiple airports without destroying in-air flights in a way that e.g. a sudden volcanic eruption or nuclear explosion might. This question also focuses on emergencies that arise quickly and without the kind of notice that would permit a planned closure (as e.g. a hurricane would).


texts: Is it possible to survive a free fall from an airliner at cruise altitude?

texts:
If an airliner were to breakup in flight, and a passenger were ejected from the cabin, would it be possible to survive the fall?

Assume that the aircraft broke up at a cruise altitude 30,000-35,000 feet. If it improved the odds, suppose the person were wearing a heavy winter jacket and a backpack with additional clothing in a plastic bag.

Is is possible the person could survive the fall? Are there steps the person could take that might increase the chances of survival?


texts:
Would using a full span spoiler and a separate flap be a better design than a flaperon for a STOL ultralight?

I understand many ultralights use 50% flaps and 50% ailerons.  The problem with this, is that it greatly reduces your Clmax.

I understand Zenith uses a full length combination flap and aileron, called a flaperon.  However I imagine using the 50% split aileron with full flap would still effect total lift.

What about using a 100% spoiler and a separate 100% flap?  Would that be a better design?  If not, why not?

See pic below


texts: Is the "PROB" in a TAF only applying to the next group or all following ones?

texts:
Let's assume I have a TAF that reads:

[...]
PROB40
TEMPO 0815/0822 5000 -SHSN BKN008 OVC015
TEMPO 0822/0909 1000 SN VV003
BECMG 0902/0904 16012KT

Which of the TEMPO / BECMG groups have a probability of 40%? All three because everything that follows PROB40 has a probability of 40%? Just the first TEMPO because PROB40 only means the one following line in the TAF? Or both TEMPO ones, and BECMG is again certain and not just 40% probable?


texts: Is there a mathematical formula to find the most efficient propeller? Is a five-blade better than a four-blade? Does software exist to aid in the calculations there?


texts: What if an airspeed prescribed by a published procedure isn't safe for a particular aircraft's operations?

texts: Departure and arrival procedures often prescribe airspeeds which must be maintained at certain fixes. 14 CFR 91.117 sets rules for airspeeds but has a paragraph which states that the airspeeds don't apply if the aircraft can't operate safely within those limits. Does any regulation or published recommendation alleviate aircraft from the airspeeds prescribed on instrument procedures for similar reasons?


texts: Could gliders be a clean, practical alternative to other forms of transport?

texts:
Would it be possible to use pure gliders as an eco-friendly mode of transport?
From what I have read so far, gliders can travel at a speed of 100-170 km/h. That would not be able to compete with a jet plane, but it could easily be faster than a car, and possibly even a high-speed train, since it can fly directly and doesn't have to follow train tracks.
So, would it be possible to build a glider that fills this arbitrary set of requirements that would qualify it for regular travel:

It needs to be able to carry at least 30 people plus luggage. Otherwise the pilots are much too expensive.
It needs to be able to fly regularly, only being inhibited by severe weather.
It needs to qualify for international, commercial passenger service in all matters (safety equipment, radio, ...)
It doesn't need to be able to fly around the year, pre-plannable months without service are acceptable.
It doesn't need to work with current infrastructure, e.g. it would be acceptable if the plane needs special runways and/or launching mechanisms.

Would it theoretically be possible to build something like this?


texts: May a Recreational Pilot demonstrate her/his own plane to a prospective buyer?

texts:
FAR 61.101(e)(12) states a recreational pilot may not

demonstrate that aircraft in flight as an aircraft salesperson to a prospective buyer;`

(Please note use of the world salesperson.)
AOPA's website publishes a question, presumably taken from the FAA knowledge test bank, which reads

Under what conditions, if any, may a recreational pilot demonstrate an aircraft in flight to a prospective buyer?
A) The buyer pays all the operating expenses.
B) The flight is not outside the United States.
C) None

According to AOPA (and other sites which publish the identical question), the answer is C) None.
So we can conclude the FAA knowledge test is saying that a Recreational Pilot may never demonstrate an airplane to a prospective buyer, no matter who is the plane's owner.
Is a Recreational Pilot de facto considered a salesperson when wishing to sell his/her plane? A lay definition of salesperson is someone whose job is to sell something. Certainly a private, non-dealer owner could not be considered to be "someone whose job...".
But perhaps the FAA has defined salesperson more broadly, or the test bank question could be erroneous (it wouldn't be the first time an official answer is subtly wrong).


texts: Is it normal for gliders not to have attitude indicators?

texts:
This answer shows a picture of and describes a "modern" glider instrument panel, with two variometers, airspeed indicator, altimeter, compass, temperature gauge and radio controls.

Notably (at least to me) missing from this is an attitude indicator (or "artificial horizon"). I had the impression that an AI was one of the more important indicators in an aircraft.

Is it frequently left off on gliders? How about other aircraft? Is this related to always avoiding flight outside of VFR (visual flight rules)? Is an AI not very useful or not useful at all in VFR conditions?


texts: Why is kerosene used in Aviation industry for turbogas and turboprop?

texts: Which are advantages (and disadvantages) compared to gasoline or petroil?


texts: What's the relation between TAS and Mach in tropopause?

texts: I understand that TAS decreases with altitude with constant Mach number in troposphere, however I'm not sure what happens in tropospause, as the temperature is constant, however the density is still decreasing. Does that mean the TAS will continue to decrease, just at a slower rate?


texts: What is this WWII four-engine plane on skis?

texts: I've seen this plane but I don't know its name:


texts: Can non-instrument rated pilots request practice approaches?

texts: I'm working on my instrument rating and wondering if I can practice ILS approaches without an instructor? Using a safety pilot, also not instrument rated, could I call approach stating VFR would like ILS into X. Or do I just call the tower and ask for it there? Or can I only do this with an instructor?


texts: Is there any website which is offering free real time tracking data of flights?

texts: Our customer always demand, and I think there is huge market of, live tracking data. We need to ease either our customers or their relatives that they have reached their destination safely. So as I was moving around, I found out that there are too many live data APIs, but I want to integrate the free live API in order to check first. Can any one give me options that provide live APIs? Also if I need to get ADS-B what can I do and how does it work?


texts: What are the FAA/CS requirements for rubber chocks? Do they include material, manufacturing processes, etc.?


texts: What is the altitude required to bypass Russia's airspace restrictions for airlines?

texts:
Given that Russia charges a lot for flights over Siberia from Europe to Asia, would flying above the
Kármán line (100km)
effectively bypass this restriction (from legal perspective) ?
If not, what is that altitude ?


texts: Is the 737 Max's AOA disagreement warning light an actual light?

texts:
The New York Times article Boeing Believed a 737 Max Warning Light Was Standard. It Wasn’t. includes the following:

When Boeing began delivering its 737 Max to customers in 2017, the company believed that a key cockpit warning light was a standard feature in all of the new jets.
But months after the planes were flying, company engineers realized that the warning light worked only on planes whose customers had bought a different, optional indicator.

later:

The warning light notifies pilots of a disagreement in the sensors that measure which direction the plane is pointed, a potential sign of a malfunction. This light could have provided critical information to the pilots on two flights that crashed shortly after takeoff in recent months.

and later:

Because only 20 percent of customers had purchased the optional indicator, the warning light was not working on most of Boeing’s new jets. Neither Lion Air nor Ethiopian had the indicator.

note: All instances of boldface have been added for emphasis.
My question is asked to clarify the nature and appearance of the warning light itself.
Is this a physical light bulb-based indicator on a physical panel, or is it graphically implemented within a flat panel display screen? In either case, if the option described above was not purchased, is the (now non-functional) warning light still present and visible?
In that case, is there any secondary visual indication that would allow one to know that it's not working?


texts: How does an airliner deal with cabin altitude at an airport above 8000 ft?

texts:
There are a number of airports above 8000 ft altitude. FAR 25.841 states:

  Pressurized cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than 8,000 feet at the maximum operating altitude

How does an airliner operating from a high airport, say from El Dorado, deal with cabin pressure? Do they actually pressurize the cabin after takeoff and depressurize it after landing?

Note: the answer can be of any jurisdiction though FAA seems relevant here as US airlines operate from there.


texts: I hold both a Sport Pilot License and a Student Pilot certificate. Can I do my BFR in a C-172?

texts:
FAR § 61.56.(c).(1) states that every two years I must have

  Accomplished a flight review given in an aircraft for which that pilot is rated by an authorized instructor.

The answer to my question hinges on the exact meaning of the word "rated". If I've been signed off to solo in a C-172, am I "rated" for that aircraft as far as this regulation is concerned?


texts: General advice on flight simulator hardware

texts:
I am new to flying and have only had a couple of lessons in a Cesna 152 but want to get some practice on a simulator as I'm quite old and don't learn quickly compared to youngsters. My instructor wasn't too forthcoming but mentioned that the Microsoft flight simulator was the best software if I wanted to get some practice of that type. I believe I would also need a flight yoke system for a Cesna 152 however am concerned that I don’t waste my money on wrong kit. I believe I would need in addition to the software  a yoke , instrument panel and rudder controls.  I appreciate that its no substitute for practical flying hours but with current lock down under COVID being strictly enforced where I am there is no chance of getting into a plane in the next few months. Please can you   advise suitable products with any links. I have also seen some ads for VR headgear would that also help me?

Thanks


texts:
How does ILS (Instrument landing system) work?

I know it provides guidance to the runway by  two signals, one modulated at 90 Hz, the other at 150 Hz, but how the airplane lock on those signals?

Which system in the plane is responsible for the ILS? Is the autopilot responsible for it?
If autopilot is used for an ILS approach, at what point does the pilot take manual control?


texts:
I saw this plane yesterday:

What is this plane? And what is the reason for it's odd-looking nose?


texts: Why is everything in aviation written in abbreviations?

texts:
please tell me if there is already a duplicate, I could't find one.

Why is like everything in aviation written in abbreviations?

ACARS Message:

  /WND 275057/MCH 81/TRB LT CHOP /SKY UNDERCAST/ICE NONE

Why don't they just write:

  Wind: 275 at 57 Knots. Light Turbulences. Not cloudy, No ice.

And also in the cockpit

HDG, SPD, ALT, LDG GEAR.

Of course, I know, its shorter and faster to read, but wouldn't it make such a bug difference if you write "Heading" instead of HDG?

Thanks, Noah


texts: Why are the power and drag curves called polars?

texts:
See Wikipedia:Drag polar and Wikipedia:Polar curve (aviation) for example.

These curves are not on a polar coordinate system. Why are they called polars?


texts: What is a demonstrated crosswind component? Is it possible to land in a crosswind greater than the demonstrated crosswind component? Is it safe to?


texts: Do rivets on airframe need special sealant to be airtight on pressurized airliners?

texts:
Do rivets on airframe need a dedicated sealant, e.g. epoxy, to be really airtight on a pressurized airliner, or is the expansion of the rivet shaft already sufficient?

As a side note, how are carbon fiber panels joined with aluminum or titanium panels?


texts:
Quadcopters use both direct and contra-rotating propellers to be able to turn and to balance the torque caused by the each of the propellers.

Propeller performance measurement:

When testing the propellers for these quadcopters, why is their performance measured only in one direction of rotation? Would it be useful to test both the right handed and left handed rotations to provide more information to the designer?

Propeller pitch selection:

Why would a designer select a lower pitch to diameter ratio for quadcopters when there are higher and more efficient ratios to choose from?


texts: What causes the adverse pressure gradient that leads to flow separation?

texts:
When reading about flow separation I generally see a diagram like this:

imp source: Wikimedia commons

This shows that the boundary layer slows as it passes over the wing, eventually creating an adverse pressure gradient. The effect being more pronounced close to the wing it will cause a reversal of flow and separation of the boundary layer.

I can easily see how this leads to flow separation, but I’m unsure as to what causes the boundary layer to slow down like this. I’ve read that the effect is independent of surface friction.

I know the air at the surface is stationary wrt the wing and its velocity increases the further away it gets. But if I look at the arrows in the diagram and select, say, the second one from the surface, it slows down as it goes along the wing, eventually reversing. At first I thought that the still air at the surface was somehow affecting it, but I don’t know how (shear stress?). But even at that, stationary air can not make it flow backwards.

So, what causes the flow closer to the surface to slow?


texts: Why do X-wing configurations missile/guide bombs use symmetric airfoils?

texts:
From all the missiles/guide bombs I have come across, I've always observed that a symmetric airfoil is used for both the wing and tail.

Why not have a cambered airfoil for the wing and a symmetric airfoil for the tail? It would provide a better range for the missile/guide bomb.

If an airfoil were to be selected for X-tail missile/guide bomb configurations, what is the selection criteria? I'm trying to better understand the reason for this generally accepted design decision.

Any answers/suggestions would be appreciated.


texts: What does "Last Call" mean on CTAF frequency?

texts:
At non-towered airports I sometimes hear pilot's using the CTAF use the term “last call” as they depart the traffic pattern. This is not listed in the AIM.

What information is this suppose to convey and should I care?

Does this have some meaning internationally that I don't know about?


texts: What would prevent a solar powered aircraft staying aloft forever?

texts:
Focusing on aircraft, not balloons, I found this question that led me to some basic research on atmospheric satellites. I imagine the technology has evolved since NASA's research more than 10 years ago.

Given the following points:

The aircraft cannot stay in flight forever, as it must land for maintenance (as would any aircraft).
In 2001, NASA planned a 40h long trip based on solar powered technology.
A fuel-powered UAV can stay up to 33h in flight.
The Qinetiq Zephyr stayed aloft about 2 weeks.
Redundancy can be added to continue operation in case of equipment failure (as in any commercial aircraft).
'Real' satellite can stay airborne for several years (payloads seem to be able to operate several years without maintenance)
If the aircraft can land, the payload and equipment do not have to be as reliable as they would on 'real' satellites, as they could be changed or repaired.

For an atmospheric satellite based on solar-powered airplane technology such as the NASA's Helios, operated in normal conditions, what is the most restrictive element that make landing compulsory?


texts: What is the difference between aluminum tape and speed tape?

texts: What is the difference between aluminum tape and Speed tape? Are these same or not?


texts: How Does the FAA Define the Dimensions of the Touchdown Zone?

texts:
Does the FAA give a regulatory definition of the term "Touchdown Zone" for use within the context of landing operations?

In 14 CFR 91.175 the FAA requires—in certain cases—that pilots must be in a position to land within the "Touchdown Zone":

(c) Operation below DA/DH or MDA. Except as provided in §91.176 of this chapter, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless—
(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under part 121 or part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

Is this zone explicitly defined? If so, where is the applicable definition found?

No definition is offered in 14 CFR 1.1. However, several uses or definitions of this term do exist in various FAA advisory documents. These uses or definitions are generally similar, but include variances. A few of these include:
AC 91-79A (referencing an obsolete document):

the TDZ is referred to as a point 500-3,000 ft beyond the runway threshold not to exceed the first one-third of the runway

AIM 2–1–5:

3,000 ft beyond the landing threshold or to the midpoint of the runway, whichever is less.

The Pilot Controller Glossary:

The first 3,000 ft of the runway beginning at the threshold.

Also of note, the runway touchdown zone markings on long precision runways generally extend to 3,000 ft beyond the threshold.


texts: Must Part 91 pilots comply with runway departures marked as NA?

texts:
I answered a recent question about the meaning of Takeoff Minimum NA and indicated that they do not apply to Part 91 pilots, but after thinking about it, I’m not so sure. I can’t find anything specifically saying that you can’t use runways marked as NA, although often the reason that the runway is not available would make using it a very unwise decision. e.g. terrain or obstacles. On the other hand an unmonitored ground facility when the tower is closed wouldn’t be an issue if you were using GPS to fly the departure.

The AIM 5-2-8 just says,

Pilots operating under 14 CFR Part 91 are strongly encouraged to file and fly a DP at night, during marginal Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC), when one is available.

Part 91 §91.175   Takeoff and landing under IFR. (f) Civil airport takeoff minimums. excludes Part 91 operators by giving limitations that only apply to Part 121, 129, and 135 operators.

A a towered field with an operating control tower, they are unlikely to allow you to to takeoff under IFR on a runway marked as Takeoff Minimum NA but is there any restriction when the tower is closed or there is no tower?


texts: How can I properly model paper airplane physics?

texts:
I am working on a game involving flying and steering a paper airplane for WP7. I want the plane to fly just like how normal paper airplanes (online game) but I can't seem to find an equation for how paper airplanes fly.

Anyone have any experience with this? In my game now, it just follows the usual motion for an object in a vacuum, which makes for some flight, but it doesn't feel perfect, and traveling at a slight downward angle makes you lose speed, which isn't right.

I am asking do paper air planes have a maximum velocity brought on by its paper design even if control and thrust was possible maybe using composite cardboard material?

On Physics.SE: Paper airplane physics


texts: What kind of malfunction is an "artificial horizon"?

texts:
I was once (like ten years ago) on a transpacific flight with Northwest from KIX/RJBB to KDTW on a Boeing 747 and our flight as delayed at the gate for about an hour because of some issue with a "floating horizon" (I remembered incorrectly, the issue was a "artificial horizon").

Is that a malfunction with the attitude indicator? What exactly went wrong? It sounded like they fixed it by swapping out a component, maybe the instrument itself?


texts: How much lift does the wing attach fitting actually carry?

texts:
How do I calculate the lift force that the the bolt that join the wings to the fuselage of a strutted or braced airplane carry?

I know in a cantilever airplane,the bolts have to carry all of the lift load on a wing but how about a strutted airplane - how do the wing attach bolts share the lift with the wing braces or struts, i.e. is the lift load shared between them, the bolts carrying half and the bracing wires or struts carrying the other half?


texts: How can the canard configuration increase the aircraft's maneuverability?

texts: I know that in many of the fighter jets, there are canard configurations like in F16, SAAB Gripen etc and heard they increase the aircraft's maneuverability. Can anyone explains how a canard helps in increasing it?


texts: What are the visual differences between Trent 892 and 900 engines?

texts:
Are there any visual differences between a Trent 892 and a Trent 900 engine?
Particularly referring to the ones mounted on the 777-200.


texts: Is Turn and slip indicator a good back-up for the attitude indicator?

texts:
I was reading my Aircraft general knowledge book, and noticed something peculiar that was written.

The book described that the turn and slip indicator works as a back-up in case of a malfunctioning artificial horizon / attitude indicator.

From my perspective this seems strange to me because of the following:

An attitude indicator shows pitch information.
A turn and slip indicator shows: "no pitch information".

Therefore the usage of a Turn and slip indicator as a back-up for the attitude indicator is not logical from my (probably narrow) point-of-view.

My Questions:

Is it true that a Turn and slip indicator is a valid back-up for the attitude indicator?

To what extent is a turn and slip indicator a back-up for the attitude indicator?


texts: How to become a expert in Flight Operations Business? (Flight Dispatch, Weight and Balance etc.. )

texts:
I am working in IT industry relavent to airline operations (like flight dispatch related products).I would like to enhance my knowledge in Flight operations area.

What are the trainings (IATA/others) or courses  recommended for flight operations related business process?


texts: How can I calculate the optimum loiter airspeed for an aircraft?

texts: I am in the conceptual phase of designing a 10 seater amphibian aircraft. I have done the initial sizing using Raymer and Roskam's methods. I have got my design point. To do a constraint analysis as well as to find the fuel fraction for loiter phase I need to calculate the optimum loiter velocity for a loiter time of 60 minutes at 7000ft. Breguet's range equation doesn't help since I don't know the fuel fraction of loiter phase. How can I calculate the loiter airspeed?


texts: Could Mach 1.4 be a better design point for SST?

texts:
There's been a number of recent proposals for design work on low-supersonic bizjets that would cruise at Mach 1.1-1.6, the common theme being avoiding a sonic boom.

The conventional wisdom is to avoid this range, and either stay subsonic or go all the way to Mach 2+, because you sacrifice some efficiency the moment you cross Mach 1:

Sharp nose and supersonic airfoils result in lower L/D across the envelope.
Thin airfoils add weight and require more fuselage space for fuel tanks.

On the other hand, staying at low Mach avoids a few other penalties:

The 12:1 slenderness of modern widebodies translates well to a low-Mach SST, allowing for a similar cabin layout. This is critical.
Skin temperature allows the plane to be built with the same resins as subsonic airliners.
Less COL shift, higher AR wings, reasonable bypass engines make it easier to meet TO lift and thrust requirements.
Speculatively, cruise altitude might be kept at FL450 to avoid stricter pressurization rules.

What I'm not sure is which set of factors matters more. It's difficult to glean from existing designs, as they're not really comparable between one another.

The Aerion's wing should behave well on landings, and it claims only a 22% fuel penalty for going supersonic. But its slender nose and long tail leave just 18% of its length for the cabin, so it can't be used as an airliner template.

This is probably caused by its role as a status symbol and regulatory weight limits; actual SST managed a proper length cabin, and the 2707 was even planned as a widebody. Thin wings have are also featured in some subsonic proposals, so they're not a total efficiency killer.

I'd imagine a Mach 1.x airliner to be a 779-sized twin, with 788-like seating capacity, area-shaped akin to the Sonic Cruiser, an ogive nose (F-16 style), Aerion-like trapezoid SNLF wings, nacelle engines.

The question is, could a low-Mach SST, if sonic boom was publicly accepted, be closer in efficiency to subsonics than to historic high-Mach designs?

To narrow down the scope, let's explicitly exclude:

Whether there is any market for such an aircraft.
Whether Mach 1.x is fast enough to make a difference.
Engines, as it's a major subject in itself. Just assume a rubber engine matching a loose trend line of TSFC~=0.4*Mach.max.

Leaving in scope the technical subject of the efficiency loss imposed by the aerodynamics of supersonic flight. It comes down to how good a L/D can high-tech airfoils like SNLF and area-ruled widebody provide, with how little compromise on capacity, in the range of Mach 1.1 to 2. Fuel per seat-mile being the figure of merit.

To help set a baseline, I've plotted a mix of historic and calculated numbers for known aircraft:

To put the question in more formal terms, I'm looking to estimate the seat-miles/kg function's behavior for an optimal design in the low-supersonic range.

The red line assumes the worst-case scenario and is based on just stuffing seats into the AS2. The green line represents a best-case scenario based on claims with the Sonic Cruiser as a baseline. The truth is probably in between.


texts: How does a fire suppression system work?

texts:
On fire events, some aircraft have a complex system, usually called a Fire Suppression System.
Where are they located? Do they work automatically, or it is necessary for the crew to activate them?


texts: Will the steep beta descent mode become illegal for new aircraft?

texts:
The PC6 is a popular skydiver carrier due to its ability to use steep nose down beta descent to get back to the ground quickly, even beating free falling skydivers.

(YouTube)

FAA AC25.1155x (I only saw the draft) proposes that a "means to prevent intentional or inadvertent selected of reverse thrust or propeller pitch below the flight regime" be required, which cannot be overridden. The intention is to prevent several accidents resulting from said deployment. The lockout means must not degrade landing performance, so the intent is not to eliminate beta entirely.

Does this mean that no new aircraft can be certified that has a descent mode from altitude similar to the PC6?


texts: FAR 91.215 (b)(3)(ii) -- transponders-- does the "or below 10,000' MSL" clause have any practical significance?

texts:
Here are some of the airspaces where FAR 91.215 requires aircraft to have transponders--

  (b) ...

  (2) All aircraft. In all airspace within 30 nautical miles of an
  airport listed in appendix D, section 1 of this part from the surface
  upward to 10,000 feet MSL;

  (3) Notwithstanding paragraph (b)(2) of this section, any aircraft
  which was not originally certificated with an engine-driven electrical
  system or which has not subsequently been certified with such a system
  installed, balloon or glider may conduct operations in the airspace
  within 30 nautical miles of an airport listed in appendix D, section 1
  of this part provided such operations are conducted -

  (i) Outside any Class A, Class B, or Class C airspace area; and

  (ii) Below the altitude of the ceiling of a Class B or Class C
  airspace area designated for an airport or 10,000 feet MSL, whichever
  is lower;

Question 1: May an aircraft with no engine-driven electrical system and no transponder operate at 10,500' MSL in the airspace 10 miles west of South Valley Regional airport (U42) near Salt Lake City, where the overlying Class B shelf has a floor at 11,000', and a ceiling at 12,000' MSL? (Link to sectional chart.)

Note that KSLC is one of the airports listed in the Appendix referenced in FAR 91.215(b)(ii)-- this is a reference to the Mode C veil.

Question 2: May the same aircraft operate at 17,500' at the same location?

Question 3: (only applicable if the answers to (1) and (2) are both "yes")-- Does the "or below 10,000' MSL" clause of FAR 91.215(b)(3)(ii) have any actual practical significance of any kind?  What is an example of some airspace where an aircraft with no engine-driven electrical system and no transponder may not operate, but would be able to operate of the "or below 10,000' MSL" clause were absent from FAR 91.215(b)(3)(ii)?

Note that FAR 91.215(b)(3) is simply an exemption to 91.215(b)(2), which appears to only apply up to 10,000' MSL, so it appears at first glance that the answers to the questions ought to be "yes", "yes", and "no".  Is this really correct?

See also related question FAR 91.215-- may an aircraft with no electrical system and no transponder overfly Wheeler AAF at 9500' MSL?


texts:
On January 23, 2015, I flew from Buenos Aires, Argentina (SAEZ) to Santiago, Chile (SCEL). It was a very comfortable night flight in a Boeing 787 Dreamliner of LAN airlines, though it was delayed.

During the descent and a pronounced turn to the left at approximately 4,000ft above the Andes Mountains, I saw through the window a wood fire in the middle of darkness with some shadows around. Then a brilliant white light blinking: three short flashes, three long flashes, three short flashes. I thought: Wow! That antenna blinked like an SOS signal!

One second after the first sequence, again: three short, three long, three short. Then I unfastened the security belt to run and tell the closest flight attendant: Sir! There is an SOS signal there, and he started to give attention to it.

After a successful landing on runway 17 L/R, I asked the flight attendant if they have a procedure to handle this kind of sightings. He told me there is no such procedure and that I should go to inform the civil protection office.

Due to a lack of enough time before the next flight, I asked a security officer to inform the civil protection office, giving her the flight number, exact time of the sighting and after calling the person in charge, she asked me for my name and details about the sighting. Trying to be descriptive, I clearly told her all details before running to catch the next flight and almost losing it.

How should passengers report SOS signal sightings?

P.S. The place of sighting was somewhere over the mountains in the west of Los Andes in Chile.


texts: Is there a public NOTAM archive that's searchable by airport?

texts: Pilotweb lists NOTAMs currently in effect. Is it possible to view or sort the history for a particular airport?


texts: How does headwind influence the results of a pitot tube and therefore the airspeed indicator?

texts:
What I know so far

I recently read about pitot tubes and their use in aircraft. For the basics I consulted Wikipedia, and also went through the definitions for airspeed, groundspeed, and the various other airspeed definitions (TAS, IAS, EAS, CAS). Furthermore I made myself familiar with aircraft speed indicators.

At first everything seemed logical, I thought I understood the working principle. But then a few days ago I came across the question how wind (headwind, for that matter) is accounted for on the airspeed indicator.

Question

Assume an aircraft that is standing still on the ground, experiencing a 60 kt headwind. Will the airspeed indicator show anything that is related to that headwind? Why/why not?


texts: Is there a European equivalent of VFR Flight Following?

texts:
In the US, Flight Following is a radar service provided to VFR aircraft on a best-effort basis. Controllers provide traffic advisories but they don't issue clearances or instructions and the pilot is responsible for maintaining separation from other aircraft, observing altitude, airspace and other flight rules etc. Flight following is only provided when the controllers' workload permits and it may be terminated at any time.

Is there an equivalent service in Europe? I've heard of something in the UK called "basic service" but I don't know if it's the same thing and if it's UK only or a Europe-wide service.


texts: Has there been research into alternatives for the vertical stabilizer?

texts: Are there some activities in research for replacing the vertical stabilizer with a turnable horizontal stabilizer? (flight direction stabilization like the birds)


texts: How to compare compressors of different efficiencies and pressure ratios?

texts:
I have two different engines, the CFM56, and the CFM LEAP-X. I roughly know the design point (take-off) isentropic efficiency and the pressure ratio for the LPC/HPC for both of them which are different from one another and can be provided as an input in a program.
I want to compare the compressor pressure ratio of the engines in the off-design (cruise) condition, which I believe will again have different pressure ratios and efficiencies. Can I somehow directly compare the pressure ratios of the two compressors? Do I need to have similar efficiencies to make such a comparison? Also, what role does polytropic efficiency play in this?


texts: Do mono spar wings need compression strut(or ribs)?

texts:
Loyolksip

Regarding airplane wings, are compression struts needed in a mono spar wing?
Secondly, are anti drag and drag wires needed in a mono spar wings?


texts: What is the order of Reynolds number inside the Compressor at cruise conditions?

texts:
I am doing a CFD study on a probe that will be installed inside a compressor of a civil aircraft for my final year project. I need to know the Reynolds number inside a compressor at cruise conditions. Probably, if somebody has its variations along all the stages it will be really helpful. HPC /IPC/LPC any might do? I may also need the reference length chosen (which is usually the chord).

Thanks a lot in advance
Abhishek VERMA


texts: Why was this commercial plane highly delayed mid-flight?

texts:
What could be the main reasons for a short-haul flight to be delayed over an hour in-flight?

Recent Lufthansa LH 2227 CDG-MUC flight took off only half an hour after scheduled time, but landed at destination delayed nearly an hour and a half.

Meaning (if I am reading these stats correctly) that this particular flight spend an hour extra in the air over scheduled time. I begin to question if there is enough fuel for the plane to stay that long extra?

I flew the very same flight few days ago and that flight also took of half an hours after schedule and landed fifteen minutes after schedule. Meaning that a plane manage to "work out" half of its delay en route. This particular, pictured flight not only didn't work out its initial delay, but also added another hour to it while being in air.

I was always told (and saw that in my small commercial flying experience) that

short- or middle-haul flights delayed 15-30 minutes on take-off,
long-haul flight delayed 60-90 minutes on take-off,

are nearly always able to land on-time, effectively "working out" their initial delay during flight, by flying faster etc. What happened or could happen here?


texts: How OK or not OK is it to consequently delete correct answers

texts:
I couldn't help noticing a small group of players very consequently deletes all my answers, leaving questions with heavily biased answers only.
Aside from it being annoying to have players launch personal attacks on me, it leaves all remaining answers to be massively opinion based, thereby eligible for deletion.
How is that OK and what can be done about it if it isn't?


texts: How to calculate the lift starting from the vertical speed?

texts:
Is it possible to calculate the lift of an aircraft knowing its speed (IAS,TAS and GS), its vertical speed, its altitude and its weight?
Because if we look at the force of an aircraft in flight: the lift is opposed to the weight and if the lift is greater than the weight, the aircraft climbs with a certain rate (vertical speed) proportional to the lift.


texts: Why do helicopters have windows near the pedals?

texts:
What is the purpose of the clear windows in some helicopters in the floor of the nose, right where the pilot's feet and pedals are?
For example, here's a Huey with windows clearly visible:

Airbus helicopter example:


texts: Is ground school required to get a Private Pilots License?

texts:
I know that there is a written exam that you are required to take, but do you have to go to a class in order to study for that test?  If I'm really good at just learning from a book, can I just learn that way, maybe take a couple practice tests and then take the exam?  Or are they going to need proof that I went to some certified class?

More subjectively: Assuming it's allowable, is it a bad idea?


texts: What is the function of cross bracing of interplane strut?

texts:
Pic 1 is the top and lower wing of a biplane called Bloop Ultralight,what is the function of the cross bracing between the interplane struts  as seen in pic 1(I'm not talking about landing and flying wire)?

Is it there to resist wing twist?  If yes, why is it not in between the interplane struts closer to the wing tip since wing twist and torsion is greatest at the wing tip?....as seen in pic 2


texts: How are north and east compents of the wind calculated, given a wind speed and direction?

texts:
I have a wind speed and wind direction of an aircraft. I need to find wind component along the true North axis and East axis.

Can anyone explain me how to do that?

Say wind speed is the hypotenuse in the Right angled triangle and angle is wind direction. How to find wind speed along north axis and east axis?


texts:
I noticed many planes, especially Boeings (correct me if I'm wrong anywhere), start engine "2" first and shut down engine "2" last.

However, I was watching an Airbus A350 cockpit video when I realised the A350 starts engine 1 first and shuts down engine 1 first. Hence, I have 2 questions:

In which order should the engines of the A350 be started and shut down?
What determines this order and are they the same/ similar on aircraft of the same manufacturer or can they differ within the same manufacturer as well?


texts: Can a commercial airliner be too heavy to take off?

texts:
According to this question's answers, MTOW (or MTOM) is the Maximum Take Off Weight, which is everything up to and including trip fuel. Then there is one step above that, MRW, or Maximum Ramp Weight, which is MTOW plus fuel used to taxi out to take-off.

Can a plane be given too much roll-out fuel, so as the plane is actually too heavy to take off, without having to do perhaps another lap around the airport?

My thoughts are that there are simply no scheduled flights which require a total amount of trip fuel that would make roll-out fuel cause the plane to be too heavy for take off.

EDIT: Although (in a comment) I am asked to possibly change the title of the question to fit more closely (include fuel), after considering it, I've decided to leave it alone. It is unlikely that a plane would be loaded to the point that it is too heavy to take off, before fuel is added. I believe it would be a 100% certainty that it was the addition of fuel that will make (all)(commercial) aircraft go beyond MTOW. There might be some edge cases of contents (payload) being too heavy, but if that were the case the plane would not even be considered for take off (without fuel).


texts: What are the advantages and disadvantages of having a single castor wheel as compared to 2 wheels in an airship?

texts:
I am working on a project to create a mid-size airship having a payload of 25kg. I am in a bit of problem regarding choosing the appropriate landing gear design for it.

Which design would be better, considering the tradeoff with weight, which is a very important parameter. Is using 2 wheels to stabilize my system further worth its weight penalty, or a single wheel would be better like Zeppelin?

I would appreciate any  help.


texts: Does the Antonov An-225 have an Auxiliary Power Unit (APU)?

texts:
Most APUs are installed in the rear, see the above image of an Airbus A380 as an example. On the An-225, no APU exhaust is visible at the rear of the aircraft.

So does the An-225 have an APU, and if yes, where is it located?


texts: What are the dimensions of the parking apron?

texts: What are the approximate dimensions of the apron aircraft zones, ramp, aircraft stands such as Airbus A380, Boeing B737, F16.


texts: Why no safety measures for air passengers?

texts:
Why have parachutes not been provided/safety measures taken in passenger carrying aircraft in case of a crash, so that at least they have some chance of survival?

It's like you are stuck in a bottle but until now, I am looking for an answer for how to save peoples' lives?

Even our cars have airbags in case of an accident but why nothing for air passengers?

Why is it not possible?


texts: Turboprop vs turbofan (in regional aircraft)

texts:
I'm trying to figure out WHY turboprops are more efficient at lower altitudes and airspeed, while turbofans are better at faster speeds and higher altitude.

Simplistically, my explanation is the following:

Gas turbine part of both turboprop and turbofan engines is basically the same, so BOTH must benefit from increasing altitude.
However, as TAS also increases with the altitude, turboprops start experiencing supersonic effects (shock waves) at propeller tips, which limits their ceiling.

Is this explanation correct? What formulas can support it? Why turbofan is less efficient than turboprop at lower altitudes?

Thanks.


texts: Do icing limits exist for parked aircraft?

texts: Are there any aircraft that have a limit on the amount of ice or snow that can be on the aircraft when stationary and on the ground?


texts: Why do planes employ vortex generators if the laminar flows exhibit a far lower skin friction drag than turbulent flows?

texts: I am a student and still relatively new regarding fluid flows. Our professor asked this and I can't find a source to answer this question.


texts: Why did the early versions of the Me-109 use a braced stabilizer?

texts:
The Messerschmitt Bf-109 had struts holding the stabilizer in place up and including the E version. I marked it with a red circle in the picture below of the 109 E-3 of the Flying Heritage Collection.

Bf-109 E-3 in flight (picture source)

Given that Willy Messerschmitt was fanatical about reducing drag, and contemporaries like the Hawker Hurricane, the Supermarine Spitfire, the Curtiss P-40, the Heinkel 112 or the Dewoitine 520 had cantilevered stabilizers, why would he tolerate a strut on the tail of his new fighter aircraft?


texts: Is cabin air freshened when a plane is taxiing or on the ground?

texts:
I know that commercial aircraft continuously freshen the cabin air when aloft by compressing and cooling the air.

Is that true when the aircraft is on the ground, at the gate loading or taxiing?


texts: What is situational awareness and why is it important?

texts: What is the definition of situational awareness? In which phase of flight is situational awareness the lowest, and why?


texts:
In a facebook group I stumbled over this nice little picture:

Also there was a discussion about the type rating of this plane, especially if it classifies as a multi-engine plane. It is a Colomban Cri-Cri (MC-12/ MC-15).

What I've learned from the discussion and this document is, that this is an experimental plane and doesn't fall in the classic regulations and that UK's CAA doesn't require a multi-engine rating for the pilot. I think that answers the original question.

But in this thread and another dicussion on another website I saw a lot of discussion about what regulations would apply if it would not be an experimental craft and what the FAA would say about it.

So my question is: There have to be specific requirements for a plane to require a multi-engine rating. To stay specific here, let's only look at the FAA. (I come from Germany, so if there would be any differences it would be interesting, but isn't required for this question)

Some people cited different paragraphs, but it seems none really applied and there was a lot of confusion. But I doubt that there is anything regarding aviation that is not tightly regulated, so I think there must be specific rules.

There is already a similar question regarding the Cri-Cri on this page here, but it has a different focus and it was stated that there would be no reason one couldn't file flight time in this plane as multi-engine flight time, but nothing precise.

So, what are the requirements for an airplane to be considered multi-engine and require a multi-engine rating to fly it? Also, why is this airplane considered single engine from a pilot perspective?

Note: I'm not a pilot, only a flight-simmer and aviation enthusiast.


texts: Does the jet blast from a large aircraft pose any risk for other aircraft nearby?

texts:
We know that the jet blast of jetliners - A320, B737 and bigger - are dangerous for people passing by, airport vehicles and even small planes, and we must always maintain a huge distance to avoid receiving this jet.

So, is there any risk or damage to other similar sized aircraft queuing for takeoff or whatever?


texts: What is automatic control connections and how does it work?

texts:
The Rolladen-Schneider LS4B control connections are automatic. This feature, also called automatic control hookup seems to be common. The last time I assemble a glider was more than a decade ago, and controls had to be mechanically (re)connected one by one.

What is automatic control connection? (I imagine it is some mechanism connecting controls when assembling wings). How does it work?


texts: Why a higher compressor pressure ratio results in higher Thrust and lower TSFC?

texts:
My professor usually asks us in our exams to plot the Thrust-Pressure ratio and TSFC - Pressure Ratio charts and justify the tendencies observed.

(TSFC = Thrust Specific Fuel Consumption).

We all know that, as the compressor pressure ratio ($\pi_c$) increases, the higher the Thrust ($F$) and the lower the $TSFC$. Here is a graph (which was taken from the book Fundamentals of Jet Propulsion with Applications, by Ronald D. Flack).

This chart was made after taking the final expressions for $F$ and the $TSFC$ (which are huge) and plotting them against $\pi_c$ using a computer. Obviously we don't have computers in the exam, nor we have enough time to derive such complex formulas. Here is an example for the (non-dimensionalized) $TSFC$:

Instead, I want to impress him with a convincing, non-mathematical, qualitative explanation of this behaviour.

Therefore my question reduces to: why, physically speaking, does the thrust increase with $\pi_c$? (The answer to "why does the TSFC decrease with $\pi_c$ can be answered saying that $F$ and $TSFC$ behave inversely to one another).

This is my attempt:
As the compressor pressure ratio increases, the flow will be mixed and burned more efficiently in the combustion chamber, therefore increasing the energy available for the nozzle to accelerate the flow. Since the jet thrust increases with the exhaust speed, we can rest assured that a higher pressure ratio will translate into a higher thrust.
The $(TSFC-\pi_c)$ behaviour will be inversely proportional to $(F-\pi_c)$, since $TSFC=\dot{m}_f/F$

NOTE: My explanation of the process, I think is a bit incomplete. For example, it doesn't explain why there is a $\pi_c$ for which $F$ will actually start decreasing (in the graph, this $\pi_c$ value is around 15).


texts: How do wide-bodied commercial aircraft achieve pressure equivalent to 6000 feet altitude?

texts:
I read an LA Times article which states the following.

To reduce the stress on the traditional metal frame, airlines now pressurize the cabin to be closer to the pressure outside. When a plane is cruising at 36,000 feet above sea level, the atmosphere inside the cabin feels like its 8,000 feet above sea level. For passengers, that can cause shortness of breath and fatigue.
But with new fuselages made of stronger, more flexible carbon-reinforced plastic composites, the plane can withstand more stress, allowing airlines to increase the inside pressure to a more comfortable atmosphere that feels like 6,000 feet above sea level.

Now I'm assuming that these are the twin-aisle wide bodied aircraft we see from Airbus and Boeing. The article mentions something about fuselage but doesn't get into the details of it. Can somebody elaborate?


texts: Why is the landing distance increased on grass runways?

texts: Checking the Cessna 152 POH it says to increase takeoff distance by 15% of ground roll (makes sense due to increased friction). Also says to increase landing distance by 45% (doesn't seem to make sense). Would like to understand why.


texts: Currency - is a safety pilot a passenger per the regs (FAA)?

texts: Per the regs in FAR 61.57, for a pilot trying to get current (for night or day) that is presently not current for carrying passengers, in a Cessna 172 where only one crew member is required, would a properly rated safety pilot sitting in the right seat but not acting as PIC count as a passenger? The regs don't seem so clear in this matter. It's always good to have a safety pilot if you haven't done something in a while, especially at night.


texts: How can pilots differentiate runways and taxiways during landing?

texts: There have been many incidents where pilots landed or attempted to land the aircraft on a wrong surface (for example Continental 1883 and Air Canada 759). Are there any tips for pilots to avoid that? Especially during nights or low visibility scenarios.


texts: How much extra drag does an external HF antenna incur?

texts: As seen in the picture, some older planes have external HF antennas that run from the fuselage to the tail.  Have any studies found the wire to be a significant source of drag or is the difference negligible compared to moving an entire plane through the air?


texts: What should a pilot do if they feel sleepy?

texts:
What should a pilot of any large commercial passenger airplane do if they feel sleepy?

What is the maximum time per day during which  the pilot may control the airplane ?


texts: Why should a Piper Seneca not take off after an engine failure below 100MPH?

texts:
In the Seneca (PA34-200) AFM, in the ENGINE FAILURE DURING TAKEOFF section, it is noted that if engine failures occurs during takeoff ground roll and 100 MPH has not been attained, the pilot must abort the take off and if attained the pilot must continue. Since Vmc is 80 MPH, why was 100 MPH chosen as the cutoff point for go/abort?

  ENGINE FAILURE DURING TAKEOFF
  The single engine minimum control speed for this airplane is 80 mph (CAS) under sea level standard conditions.

  a. If engine failure occurs during takeoff ground roll and 100 mph (CAS) has not been attained, CLOSE BOTH THROTTLES IMMEDIATELY AND STOP STRAIGHT AHEAD. If inadequate runway remains to stop, then:
  (1) Throttles - CLOSED.
  (2) Brakes - apply maximum braking.
  (3) Master switch - OFF.
  (4) Fuel selectors - OFF.
  (5) Continue straight ahead, turning to avoid obstacles as necessary.

  b. If engine failure occurs during take-off ground roll or after lift-off with gear still down and 100 mph (CAS) has been attained:
  (1) If adequate runway remains, CLOSE BOTH THROTTLES IMMEDIATELY, LAND IF AIRBORNE, AND STOP STRAIGHT AHEAD.
  (2) If the runway remaining is inadequate for stopping, the pilot must decide whether to abort the takeoff or to continue. The decision must be based on the pilot's judgement considering loading, density altitude, obstructions, the weather, and the pilot's competence. If the decision is made to continue, then:
  (a) Maintain heading and airspeed.
  (b) Retract landing gear when climb is established.
  (c) Feather inoperative engine (see feathering procedure).

Original image of text.


texts: How hot is the air at the compressor inlet at supersonic speed? For instance the Concorde at mach 2.2 or other jet engines at even higher speeds.


texts: Is an elevon (elevator + aileron) considered as an all-moving control surface?

texts: The delta wing on Concorde uses elevon as its control surface. Is the elevon considered as all-moving control surface?


texts:
How are foam cores shaped for tapered and swept back wings?
I understand that many constant chord, constant thickness rectangular wings use the same sized airfoil shape from root to tip. Let's assume the wing uses a classic NACA airfoil shape such as 650-18.
How would a foam core wing with a classic NACA airfoil shape, swept back 10 degrees be shaped?  Is the wing, using the same airfoil shape, NACA650-18 just rotated back 10 degrees from the root?  In this case, in cross section longitudinally (along the plane's y axis, in the direction of airflow), the actual airfoil shape would no longer be the same shape as the rectangular non swept wing, even though the geometric perpendicular cross section of both wings is exactly the same. Is this correct thinking?


texts: How long does AFSP processing take the second time?

texts: If you've already completed the fingerprinting for the TSA's Alien Flight Student Program and been approved to train at one flight school, how long does it take to gain approval to fly at another flight school?


texts: Why would a helicopter climb in a spiral?

texts:
I was just watching the James May's Toy Stories Christmas Special Flight Club*, and in it he commented that the helicopter was making a spiral climb to 8,000'.  Why would the pilot spiral, not just essentially go straight up?

* An excellent series if you're a big kid who enjoys toys, and as a bunch o' GA pilots, I'd think that covers most of you!


texts: At what angle of deflections do rudders become inefficient?

texts: This article (picture) says rudders for ships can deflect 35° max,so at what aoa does an airplane rudder lose its efficiency,at what " angle of deflection " does it start to stall ?


texts: Why might American Airlines fly a 767 from JFK to EWR?

texts:
I was browsing FlightAware and saw the following:

This is an American 767 flying from JFK to Newark (EWR).  Surely this isn't a passenger flight...this isn't one of American's normal routes.  Why might an AA 767 be making this flight?


texts: Why are winglets swept back and not front?

texts: A winglet is defined by its airfoil shape, profile, sweep angle and height. In case of the sweep angle, why does it always mean that the winglet is swept back. What is the disadvantage of having a front sweep angle


texts: How can I get 'lead point' for aircraft to intercept final course?

texts:
As controller, I always wonder when should I instruct aircraft to turn. The aircraft does not turn at right angles as soon as instructed, but rather has turning radius. So, I tried to find the formula but failed.

If speed of aircraft is 300 kts, and he is instructed to make 90 degree, how long distance the aircraft need to turn? I make image, and I wonder the formula for 'x'


texts: If a twin-engine airplane's propellers both rotate in the same direction, do they still produce a left-turning tendency?

texts: If an airplane with two propellers has both propellers with the same rotation direction (say, both the propellers rotate counter-clockwise as seen from nose to the tail), will  be the four left-turning tendencies still be generated?


texts: Is there an order for the instructions of a go-around?

texts:
Scenario: Aircraft on final is approaching the threshold. A departing aircraft is slow to roll and ATC must issue a go-around instruction.

ATC: PULL UP AND GO AROUND. TURN LEFT HEADING 360 MAINTAIN 3000'

or

ATC: PULL UP AND GO AROUND. MAINTAIN 3000' TURN LEFT HEADING 360

Is there a correct order to follow for these instructions. Set aside the reason for the go-around is obvious and turning first would appear to be prudent. In simple terms, it there anything that prevents a pilot from turning first, climbing first and then turning, or perhaps making a climbing turn?

* I'm a controller.


texts: Our flight was delayed from takeoff because the captain reported it to be "out of trim". What does this mean?


texts: How hazardous is it if an engine cowl falls off?

texts:
There was recently an incident where the engine cowl of the starboard engine of a United Airline's Boeing 777 fell off during flight:

'Scariest Flight of My Life.' United Airlines Made an Emergency Landing After an Engine Cover Flew Off
Engine Cover Blows Off on United Airlines Flight
United Airlines passenger jet's engine cover rips apart over Pacific Ocean

All available articles seem to suggest it was 'sort' of an emergency and they did in fact do an emergency landing...

  A United Airlines flight from San Francisco to Honolulu made an
  emergency landing Tuesday after an engine cover reportedly flew off
  mid-flight.

... with people even asked to brace for impact:

  “They let us know that we had to brace for impact in case there was a
  rough landing,” she said.

It seems logical that the cowl coming off could be a sign of loss in structural integrity around the engine (also of the engine itself?).

Another issue could be ingestion of debris (especially near the engine inlet).

How hazardous is such a case of the engine cowl falling off?

Note: I do understand that a twin engine aircraft can continue flying after a single engine loss however due to the reduced performance an emergency landing would make sense.


texts: Can TAS at different altitudes be calculated if only one performance point is given?

texts:
If the POH only gives TAS at only one altitude, can we calculate the TAS at other altitudes?

Here is a snippet from the POH of Remos GX. If we set the RPM to 5,200 then at 3,000 feet MSL ISA we get 107 knots. Can we calculate the TAS at 6,000 feet?


texts: What is the difference between a nacelle and a cowling?

texts: I see these terms used almost interchangeably. To my understanding they both refer to the covering of an engine. Is there a technical difference between the two?


texts: What are the reasons to evolve from trim tabs to moving the entire surface (e.g. stabilizer)?

texts:
Modern commercial aircraft use stabilizer to trim instead of trim tabs. What are the advantages and disadvantages of this design choice?

Have aileron trim and rudder trim evolved in a similar way to move the entire control surface rather than aileron / rudder trim tabs?


texts: Are there any accurate books that help with identifying aircraft when planespotting?

texts:
I want to start planespotting and I'm looking for the best and mosts accurate registration book.

I want this book to be:

accurate
checkable (to check planes I have seen)
have almost every plane
codes (IATA | ICAO)

If anyone knows a book I would love to hear it!


texts: Why hasn't the US military performed aftermarket modifications on certain aircraft?

texts: The US military emits more CO2 annually than several countries. Winglets have been proven to work well in the commercial sector to reduce fuel burn, therefore reducing both CO2 emissions and fuel cost. The US military doesn't really lack research or production/modification capability, so why have winglets not been installed on non-fighter/attack aircraft? (Think C-130, E-3, KC-135...) They would reduce CO2 emissions and fuel costs, so why not implement them?


texts: Was the runway upgrade at Mataveri Airport on Easter Island really related to the Lee Correy novel "Shuttle Down"?

texts:
This answer to the question Could the Space Shuttle have landed on any long runway other than those specially reinforced at Kennedy (TTS), and Edwards (EDW)? says:

The Mataveri Airport on Easter Island was a planned abort site for the Space Shuttle. Since the Space Shuttle has no means of propulsion, you might want to have a fairly tight mesh of potential landing sites in event of an emergency.
As a nice side-effect, the long runway allowed for larger passenger aircraft to service the island, which boosted tourism. A nice win-win situation.

What caught my eye is the comment:

The runway improvement happened only after the problem of an unprepared emergency landing there occurred... in a novel. But then none of the Vandenberg launches for which it would have been a launch abort site ever ultimately happened.

followed by this comment:

He's probably talking about Shuttle Down by Lee Correy. https://en.wikipedia.org/wiki/Shuttle_Down

Question: Is this timing factually correct? If so, was this coincidental, or is there in fact some causal aspect to the relationship?


texts: Why do civil aviation aircraft not routinely carry missile defense systems?

texts: With all the incidents with civil aircraft and missiles, why do civil aircraft not carry flares and other defensive measures by default? If official aircraft carry them it is technically possible to fit them, isn’t it? With the possible fallout and the enormous loss of life, why do air defense systems allow the operators to target civil aircraft in the first place?


texts: What is the difference between a Sub-Charter Flight and a Codeshare Flight?

texts: What are the main differences of this two types of flights?


texts: What licenses should I get for the (flight) equipments that I want to make?

texts:
For making and selling all equipments of aircrafts what or which licenses should I get? and from where? Will I be able to sell them all around the world?
Edit: This question is different than this one. One of them is for a new equipment and another is to modify them. It looks they need different licenses. Please vote to reopen it.


texts: Which atmospheric factors that can affect the performance of an aircraft while flying a circuit?  Apart from the general wind shift.


texts: Best Way to certify DO-178 Communications Stack?

texts:
We currently have a piece of hardware running an RTOS that needs the communication stack to be certified to DAL-B. Everything has already been developed for non commercial aerospace applications, although we now have a commercial aerospace customer who is interested in our solution.
The communications stack handles a variety of different communication methods, and we're deciding on a make vs buy decision. These communication methods include ARINC 429, RS422 and Ethernet.
Are there any products out there that are DO-178 certified and handle these communication protocols? Or will we need to go through the certification process for our own implementations?


texts: In which phases of flight should the carb heat be turned on?

texts:
I have about 200 flight hours in a fuel-injected C172. I have just jointly bought a C152 with a carburetor and I am getting used to using the carb heat. I am scared whenever I hear stories about engine failures due to carb icing.

What I know is to turn CH on when:

RPM lower than 2000
When visible moisture is in the air and when it's raining

But should I leave CH on when taking off in the rain? Can you give me some ideas about other phases and conditions of the flight when I should turn on the carb heat?


texts: Why do aircraft leave the cruising altitude long before landing just to circle?

texts:
Often flights will leave the cruising altitude long before the actual landing. They will go down to a couple of thousand feet and stay at that altitude and  circle for quite a while in waiting loops before it's actually their turn to land. It can be seen basically all the time at Heathrow Airport (LHR). But also for example in Munich Airport (MUC), where flights often come far down over the city and then make wide turns towards the airport.

So I'm wondering: if it's already clear ahead of time (and I'm sure mostly it is) that it's not their time to land yet, why not circle at higher altitudes? Often those waiting loops occur over dense populations and thus create quite some noise on the ground.


texts: How can you do preflight fan inspection when it's windy?

texts:
While sitting, bored to tears, intermittently scanning the 'Delayed' display next to my flight, I've looked out of the airport windows.

Out on the stand, amongst the baggage and fuel truck activity, I've seen a technician examining the engine fans with a torch (flashlight), presumably part of a mandatory pre-flight inspection procedure, looking for FOD, cracks etc.

It occurred to me: What does the techie do on a windy day when the fans are spinning too fast to examine by eye?  Is there some way of braking the shaft to stop the windmilling?


texts: How can I improve the reception of my coaxial collinear antenna (1090 MHz)?

texts:
I've built a coaxial collinear antenna (16 arrays), according to this guide but having some issues picking up traffic from the West (?). I'm not very experienced in the area, so I've no idea where to start or why this is happening.

The antenna is located in my living room and is aprox. 2 meters.


texts: Can one use a calculator for the EASA part 66 exam?

texts: For the first 3 modules you will need to do some calculations, is a calculator allowed?


texts: What is the origin of the waypoint WORUM (neayby Houston)?

texts:
I'm reading the book "Skyfaring".
There is a sentence "TQELA, WORUM, CRVZA (beer), CARNE (meat),
QUESO (cheese) for the city’s cross-border
culinary traditions"

What is the origin of WORUM?
Is it related to some food?


texts: What's the difference between a TSO Authorization and a letter of TSO design approval?

texts:
FAA can issue two types of approval for a TSO part application: TSO Authorization and letter of TSO design approval. What's the difference?

Does it relate to the approval being design-only or production only?

Also, do other Airworthiness Authorities have a similar difference?

According to 14 CFR 21 Subpart O §21.601:

  (2) A TSO authorization is an FAA design and production approval
  issued to the manufacturer of an article that has been found to meet a
  specific TSO;

  (3) A letter of TSO design approval is an FAA design approval for an
  article that has been found to meet a specific TSO in accordance with
  the procedures of § 21.621;

  (4) An article manufactured under a TSO authorization, an FAA letter
  of acceptance as described in § 21.613(b), or an article manufactured
  under a letter of TSO design approval described in § 21.621 is an
  approved article for the purpose of meeting the regulations of this
  chapter that require the article to be approved;


texts:
Headsets such as the Lynx Micro System are modelled on ear defenders and physically attenuate the noisy cockpit environment by clamping hard onto your noggin. Most modern GA headsets (e.g. Bose A20) seem to be built with far less attenuation, don't clamp on as hard, and tend to rely on ANR features rather than isolating the ear.

Naively, it seems that this would pump more audio power into the ear. Granted, it will be in opposition to the original noise, but it seems it would be very tricky to get the cancellation exactly in phase. So, is there a risk that using ANR and less attenuation would not be as effective in preventing ear damage as passive attenuation?


texts: What is the sense of the Aerodynamic Centre for Design Process?

texts:
This topic has been discussed already several times, but I do not really get it. I think this one is a quite nice explenation: enter link description here

So I understand that the Aerodynamic Centre does not change with angle of attack. But what I do not get: how this helps in a pre-design of my aircraft?

Because: for stability calculation, I have to consider the forces acting on the whole aircraft and the corresponding lenghts (moments).

So regard a stationary horizontal flying aircraft: when I make the equilibrium of moments around the centre of the gravity, I have to regard the force F_cp,w at the centre of pressure of the wing (resulting lifting force) with distance l_cp (from centre of gravity) AND the force F_cp,t (resulting lifting force at the tail) with it's lever arm l_cp,t .

The balance becomes around the centre of gravitiy: F_cp,w * l_cp,w = F_cp,t * l_cp,t

When the angle of attacks change, F_cp,w*l_cp,w will change since the centre of pressure will move and the resulting lift will change.

So what I assume: there is a trick with which I can make the moment of equilibrium around the centre of gravity and where l_cp,w remains constant = Aerodynamic Centre

But I can not imagine how this is working with the balance of moments.

Can someone help? I am really confused.

Thank you very much


texts: Are airfoil profiles patented? If not, why?

texts:
For something that takes so much research and can effect performance drastically, there seems to be no patents on airfoils.
Too simple in appearance to patent? They appear simple at first but the performance characteristics behind them are quite complex.
I have found patents describing 3D objects such as turbofan blades using a combination of airfoils, twist and sweep combined. There seems to be nothing showing or describing a 2D profile of a wing unless it's flaps.


texts: What are the differences between Canadian VNCs and US Sectional charts?

texts:
I've been looking at Canadian VNCs (VFR Navigation Charts) and they look surprisingly different from US sectionals. A big difference seems to be how the airspace is designed, but there seem to be a lot of other differences in how information is displayed. For example, here is the Denver class B airspace:

You have your basic upside down wedding cake, and a mode C veil.

Now here is the Calgary, Canada class B airspace:

Even though it's not a full picture of the airspace, there are some differences that jump out, like the choice of colors to indicate the airspace boundaries and elevation, and the fact that the airspace is HUGE! There is also no clear indication of a mode C veil, or the bottom/top of the airspace. Another thing I've noticed is the huge number of airspace boundaries, indicated by the lines that looks something like this: -_-_-_-_.

One more thing. There is no information about the Calgary or Springbank airports. Are airspace elevations, airport elevation, and frequencies all things you have to look up separately?


texts: Why does a higher load factor increase stall speed?

texts: I think that’s self explanatory, why does load factor (G) affect stall speed? Why does load factor result reaching the critical angle of attack at higher airspeed?


texts: During single-engine taxi, how is the asymmetric power compensated for?

texts: For various reasons (e.g. noise, fuel savings), some airlines allow single engine taxiing. Obviously, this produces an asymmetric thrust during the taxi. If the left engine is used, the aircraft always wants to steer to the right. How is this compensated? Do pilots use the tiller all the time to countersteer, or pedals, or brakes? Is there a possibility to "trim" the aircraft during taxiing?


texts: How much time do pilots have to execute a TCAS Resolution Advisory?

texts:
The Wikipedia entry for TCAS (Traffic collision avoidance system) states for resolution advisories (RA):

"When an RA [Resolution Advisory] is issued, pilots are expected to respond immediately to the RA unless doing so would jeopardize the safe operation of the flight" (Source).

Is there a general rule of thumb as to what "immediately" translates? How many seconds (or distance?) remain from time of resolution advisory to closest point of approach? Although RAs are usually accompanied with traffic advisories, I assume there is still some response time already calculated in...


texts: Why are some pitot tubes more prone to icing than others?

texts:
I understand that there were several cases pitot tube failure in a certain way.

The pitot tubes were clogged by ice when the airplane was in cold and wet conditions.
The remedy was to exchange the pitot tubes by a different model from a different manufacturer.

As an example, there was an Airworthiness Directive (DGAC 2001-354) applying to the A330 and possibly others, explicitly requiring to replace the model installed when delivered by a specific other model.

The A330 originally came with pitot tubes from Goodrich Sensors and Integrated Systems,  part number 0851GR. The Airworthiness Directive of 2001 required to replace these by pitot tubes made by Thales, part number C16195AA, or a specific, more recent model from Goodrich.

I assume all models from all manufacturers have the same basic construction, like all can be heated, for example.

What is it in the construction of the pitot tubes that makes the difference?

Is it just a design flaw in the Goodrich series that was fixed later? Somehow I expect it to be something more general. Are there other manufacturers building pitot tubes with a similar flaw? (That would be a good reason to require replacement with a specific model.)


texts: How do airplane designers determine flap deflection angles for flaps of various % wing chords?

texts:
How do airplane designers determine flap deflection angles for flap chords of various % wing chords? E.g. flap chord of 30%, 40% or 50% of wing chord.
I understand most flaps' chords are about 25% of the wing chord, but I understand Rutan's Grizzly had a flap chord of 55% of wing chord.
I assume you could use theory to figure this out, but that doesn't mean it works like that in the real world.
Is this information readily available in graph or chart form?
I thought I saw a link in a post on StackExchange re this from Peter Kaempf, but I can't find it.


texts: Wind correction on downwind during circling

texts: A timing must be started when flying abeam the threshold on a circling approach. The FCTM of the B777/787 mentions 35 seconds and the SOPs of the Embraer 190 30 seconds. Do they need to be corrected for head/tailwind? If yes, how are they corrected?


texts:
I have a PPL license in the US and I want to do a European ATPL license.
How does it work? Do I have to attend a school or can I do all online?
Do I have to physically take the tests somewhere in Europe or can this be done somewhere online as well? How did the COVID-19 change these things?


texts: How was flutter mitigated in jets such as the F-15 and F-16?

texts:
As I understand it flutter was a serious problem for early jets, like the XF-104. Flutter can affect any of the extended members of an aircraft during high-speed flight, including the wings and the vertical stabilizer. The problem seems to have solved, however, by the time that the F-16 and F-15 were designed.

How is flutter mitigated in the F-15 and F-16?


texts: Is it possible to tilt a propeller for attitude control, similarly to jet thrust vectoring?

texts:
Are there examples of propellers tilted in a controlled way to help in attitude control for pitch and yaw, adding a torque component?

Tilted propeller assumption

This would be similar to thrust vectoring in jets.

Vectored thrust principle

Alternatively could a swashplate similar to the one used in helicopter main rotor be used to generate asymmetric thrust?

(I think this excludes convertiplanes where the propellers are converted into rotors to take-off, land or move vertically.)


texts: Looking for the correct propeller shape to create a small copter

texts:
I am trying to create a mini flying quadrocopter using a Raspberry Pi (mini programmable computer). So far I have hooked up the RPi to 4 motors with controls to each. I'm pretty happy with that side of it.

The part I need help with is the design of the propeller; my motors are not massive and I want to ensure I get the best design for maximum thrust to weight as well as manoeuvrability.

What do I need to look for in propeller design considering my limited motors?


texts: What are some "FAA approved" simulators for home that I can log time on?

texts: I'd assume xplanes on iPhone or Android would not be log-able, but wanted to know if there is a affordable simulator kit for home usage that'd help me logging time for IFR requirements?


texts: how to calculate power required for engine of duct fan?

texts:
I need 600 N thrust for my aircraft. I am planning to use duct fan. according to calculation of duct fan:
T=Ct.ro.A.V^2
Ct=0.03
ro=1.09 (in my place)
A=(0.26^2)*3.14=0.21225 m^2
v=300 m/s
then T=624 N
how I calculate the power of engine that can rotate the blade?
(sorry for my bad English)


texts: How does the pilot control the Dassault Rafale?

texts: In the Dassault Rafale, how does the pilot maneuver the plane? I would expect to see a joystick centered between the pilot's legs. Instead, the Rafale has what appear to be two joysticks on both sides of the pilot. How does the pilot use these two joysticks to control the Dassault Rafale?


texts: Has any pilot successfully flown through a hurricane with a single-engine prop plane?

texts:
Has any pilot successfully flown or could a pilot crab through a hurricane using a plane such as a Cessna or bi-plane?
Would acrobatic planes work better because of their nimble agility and high power-to-weight ratio, or would heavier aircraft be more stable?
Are there any prop singles that would be particularly well suited?


texts: Hydrogen as fuel for jet engine or afterburner

texts:
Why is hydrogen not used as fuel for fighters? I understand that hydrogen engines are not yet developed but why is there no research going on in that file.
Can't hydrogen be used in specially designed afterburners?
After all, is has like 3 times the energy density of aviation fuel.


texts: What causes hunting movement in helicopter rotors?

texts:
The blade of an helicopter rotor can have three hinges: pitch hinge, flapping hinge and lead-lag hinge.

Lead-lag (dragging): movement of a blade forward or aft in the plane rotation. Lead lag is facilitated by a lead-lag hinge in the rotor system or through rubber like bearings that allow individual rotor blades to move back and forth in their plane of rotation.
This helps balance the blade system and reduces vibration. The drag brace or drag damper resists the movement of the blade around its lead-lag hinge on a semi-rigid rotor system.

In the same plane, we have also the hunting, defined as the tendency of a blade to oscillate ahead of or behind a position which would be determined by centrifugal force alone.

Why should the centrifugal force alone determine a movement aft and behind the plane of rotation?


texts: What are these red lights next to an airport runway?

texts: What are these red installations at the end of the runway? They shine bright like a laser but I don't think they would install those near an airport.


texts:
I'm learning X-Plane 11 and started to use an add-on called FS Economy.

One of its missions is to fly to small airports that I can't find on skyvector, so I'm unable to plan a direct flight.

I usually fly to the nearest charted airport, and fly using the GPS from there. Not knowing any information like runway length beforehand.

How realistic is it in the real world that an airport would not be charted, and how are flights planned to such airport?


texts: What does the zig-zag pattern on Hawker Hunter's leading edge represent?

texts:
On some Hawker Hunters, there is a zig-zag on the leading edge of the wing, as shown below.

Why do only some Hawker Hunters have this feature, and what is it for?


texts: Are low pressure (LP) compressors and booster compressors the same thing?

texts: Based on the above picture, are "LP compressor" and "Booster compressor" different names for the same thing or are they actually different things?


texts: What are different components of an engine pylon?

texts:
What are the different structural components that are inside the fairing of engine pylon and what are the functions of each part?
The pylons for each aircraft are made of Ti-64 alloys, can they be made using Aluminium alloys or the temperature requirements are very high so Aluminium cannot be used?
Thanks


texts: Airbus is to fly-by-wire as Boeing is to...?

texts: If the control system in an Airbus is fly-by-wire, then what is the control system in Boeings? How does it work? What are its general differences from the fly-by-wire?


texts: When an emergency happens, why do pilots need to stay on the current ATC frequency?

texts:
Per the below order, I need to stay with the initial ATC frequency during an emergency, what is the benefit to do so? What if the aircraft entered into the airspace controlled by anther ATC or the aircraft is no longer within line of sight?

FAA Order J7110.65V, §2, ¶10-2-2:

  Although 121.5 MHz and 243.0 MHz are emergency frequencies, it might
  be best to keep the aircraft on the initial contact frequency. Change
  frequencies only when there is a valid reason.


texts: Should spoilers and reverse thrust be deployed before nose gear touches down?

texts:
On airliners, should spoilers and reverse thrust be deployed before nose gear touches down?

I used to thought that deploying them will affect the handling characteristics, so it is best to wait until all wheels are on the ground; but I've seen pilots do it both ways. Does it depend on landing distance and runway condition?


texts: Is the A-10's cannon effective against tanks?

texts:
Perhaps this isn't on-topic, but is the A-10 effective against tanks (tank armour) when using its cannon?

For example, this page claims:

  Using the cannon, the A-10 is capable of disabling a main battle tank from a range of over 6,500 m.

Is that true?

If that were so, why does a "main battle tank" (e.g. an M1 Abrams) have a 120 mm gun -- contrast that with the A-10's 30 mm cannon?

I thought that in WW2 you needed something like a 75 mm or 88 mm gun to be effective against the then-heavy tank armour. And the gun on a "main battle tank" has if anything increased in size since then -- or converted to missile instead of projectile -- is a 30 mm cannon effective?

Is the armour-penetration of an A-10 exaggerated (if it is effective against only e.g. softer armour than main battle tanks)? Does the cannon being mounted in a plane make it especially effective (I'd guess not, the muzzle velocity of a GAU-8 is 1000 m/s and and A-10's airspeed only adds 200 m/s to that)? If it is effective then why isn't that the primary armament of a main battle tank?


texts:
According to this question, life jackets are not mandatory in planes that do not fly over large bodies of water. However, I have never been on an airline flight without life jackets (and the corresponding safety demonstration).

Why do airlines not remove the life jackets from planes that fly over land? The plane would be lighter and the safety demonstration shorter. Moreover, it can not be hard to dedicate different planes to different routes and avoid returning the life jackets each time the plane has to fly over water.


texts: What does ''NAV ILS OUT OF SERVICE'' mean?

texts:
Just curious about the NOTAM below:

  !SMF 01/045 (KSMF A0080/19) SMF NAV ILS RWY 16L OUT OF SERVICE
  1901180419-1901262359

Does that mean only the glideslope is broken so we can still do a LOC approach, or are both the localizer and glideslope broken?


texts: Does the required torque to spin a propeller increase with RPM?

texts:
I‘ve currently been experimenting with different propellers: 12x12 prop, 16x12 prop (both two blades) and a 22x14 (6 blades) prop. They were propelled by a 2.4 kW electric motor with 260 kV on a 6S/5200mAh/12C battery setup.

The 12x12 prop produced 2 kg of thrust at full throttle, the 16x12 produced 4.5 kg of thrust. So I thought the 22x14 would produce around 6 kg because its bigger blade area would be more efficient. However, I got only 0.8 kg of thrust and recognized that the motor would slow down at a certain RPM.

I have to say the big prop is pretty heavy so could it be that the motor would have enough power to spin the prop faster but it lacks enough torque to get it there?


texts: What is the main source of yaw stability?

texts:
I am creating a flight simulator and I need to implement lateral and longitudinal stability.
Roll stability is now working because I am computing the lift of each wing independently.
But yaw stability is confusing to me.

What is the main source of yaw stability : is it the weathervaning effect of the tail or is it the sweep angle of the wing ? Which one is the more responsible of stability ?

When I implement weathervaning effect by applying the wind at a certain point of the tail, the problem is that the oscillation will continue and the plane will always overshoot as he is not losing any of its angular velocity. So it will never align into the wind but will keep overshooting from negative to positive angle.

So my other question is : in real life, what does prevent the plane to overshoot wind direction?
When I just apply some scaled-angular drag value to the plane, it helps to dampen the oscillations, but the plane is wayyy to slow to align into the wind and thats just aweful to controll and not realistic at all. So I guess angular drag is not the answer why oscillations stops in real life. There must be another force depending on wind speed or I don't know...

And longitudinal stability is also confusing to me.
I know that it depends on the position of CG, CL and the downforce generated by the tail horizontal stabilizer.
But what about the weathervaning effect ?? Isn't it the main force that explains why the plane align into the wind on its pitch axis ?

As you can see I am a bit confused. I already looked many websites and I mainly understood how stability and flight dynamics work, but as I am working on a simulation, I need some equations to implement, and some concrete values to understand which forces are bigger than others.

Thank you !


texts:
As I understand from the answer to this questions, plug doors are larger than the hole they mus fit in so that they are plugged thanks to air pressure, leading to several advantages. Then, I found this video of a type-C door operating. This door does not seems larger then the hole it must fit in and that confuses me.

Is this a plug-door?
Is there something I miss?
Is there other types of door that are not plug-door, or that are plug-door but don't look like plug-door?


texts: Why the gradient of $C_L$-$\alpha$ graph increases with the Mach number?

texts: From the JAA ATPL Book 13 (Principles of flight) the gradient $\frac{dC_L}{d\alpha}$ of the $C_L$-$\alpha$ graph increases for higher Mach numbers. Can someone explain why this is the case?


texts: What does "mission mixing" mean for long-range aircraft?

texts: I know very little, like long-range aircraft will be used for short-range and medium-range operations. But what is the purpose of using them like that? Also I want to get complete details of "mission mixing" in layman's terms.


texts: What is the best word for lateral translational movement in a rotorcraft?

texts:
I'm talking about movement left and right without changing attitude. This is a motion that can be done with a quadcopter and to a limited extent a helicopter (I presume).

On a helicopter a left/right movement of the cyclic will command a roll motion from the rotor, but in a hover the aircraft would only roll slightly then begin to move sideways. Does the pilot just call this a roll or is there another, more appropriate word?

I thought of slip or crab, but those describe specific attitudes associated with forward flight. They don't seem to fit the bill here.


texts: Why are dirt and bugs on an aircraft so bad?

texts:
It's noted in many POHs to keep your aircraft clean all the time, but is there a reason to this?  Dirt hardly add any sort of weight to the aircraft, bugs are extremely small and other things such as cars easily move even when dirty as a mud pig.

Does having dirt or bugs on your aircraft seriously affect the structure or performance signficantly?
If so, why?


texts: What does it mean when the controller uses the word "request"?

texts:
I recently had the opportunity to fly a PAR approach into Büchel Airbase in Germany. It was a ton of fun and I'll definitely try it again when I get the chance. However, as we were getting set up for the approach I received the following call

  (callsign) request heading

It caught me off guard, and it took a while but I eventually interpreted it as "say heading" and gave him my current heading. He didn't complain, but I'm still not sure if that's what he wanted.

A bit later I got a similar call

  (callsign) request QNE

However, I was unfamiliar with that Q-code1 and only later found out it means "pressure altitude". Q-codes suck. Anyway I said "Say again" and he came back and asked how many were on board (which I incorrectly assumed at that point was what QNE meant), again, using "request".

Anyway, I've never heard a controller say "request" before, is it just army version of "say"? I'm pretty sure the guy was German, so it might be a German military thing, or a NATO thing, or just a simple mistake on his side?

1: As a private pilot in Europe, you pretty much need to know QNH, QFE, QDM and QTE


texts: Why a parachute for aerobatics only when carrying a passenger?

texts:
Per FAR 91.307:

  Unless each occupant of the aircraft is wearing an approved
  parachute, no pilot of a civil aircraft carrying any person (other
  than a crewmember) may execute any intentional maneuver that
  exceeds...

So if I'm flying aerobatics solo, I'm not required to have a parachute. But if I have a passenger, both are required to have one.

What is the rationale for that?

I suppose that in something like a Super Decathlon, where the pilot must exit the plane before the passenger, it would be senseless to have one for the passenger but not the pilot. But is there anything more to this?


texts: What does the SOG part of this METAR mean?

texts:
CWKX 231700Z AUTO 12001KT M05/M07 RMK AO1 SOG 32 6023 SLP123 T10471068

Does anyone know what “SOG 32 6023” means?
Also why is that type of metar have a bunny icon in it instead of the M or the classic circle?


texts: How to execute a gear up landing on aircraft with low propeller?

texts:
On some GA aircraft such as the Piper Malibu, the propeller would touch the ground if the gear was up. How would you land the plane when gear actuators fail?

I would pull out the mixture knob and turn off magnetos, so the propeller is stopped when it touches the ground, but what is the official/best way to do this?

You can assume the propeller is constant-speed.


texts: Why are these windows on some airplanes red?

texts:
There are some red windows on the 737 and the CS-300 as well. Why are they painted red?
Source

Source


texts:
I am interested in historic fuel prices;

How much did Avgas cost in 1940?


texts: How efficient would it be to have a plane with the cockpit in the back?

texts: Would it be efficient to have a passenger planes cockpit move to the back of the plane, rather than the front? What I have in mind is cameras on the fuselage and nosecone that connects to the cockpit and give the pilot a wider viewpoint


texts: What is the purpose of a USB port in the cockpit?

texts:
I'm definitely new to the site so apologies if this question is naive but google turned up no answers for me:

I was reading this article and read the following paragraph:

  As an example, Hypponen said he had recently spoken to a European aircraft maker that said it cleans the cockpits of its planes every week of malware designed for Android phones. The malware spread to the planes only because factory employees were charging their phones with the USB port in the cockpit.

The question that immediately sprung to my mind was:

  What is the intended purpose of USB port(s) in the plane cockpit?

Was it really intended for charging devices like phones? That seems naively insecure.


texts: Is there an FMC not connected to the AP/FD?

texts:
Is it possible to have an FMC to compute the performance and navigation without having it linked to an autopilot or flight director?

Does/did such setup exist?


texts: What is the location of AC for typical modern airplanes?

texts:
Some sources state that AC must be located behind CG, so that AC is stable.
There is a source, which throughout the study of stability and control consider AC located ahead of CG and positive cambered tailplane, stating that such airplane will be stable.
I understand that there is not only one right decision and it's possible to design aircraft with AC located both behind CG and in front of.
The question is, what is typical arrangement of CG and AC for most modern large jet transport aircraft? (especially interested in b737 and a320)


texts: Has a micro-burst or wind shear caused fatalities on takeoff?

texts:
Delta Flight 191 at Dallas-Fort Worth (1985), TANS Perú Flight 204 in Peru (2005), FedEx Express Flight 80 in Japan (2009), and Eastern Air Lines Flight 66 at New York's JFK, are all examples of aircraft fatalities due to wind shear or micro-bursts during approach.

Have there been any airliner fatalities due to micro-bursts or wind shear on takeoff?

 source

UPDATE: As a hobby, I have spent my life following aircraft accidents. At the outset of this question, I was unaware and doubted any such occurrences had happened. The answers have certainly been an eye opener and shows the breath of knowledge this group has.

So far:

Canadair C-4 Argonaut three crew and 29 passengers killed
Pan Am Flight 759 all 145 on board and 8 on the ground killed
Spantax CV-990 crash of EC-BNM off Arlanda (1970)
Continental Flight 426, Denver, (1975)
Continental Flight 63, Tucson, (1977)
United Flight 663, Denver, (1984)
(possibly - AeroméxicoFlight 2431) (2018)


texts: What is the difference between "x" and "+" configuration in missiles?

texts: What is the difference between "x" and "+" configuration tail fins, and what are the advantages of each in free flight? (for example JDAM missiles)


texts: Why is the MiG-23 landing gear nontraditional?

texts:
The MiG-23 has a very nontraditional landing gear setup. Why has it been designed the way it has as opposed to the more traditional method of a single compression strut that is raised into the fuselage.

(Source)


texts: What is the use of Stub Wings on Helicopters?

texts:
Some Helicopters like Russian Mi-24, UH-60 etx have Stub Wings. What is the role of such wings?

Russian Mi-24

UH-60


texts: Should depressurization be considered in the event of an inflight cabin fire?

texts:
Uncontrolled cabin fires only need a few minutes to spread throughout the cabin of an aircraft, killing everyone onboard and destroying the airframe.

Now, we all know that depressurization and fire do not combine; the lack of oxygen will eliminate one of the elements necessary to keep the fire alive. So if an aircraft had a way to depressurize the cabin and eliminate oxygen in the event of a fire, the fire would be extinguished, saving lives. Of course this applies to flights above 14,000 ft. I know that depressurization is dangerous but there is a better chance of surviving a depressurization than surviving flames.

Does a mechanism exist to depressurize the aircraft in case of uncontrolled fire in the cabin? If so, under what circumstances would it be used?


texts: What does Alternate NA mean on an approach plate?

texts: The ILS Y or LOC Y RWY 3 approach at Raleigh Exec Jetport at Sanford-Lee County Airport (KTTA) in Sanford, North Carolina features the alternate minimums symbol with an NA next to it. Normally this symbol means that the airport has non-standard alternate minimums. What does A NA mean in this case?