texts: What is Flexible Gunnery in the US Air Force?

texts:
I read many times in English Wikipedia that some servicemen were trained in Flexible Gunnery schools, but I don't get what that exactly means.

Example:

  In January 1942, the 2d Air Force was withdrawn from the Western Defense Command and assigned the operational training of units, crews, and replacements for bombardment, fighter, and reconnaissance operations. It received graduates from Army Air Forces Training Command flight schools; navigator training; flexible gunnery schools and various technical schools, organized them into newly activated combat groups and squadrons, and conducted operational unit training (OTU) and replacement training (RTU) to prepare groups and replacements for deployment overseas to combat theaters.


texts: Is it possible to recover from a flat spin?

texts:
In Top Gun, Maverick's F-14 enters a flat spin after flying through another F-14's jetwash, forcing him to eject and causing the death of Goose.

Is this scenario possible or was it only created for theatrical purposes?

If not, how does it happen, and how can it be avoided, especially for other types of aircraft such as the B-2?


texts: How to avoid talking over others when using different send/receive frequencies?

texts:
Related to this question about flight services: when I talk to FSS over the generic or the local receive-only frequency while listening to the VOR voice channel, how do I avoid talking over others on the same frequency?

Intuitively, I'd listen to the frequency I'm going to be transmitting on for a bit, then send my request, and then wait for a reply on the other frequency, but that seems like it would be distracting to configure in the radio.

So how would I configure my radio for contacting FSS in this way?

Edit: this is specifically about the case where other aircraft do not necessarily hear the controller speaking to you, so they may start transmitting at any time while I'm receiving the response.


texts: Are CVR and FDR reset after every flight?

texts:
Recording the thousands of parameters and voice conversations must take a huge amount of storage, and so I am wondering, how frequently is this data "deleted", so it can be used again?

For example, after every successful flight, is the CVR and FDR data deleted or it records maybe 10 flights or so, and then is reset?


texts: Can actual instrument time count as simulated instrument time for the PPL?

texts: Just wondering if actual instrument time can be added with simulated instrument time for the requirements of the Private Pilot minimums (3 hour instrument). I have actual instrument time from when my CFI showed me what it was like to fly in clouds. (USA)


texts: What maneuvers can a non-pilot perform when flying with a private pilot?

texts: I recently got my private pilot license and will soon be taking people for rides. My son wants to get his license (he passed his written test), so I was thinking I could introduce him so basic maneuvers. As a pilot, but not an instructor, what can I safely let a non-pilot do? Obviously anything in the pattern will require myself to be in control, but is it OK for a non-pilot to do slow flight or steep turns? Or would it be better to just perform them myself and let them see how its done? As pilot in command, it comes down to what I feel is safe, but are there any regulations that prevents a passenger from taking the controls and doing some turns? I don't remember this being covered in ground school or any of the training books.


texts: What is a rule of thumb for when to begin a descent?

texts:
What rule of thumb would you use for your airplane insofar as how far from your destination you would begin your descent given an expected straight-in approach and landing in no-wind conditions and no ATC or traffic restrictions? How would your weight influence that rule of thumb, bearing in mind that the heavier you are, the more potential energy you have to dissipate?

With those same conditions, what rule of thumb would you use to determine how close to the airport you could get before descending and still come straight in if you had an empty airplane save for necessary fuel and if you were allowed to use any aircraft configuration you wanted, and what would that configuration be?


texts: Getting the cl vs aoa plot from Cp distribution

texts:
I am making a CFD simulation where my goal is to calculate the section lift coefficient vs angle of attack plot of an airfoil.
From Fundamentals of Aerodynamics (Anderson, 2018), I get the following expressions to calculate the cl from the Cp and shear stresses distributions, but since I'm doing an inviscid flow simulation, I don't know if I can just ignore the shear stresses components of the formulas and still get a good enough approximation of the cl vs aoa curves:


texts: Are there statistics showing the relationship between safety and the age of aircraft?

texts:
Some people seem to believe that some airplanes are less safe to fly just because they are older than others. As a pilot myself who has learned that the safety of aircraft is nothing to do with their age as long as they are properly maintained in accordance with the regulations regarding airworthiness, I take the idea to be wrong and try to talk those people out of their idea whenever I come across them. Some people are persuaded but some are not.

I believe there are nothing better than brute facts in changing one's belief and here is my question: Are there statistics that support the idea that old aircraft are no less safe than new aircraft?


texts: What is the power source of the clock in glass cockpits?

texts:
I always get the impression that, once the shutdown & secure checklist is completed, there would be absolutely no electricity to any components in the cockpit or any aircraft systems.

However, most flight management computers know the current time. The time is also needed for GPS positioning.

How does the aircraft keep the time when the power is off? Is there a very small battery (similar to computer motherboards) which needs to be replaced once every few years, or is there a tiny electric current drawn from the batteries at all times?


texts:
I just started my studies towards PPL, and am looking into buying a good ANR aviation headset for flying on Cessna 172.

I have an office job, and I'm dealing with a lot of noise, hence ideally I'd like to use this headset with my computer as well (as buying 2 ANR headsets for different purposes is quite an expense).

From what I understand aviation headsets normally have 2 jacks with a different diameter. There are probably adapters to convert them to a standard 3.5 mm jack, but I wonder if it affects its noise reduction capabilities.

Conversely, can I buy a PC-compatible headset, and use it for flying with an appropriate adapter?

Also, most ANR headsets seem to operate on AA batteries. Are there any with lithium-ion battery instead, so that it can be recharged?


texts: Do we have a unit to measure turbulence?

texts: Do airplanes have any way to quantify the turbulence like if shakes are there or the some kind of air drift is happening every parameter of these have some units but do collectively there is any such unit which can quantify the turbulence?


texts:
I'm a student pilot doing all VFR flying and making flight plans for training. I've heard that most people don't file a flight plan for VFR outside of training though, and instead request "flight following" from nearby ATC.

When can I do this in flight? Which ATC can do this for me?


texts:
Years ago my father worked for Eastern Airlines out of Miami (that should give you a timeframe) and he was an electrical engineer.  I recall once he told me that the pilots (one or more) used to intentionally damage the CVR microphone in the cockpit by twisting it until the contacts broke.  Their reasons are not relevant for this question.

My question is, knowing what model planes they flew back then, (727, Tristars, A300s, 757, etc) how did the mechanics know that the mic was not working?  Would the system show it as a fault or did the CVR tape review show that there was no data from that mic?  The former I'd think would allow them to track down the pilot(s) that were responsible for this act.

Also, on planes with more modern electronics, would this fault be detectable immediately or at least before the next flight?


texts: How often is communication lost with aircraft?

texts:
I just read the NTSB press release of Northwest Airlines Flight 188 that flew more than one hour without making any radio contact. I imagine there may be many causes for losing radio contact with the ground (distraction, electrical failure,...) and I found a video (in French) saying that one way to solve the situation is to send a fighter to have a closer view of the situation and possibly assist the pilots.

I wonder if the situation of losing contact with an airplane is frequent? I imagine it happens between one and ten times per month over a region as big as the USA, but that is just a guess.


texts: Is IAS without instrument error the same as CAS?

texts:
I was reading a POH which stated something along the lines of

  NOTE

  Except as noted, all airspeeds quoted in this handbook are Indicated
  Airspeeds (IAS) in Knots and assume zero instrument error.

Why didn't they denote that as CAS (calibrated airspeed) instead, which is without instrument error? Is there a key difference between the two that I'm missing?


texts:
I just listened to the recent BBC podcast episode Aerotoxicity: the hidden dangers of flying and there were interesting claims there:

Cabin air in modern passenger aircrafts comes directly from engines (it's called bleed air).
This air is unfiltered and during so called fume events it may contain toxins from engine oil and other fluids. These toxins are called Tricresyl phosphate and persons exposed to them for a long time may suffer diseases of nervous systems, from psychological problems like depressions to neurological symptoms, like unexplained pains, severe headaches, etc.

As they said in the podcast, there are allegations that these

  ...fume events have not only made many ill, but they are being blamed for premature deaths

and that there are

  ...hundreds of legal cases going through the court.

I have never heard about this danger before and I consider the BBC to be very reliable source of information, so it surprised me. Are you aware of any study which would prove this danger?


texts: What is the criteria for determining whether an airport will be towered or uncontrolled?

texts:
I thought about this in reference to the question about Schamburg Airport in Chicago.  Is there a particular criteria for an airport, for instance the amount of instrument traffic going into and out of an airport, high density flight operations, etc., which would require the FAA to classify an airport as a controlled environment and surrounded by controlled airspace (Class D, C, or B) all the way to the surface?

I guess by question is targeted at what is the threshold between where the FAA will require an airport to be controlled and where it is allowed to be uncontrolled yet allows for reasonable and safe flight operations in the National Aerospace System.  I understand the basic differences between Class D, C, and B airspace designations, but I want to know if that is regularly evaluated and assigned new airspace designations surrounding the airport and control requirements.


texts: What's that rattling noise from parked jets?

texts: While walking around the airport on a windy day I occasionally hear a tingling or rattling noise from the engines of the parked jets. You can see the fans rotating in the breeze. What’s causing the noise? I should add that the aircraft are not in use, just parked with the engines uncovered.


texts: Do you need a rotating beacon if you have strobes?

texts: If I were to replace my left nav light with a SkyBeacon ADS-B + strobe, could I remove the rotating beacon at the top of the tail?


texts: How does setting takeoff flaps improve aircraft performance?

texts:
A study guide I recently found indicates that Vmc and aircraft performance improve with takeoff flaps set. The Vmc improvement makes sense but the performance improvement does not. At a basic level, drag = bad and flaps add drag...a lot of drag.

The question is, "how does aircraft performance improve with takeoff flaps set?"

The Airplane Flying Handbook (FAA-H-8083-3B) page 12-17 indicates that takeoff flaps will degrade aircraft performance:

  If flaps were used for takeoff, the engine failure situation becomes
  even more critical due to the additional drag incurred.

See also FAR 23.149.


texts: Where do flight sims get their data on aircraft flight characteristics?

texts:
Flight sims offer very realistic simulations of how a particular aircraft feels, claimed by pilot interviews on youtube.
But how do sims get their data?
First, does all this data even exist, i mean companies have data on how the aircraft changes control for example, due to some wind turbulance, or the slight turn of the steering?
Second, how do companies get this data? Particularly for fighters.
Third, how do they manage to offer such a realistic experience?
Are they in direct communication with the aircraft companies / goverments?
Isn't data like this confidential?


texts: What runway has the steepest climb requirement on take-off?

texts:
What runway has the steepest climb-out requirement upon take off?

This would probably be due to the need to avoid some natural obstacle, such as a mountain.


texts: How are operators of small UAS craft supposed to know about flight restrictions?

texts:
The FAA is requiring all operators of small unmanned aircraft systems between 0.55 and 55 pounds to register. This is to help ensure that operators of model aircraft and drones act in a responsible manner, etc.

In the Registration and Marking Requirements for Small Unmanned Aircraft document available from the FAA (PDF), there are examples given of drones being flown near wildfires that interrupted firefighting efforts, despite a temporary flight restriction for the area surrounding the fire.

It seems obvious to me that operating an RC aircraft near a wildfire might not be a good idea. However, "temporary flight restrictions" could exist in other cases that aren't quite so obvious. There is no requirement (as far as I know) for sUAS operators to check NOTAMs, aviation charts, etc.

How can an operator be sure they are in compliance in every situation? It seems like it might be very easy to violate some regulation inadvertently.


texts: What's required for a plane certified to fly to Antarctica?

texts:
What special features besides the obvious long range does a plane have to have to fly to and land in Antarctica?  I know not just any plane can make the trip, but I couldn't find many relevant regulations or certification requirements.

It seems like the C-17 and LC-130 are some of the most popular for these flights, based on the "US Antarctic Program Inter-agency Air Operations Manual" and this site. The manual does list other aircraft that can use Pegasus White Ice Runway: "C-5, KC-135, C-17, C-130, LC-130, P-3, A-319, and smaller aircraft".  I also know the Basler Turbo BT-67, DeHavilland DHC-6 "Twin Otter" aircraft, and C-141 are traditional polar operations planes.

The only applicable regulations I could find were:

In VOLUME 3   GENERAL TECHNICAL ADMINISTRATION, CHAPTER 29   PROVING
AND VALIDATION TESTS, 3-2438       CLASS II NAVIGATION AUTHORIZATIONS
D.4) North Polar (OpSpec/MSpec B055) and Antarctic Airspace
(OpSpec/MSpec B050). Applicants proposing to conduct terminal area
operations within these areas must conduct validation flights. No
requirement exists for validation flights for those applicants
conducting overflights if previously authorized in OpSpec/MSpec B036
and B040. During validation for approval of overflights of these
areas, test teams should include in-flight planning, contingencies,
CNS requirements, “fuel freeze” procedures, cold weather altimetry,
applicant’s reaction and passenger recovery plan, and emergency
airfield procedures.
Airplanes must have enough fuel to reach an off-continent alternate
if they arrive and cannot land.
I also remember reading somewhere that these aircraft had to have
fuel temperature and/or manual fuel level indicators to help prevent
fuel freeze.

So what special features or parts does a plane need to make an antarctic trip besides long range?  Why are c-130's and DHC-6's perfect for this kind of mission?

Note: Obviously pilots also have to have very specific and special training for Antarctic missions, but I'm focusing on the planes themselves in this question.

Image source


texts: Can a human get sucked into a jet engine?

texts: Can a human get sucked into the jet engine of a normal modern airliner? if so has it ever happened and what is the minimum or maximum weight that these engines can suck? As a safety measure, wouldn't light weight but high strength retracting safety covers that cover engines when the aircraft is parked protect both humans, equipment and engines? Of-course it would have to take into account the need to minimize weight. Also it could have the option to be controlled by the ground team supervisor remotely as an extra safety measure.


texts: Where do aerodynamical contrails get their condensation nuclei from, when forming at high altitude?

texts:
On this website, it is explained how aerodynamical contrails form:

  It’s formed by the reduction of pressure in the air as it moves over the wing.  When the pressure of a gas falls, then its temperature also falls (the same principle as is used by your refrigerator).  The reduced temperature cause small drops of water to condense, which then may freeze.  The (frozen) drops get larger as more water condenses on them.

Here is a photo of aerodynamical contrails forming at high altitude:

Source

As can be seen, the aerodynamic contrails start right at the wing. What I want to know is, where the oversaturated air condenses. "Normal" contrails coming from the engines use the soot from the engines as condensation nuclei. But what about the aerodynamic ones?

I think the water vapour condenses on the wing, but I need to know it for sure.


texts: Why are modern commercial airplanes still so noisy?

texts: After years of scientific research on the performance of commercial aircraft like 777's or A320'S, the cabin noise is still very loud. Modern aircraft have new features like serrated engine nacelles, like on the 747-8 or 787 engines; improved aerodynamics; vortex generators; cabin insulation, etc. So why do aircraft still have so much cabin noise after all these improvements?


texts: Do any aircraft have liquid-cooled brakes?

texts:
Aircraft wheelbrakes, especially those on heavy aircraft, get really, really hot during landings and rejected takeoffs, and cool down very, very slowly without active cooling.  This imposes limits on how short turnaround times can be between flights, in order to avoid overheating the brakes and wearing them out (which would be bad).  To counter this, many aircraft that make frequent, short flights have brakes with forced-air cooling.

However, air, being a gas, is far from the best coolant available; do any aircraft use liquid-cooled brakes for maximum brake cooling capability?  This seems like it would be most useful for very large aircraft that make frequent short, heavily-loaded flights from short fields.


texts: What common forms of deice and anti-ice exist and what future alternatives are being researched?

texts: For the leading edges of aircraft's flight surfaces, there are a few more common deice and anti-ice methods available. What are the most common systems? What are the alternatives? Is there any research going into alternatives where new technology might provide better or more cost effective solutions?


texts: Today my wife witnessed 3 fighter jets taking off from Teterboro Airport in NJ. She even took a video. How common is it for military jets to use civilian airports?


texts: What is the strange object on 737-800 exterior, on the aft right side?

texts: I was unable to locate this on a "real life" picture of the aircraft, so have attached an image from my simulator. What is the function/purpose of this object on the exterior of the 738? It seems like it would decrease efficiency so it must surely serve an important role? Thanks.


texts: Why isn't the course fixed along an airway?

texts: Why does in some cases magnetic course (not magnetic variation) change between navaids along a same airway? Isn't it supposed that a straight line in an aeronautical chart representing an airway has always the same magnetic course between navaids? Apparently that isn't so, but I don't understand why isn't so.


texts: How do I calculate FPNM for standard take-off minimums?

texts:
I have trouble understanding and calculating FPNM for standard take-off minimums.

As I understand, the formula is: (Ground speed)/60 * FPNM = FPM

Let's say the ODP says:

  565' per NM to 2800, or 1000-3 with minimum climb of 370' per NM to
  2800, or 1500-3 for climb in visual conditions

With a Cessna 172S, could you let me know whether the aircraft is able to meet this requirement? Here is the rate of climb chart:


texts: Are there helicopters with vertically mounted turbines?

texts:
On the helicopter representation in this answer, the turbine is horizontal, with gear required to drive the vertical-axis propeller.

Are there helicopters where the turbine is vertical and directly driving the propeller, without gear? What are the advantages and drawbacks, or why isn't it possible if so?


texts:
When the pilots enter their flight plan into the FMGS, the route will be shown on the ND. Can the autopilot automatically turn when needed with the given plan, or the pilots have to manually adjust the heading everytime?
And if possible how do they can manually turn the aircraft within autopilot when needed like: landing, etc.


texts: Why are almost all STOL aircraft high-wing?

texts:
Isn't ground effect a big factor in STOL operations?  Don't low wings produce greater ground effect than high wings?

Or is it a practical concern, that most real-world STOL operations are in unimproved or slightly-improved locations, and high wings are more likely to clear "runway" obstacles?


texts: What are those things on the B747 engine pylons?

texts:
I noticed some dots and lines on the Boeing 747 engine pylons. What are they?

The above image is as seen in this video at 2:18.


texts: Are engine casings expected to contain turbofan blade fragments?

texts:
On Southwest 1380, initial indications are that a fragment of the engine blade pierced the engine casing, which then hit the airplane window (or perhaps a part of the casing did). According to the BBC,

  Mr Sumwalt also said a casing on the engine was meant to contain any parts that come loose but, due to the speed at impact, the metal was able to penetrate the shell.

Is this an reasonably expected containment failure?  Or is the failure to contain surprising to industry experts?


texts: If I ferry an aircraft to the United States (from say the UK) is it a commercial or private flight?

texts:
If I am paid to ferry an aircraft from the UK to the US and then leave the aircraft in the US, is it a private or commercial flight?

I am not carrying passengers or cargo, but perhaps the aircraft itself becomes cargo if it is left in the US.

I guess my question follows on somewhat from this below:

What is the difference between a private and a commercial flight according to the US Customs and Border Protection?


texts: Why is an unpressurized takeoff performed?

texts: Why would an aircraft perform an unpressurized takeoff? What conditions lead to this being beneficial?


texts: Is threshold crossing height and glide path angle the same for ALL airports and applied to ALL aircraft?

texts:
It seems to be agreed (at an international level) that these values are standard and should be respectively 50 ft and 3 degrees. Are all airports following these rules, and are they applied to all type of aircraft?

Why would departure operations not have the same kind of constraints?


texts: Where does the "APU Auto Shutdown" message appear?

texts: I'm trying to find out if and where the "APU Auto Shutdown" message appears on the ECAM.


texts: Why is the total count of people on a plane given as the number of 'souls' on board?

texts: Why don't they just say 'people' on board, why souls? What is the origin of this term? I'm thinking it comes from sailing as I think I've heard that term in reference to crews out at sea, but I'm not a sailor so I don't know.


texts: Why are the cockpit controls of airplanes so complicated?

texts:
For a layman like myself, the cockpit of every single modern airplane that I've laid my eyes on seems like a complex, intimidating mess with knobs, buttons, screens and levers literally covering every single square centimeter. Every time when seeing this, from my point of view, chaos of control surfaces and indicators, I'm always thinking to myself "This HAS to be possible to make easier!"

Maybe my intuition is correct. Maybe it isn't. Anyhow, I can see a lot of possible reasons why one actually would want cockpits to be designed in this way. Maybe it makes it harder for an amateur to just wing it (no pun intended) and make it looks like (s)he knows what (s)he's doing. Maybe it forces the pilot to really understand every single nuance of the plane and its operation before even being able to taxiing. Maybe it fosters speed and security in an emergency situation by having everything accessible right away, accessible through muscle memory on the part of the pilot.

Or maybe most cockpit designers like to make the operation of aircraft a pain in the behind for everybody else. I don't know.

What's the design philosophy behind the design of the cockpit controls?


texts: Why do (jet) airplanes fly at tropopause (and not higher)

texts:
I've got a question which is nearly answered by the following thread however not fully to my satisfaction.

Why do jet engines get better fuel efficiency at high altitudes?

The question ultimately comes down to:

Why do jet airplanes fly around tropopause and not higher ?

In the following I will relate what I believe to know and try to explain the reasoning in my mind. Please correct me in all cases where my reasoning is not entirely correct.

Here is what I get.
-Fuel efficiency becomes better with altitude

This is because even though air gets less dense in altitude (amount of oxygen per volume decreases) the ram effect compensates so that the same amount of air enters the compressor. So in comparison with low altitude,  in high altitude the same amount of air is entering the compressor so the same amount of air (number of oxygen particles) enters the combustion chamber. If the same amount of air enters the combustion chamber the same amount of fuel will be used to combust. so the same pressure and temperature is created inside the combustion chamber.
What we need for higher propulsion of the gas is the highest possible pressure difference in comparison to the ambient pressure. Higher pressure in the combustion chamber is limited by the maximum temperature the turbine blades are able to resist, so the only way to get more propulsion is a lower ambient pressure wich is the case in higher altitude.

On top of that, thermal efficiency increases with lower temperatures. meaning more of all the energy inside the fuel is transferred into heat and pressure  when combusted. Only this is no more than approximately 5% in higher altitude.

These two lead to my conclusion that in altitude you will need high speed (to create ram) this will make your engine give more propulsion/thrust for the same amount of fuel burned when flying at the same speed at lower altitude. So you are able to reduce fuel burned to create the same thrust in high altitude and thus increasing fuel efficiency.

What I also know is that airplanes try to fly around the tropopause. Does it have anything to do with the characteristics of the tropopause ?
because  why don't they fly higher ? is this because temperature doesn't decrease anymore ? (this is the original story I recall from my classes a few years ago but I can't find the reasoning behind it any more) I find it now hard to believe since thermal efficiency is almost negligible.
Perhaps this is because the structure of the airplane is not able to withstand the pressure difference due to the fact the cabin pressure needs to remain below 10.000 feet ? In this it would still be true that an airplane flying higher and higher than the tropopause would get more and more fuel efficient. But also this I find hard to believe because with newer and modern composites an aeroplane should be able to withstand higher pressure differentials without adding weight and so be able to increase fuel efficiency by going higher. Cheaper and easier than developing more efficient engines I believe.

So where am I wrong ?


texts: How come I see some large planes, such as the 747, classified as either Category 5 or 6 Gate Sizes, depending on the publication. Why do some sites count the plane as one size, while others state otherwise? Is there a definitive guide, or is it relative to the country/airport?


texts: Descent of Light attack aircraft to loiter altitude

texts:
How do Light Attack Aircraft (LAA) such as the Embraer Super Tucano descend from their cruise altitude to their loiter altitude to be on-station above ground troops? I want to know the way these airplanes descend and what are typical rate of descent and descent gradient. Do they descend steeply and accelerate?
I know that commercial airplanes descend at a 3 degree angle. Do the LAA also descend at this angle?


texts:
How to pronounce ICAO, correctly?
Civil Aviation students claim that their teacher told them to pronounce it as

  /ˌaɪˌkeɪˈoʊ/, eye-KAY-oh

but when I look at Cambridge Dictionary it pronounces ICAO differently: https://dictionary.cambridge.org/us/dictionary/english/icao

So, how do you pronounce it correctly in Aviation?


texts: Is Jetman flying above other aircraft allowed? How it is possible?

texts:
According to the Times of India:

  Yves Rossy and Vincent Reffet - have achieved the rare feat of flying with the innovative Jetman wings, on either side of an Emirates A380 aircraft, the world's largest passenger aircraft, 4000 feet above sea level.

My Questions are:

Is flying near other aircraft is legal?
How they avoid getting into jet turbulence and other forces?
Is there Jetman suit available to catch up to the jet engined planes?


texts: Does the order in which engines in commercial airliners are turned on matter?

texts: I've seen videos on youtube where the pilots always turn on engines 4 and 3 (in a B747-4) first and then turn 2 and 1 on after pushback. Is there a reason behind this, and does the same reason apply to all multi-engine aircraft?


texts: Are an aircraft's nuts and bolts generally either all Imperial or all Metric, or can they be mixed?

texts:
This is a low-tech question, but I was wondering about the distribution of imperial vs metric hardware on aircraft.

When current commercial aircraft land at major airports, a mechanic will know which set of wrenches to grab. Still, I wonder is everything metric, or are some commercial aircraft still imperial? Could an engine or some subsystem use one kind of hardware on a plane that mostly uses the other?

What about at a more remote airport visited by a wider variety and vintage of aircraft? Would a mechanic need to go up and check before deciding which toolbox to use?

Found in this comment under this answer


texts: How are coefficients of equation of sideslip angle in the paper "A general Solution to the Aircraft Trim Problem" calculated?

texts:
I am sure many of you guys must have read the paper, "A General solution to the Aircraft Trim Problem" by Marco, Duke and Bernt. I am working with the turning of the Aircraft and I am not able to understand the calculation of Beta (sideslip angle) given in equation 72.

What I am able to understand is that the author describes the wind frame and body frame by 2 simple plane equations and then takes a dot product of the two planes to calculate beta.

The problem I am facing is with the calculation of the coefficients of the plane. They say that the coefficients can be expressed according to equation 67, which is nothing but axis transformation equations. Can anyone help me with the detailed calculation of those coefficients.

I have attached the above mentioned part as link to image file. Please have a look into it.

Link: A general solution to the Aircraft trim problem


texts:
The startup process in many military aircraft is, complicated, to say the least.
It takes a lot longer than most would think. An F-16 from cold is required to be able to scramble within 5 minutes if on alert (armed, fueled, and pilot ready), 15 minutes if not.
I also know that during the Cold War when the situation was expected to deteriorate, they could deploy B-52's to all runways (civilian airports included) that were longer than 9,000 feet, just sitting there with engines running ready to go. (Terrifying to think about...)
I also found this:

Default NATO QRA alert time is 15 minutes (in DEFCON 5), although the local CRC can lower that to ten (DEFCON 4), five (DEFCON 3) or even two minutes (DEFCON 2) depending on current state of affairs.
At 5 minutes (DEFCON 3), the engines would be running idle 24/7, at 2 minutes (DEFCON 2) there are pilots in the cockpit 24/7.

Anyways, an F-16 can scramble in 5 minutes. But an F-22 has an automated start process. IIRC, the checklist is something like...

Master Switch On.
Throttles Forward to idle.

I understand that this may be classified, but I was wondering if anyone can put me in the ballpark.


texts: How do I select an appropriate controller gain for this roll control autopilot?

texts:
I'm trying to select a suitable K value for this roll control autopilot, based on:

Instead of the Gyro, I've also just considered a negative unity proportional gain feedback. How do I select the appropriate controller gain K for the system? (I'm feeding a step impulse into the system). I know that for each aircraft it would be different, for a fighter jet you want quick response times, but maybe not so much on a commercial airliner. What I'm trying to find out/understand is there design criteria/a method to selecting this value?

Is there a overshoot(%) I should aim for?
Is there a required damping ratio set?
Or do I eyeball it, and find a balance between the time to settle and overshoot(%)?


texts: How can flight attendants respond to an immediate medical emergency?

texts: When an airplane is about to takeoff (after leaving the gate), how should the flight attendants respond to an emergency with a passenger which requires medical immediate assistance?


texts: Question about the difficulty of a couple of airplane maneuvers

texts:
I have a hypothetical scenario and I was wondering if any experts might be able to speak to it.  I will lay out the scenario, with a couple of specific questions, and maybe some honest answers will come if I leave out the dog whistle words :)

A plane is travelling at 322 Knots at 6800 feet and wants to simply
point the nose down and hit the ground somewhere within a target of
34 acres.

A plane is traveling at 336 knots at 6800 feet and begins a spiral
decent reducing speed over the next 2'40" completing a 270º turn,
coming out of the turn at 2200 feet.  The radius of the descending
circle at about 2.75 miles.

From the altitude of 2200 feet, travelling at 312 knots, said plane
increases speed over the next 40" finishing at the wall of a great
invisible barrier going 488knots, just five feet of the ground. The
descent rate increases exponentially beginning at 3200ft per minute
until getting to 5800 feet per minute travelling from 418 to 488
knots from 1200 feet to 5 feet in 12 seconds.

How easy or difficult would any of these maneuvers be to undertake, say in a Boeing 757, for a pilot who

had just been hired by a major airline?
Has several 1000 hours of flying experience
Could fly a Cessna if someone sat next to her to watch in case things went south (literally).

A sincere thank you - while this post may seem to have some snark, it is asked with 100% intellectual sincerity.

Calvin


texts: How are duplicate call signs dealt with?

texts:
Many airlines (at least here in the U.S.) have flight numbers that use different aircraft for different legs of the flight. For example, Delta 158 uses a 747-400 from Incheon International in Seoul to Detroit, then an A320 from Detroit to Boston a couple of hours later. This got me to wondering what happens if an earlier leg is delayed such that it's arriving around the time that the next leg is departing the same airport? In particular:

Will both flights use the same radio call sign? That is, will they both be "Delta 158" (ignoring the "Heavy" difference in this particular case?)

If they do use the same call sign, how do controllers know which one is talking, especially if they end up on the same frequency at some point?

It seems like this sort of situation would happen somewhat frequently, at least here in the U.S. where it's common for a given flight number to include multiple legs and for those legs to operate on different aircraft.

This question is related, but doesn't actually address this particular question: Why are some ATC call signs different than the flight number?


texts: What is the ground idle fuel flow of an A320 (CFM or IAE or neo)?

texts: Standing on ground, what is the idle fuel flow of an A320? ISA conditions, both engines running?


texts:
When do you contact ATC when departing from a non-towered airport into class B controlled airspace?

This is the situation where the uncontrolled airport sits under the Class B shelf.


texts: How long does flight planning take / when is it done / how is it done?

texts:
When I left an A320 today, the fuel truck was already there and refueling the aircraft. (At least, the hose was connected.) Also, a FA said they will fly back within 40 minutes.

This isn't much time, and I wonder if they start to refuel the aircraft before actually calculating the required amount. (Since it's a 4h flight, they'll need quite some fuel.)

So I'd like to know how much time is needed for flight planning of an airliner. Maybe some planning for the next flight can already be done in advance during the current flight? Maybe some part can already be done by others?  Or does the entire process take just a few minutes today?

It's also not clear to me what is done during flight planning. Of course planning the route, including possible ways to divert the aircraft, and amount of fuel. What else?

EDIT: To make it more clear: I'm asking about the work the pilots have to do to prepare for the next flight


texts:
I am searching for airports that have ILS (not sure if there is a "law" that any airport servicing civil flights must have one).
So I googled around and found this nice site http://www.azworldairports.com.
So I've been looking at airport in Vienna and in airfield section there is following:

Runway 1: Heading 11/29, 3 500m (11 482ft), 75, ICAO Cat. I, 3B, Aircraft size max: E, Rwy 11, ILS 114, Lighting: 11 CAT 1/PAPI, No Restrictions, Rwy 29, ILS 294, Lighting: 29 CAT 1/PAPI, No Restrictions
Runway 2: Heading 16/34, 3 600m (11 811ft), 75, ICAO Cat. I, 3B, Aircraft size max: E, ILS 162, Lighting: CAT III B/PAPI, No Restrictions

What exactly is ILS 114 / 162 / 294?


texts: When would these two fixes at KMEM be used?

texts:
When flying IFR into a class B airport you usually file a STAR at the end of your plan. After the last fix on the STAR you will then receive vectors from ATC to the approach for the assigned runway. At that time you would use the appropriate approach plate for information to complete the approach.

I was looking at some of the approach plates for KMEM and some of them contain multiple IAF's. For example, if you are coming in on the HOBRK 1 STAR and are assigned 36C it says that you should turn right to 53° and expect vectors after ROCAB.

But when you look at the approach plate for 18C you see two extra IAF's, OWAFO and IHTEM being approached directly from the UJM and HLI VOR's respectively.

If one should expect to be on vectors by that point when would these other two IAF's be used?


texts: What happens to US military demo teams following unexpected pilot turnover?

texts:
Following up on recent events involving the Blue Angels and the Thunderbirds, what is the typical procedure for these teams following a unexpected turnover of a pilot (in this case, a fatal or other serious crash)?

Do these teams have a "B" team in training to pull talent from, or possibly have a larger pilots roster that will rotate in and out throughout the season to pull from?  Maybe even have multiple teams that trade off show duties and training during the season?

(I assume that the Thunderbirds will just paint up a new plane and give the pilot a good pep talk).


texts: Do we shake more if we are seated towards the tail rather than in the middle or the front?

texts: Just like in buses on road, we feel more shaky when we sit in the back seats than the driver and other sitting in front. Is it the same for flights when we are in clouds?


texts:
EASA and FAA have placed a 300hr inspection AD on select Dreamliner Trent 1000 engines after multiple failures. Here is a photo of an AirNZ engine.

https://leehamnews.com/2018/04/14/faa-ad-may-severely-limit-etops-of-rr-powered-787s-sources/#more-26889

Update from comment on reference article:

The AD specifically refer to :
Intermediate Pressure Compressor (IPC) Stage (Rotor) 1 blades
IPC Rotor 2 blades
IPC Shaft Stage 1-8 Rotor assemblies
Previous stories had RR ‘offloading 35% of the Trent 1000 development risk to its partners The IPC module is done by Kawasaki. This seems to be different to the other known issue on the Trent 1000 of the fatigue cracks of the Intermediate TURBINE

What causes this much damage?


texts: Are there airports that in general don’t allow VFR traffic and e.g. don’t even have a VFR chart published and just allow IFR traffic?


texts: When can airliners fly from Israel over Tunisia's and Algeria's airspace?

texts:
Per flightradar24, on August 25th 2019, an Air Europa Boeing 787 flying from Tel Aviv to Madrid flew over Tunisia's and Algeria's airspace.

I thought flights departing from Israel or flying to it are banned from the airspace of Arab countries that don't have diplomatic relations with Israel.

For example, flights between Israel and India fly around the south of the Arabic peninsula. Flights between Israel and South America fly north of the Gibraltar straights.

Does someone know how did this happen, if it is a one off or a change, who authorizes this. Maybe this can happen in case of bad weather or an unplanned contingency.

While I did not find an official source stating that such flights are forbidden from those two countries airspace, see here for an informal one: https://ops.group/blog/countries-with-bans-on-flights-to-israel/

Thanks


texts: Performance metrics of a propulsion system - optimising a propulsive fan system

texts: I'm designing an electric fan propulsion system for a hybrid-electric business jet. The hybrid business jet uses a series hybrid configuration and distributed electric propulsion. The electric fan propulsion system is for the distributed electric propulsion part of the engine and consists of the fan, intake duct and propulsive nozzle. So far, I've designed it so that the efficiencies of each component is as close to 1 and optimising the fan pressure ratio so the mass flow rate is large and the exit velocity is small (to improve propulsive efficiency). I'm currently unsure whether there are any other parameters I'm failing to consider and would like some more insight.


texts: Why do fighter jets land faster than Jumbo commercial aircraft?

texts:
From my own understanding, the bigger (and heavier) aircraft, the higher approach speed it needs to keep itself from stalling. According to this site, the approach speed of an A380 is 140 knots, and 160 knots for a 747. In contrast, the F-16's landing speed is 141 knots, and 135 knots for the F-35C.

Doing mass-to-speed ratio, it doesn't make any sense to me. Could you explain why do fighter jets land faster while they are lighter than large commercial aircraft?


texts: What happens if a parachute does not open while skydiving?

texts: While skydiving we have to jump from the airplane at a certain altitude above Earth. So if for some reason the parachute doesn't open, then will that person (or any object similar to a human body) fall to Earth or will it be incinerated/vanish in the sky due to air-friction in space before coming down to the Earth?


texts: I am performing a review of aircraft maintenance. i intend to reconcile the MMEL for airbus 320 along with the operators MEL. Based on my information, the MEL is supposed to be more restrictive than the MMEL as it considers operational hours, operating conditions and many such factors. In this case, is it OK it the MMEL and the MEL have the same item list? Shouldn't the MEL have some more items?


texts: Is jet fuel typically injected before or after the flame holder in an afterburner?

texts: I don't have the best grasp on the intricacies of afterburners but I'd assume that if the engine has a flame holder then fuel would be injected before it in order to allow it to heat up to autoignition by the time it reaches the flame holder. If not please explain, thanks.


texts: Is the freestream dynamic pressure higher during cruise or during landing/takeoff?

texts: I was trying to calculate the forces generated by an uncommanded flap deployment during cruising flight ($M_\infty=0.85, Alt.=36kft$) in comparison to the forces say, during landing. Assuming similar geometries, the forces will be proportional to the freestream dynamic pressure. If $q_\infty=\frac{\gamma}{2}p_\infty {M_\infty}^2$, the Mach number will be higher at cruise but the static pressure will be lower due to altitude. Thus, it is not immediately obvious to me which flight condition has the higher dynamic pressure. Does anyone have reasonable numbers for $q_\infty [lbf/ft^2]$ at landing vs cruise for a modern commercial airliner so that I can compare?


texts: Would a slower and larger rotor blade be practical?

texts:
Essentially a rotor is a rotating wing and the design of that wing generates lift. My question is this, why not increase the surface area of the rotor and slowdown the rotor speed. Rotor strength will also be increased. Slower rotor speeds will also reduce the turbulence created by the larger area of the rotor.
I believe that this will also increase efficiency as the reduced speed can result in smaller engines being used to do the same work.


texts: Could the center of rotation of a spinning aircraft move away from CG?

texts:
Picture a barbell shape or twirlers baton spinning.  Perfectly symmetrical.  Rotating at its center of gravity.

Now replace one of the ends with fins of equal mass an spin it again, once in a vacuum, then in air.  Will the centers of rotation be different?  Why?  Could this apply to aircraft?   Thanks.


texts: How strong someone should be in order to fly without "power steering"?

texts:
Planes these days use fly by wire systems while older ones had a mix of hydraulics with electronic assistance like the MD-11 (And maybe 737-800?).

But what would happen if you lost the electronic systems and you had to fly manually? I remember an incident of this happening in a MD-11 and pilots using raw muscle power to operate the flying surfaces (And using something like 10 kilos of force only to keep the yoke in place) or putting 10 kilos of force to the yoke constantly (My memory isnt exactly bad. It was a months ago)

So How much raw muscle power is needed to fly an MD-11 or an 737-800 without assistance for 10 minutes and then land? Through two pilots or as a single person.


texts: How to calculate altitude in a flight simulation?

texts:
I guess altitude from sea level in the real aircraft is read from barometer, while for the altitude from ground a radar is used. For the purposes of very simple simulation, and assuming aircraft is on ground at certain airport at certain altitude.

The starting variables are then nothing but a throttle position, which over time increases, which translates into speed. And once the aircraft is airborne also the pitch. For this purpose I would not assume any roll, wind or other factors. The aircraft engine has certain torque % and pilot pulls the nose up to achieve certain pitch.

Is it possible to get the altitude simply as the function of pitch and torque % Or to put it differently what are the minimum variables to take into account to come up with an altitude?

UPDATE

Obviously there's something wrong with the question because it resulted in the explosion of complexity, even touching the topic of atmospheric re-entry.

What I want to know is, as a pilot of a simple simulator, standing still on the runway, I can only change two things.

Throttle, and some time later
Pitch

I don't have to do anything else whatsoever in simple sims, I click on + to set the throttle to X, and when the speed is Y, I pull the nose up, and now the altitude keeps on picking up. How do those two changes to those two variables (throttle, pitch) eventually give me the altitude and speed, through a series of equations (that needn't be neither simple nor linear)?


texts: "All exterior lights" when crossing a runway? Landing light, too?

texts: AIM 4-3-23 (f) says "all exterior lights should be illuminated when taxiing on or across any runway".  AC 120-74B 7.h.2.c has similar words, except that it's limited to "crossing a runway".  Both conflict with other guidance, which would imply that turning on the landing light is a signal of your intent to take off.  Seems that it should be "all exterior lights except landing lights".  How do the pros interpret this?


texts: How to find the remaining fuel without electrical power on the MD-80?

texts: After a flight, how to find the remaining fuel without electrical power (even the APU) on the MD-80?


texts: Why can't airline pilots listen to music while flying?

texts:
In an interview I read, a 747 captain (Mark Vanhoenacker, an American British Airways pilot) says he doesn't understand why he cannot listen to music inflight, when for example surgeons – who literally hold peoples' lives in their hands – can:

  Can you ever play music in the cockpit?
  Sadly no. Sometimes when your flight is delayed, on the ground waiting
  for a couple hours, without passengers on board, you might put some
  music on in the cockpit. On the radio, you might hear a little music
  break through on an air traffic control frequency, those frequencies
  aren't much higher than the ones used by commercial radio stations.
  But as for listening to music while flying, no—which I don't
  understand! I think surgeons can listen to Beethoven if they want,
  right?

I looked that up and sure enough, some surgeons really listen to music and it even improves their performance:

  "From classical to rock, music can be heard in operating rooms across
  the world. When plastic surgeons listen to music they prefer, their
  surgical technique and efficiency when closing incisions is improved,
  a new study shows."

So why is it not allowed for airline pilots ?


texts: Should ADS-B airborne and surface squitter transponder registers both be updated regards air/ground status?

texts:
ADS-B have two position squitters, airborne and surface. As far as i know, airborne position is broadcasted on air and surface position broadcasted on ground.

There is a "Squitter Capability Subfield" in BDS Register 10, which needs to be set if both airborne and surface position registers are updated within last 10 seconds. This kinda implies both registers shall be updated all the times.

Is providing data for both squitters necessary regardless of aircraft's vertical status? Can we select one of these squitters and provide data only for it?


texts: Are there special safety considerations when flying to/in Atlantic Canada?

texts:
I'm considering a trip to Nova Scotia from New York in a Cessna 172 or a Piper Archer. The trip is about 3.5 - 5 hours long and could involve some small open ocean portions. Since Nova Scotia has variable weather, high wind, and is pretty rural, I'm interested in knowing if anyone has any recommendations, warnings, or resources for flying to Nova Scotia or Newfoundland.

I know this questions is pretty broad, so I welcome any suggestions for narrowing the scope. I've just had a hard time finding anything on the internet about making a trip to the area.


texts: What drives the design decision of where to place the refueling receptacle?

texts:
What has driven the decision to place the refueling receptacle behind the pilot and to rear of the plane.  Is this simply driven by the change away from drogue and probe and the location decided by the preference of the pilots, the manufacturers or the service, any ideas?

As earlier aircraft appear to of a variety of locations of the receptacle.

I realize the pilot does not have to fly the probe into its receptacle, that is done by the tanker operator.


texts: What is the force to change the pitch of a variable pitch propeller?

texts:
At the moment I am struggling with the problem that I do have an idea how to calculate this force by using the blade element theory and going over a whole propeller blade in order to calculate the torque inside the blade. I need this torque in order to calculate the force necessary for changing my pitch inflight. Is the blade element theory the correct way to calculate this?

Source: Nelson, Wilbur C.: Airplane Propeller Principles (John Wiley & Sons, 1944).

Also I do lack information regarding the airfoil data. Is there a good estimate on how high the coefficient of torque will be? Is there a good airfoil database for propellers online?

The assumption that cm=-1/4*ca does not work, as profiles on propellers are not even plates.


texts: What is oil thermal expansion in the CFM LEAP 1A engine for the A320NEO?

texts:
While I was going through the FCOM's SOP, normal procedures chapter, preliminary cockpit preparation section I came across the term oil thermal expansion. In the image below it is mentioned in the note section that

  IF THE ENGINES HAVE BEEN SHUT DOWN FOR MORE THAN 60 MINS, DECREASE THE ABOVE QUANTITIES BY 3 QTS TO TAKE INTO ACCOUNT OIL THERMAL EXPANSION.

What exactly is this phenomenon and why does it require us to reduce the oil quantities mentioned when carrying out the engine oil quantity check?


texts: Why is polar curve of a glider dependent on flight load?

texts:
This is my first question here.
I'm just a glider in education phase and not yet a pilot, but because I'm also physicist, I'm interested in some details more than other people.

My question is simple:

I know what a polar curve is. Why is this curve dependent on the wing load?
For my knowledge in aerodynamics the polar curve is a property of the airplane/wings, but not dependent on flight state. Otherwise I know from my flight instructor, that gliders are often filled with water to increase weight, which gives a better gliding ratio.

What I mean you see on this curve: why is the curve changing with wing load?
My only answer would be, that wings are flexed differently under different loads and that the different curves arise from (slightly) different geometries. Is there something else I have overseen?


texts: What preparations should I have to fly from the US to Mexico?

texts:
I am holding a US private pilot certificate with instrument rating, and planning to fly a single-engine aircraft from US to Mexico.

Regarding legal, visa, airspace/ATC knowledge requirements, flight plan filing, what do I need to prepare and how may I find the materials (in English).


texts: Are private jets allowed to land at London Heathrow?

texts:
Heathrow is among the worlds busiest airports, with traffic mostly (entirely?) from airliners. Are private/business jets (e.g. Gulfstream G650 or Cessna Citation X) allowed to land at Heathrow?

If so, what are the landing fees and what criteria do they use in charging them?


texts: Are life jackets mandatory on planes that will never fly over water bodies?

texts: Supposing I'm a regional carrier and my routes never pass over water bodies (sea or lakes which are over a certain size). Am I obliged to carry life jackets on my plane?


texts: What regulation says that a manufacturer must support a fleet above a specific size?

texts: Beechcraft bought back Starship to reduce the size of the flying fleet so they could stop supporting them. What regulation defines the fleet size a manufacturer has to support?


texts: What is the least expensive way to become a commercial pilot in the UK?

texts: Besides the RAF is there a way of becoming a pilot without spending tens of thousands of pounds on flight training? I'm finishing university and looking to go into a career in flying, I can't join the RAF since I am partially colourblind so I would not be allowed to train as a pilot in the Air Force.


texts: Could an airliner with only one functioning engine recover from a stall?

texts: If a modern commercial airplane such as a Boeing 787 would stall with only one functioning engine, is it possible for the pilots to right it or would it require two functioning engines?


texts: I have read that jet engines, at least the under-wing ones, are attached to the airplane by shear nuts and bolts so that in case of unstable forces in or on the engine, the engine would fall off to prevent further damage to the airframe. Have there been any incidents and or accidents where the engine has fallen off the plane in accordance to this design feature?


texts:
Whenever I watch cockpit footage of test flights there is always an added device with big clock-like digits centered above the glareshield.

They come in different shapes as shown below. What are they called and what are they for?

I'm thinking it's to timestamp the multi-angle video cameras, but I highly doubt that's the answer.

Images linked to sources.


texts: Why does the Boeing 747 have a nickname but other aircraft do not?

texts:
Boeing 747 is commonly called Jumbo Jet.

How did it get this nickname and why other airplanes do not have nicknames?

Please note that I am not talking about official names, e.g, Boeing 787 Dreamliner.


texts: Does making a mistake mean you lose your cert?

texts:
Disclaimer: I haven't been in, nor do I plan on having an accident. That said, this has always been a question of mine.

Let's say I'm flying a little Cessna or ultralight around Ohio. Maybe the wind is stronger than expected aloft and I run out of gas before making it back home. Clearly I need to put it down on a road or field if I can.

After this happens, does the FAA revoke your certificate?


texts: Expendable wingspan, long range early airplanes

texts:
Reading this question, I was wondering if, at some point early in aviation history there may have been airplane designs or concepts replacing or anticipating variable swept wing by "expendable wingspan wing"?

For example, some heavily loaded bomber airplane barely able to take off with its full wingspan, could jettison part of its wingspan once its mission is completed (having dropped bombs & burnt most of its fuel), in order to flee more quickly from enemy skies.


texts: Are matches in checked baggage a safety problem?

texts:
A friend of mine checked in on Singapore Airlines a bag which had a box of matches in it. They are regular matches and not the "strike against anything" type.

My friend subsequently realised that these were banned on that airline, and went back to the baggage check-in location. The baggage check-in staff said that it was not worth the bother to retrieve them, and that security personnel later on would remove the matches if they thought they were a problem.

Presumably there is some chance the personnel later on would miss the matches, but the staff did not seem to bothered by this, which suggested to me that maybe there was no genuine safety problem here.

What's the rationale for this rule existing? Of course in life on the ground matches do not generally spontaneously ignite, but I wondered if maybe different conditions in the cargo hold made matches more likely to ignite on their own?


texts:
If the pressure goes always from high to low, we should have a compression, due the lower pressure of the air stream over the upper surface, and an expansion in the airstream in the lower surface.

So What causes the "suction" on the upper surface of an airfoil and the "pushing" in the lower one?

I undestand why there is a region of high pressure and a low pressure around the airfoil. But I am a little bit confused about the effects of the external pressure (Free stream) on the airfoil stream.


texts: Which kind of stability do aerobatic aircraft have?

texts:
I'm designing an aerobatic aircraft similar to EXTRA 330SC.
I would like to know about stability: lateral and longitudinal, static and dynamic.
I read that aerobatic aircraft have neutral static stability.
Some books relate Cm to AoA.  Others relate Cm to CL.
Please detail more about this or provide some bibliography.


texts: Do hours flying "advanced ultralight" aircraft contribute towards your license in Canada?

texts:
I'm interested in the business possibilities of offering flight training in Southern Ontario, in particular using advanced ultralight aircraft. I realize that this is uncommon, of course, but my question is one of regulations.
How many hours flying an advanced ultralight aircraft can count towards a student's:

Recreational license?
Personal license?
Commercial license?

I'm not sure how to read the CARs here in 421. Would a Pipistrel Alpha Electro (classified as an Advanced Ultralight in Canada) or Pipistrel Velis count as "aeroplane"?


texts:
Ok, before you say, "Military Training Routes are used for... uhh... military training," let me elaborate.

I've read about how they work with ATC and speed restrictions etc. What I'm wondering is what they do on them.

Take, for instance, IR-504. It starts in the middle of nowhere about 20 miles south of the BUM vortac in western Missouri, almost 70 miles from the nearest Air Force Base. It takes numerous turns and meanders, seemingly randomly all over northeastern Kansas. It finally ends in an MOA in the middle of the state, but once again, not by a base or anything.

I can't see any rhyme or reason to the routing and can't imagine what it would be used to train for. It's not bombing practice; only a very small section is inside an MOA. It can't be terrain following exercises; its an IFR route and 3 digits means over 1500ft agl. Besides, what terrain could they be following? We're talking about central Kansas here.

What in the world do they use these routes for?


texts: Why doesn't the A380 use its outboard thrust reversers?

texts: One thing I noticed with the A380 is that it only seems to use the inboard thrust reversers while landing. I suspect it relates to FOD ingestion or perhaps damaging the runway. This is strange though, because the 747-8 (which also has a large wingspan and very large engines), does use all of its thrust reversers during landing. Does anyone have an official answer on why this is?


texts: When departing from a class C or D airfield, what is the proper VFR procedure?

texts:
Specifically, when is it legal to turn to your on-course heading?

I find that sometimes the tower will give me an instruction to "turn on course" but sometimes they don't. Are you supposed to stay on the runway heading when you do not get the instruction to turn on course, or do you just go ahead and turn after reaching some altitude?


texts:
In an airliner, where does the APU draw its intake air?

Is it a similar location for all airliners, or do different options exist?


texts:
Can anyone identify which comms/nav system the circled antenna belongs to?

Thanks.


texts: How is aircraft control positively transferred between pilot flying and pilot not-flying?

texts:
I am watching the video NTSB Animation Flight 1549 Hudson River Landing US Airways  (Youtube) and at 0:36 in the video, after the bird strike, you see the following dialogue:

HOT-1: my aircraft
HOT-2: your aircraft

I was curious to know what the formalities behind this is.  Could HOT-2 also claim the aircraft?


texts:
Regarding Flight 007 that got shot down in the Soviet Union, this was reported in the New York Times:

Study Says Korean Airliner Was on Its Intended Course When Downed in '83 (nytimes.com)

Excerpt:

  A retired airline navigator has gathered evidence that in his view
  shows that the South Korean airliner shot down over Russia in 1983 was
  on a deliberate flight path and did not stray accidentally into Soviet
  territory.

  A principal part of his analysis is his refutation of what has been
  the prevailing theory, that the plane unintentionally flew off course
  because of a single-digit mistake in keying flight coordinates into
  the navigation system.

  Leading aviation officials accept the refutation as correct, but still
  insist that the incursion was accidental and not deliberate.

We know this was a modern (at the time) Boeing 747 with a complex inertial flight management system.

No, I do not believe the theories about this being intentional.  Nobody would risk a plane full of passengers like this on purpose.

In 1978 the KAL flight 978 went astray and was forced down on a frozen lake inside Russia.

Korean Air Lines jet forced down over Soviet Union - Apr 20, 1978 (history.com)

I would think this would be on their mind as they prepared for the flight.

So my question is:  How did KAL 007 get so far off course?

Follow-up:  Wouldn't they have noticed?


texts: How long before a Medivac should the pilots be ready?

texts:
If you are on home reserve how long is it required that the operator notify you of a flight before required Take off time?
Is there a regulation or documentation to support this or is it operators discretion


texts: Does operation under ETOPS rules require additional procedures in flight during the ETOPS segment?

texts: During Extended-range Twin-engine Operations (ETOPS), are there any special procedures pilots have to follow? I am asking for specific procedures / tasks during the ETOPS segment of a flight, not what happens before entering the ETOPS segment (check ETOPS items on MEL, calculating Equal Time Points, check communications, ...). Maybe additional checks (engine, fuel, oil) during cruise flight that are not done when not operating under ETOPS rules?


texts: In an emergency, how much runway does an A320 need to stop safely?

texts:
From time to time I land at Wellington Airport in an A-320.

The runway has sea at either end and is 2,081m (6,827ft) long.

There's never been a problem but I find landing there a bit nerve wracking (the frequent high winds in the area means just getting the plane over the fence is sometimes a little more exciting that most would prefer).

I imagine that getting the wheels onto the runway as soon as possible is a priority so you can start braking but I wonder in a flat out emergency how much runway does an A-320 need (full of passengers/cargo but not much fuel) to stop if nothing else matters but stopping ?

EDIT: I meant to say I do appreciate that wet/dry runway and head wind strength would influence this quite strongly but I'm just looking a ballpark figure.


texts: How can a designer maximize the glide ratio of an aircraft with low aspect ratio wings, other than by increasing the aspect ratio?

texts:
As I understand it, the gliding range is given by a lift to drag ratio—hence to increase the gliding range, I would want to increase the lift and reduce the drag as much as possible.

To that end, apparently, it seems that high AR fits both the bills. However, does that mean that I will not able to enhance the gliding range with low AR wings at all?


texts:
I was reading this question about turbulence and how pilots foresee it, and in one of the answers, @Rhino Driver states:

  Weather Radar Just like using your eyes, except the radar can see further through haze and other clouds. Typically this is useful for finding embedded thunderstorms, but it can also be useful to find areas of potential turbulence

And that make me wonder...

How does the airliner's on-board weather radar work?
Is it connected to ground base stations to synchronize the weather info?
What kind of "weather types" can it detect? (i.e. thunderstorms, light rain, clear weather)


texts: Amazon Atlas nose-down elevator deflection?

texts:
In this link I read about the crashed aircraft:

  The airplane then pitched nose down over the next 18 seconds to about 49° in response to nose-down elevator deflection.

I feel that this is a common mechanism, unknown to non-expert, like me. What does it mean?

Interested in a rather intuitive, relaxed explanation, rather than an analytical one.


texts:
Given that it is long haul aircraft, and is most widely used by airlines in that capacity:

How often do they replace the whole tire?
How much does 1 tire cost the airline?


texts: Hub-and-spoke networks: fixed and variable costs

texts:
In the economic literature, many authors sustain that hub-and-spoke networks:

Increase the fixed costs sustained by the airlines (due to minimising the risk of congestions at the hubs). In particular, the fixed costs of a hub is expected to increase with the number of spokes.

Reduce the marginal costs (by allowing for a more  efficient use of aircraft and other inputs).

Could you explain this with an example?


texts: Are taxiways numbered in a predictable order?

texts:
When taxiing at an airport without a full-blown airport diagram (most commonly, a non-towered airport), how does a pilot know whether taxiway A (Alpha) is on one end of a runway, or the other? Or, in the case of taxiway exits, how does one know whether exit A1 is at one end of a runway, or the other?

In other words, are taxiways numbered in a predictable or consistent way? An example would be, “Exit A1 is always located at the easternmost exitway of Alpha”. If they are, is this because of custom or regulation?


texts: What is this plane from WWII (probably French or Allied forces)?

texts: Picture should have been taken after or during the end of World War II, probably close to Marrakech French base (but that is not sure). Can anyone tell us what these planes are? My grand father could be one of the pilots and I would like to find information on him.


texts: How are bird strikes tested in helicopters?

texts:
Bird strikes are pretty well tested for planes, but what about helicopters?
Do they happen as frequent as planes and if so, what would be the possible outcomes?

Do helicopter emergency procedures include a "bird strike" event?


texts: How is the airfoil of a fixed wing ultralight constructed?

texts:
This is a good example of the type of ultralight I am trying to build:

(Source)

How might the airfoil be constructed in this plane?

My guess was that it's mostly created by the cables that suspend it, but then again, one like this:

(Source)

Doesn't have those cables, so how are the wings constructed?

wood?
a bag of helium?
something else?

If you could link me to some sort of visual it'd also be much appreciated.


texts: Why would the engine quit when turning on the R magneto after an overhaul?

texts:
I just finished overhauling a Lycoming O-360; it's currently on a stand, i.e. it's not in the aircraft. I replaced the capacitors and point gaps on both the L and R mags. I adjusted the E-gap and engine timing at 25 degrees as per the engine plate.

I have two toggle switches connecting the P-leads to ground: one for the R mag and one for the L mag. I turned on the L mag only to start and when I started the engine for the first time it fired up right away. But when I then turn on the R mag the engine just stops.

I can start the engine on the L mag only any time. As soon as I turn on the R mag, the engine dies. It’s as if when I turn the R mag on the L one goes off. I did everything I could to troubleshoot but I did not find where the is. What could be the issue?


texts: What is the problem in the satellite data of MH370

texts:
In the Inmarsat data of MH370, there are handshakes (BTO) with time (UTC) at: 19:41, 20:41, 21:41, 22:41, 00:11,00:19. Normally it pinged every hour, but why the 2nd to last happened at 00.11 that was 1.5 hour after the previous one? The last one happened at 00:19 is for what reason?

Also can ping be stopped manually, e.g. by turning off the power, then there will be no ping?


texts: How can I get a ride in the jump seat as a non-professional pilot?

texts:
A couple of years ago, I had a strong fear of flying. Now, I really enjoy it. In fact, it is a dream of mine to sit in  the jumpseat of an A320 during takeoff. I've had a handful of flying lessons.

If I took my logbook and explained my interest to the captain, is there any chance this could happen? If not, how could I make it happen?


texts: How can a small ducted fan produce a large amount of thrust?

texts:
This 15.2 cm ducted fan by Schuebeler can produce 175 Newtons of static thrust. How is this possible in such a small diameter?
If this seems normal, then why and how can this ducted fan produce that much force?


texts: What are the pros and cons of a pulsejet?

texts: I've heard pulsejet powered aircraft can fly at very fast speeds but are there any drawbacks to this type of engine? And are the disadvantages greater than the advantages or vice versa?


texts: What is the proper procedure to change VFR altitude when changing heading from east to west?

texts:
When you fly from west to east, sometimes your route heads west to avoid obstacles or to clear class B or C airspace.

According to hemispheric rule, let's pretend I selected 7500 feet for VFR to the east. En route to a destination with flight following, when I change heading to the west and the route to the west takes about 30 mins, can I remain the altitude until I get a new instruction from ATC? Or, should I request descent/climb and follow the hemispheric rule?

The destination and the post-take-off route are to the east, but when most of the route is to the west, it makes me confusing to select a proper altitude.


texts: Are turboprops more efficient than piston engines (thrust per fuel consumption)?

texts:
I want to compare two types of engines: Turboprops and piston engines. I want to know which one is more efficient. There are many types of efficiencies, so I will specify: thrust (in newtons) per fuel consumption (kg/second).

Right now I don't care about power/weight ratio or max speed or horsepower. Those are all valid concerns for aircraft design, but I'm trying to pick exactly one criteria and figure which engine is more efficient in its terms and its terms alone. I don't want to mix criteria. I want to focus on one aspect, get an answer to it, then move on to the others later.

A complication is that piston engines usually give their output in horsepower. I have no idea why this is. What's ultimately needed is thrust. I realize that a propeller engine's job is to create torque, and thrust will depend on blade length and airspeed. In that case, I can't understand why those engines don't specify their output in torque.

Citing engines that actually exist (and citing their specs) will answer this question as long as the choices are modern, good engines.

(I did not include turbojets or turbofans for fear of being too broad. I picked two propeller engines and don't want to mix them with jet engines.)

One more thing. I realize that engines are capable of varying levels of thrust. It's my understanding that max thrust is usually more inefficient than cruising thrust. Therefore, I will ask for thrust/fuel-consumption figures of an engine at typical cruise conditions.


texts: What is the relation of AIR BLEED IN message with the pack system on an Airbus A320?

texts: Before the power-up, if the pack switches are set to the ON position and the aircraft is powered up with the APU bleed off, is there a chance that the AIR BLEED IN maintenance message comes up on Lower ECAM page?


texts:
I noticed this little hole that is right in front of the cockpit window of the F-22 Raptor. In some photos, it seems to be closed, while in other photos, it's open.

Does anyone know (or think they know) what the purpose of this hole is? Is it a ram air intake for air conditioning? Or is this classified?

Here are examples:

Closed hole:

Open hole:


texts: Can an FAA-certified pilot rent/fly a GA aircraft in England?

texts:
I am a U.S. certificated pilot in the U.S.A. I have about 1200 hrs flying mostly general aviation.

I will be traveling to England with family in March 2019 for a personal vacation. I would like to know if anyone on StackExchange has rented an airplane in Englad before and what their experience in doing this was.

In addition, it looks like it would be pretty easy to qualify for an EASA license in England. Any advice/insight on how to go about this?


texts: How can I keep my IR currency outside the USA?

texts:
I am an FAA PPL/IR holder living in Spain.

My IR license was issued in May 13 of 2016, it has been over 6 months so now I need to log my 6HIT with a safety pilot.

Is it possible to complete the currency requirements in a simulator even though I have gone past the 6 month mark without flying? Is it possible to complete the currency requirements in the EU with an instructor?

Thanks for any help, my flight school is being really unhelpful as they seem to actually know far less than I do about FAA regulations, this is my last hope!


texts: What is the difference between an Instrument and Equipment?

texts: In an aircraft, what things is an instrument and what things is an equipment? For example the ILS, is the Antennas located in the runway considered to be an instrument or an equipment? Or is there another example to differentiate both?


texts: What suits best for lateral controllability at high Angle of Attacks- a vortex generator or wing slots?

texts:
At high angle of attacks, the prominent problem is the separation of airflow. And if this airflow separation is near ailerons, we lose lateral controllability.
And the solution is making the flow turbulent.
By adding slots in a wing at correct positions, we are capable of re-energising the flow. It is the same thing a vortex generator does (I presume).
But what device is best suited for the current case?
From an unknown source, I found:

At high angles of attack, the airflow over the ailerons can be separated from the surface. Vortex generators, positioned just forward of the ailerons, are designed to re-energise the boundary layer and help to prevent this separation. This makes the ailerons more effective at high angles of attack

(I do not how effective this reason is.)
And therefore, please consider the case of Leading Edge Slats (which creates a slot) too. At a high angle of attack, a LE slat helps by re-energising too. And If we have a turbulent flow (by employing LE slats) in the early stage, (I think) it is better than the case where we put vortex generators near ailerons, which may encounter an already separated flow.
Edit: The aspect of lateral controllability dictates the conditions where one wing can be at higher AOA than the other. Will Slats not fail to provide the desired effect due to its symmetrical effect (increasing CLmax simultaneously for both and stalling one of the wings and making into a spin)?
Does the "symmetrical effect" apply to VG and slots near the aileron too?


texts: How should time as safety pilot be logged?

texts:
Let's take a classic example. An instrument rated pilot is flying a C-172 and wants to maintain instrument currency. The pilot goes flying and performs some approaches, holding and intercept/tracking to maintain that currency, all while under the hood. In order to maintain a safe condition, a safety pilot is brought along to maintain VFR conditions.

The question is, how should the safety pilot log this time? In this condition the safety pilot is a required crew member, but is this time technically SIC or is it PIC?


texts: What is the speed of a standard airliner during the different phases of the flight?

texts: I would like to know how does the speed of an airliner vary as a function of time.


texts:
They can be seen in many —mainly military— jet engines. Do these bolts recibe an special name?

J79: the fasteners are everywhere

EJ200: they can be discerned in the rear flange


texts: Are aircraft accidents more frequent in specific countries?

texts:
In the past months I heard about several aircraft accidents that happened to occur in Russia, Indonesia, Malaysia... and I was wondering if some countries are actually more connected to accidents than other.

Is there some statistics on this topic? and if so, do they confirm this alleged over-representation, and do we know the reasons behind?


texts: Have other designs for individual gasper ventilation been tried?

texts:
The air gaspers (in large passenger aircraft) above the passengers' heads are fed from the main air conditioning system, at least in all aircraft that I am familiar with (see also this answer). This design probably makes sense, as it's very simple (no moving parts other than the gaspers) and takes advantage of a system which is already installed in the aircraft to provide additional functionality.

Still, I'm curious:

have other designs for individually adjustable passenger ventilation been tried (i.e. installed in large passenger aircraft), and why were they abandoned in favour of the current design? Off the top of my head I can think of a system with little fans above each seat - although it's probably far more prone to breaking than the current system.
Some cars have individual climate control (where the air supplied to each occupant can have a different temperature), has that ever been tried on a large commercial aircraft?


texts: Why the 747 testing GE-9X doesnt have a winglet?

texts: News says it is a 747-400, but it doesn't have a winglet.


texts: What is this aircraft with a big gun on its back?

texts:
It looks like there is a really big gun on the back of this aircraft.

https://www.instagram.com/p/BQVqnYCAlZU/

I found it on Instagram. What is this?


texts: What flight controls should be used to counter asymmetric yaw?

texts:
How should the autopilot or pilot handle asymmetric yaw, as with one failed engine on a multi-engine turboprop whose engines are not on the centerline?
Should one apply roll control or rudder control?


texts: What is the tail rotor rpm for the Sikorsky S58 helicopter?

texts: I need to know the TR rpm for Sikorsky S58. I have tried searching for it and calculating it based on some assumptions I've made. I would like to know the true rpm value and not assume it since this is for research purposes.


texts: Why do most aerobatic aircraft have conventional landing gear?

texts:
I was browsing images of aerobatic aircraft on Google and noticed that the vast majority of them have conventional "tail-dragger" landing gear.

Is there any practical reason why this is the case, or rather an aesthetic preference?


texts: How are aircraft identified as unregistered?

texts:
When someone operates an unregistered vehicle on public roads we know how they are caught: Police routinely pull people over, and they always check registration of vehicles.  In fact, police will frequently "run tags" without even stopping cars.  They have a realtime connection to a nationwide registry that can report the details of the tagged car and whether a tag is expired or stolen.

Apparently there are a good number of fines and prosecutions for operation of unregistered aircraft.  And at least some are reported by ATC.  I'm going to assume that nobody is foolish enough to file a flight plan listing an unregistered aircraft ID.

So how does ATC check aircraft registration?  Do they have live access to the registry?  When someone calls an ID over the radio are there controllers that routinely check the ID's registration?  Is it illegal to make up an ID for radio interaction with ATC?  Are there people that visually watch for tail numbers and discrepancies with radio calls?


texts:
In a meeting with aviation experts, the terms black routing and red routing were discussed. What are they? From the discussions I was able to put together that either the TMU (Traffic Management Unit) or the controller can see two routes for a flight, a cleared route (black route?) and an agreed route (red route?).

I don't know what display they were referring to and if it was the controller that was looking at the display or if it was some traffic management display.


texts: What are the differences in design considerations for ground attack and air dominance aircraft?

texts: What parameters and types of performance are designers trying to maximize when building an air dominance fighter plane rather than a ground support fighter? What are the trade offs between them - what do I sacrifice to make a great fighter aircraft vs. a great ground support aircraft?


texts: Flying from right seat of Socata TB9 - confused about Pilot manual limitation (US regulations)

texts:
I was comfortable flying from the right seat in my Grumman American AA5A and would let non-pilots sit in the left seat to introduce them to flying. I was expecting to do the same in a friend's TB9, but this text gave me pause.

Given the the Socata TB9 (Tampico) is generally considered a primary trainer I was surprised to find the following in section 2 (Limitations) of the Pilot Information Manual

  CREW LIMITATIONS Minimum crew: 1 pilot
  (1 pilot required at L.H.
  station)

I am confused how to interpret this.

How is it legal for a CFI to train a "non pilot"?
Does it mean that as long as there is a body in the left seat anyone can fly it (from the right seat?)
What does "pilot" mean in this case in the Pilot Manual? Is "Student pilot" defined only when there is a CFI in the right seat?

I have seen placards on tandem airplanes that allow "solo flight" from one of the two positions for what I expect are CG limitations - but am baffled by the perceived limitation in this manual as-written.


texts: What do EU pilots use for IFR enroute charting (besides Jeppesen)?

texts: Is there something equivalent to FAA IFR enroute charts for the EU, where you can see published routes, holds, minimum altitudes, etc?  I can find terminal area procedures in the AIPs, but the Eurocontrol enroute charts contain hardly any useful information.


texts: How do pilots "turn an airport around" at nontowered fields?

texts:
Consider Homestead Airport, a fictional paved, non-towered airfield in the exurbs of Bigtown, USA that has become popular as a home field for recreational pilots. The airport's busy enough that addressing "Homestead traffic" on MULTICOM any given daylight hour isn't just talking to yourself; there will be at least one other plane in the pattern and a couple more on the ground, however there isn't enough traffic yet to justify hiring ATCOs to run the field. The sole runway is 13/31.

On the Saturday in question, there's a southeasterly wind at sunrise and so traffic starts the day using runway 13. However, the wind suddenly changes just after noon as a norther blows through, such that the five or six aircraft currently in the traffic pattern now need to use runway 31.

What is the standard procedure, if any, to establish the new traffic pattern at the airfield given the wind change? I'm especially curious as to how traffic already in a pattern for the now-downwind runway would be expected to maneuver to establish the new pattern, especially if the segmented circle or AFD indicate traffic should stay to one side of the airport regardless of runway direction (for instance a left-hand pattern on runway 13 but a right-hand on 31, to keep traffic away from a developed neighborhood to the southwest).

Bonus question: At the time a transition to the new runway direction is needed, there is an aircraft holding short for runway 13, with another behind him. These aircraft need to taxi down to the other end of the airfield, and quickly, or they'll be staring at the nosecones of exiting planes. There is a single taxiway, too narrow to 180 on especially with other aircraft using it, and the nearest runway exit is halfway down the field, so aircraft on the ground must taxi down the runway in the opposite direction to get to the correct end. What radio comms are recommended/required to advise traffic in the pattern that the runway has taxiing traffic?


texts: How can the cruise speed be larger than Vne?

texts:
I recently read the POH for a M20V, the advertising for this aircraft states that the top speed is 242 KIAS. The POH gives the Vne at 196/195 KCAL/KIAS.
I have found a similar discrepancy, the Vl3 (light sport aircraft) mentions the aircraft has a Vne of 165 KIAS, yet one of the engine choices gives the plane a max cruise speed of 195. I find these numbers confusing can anyone shed a light on this?


texts: How is the central hub / shaft casing of a two-spool jet engine assembled?

texts:
This is the usual view of a two-spool turbine engine:

(From source)

I don't know if shaft casing or hub are correct names, this is the external skin of the volume around the N1/N2 shafts.

I can't find a description of how this volume is made. It seems descriptions omit a number of elements for simplicity, for instance, this drawing from this answer:

(Source)

My interest is about the green area. It's not clear to me:

How airtightness is obtained overall on both sides of the core air duct?
How airtightness is obtained in locations like 1, 4 or 5 when rotating elements meet stationary (or N1) elements?
How torque is transmitted from the HP turbine to blade 2? or how elements (like 3) between the turbine and the compressor discs are assembled together to form a rigid wall/pipe?
How stators (like in 3) are fixed?
Why the central hole size varies for the rotor discs (like 2)?

Cross-sections would help but I can't find ones.

Bottom line: Without necessarily entering into details (but they are welcome), could you provide an overall description of how this "hub" is assembled, particularly the HP part?


texts: What are the different variants of ILS intrumentation?

texts:
Background: I'm a huge aviation enthusiast with a lapsed PPL. Have flown some larger aircraft on MSFS, but never flown anything in real life bigger than a C172.

I was lucky enough to do a bit of Simulator time on a B737 simulator this weekend. One thing I wanted to try out was an ILS approach in very limited visibility. The instructor set me up, and asked what ILS display I was "used to seeing". I described it, and she set it to this - totally what I was expecting:

(Thats the purple vertical bar for centre line and purple blip for glide slope).

So, my question is, what was the "Other" option? This may be specific for a B737, or it may not. Why are there 2 types of instrumentation for an ILS approach? Is one a newer system, and is it therefore preferred.


texts: Do I have to declare an emergency if I cut into fuel reserves?

texts:
In another question, I wrote

You only need to plan for regulatory reserves. You don't actually have to land with them

and @Jan replied:

you have to declare emergency if you do cut into them though and that will quite probably get you an investigation

I have never heard that you must declare an emergency if you cut into your reserves (regardless of the stage of flight), and I'm wondering if there is any regulation to back it up.
The only reg that I could find that comes close is NTSB 830, which lists a set of criteria for notifying the NTSB within 10 days:

(a) An aircraft accident or any of the following listed serious incidents occur:
(1) Flight control system malfunction or failure;
(2) Inability of any required flight crew member to perform normal flight duties as a result of injury or illness;
(3) Failure of any internal turbine engine component that results in the escape of debris other than out the exhaust path;
(4) In-flight fire;
(5) Aircraft collision in flight;
(6) Damage to property, other than the aircraft, estimated to exceed $25,000 for repair (including materials and labor) or fair market value in the event of total loss, whichever is less.
(7) For large multiengine aircraft (more than 12,500 pounds maximum certificated takeoff weight): (a bunch of other things)

I'm interested in the answer for Parts 91, 135, and 121, under FAA regulations.


texts: Will this specially shaped can produce any lift?

texts:
I am wondering if a specially shaped can will produce any lift as it moves through the air.
Please reference the drawing below:

This drawing is showing a hollow can that has been cut so that it will have one side that is higher than the rest of the can. The top of the can is open while the bottom of it is sealed with a plate. This higher side of the can will be moving into the wind as the can travels forward. The can will not be angled, the bottom of the can will remain parallel to the the air flow. Also, the can will be made of a very stiff material so that the higher side of it will not bend backwards.
I believe what will happen is that the air flowing over and around this higher side will lower the air pressure inside of the can and the higher air pressure located below the can will be pushing up on it thus creating lift. I'm pretty sure that this is what should occur, yet I'm asking this question to get verification on it because I am not an engineer and I have a limited knowledge of aerodynamics.
EDIT
To keep the can held firmly in a vertical position so that it doesn't topple over in the wind and to keep it perpendicular to the ground, it could be attached to a side of a car like how a car's side mirror is attached.


texts: What is the name of the format of route with the dots? Eg. DTW..LAYNE.DXO006 (...)

texts:
I found in our data a route formatted with dots instead of spaces and DCTs. Example:
DTW..LAYNE.DXO006.BNNET.YQG341.DIRKS.J38.GRB/0052

What is the name of this format?

Second question: Sometimes instead of .. and . after the departure airports there is ./. . What does it mean?

Example: KIAH./.ABCD..BEREE.BEREE1.KDFW


texts: Why does this Strikemaster have a textured leading edge?

texts:
I was at Duxford recently, and spotted a Jet Provost Strikemaster that had a rough texture applied to a portion of the leading edge of the wing.

Why was this applied?


texts: Why are ethanol piston engines apparently cheaper to maintain than avgas piston engines?

texts:
In the course of hunting for examples of 100% ethanol-powered piston engines, I found the Embraer EMB 202 from Brazil that is modifiable to be that way.

But the article also says "The alcohol fuelled Ipanema engine also has 20% lower maintenance and operational costs." (no citation there, howerver.)

I also found this PDF that says similar things:

  Avgas is slightly cheaper on a per-kilometre basis than ethanol, but the lower maintenance costs associated with the use of ethanol ultimately make it a cheaper fuel option for pilots.

Why is this? What exactly are the modifications made to normal engines that somehow reduces operation costs? And why aren't these modifications made to normal engines that just keep using avgas?

(Please: let's not get into an off-topic argument about whether ethanol should/will replace petrol products. I already know avgas is about 40 MJ/kg and ethanol more like 28. This question is not about that and I hope it doesn't become another casualty in that flame war.)


texts: What are the specific side step minimums for an approach?

texts:
This question piques my curiosity a bit on this subject.  In regards to circling approaches the AIM 5-4-19 states that

a. ATC may authorize a standard instrument approach procedure which serves either one of parallel runways that are separated by 1,200 feet or less followed by a straight-in landing on the adjacent runway.
b. Aircraft that will execute a side-step maneuver will be cleared for a specified approach procedure and landing on the adjacent parallel runway. Example, “cleared ILS runway 7 left approach, side-step to runway 7 right.” Pilots are expected to commence the side-step maneuver as soon as possible after the runway or runway environment is in sight. Compliance with minimum altitudes associated with stepdown fixes is expected even after the side-step maneuver is initiated.
Note: Side-step minima are flown to a Minimum Descent Altitude (MDA) regardless of the approach authorized.
c. Landing minimums to the adjacent runway will be based on nonprecision criteria and therefore higher than the precision minimums to the primary runway, but will normally be lower than the published circling minimums.

However I’m not aware of any approach plates which list specific side step minimums on them for airports with parallel runways where sidestepping is commonly used.  Examples below are from Boeing Field in Seattle, WA, and John Wayne in Santa Ana, CA.

So my question here is as the plates do not specifically publish a side step set of minimums, should the approaches be flown down to the localizer MDAs or use the Circling MDAs?  Is this up to a pilot’s preference or is it a matter of just how far away the landing runway is from the parallel approach runway?


texts: How do you cope with an asymmetric flap extension?

texts: How do pilots cope with an asymmetric flap extension? What are the procedures for this type of occurrence which I suppose are similar on all aircraft?


texts:
My 7 yo is really keen on taking up aviation as a career.
I have seen multiple times where kids at the age of 15-16 get licenses to fly. How does that happen?
Looking for some advise on how to start this journey for my little man?


texts: How to determine aircraft altitude and speed, as a passenger?

texts:
Is it possible for a passenger to determine the aircraft's altitude and or speed or location using any mobile apps.

Not all airlines have displays with constant info about this. I had tried using Google maps, but it did not work, maybe because there was no internet/wifi on the aircraft.

Any simple method?