texts: On average, how much fuel is left in commercial flights after landing?

texts:
I recently asked what kind of fuel reserve airlines were required to have. It turns out there are international guidelines for that, which for commercial flights are:

Per ICAO Annex 6, Part I, section 4.3.6 "Fuel Requirements," airplanes
should calculate their required fuel quantity as follows (summary; see
below for actual ICAO text):

Taxi fuel
Trip fuel (to reach intended destination)
Contingency fuel (higher of 5% of "trip fuel" or 5 minutes of holding flight)
Destination alternate fuel (to fly a missed and reach an alternate)
Final reserve fuel (45 minutes of holding flight for reciprocating engines, 30 minutes for jets)
Additional fuel (if needed to guarantee ability to reach an alternate with an engine failure or at lower altitude due to a pressurization loss)
Discretionary fuel (if the pilot in command wants it)

Considering a flight has many unknown, the same connexion using the same airplane will have different fuel requirement and fuel remaining, simply depending on the date you decide to have a look at the data.
Is there any statistics of how much fuel is left on average in aircrafts after landing of commercial flights?
It can be an average for commercial flights in general, a breakdown of short / medium / long haul flights, expressed in percentage of tank volume or in liters / gallons / weight. Or any usable measure I did not think of that can be used to do basic calculations.


texts: What airfoils are used for the current generation of general aviation VTOL aircraft?

texts:
What airfoils are used for VTOL ultralights at 60-70 deg AOA without flaps or slats?

An example of this would be the Blackfly with a takeoff distance of 3', about 25% of it's own length....!!!!

I understand most airfoils stall at about 15deg, slats and flaps allowing up to 30 deg AOA such as with the Zenith 701.

Yet the Blackfly has no slats or flaps and has controlled flight even at at 60,70,80,90 deg AOA.

I assume the distributed propulsion reduces the LOCAL AOA significantly, so that lift is only via the props from say 40-90 deg AOA, and then wings start to generate lift at about 40 deg AOA even without slats or flaps.

Yet, I was told distributed propulsion only works for low AOA. Very confused....

What airfoil type is used for this?

Would an airfoil like the Selig 1233 or Eppler 399 be appropriate for this?
I understand these are low Re airfoils, but these usually stall at a lower AOA than a classic airfoil like the NACA65018 used in the Zenith701.

Or do you need something very fat that will stall at a much higher AOA, like an airfoil with 25%-30% thickness?


texts: Malaysia Airlines Flight 370 - Why didn't Malaysian Air Force scramble jets?

texts:
It seems odd that a large commercial aircraft can deviate radically from its scheduled flight path without the military doing something about the situation. Malaysian military radar tracked the plane for about an hour after said aircraft had dropped off the air traffic controllers radar.

Why were no jets scrambled?

Has Malaysia not heard of "9/11", and how commercial aircraft were used by terrorists?

Which other countries military also pays such little heed "9/11"?


texts: Why does the DC-9-80/MD-80 have this cusp in its fuselage?

texts:
The fuselage of the McDonnell Douglas DC-9-80 (also known as the "MD-80") has a pronounced cusp at floor level, as can be seen in this diagram (courtesy of Boeing, eater of McDonnell Douglas - at least, according to @JWalters):

Although the DC-9-80/MD-80's fuselage cusp is nowhere near as extreme as the Boeing 377 Stratocruiser's, it still seems like an unnecessary stress concentrator with no apparent reason for being there; why did McDonnell Douglas put in the cusp, despite its potential for accelerating fatigue damage to the fuselage?


texts: Why do airlines split themselves into domestic and international subsidiaries?

texts: As an example, Air Canada operates its own brand for international flights, but has a subsidiary called Air Canada Rouge for domestic and US flights. What's the reason for creating such subsidiaries?


texts: During the early design stages, what parameters are considered in determining the weight of an aircraft?

texts: What parameters are considered in estimating the weight of an aircraft in the beginning of the design process?


texts: What is the reference used when measuring flight speed?

texts:
I'm a physicist who was amused by the argument in the comments of this question about gravity.  The correct answer about the affect of the accelerating reference frame of the plane on the apparent gravity depends on how the airliner's speed is measured.

I know very little about practical aviation.

When I'm on a trans-Atlantic flight moving 900 km/hr, with respect to what am I moving?  Is that my speed relative to the ground (which is also moving)? relative to the local atmosphere (which could be additionally moving due to wind)? relative to some imaginary, absolute grid hovering above the Earth's surface? relative to the "fixed stars"?

This is probably a duplicate, but I can't seem to find the right search terms...


texts: Does a RC aircraft require suspension in landing gears?

texts: we engineering students are preparing for a particular competition with dimensions of 170 in. (length + breadth + width) for that competition we require landing gear but for that are we supposed to use suspension in it?


texts: What is the meaning of "altimeter three-zero-one-one"?

texts:
I've been listening to a lot of liveatc.net recently (mostly at CYVR).

What does it mean when the ATC give an "altimeter" reading (usually around the 3000 area).

  Altimeter three-zero-one-one.

I'm assuming it's like a QNH setting? But not in kPa?

Addon Question:

Is inches of mercury specific to the Americas? North America or other places as well? I've only flown in South Africa where we use kPA (SI). We'd get information from tower along the lines of QNH 1013.


texts: What is required to be an "FAA-qualified helicopter aerobatics pilot"?

texts:
Chuck Aaron is the only FAA-qualified aerobatic helicopter pilot - How'd he do it?

What requirements does one need to meet in order to perform aerobatics in a helicopter?  Specifically, the training/qualifications and FAA paperwork necessary.
Who certifies said pilot, if there is no one certified themselves to do so?


texts: How does the modulation of the transponder work?

texts: The transponder works in PCM (pulse code modulation): how does it work in the transponder? I can find explanation of what PCM is, but not if the signal sent from the transponder antenna is digital or analog, and I do not understand which are the advantages of using PCM.


texts: Does intake mass-flow rate vary linear proportional with turbine fan speed?

texts: Is jet turbine intake mass-flow rate linear proportional with its fan speed (N1)?


texts: Is there a convention for type of switch used and where?

texts:
In most cockpits, you'll find the full gamut of switch types in use. Toggle, rocker, push-button and more. Each has their own "feel" and might be used for different situations.

Is there any convention for what type of switch is used in a cockpit, and where/for what?

Such as, is the Generator usually/always a toggle switch, and would it be "weird" or unexpected for it be a rocker switch instead? Everything could be a toggle switch, so why do manufacturers choose to use different types of switches for different things?

The 737's overhead panel uses toggle, rocker, push-button, and rotary dial all together:

These images are from a simulator, but the aircraft is modeled after the TBM 850. In it, you'll notice toggle, rocker and push-button switches:

Same thing up top in the same aircraft:

Here's a real image showing the same thing:


texts: What regulations in the US exist for jetpacks?

texts: In 2010 Fox News posted an article in which they quoted a representative of the FAA saying that the FAA might not regulate jetpacks (the representative did say that they could fall under Part 103). Do any regulations exist in the US for jetpacks?


texts: Why was pitch angle protection not active in the CRJ 200 during the crash of Sweden Air 294?

texts:
I have read about the CRJ 200 Sweden Air 294 crash. I understood that the main cause of the accident was faulty IRU and wrong declutter PFD design. The human error also lead the aircraft into a catastrophic condition by not having good communication between the pilot and FO about a miscompared reading of PFD. But some questions are still buzzing my mind. The questions are below:

Is there any pitch angle protection in the flight control system of a CRJ 200?
Did the aircraft fly using autopilot when the miscompare happened? If yes, what is the reference attitude for the autopilot?
If the aircraft used autopilot, so when the pilot tried to push the yoke to pitch down the aircraft, did the aural alert of disconnecting the autopilot alarm the crew that the aircraft is in level off condition (not pitching up steeply). Also, did the CRJ 200 also use breakout force of yoke to disconnect the autopilot?


texts: increasing lift in a plane by placing engine in such a way that the air coming out of it washes over the wings to create more lift

texts:
I was wondering if the engines of a plane can be placed in such a way so that the air coming out of the engines goes from over the wings so that the velocity of air over the wing is higher and more lift is generated. has this ever been done? if not than why?and what are the pros and cons of this design?
i mean something like this


texts:
I was looking for airfoils, and I came across an interesting design. It's called a KFm1 step airfoil. Those of you in model aircraft design might have heard of it. However, I've never really seen one of these in normal aviation.

My questions are:

Why don't they work for full sized aircraft?
Is there some way to make them work?
What gives this airfoil its properties?


texts: What are the most popular areas to do private pilot flight training in the United States?

texts:
Are there any statistics on the most popular states to do private pilot flight training in the USA or a similar measure?

I know Florida is very well visited, but I was wondering if there were other states which also have high number of students.


texts: What information does a pilot have about aircraft operating on an intersecting runway?

texts:
This incident at O'Hare from July 2006 made me wonder what information is available to a pilot (specifically, in an airliner) regarding aircraft that are using an intersecting runway.

In this incident, the controller had a United 737 line up and wait on 27L because the United flight wasn't ready to go yet while an Atlas 747 was on final for 14R. Once the United pilots radioed that they were ready, tower cleared them for takeoff on 27L, despite the fact that the Atlas 747 was touching down on 14R and was about to cross 27L on the roll-out. The Atlas flight did call out that he was on final, but that's the only indication I can see from the video that the United pilot has regarding the position of the Atlas flight. Judging from the below airport diagram, it appears that the ORD terminal would have been between the two aircraft at the time the United pilot was cleared for takeoff, so the aircraft wouldn't have been able to see each other until they approached the intersection.

Obviously, the controller shouldn't have cleared the United flight for departure until Atlas was out of the way. However, given that he received the takeoff clearance from Tower, I'm wondering whether the United pilot would have had any other tools at his disposal to detect the position of the Atlas 747 and realize that the controller made a mistake (before he saw a giant 747 roll out in front of him on the runway and before the controller realized his mistake.) Specifically, do airline pilots have any additional means for determining the position of other aircraft on intersecting runways aside from relying on ATC, listening to the Tower frequency, and looking out the window?

I'm aware of TCAS for use in-flight, but I'm not familiar enough with it to know if it would help in an intersecting runway situation like this where both aircraft are on the ground.


texts: Are there any GA trainer aircraft without toe brakes?

texts: I'm a student pilot, and I've built about 20 hours on a Cessna 172. I also have an old ankle injury that makes it hard to bend my left ankle, and I'll probably be getting an ankle fusion later this year. I know I won't be able to work the left brake with a fused ankle. Are there any good options for trainer aircraft with other kinds of brakes?


texts: Why does JBU1825 from Ft. Lauderdale to Lima show a large zig-zag in the route?

texts: Why oh why is this non-stop flight flying such a zig-zag? (screenshot from FlightAware)


texts: Where are the grounded 737 Max planes being kept?

texts:
With various countries grounding the 737 Max, where are they (their carriers) keeping the grounded planes?  Are they simply being kept at Gates of various airports (which I doubt since gates are expensive and/or logistical reasons)? Are there "holding areas" at some airports?

While I understand some carriers just fly a few of these, what about those carriers with larger fleets, such as ones in China or the EU?


texts: Why isn't airport relocation done gradually?

texts:
Recently Istanbul airport (IST) was relocated from Atatürk over 2 days. Munich Franz Josef Strauss (MUC) was also moved overnight from Munich Riem. Doesn't it cause chaos, since most employees are new to the place and equipment, work procedures are not well established? E.g. some people do not have badges with correct security clearance.

Why not do it gradually over longer time? Move airline by airline -- smaller first, bigger later.


texts:
I'm surprised this hasn't been asked before but I could find any question on here for it.

Who picks the tail number for a new aircraft?

Is it automatically assigned by the authorities you are registering with or can the new owner pick any number as long as it's not already I use?

If it's auto generated by the authorities, can you purchase the equivalent of a custom car registration plate if you want a specific number?

I've tagged CAA but would be interested to know if the FAA is the same.


texts: What kind of plane could be leased back to a flight school?

texts: I was having a brief chat with the CFI at a local club/school and he talked about lease back, assuming that the maintenance and insurance is paidfor by the lease back and isnt an issue the question is this, what sort of aircraft can I buy to lease back, is there restrictions on the age or hours on a hire aircraft or can any 2 seater do the job, I am getting back into flying after a long break and want to get back into aerobatics, so something like a 150/152 aerobat would be ideal, there are no aerobatic planes in my local area so there is an incentive on both sides to do this ?


texts: What are the pros and cons of high-wing compared to low-wing design?

texts:
What are the advantages and disadvantages of a high-wing vs. low-wing aircraft design? When might one prefer one to the other?

Is the answer the same for large and small aircraft?


texts: Is autorotation possible from a 0 rpm start at high altitude?

texts:
I am working on an enclosure that is to be ejected from a rocket at apogee (10,000') and fall to a target altitude at a descent rate below 20ft/s before releasing its payload. The idea is to have coaxial rotors with collective pitch control deploy and autorotate to slow the descent of the enclosure and payload.

My question is how I can start autorotation with blades that have essential zero angular momentum, and are there special considerations for the use of coaxial rotors?


texts: How do I calculate density altitude by hand?

texts:
I've seen the following equation for calculating density altitude on a dozen websites:

[ (OAT - ISA) * 120 ] + Pressure Altitude.

But it was never very clear what the units of measurement are supposed to be.

Question 1: Are OAT and ISA in Celsius?

Question 2:
So for example, if current true altitude is 6000 feet above sea level then:
ISA = 15 + (-2C * 6) because for each 1000 feet we lose 2 Celsius. Does this mean to make this calculation I just substitute field elevation for true altitude? So ISA is equal to 3.

If the outside air temp is 10C, then we have 10 - 3 = 7 multiplied by 120 = 840.

Question 3:
Pressure altitude confuses me a little bit, I read that it is the altimeter reading when the Kollsman window is set to 29.92" hg. So let's say I'm sitting in my airplane on the runway, I set my altimeter to 29.92 and it reads 6200 feet. In this case my final equation would be: 840 + 6200 = 7040 feet density altitude.

What happens if I don't have access to my plane's barometer, is there another way to calculate pressure altitude?

Question 4:
How does this all change if I'm trying to figure out density altitude while flying the plane? OAT is the air around the plane. What about ISA? Do I calculate pressure altitude by resetting my Kollsman window in the middle of the flight to 29.92" hg? Is it normal to try to figure out density altitude while up in the air?

Question 5:
Does this entire equation change or become meaningless above a certain altitude threshold, such as 10,000 feet above sea level?


texts: Why was the A340 developed with four engines?

texts:
The predecessor to the A340 program begun in 1982, when Airbus released the first specification of the designated TA9 and TA11 programmes and in 1986 the TA9/TA11 programmes were officially launched as the A330 and A340 development programmes.
By 1986 Airbus, with their 310 aircrafts, as well as Boeing, with their 757/767 aircrafts, already had twin-jets flying under the ETOPS90 and ETOPS120 rule, introduced in 1985.
Meanwhile Boeing presented the predecessor to the 777 programme, the 767-X ("enlarged" 767) in 1986, but due to customer demand launched the clean sheet 777 twin-jet programme in 1988.

Reading up on that history, I wonder why Airbus did not opt to redesign the A340 with two engines, rather than four.
I judge, that by the mid-80ies, the feasability of two engines for a widebody long-range aircraft with more than 300 passenger was already clear. The loosened ETOPS rules meant, that even regulators were paving the way for such an aircraft.

What was to rationale of Airbus to develop the A340 into a four-engine airliner, while at the same time, Boeing was developing the 777 as a two-engine airliner?

EDIT:
I found another question and answer, which states that ETOPS was the reason. But ETOPS rules were introduced in 1985, while A340 development programme was launched in 1986. So Airbus made a decision despite being ETOPS already in place.


texts: Can Ballistic Parachute Recovery Systems be safely deployed in a storm?

texts: Suppose the plane is in a thunder storm, and the pilot loses control of the airplane. Would deploying the ballistic parachute be a safe option? Meaning, is it likely that everyone would come out alive? Assume that as soon as the plane hits the ground at a reasonable speed the occupants are safe(as in, there's no ocean to drown in). Has this ever been done before?


texts: Are the instrument panels in the cockpit spill / waterproof?

texts:
There are multiple switches and buttons in the cockpit, with different shapes and layouts. Are they spill proof?

What if the pilot spills water or coffee on them, will they still function?


texts: Where can I find FAA procedure amendments?

texts:
I'm looking at the IFR Takeoff Minimums and (Obstacle) Departure Procedures for Goodyear, AZ (KGYR). It says:

  Takeoff Minimums and (Obstacle) Departure Procedures AMDT 1 14317
  (FAA) Departure Procedure: Use POTER RNAV Departure

I would like to read this amendment but my Google-Fu is failing me. Help?


texts: Are there full scale helicopters capable of sustaining inverted flight?

texts:
Background

I'm a model aviation enthusiast and really enjoy seeing how far people can push the limits of aerobatics. Model aircraft are able to push the limits well beyond full scale due to their small size. I understand that this is only possible because models are small* so they can withstand forces that would kill any occupants in a manned craft. Also, model aircraft are typically overpowered when compared to full scale aircraft

For example, I don't have a model plane that isn't capable of a 30 degree climb, and it's quite common for aerobatic model airplanes to have thrust to weight ratios exceeding 1.5:1 or even 2:1.

Question

When I first saw some of what model helicopters were capable of I was blown away. Having also seen some full scale helicopter aerobatics (Red Bull Demonstration) I've been wondering just what full scale helicopters are capable of.

In the Red Bull Demonstration it looked like the helicopter might use some negative (or at least neutral) collective while rolling, however it did not appear that it would have enough to sustain an inverted hover or inverted flight. This got me wondering: has there been a full scale helicopter capable of sustaining inverted flight or an inverted hover (which takes even more power)? If there hasn't, would it be possible to purpose build a helicopter that would be capable of doing so?

Note

I'm just wondering about technical possibility of creating a machine capable of this maneuver. For the scope of this question, please ignore the regulatory, legal, and economical obstacles that would need to be overcome to attempt such a feat (not to mention finding a pilot willing to try).

Also, I'm only asking about full scale inverted flight. I understand physics get in the way very fast if someone were to try to design a full scale helicopter capable of all the aerobatics models do.

*some model airplanes and helicopters can be greater than 35% full scale, but that is still small when compared to full scale aircraft.


texts: What is the difference between F-16C and JF-17 in terms of role?

texts:
What is the difference between F-16C Fighting Falcon and JF-17 Thunder in terms of role?

When does someone use an F-16C and when does someone use JF-17?


texts: How is ACS different from PTS and when does it replace PTS for FAA certification?

texts: I've read some documents and articles that reference the FAA's new Airman Certification Standards (ACS) that will soon replace Practical Test Standards (PTS). What is different about ACS and when does it take effect?


texts: How can someone without a pilot's license arrange an initial test flight for a homebuilt aircraft?

texts:
I think this has more to do with culture and expectations than actual rules, so maybe this might attract opinionated answers, but I still want to know what people think:

If a person were to construct their own homebuilt, like a Kitfox or RV, without first obtaining their PPL, how can they go about completing the 25 hour initial test phase required for the new aircraft?

This encompasses a subset of questions:

Is it customary to pay an experienced pilot to do it, acknowledging the risk involved with the activity?
Or is free use of an aircraft and loggable time/experience compensation enough?
Is it generally hard to find someone willing to do this for you (maybe do this with you is a better phrase since you will be part of the ground crew)?


texts: Can you verify that this aircraft is not a variant of the T-34 Mentor?

texts:
On this page, near the bottom, the aircraft below is identified as a T-34. I'm wondering if that's correct, but before I contact them to point out a possible mislabeling, I'd like to find out what it is or is not.

UPDATE -- I sent en email to The Catalina Island Conservancy, and they have changed the image to correctly show it as a Nanchang CJ-6.


texts:
Why was the F-117 retired after so few years in service (Approximately 25 years) while other military aircraft are in service for many decades? Many of the 60 built should still be air-worthy.

For example, the F-15, F-16, and F-18 models have been kept in service for 40 years.


texts: How can I identify the FAF on this Jeppesen chart?

texts:
According to this Jeppesen ILS Approach Chart:

How can the FAF be identified?

Would it be the point at which the G/S is intercepted?

What is the difference between FAF and FAP?


texts: Why were "pattern a" and "pattern b" removed from the Instrument Flying Handbook?

texts:
If you search around on the Internet, have an older copy of the Instrument Flying Handbook, or talk to a seasoned CFII, you may run across the concept of "pattern a" and "pattern b." These were exercises which involved tracking courses, flying procedure turns, hold entries and sometimes constant speed climbs and descents. They seem like valuable maneuvers for honing instrument flying skills.

At some point in the last several years they seem to have been removed from the Instrument Flying Handbook. I don't actually own an out-of-date copy of the handbook to verify this, but if they were removed I'm wondering if anyone knows why. Does the FAA frown upon the use of these maneuvers in training?

Beyond the question itself, I'd love to find a current publication that teaches pattern a and pattern b for reference.


texts: What is the purpose of the string taped to the front of the canopy on gliders?

texts: What is the purpose of the piece of string taped to a glider canopy? Is it effectively a turn coordinator, but then what advantages would it have over a gauge such as the ones fitted in powered aircraft?


texts: What do these symbols mean in an airport?


texts: Why do some fighters have two engines and other have only one but still give the same performance?

texts:
The F-16, F-35, and Gripen have single engines.

On the other hand, the Ching-kuo (Taiwan) and F/A-18 have double engines, but the combined thrust of two engines is almost equal to the single engine thrust.

Why do some aircraft use double engines?


texts:
In this question it is mentioned that the fan, compressor and turbine blades are mounted loosely in the disc. This is well demonstrated by this video posted by RedGrittyBrick.

What is the reason for this?


texts: Do crosswinds affect which pilot lands the plane?

texts: I know the crew usually decides ahead of time which pilot is to be PF for each phase of the flight. If, when they arrive at their destination they discover a considerable crosswind component, does that ever change that decision? It seems that the upwind seat would have a considerable visual advantage. (or maybe that isn't true?) Also, do airlines have guidelines on things of that sort requiring that the PIC fly the landing?


texts:
I frequently observe people arguing (on this very web site) about the question if falling is a mode of flying or not. It appears to me that the majority of people have a strong opinion that it is not.

Surely it is a matter of definition. I made the effort to look it up in a number of online dictionaries. Most sources provide many possible options to define flight, like Merriam-Webster:

  1a : an act or instance of passing through the air by the use of
  wings

but it continues with

  2a : a passing through the air or through space outside the earth's
  atmosphere

Wikipedia tried to put everything into one paragraph:

   Flight is the process by which an object moves through an atmosphere (or beyond it, as in the case of spaceflight) without contact with the surface. This can be achieved by generating aerodynamic lift associated with propulsive thrust, aerostatically using buoyancy, or by ballistic movement.

Flight may be aerodynamic, propulsive, aerostatic, or ballistic.

When one throws a ball, the ball is flying. It flies until it hits anything else than air. Why would it be different if the ball is thrown upwards, or pushed downwards, or just dropped?

In my understanding, falling is just a very special case of flying. Is this correct?


texts:
Can quadcopters still fly with propellers at an angle? By this I mean like the whole motor mounts will be situated along a certain slope (so as to be neither horizontal nor vertical).

UPDATE
I meant something like this (I know it's a crude diagram, but I hope it gets my meaning across better):

I don't think that's how most drones fly, if the surfaces the motors are on are folded in a way that resembles a flying motion of birds or butterflies.


texts: Is it harmful to operate an engine "over square"?

texts:
Never Fly Your Engine "Oversquare!" is an old recommendation. This wisdom cautions pilots that selecting a power setting with a manifold pressure in inches higher than the RPM in hundreds is damaging to the engine -- e.g., 2300 RPM dictates using no more than 23 inches manifold pressure.

Pilots are instructed by flight instructors to always reduce the manifold pressure before the RPM on power reductions, and increase the RPM before the manifold pressure on power increases. From this, it seems even short periods of "oversquare" is harmful during takeoff and landing. What about cruise?

Is it harmful to operate an engine for long periods "over square"?


texts: Can a turbofan have a fan driven electrically so as to run at optimal speed?

texts:
I just watched this pretty dumbed-down video about the idea of putting a gearbox in a turbofan so the fan can run at its optimum slower speed while the core runs at its optimum high speed.

And I immediately remembered this answer from Peter Kampf that said basically, a normal gearbox would have huge waste heat.

Then I suddenly remembered an old question of mine about driving a helicopter engine with a diesel-electric system.

So now the obvious 2-and-2 together: Can the fan of a turbofan be driven with an electric motor (powered by the already-existing generator of the engine)? Or the more detailed questions: Can an electric motor be small enough to fit around the fan's axle and still power the fan? How much it would weigh? I'm interested in large turbofans on the orders of 100 to 500 kN, but I think that would make the task easier since there's more room plus weight increases have diminishing returns against a huge airliner.

This would have obvious advantages. The fan:core ratio can be variable without any gearing. Presumably much less maintenance, or at least no more maintenance than the generator requires.


texts: Why does airport security use numbered baskets for my carry-on stuff to be x-rayed?

texts:
I recently flew from TPE and noticed that there, the baskets for the carry-on stuff that gets scanned are numbered:

I can't think of any reason why this would be useful. Can anyone explain?


texts: How does the F-22 Raptor radar reflector work?

texts:
The F-22 Raptor (and other stealth aircraft) can be made more visible to radar by using radar reflectors, or in other words, radar cross section (RCS) enhancers. In the comments section of this answer to a question posted on Aviation Stack Exchange it was speculated, that the RCS enhancer used in F-22s is empty, sparking further wondering whether this was in fact possible.
So the question here stands: how can such a small device improve the visibility of a stealth aircraft sufficiently to make it a clear radar target?
The RCS enhancer on F-22 seems to be less than half a gallon (4 litres) in volume.


texts: Does having a halo effect after LASIK disqualify you from being a pilot for the Air Force or commercial pilot?

texts: I had LASIK a while ago and I have some halo effects when I look at lights at night, and was wondering if that alone is something that would disqualify me from being a pilot for the Air Force or an airline?


texts: Are emergency actions an appropriate part of a captain's briefing in a light aircraft?

texts:
It is generally considered that giving a captain's briefing when flying passengers in a light aircraft for recreational purposes is a good thing to do. I'm asking about flying people who may not be used to light aircraft, such as friends and family (as opposed to other pilots, who we often fly with).

In general, I give a few pieces of information:

What will happen on the ground
When to avoid talking (i.e., when it looks like I'm listening intently and noting something down, when we're approaching to land)
Where we're going, what will happen during the flight
What to do if they feel unwell

Then there is the bit I'm going to ask about; people are used to hearing about "emergency exits", and evacuation procedures etc. when flying on an airliner, so I usually consider it prudent to supply the same sort of information about a light aircraft emergency:

How to open the doors if jammed by damage
To get out as soon as we come to stop
To move as far away from the aircraft as possible, even if I am unable

However, I'm starting to wonder if this sort of information would be scaring the bejesus out of my inexperienced passengers. In the next couple of years I'd like to fly my kids who are still fairly young. I definitely do not want to make it a scary experience for them when the time comes.

How do other light aircraft pilots approach this conundrum? Be safe, and supply the important information while possibly scaring passengers, or avoid the "nitty gritty" of an emergency knowing that it is a rare occurrence indeed?

It strikes me that I could provide this information if the time comes to make an emergency landing, however knowing my own limitations I know that if that time does come, I will probably be too overwhelmed with aviating to be thinking clearly enough to provide the important information.

What is the "right" amount of emergency briefing?


texts: Where do airplane variant numbers come from?

texts: For example, the new B787-8 and B787-9.  Is there any significance in why they started with -8, versus the older 737s which started from -100?  Or B757-200/300?


texts:
The title really asks it all: When can a pilot disobey ATC commands?.

Of course, the pilot has the final decision, but when would the pilot really disobey someone in ATC with much more knowledge of planes and other potential hazards near by?


texts: What is an aileron bushing,and what's its use?


texts: What is the average total flight time to get a private pilot license in SF bayarea, CA?

texts:
I've heard that to get a private pilot license in bay-area, CA, San francisco is a little bit harder than other place, because of difficult and busy airspace, ATC, air traffic and some reason.

Do you have any idea what is the average total flight time to get a PPL it in bay area? Thank you.


texts: What is the difference between a pitot tube and a pitot-static tube?

texts: What is the difference between a Pitot tube and a Pitot-static tube? If an aircraft fitted with Pitot tube and static holes on the fuselage, is it necessary to consider the static pressure measurements to calculate the airspeed?


texts: Why are both ATC and TCAS tasked to prevent collisions although TCAS takes precedence anyway?

texts:
« The primary purpose of ATC worldwide is to prevent collisions
  [...] Many aircraft also have collision avoidance systems, which
  provide additional safety by warning pilots when other aircraft get
  too close. » (source)

Why is ATC tasked to prevent collisions, when for this specific purpose aircraft already have "collision avoidance systems" on board, which even take precedence over ATC in case of conflict ?

This may look like an apparent contradiction to laymen.

I presume that there are several reasons for this, including:

Because not all aircraft are TCAS-equipped.
Because ATC ensures separation minima (although TCAS could be extended to enforce separation).

Which other reasons are there ?


texts: What are the advantages of the B747-8 airfoil over B737's airfoil?

texts:
The Boeing 747-8 has a new airfoil design much different than a Boeing 737's airfoil.

Boeing 737 airfoil:

(source: How Airplanes Fly?)

Boeing 747-8 airfoil:

(source: Boeing)

I am a little confused of why it is shaped like this. What are the advantages of this new profile?

It is also more thin, wouldn't that reduce the amount of fuel stored in the wings?


texts: Did the First Officer of Ethiopian Flight 302 trim in the wrong direction?

texts: Looking at the accident report of Ethiopian Airlines Flight 302, it says the cut out switches were used. But the manual trim moved from 2.3-2.1? My reasoning for asking this is because the timeframe on this specific input is 5:40:42-5:43:11 which goes up to the point the crew re engaged the electric trim motors. It sounds like they’re being vague for a reason. Did the First Officer trim in the wrong direction and then tell his Captain “It’s not working”?


texts: Why is 3000 psi the most common hydraulic pressure used in commercial aircraft?

texts:
As per the article on this website (from 2002), most of the aircraft use 3000 psi as hydraulic pressure:

  Since the 1970s, military aircraft have been using 5000 psi hydraulic
  systems, which use lighter-weight components to actuate the flight
  control surfaces. Passenger aircraft have been relegated to 3000-psi
  hydraulic systems (with the exception of the Concorde, which features
  a 4000 psi system).

What is the technical rationale behind using 3000 psi? Is there any historical reason or regulation to use 3000 psi only?


texts: Why are the windshield wipers in the A320 power-up checklist?

texts: I was watching the startup sequence for an A320 and it struck me as unnecessary minutiae to ensure the wipers are off before power on. Is there something important that I'm missing that puts windshield wipers in the same list as thrust and gear levers?


texts: How is combustion flame maintained in the combustion chamber after igniters are switched off?

texts:
During start phase of a jet engine, igniters in the combustion chamber create sparks to initiate combustion.  As far I know, when the engine reaches self sustaining speed, igniters get turned off (this might be different (takes longer) in an Airliner due to FAA regulations during take off).

My question is how do flames in the combustion chamber (or canisters) get sustained (like a candle) without igniters support?


texts: Robinson R22/44/66 Headset Plug For Bose A20 Headset

texts:
What type of headset connector plug is used on R22/44/66 Helicopters?
Is Bose A20 Headset a good one to be used on helicopter?


texts:
Is there a maximum height a propeller airplane could fly?

Some lower bounds for maximum flying altitude:

12,000m (39,370ft): Antonow An-70, produced 1994
12,310m (40,387ft): Lockheed Martin C-130J Super Hercules, delivered in 2012
12,500m (41,010ft): Piaggio P.180 Avanti, production started in 1986
29,523m (96,860ft): NASA Helios HP01, record altitude reached in 2001

Just for comparison: Low earth orbit is about 160,000m.

Upper bounds: I don't know. I guess at some point there is not enough air to get lifted.
And nobody build an airplane with solar cells that flies to space.

I guess important factors for such an upper bound are:

Weight of the airplane,
Size, shape and speed of the propellers
Speed of the propellers


texts: Are all the engines on a multi-engine plane the same?

texts:
In general, are there any differences between the engines on a multi-engine aircraft? Are engines designed to be specifically for the left or right wing, or inboard or outboard for a 4-engine aircraft?

What about the tail engine on a tri-jet like the DC-10? Is it the same as the two wing-mounted engines?


texts: How do oceanic lateral offset procedures work?

texts: I was reading a forum for professional pilots and ran across a thread on lateral offset procedures during oceanic flight (apparently having the FMS offset the aircraft from the centerline of an oceanic track). How does lateral offset work? Is it required for all oceanic aircraft or optional for some operators? Is it explicitly assigned by ATC or is it an implicit part of oceanic flight? What is its purpose, and why isn't it used in non-oceanic airspace?


texts: What is the rate of acceleration based on downward pitch?

texts: In other words, I want to understand how gravity converts into thrust in respect to pitch. What is the general mathematical relationship? (For visuals, imagine a bird diving to gain speed.)


texts: Is a magnetic compass required for an IFR flight?

texts: Is a stand-alone magnetic compass required for an IFR fight when the aircraft has a glass panel with a Horizontal Situation Indicator?


texts:
Sorry for the slightly strange question, but Ryanair (Europe's Largest Low Cost Carrier) decided that seat back pockets took too much effort and got rid of them, and it appears the sick bags in the process.

(source: poloconghaile.com)
So the question comes up...
What happens when Ryanair flights encounter turbulence? I can hardly imagine the Flight Attendants handing out bags ad-hoc when it's sufficiently shaky to cause motion sickness among the passengers.


texts: Why are 4 blade propellers often in X or + position when the aircraft is parked?

texts:
Is there a meaning to the position of 4 blade propellers on parked warbirds?
A lot of old pictures have them at X or + positions.


texts: What happens when you put vortex generators on both sides of a symmetrical vertical tail?

texts:
What happens when you put vortex generators (VGs) on both sides of a symmetrical vertical tail?

I understand a horizontal tail with a classic foil like a NACA 0012 has a max cl of about 1.5.

I understand VGs add about 0.6cl.

What happens when you put VGs on both sides of the vertical tail?

For sure it will allow lower speed or better control at lower speeds, but will it actually bump the max cl from 1.5 to 2.1 at positive and negative angles of attack?

That's a 40 % increase in performance!!!

So.... can I decrease my vertical tail by roughly 40% and still get a similar EFFECTIVE vertical tail volume ( vertical tail moment)?


texts: Can I work on aircraft without an A&P license?

texts: Can I work at a place where I pull parts, drop engines, hang engines which get sold back into the aircraft market? Am I allowed to do so without a A&P License? I've been told that it is legal if you're supervised. If so what is considered supervision? I live in California with no aircraft schooling at all if that matters.


texts: What are the disadvantages of a twin boom aircraft?

texts:
Not to be confused with twin fuselage design.
Especially for high wing span UAVs, twin boom design seems to be a better option as it will reduce wing bending in flight. But it is not normally used, are there any aerodynamic(or otherwise) disadvantage of this design?


texts: What's the aisle width of long range business jet?

texts: What's the average aisle width for long range business jet such as Gulfstream G500?


texts: Travelling at faster than mach 1, how sharp could Concorde turn to avoid injury to passengers?

texts: To avoid injury to passengers (too many G's) was there a max 'sharpness' of the turns it made when travelling at certain speeds?


texts: Does any country issue daytime-only commercial licenses?

texts:
I got my PPL last year (EASA, UK) and I've always been interested in the commercial route. However, due to my red-green colour blindness I've failed the Ishihara, Farnsworth D15 and CAD vision tests which are accepted by the UK CAA to obtain an unrestricted medical. By now I've accepted that going all the way to ATPL might not happen for me, but I'm still interested in any other style of commercial flying that could remain an option.

My question is - can I theoretically get a CPL which would allow me to fly only during the day? Is there any such thing as a Class 1 medical which is restricted to daytime only, like my current Class 2? Can I get an IR with colour deficiency, or just not get one at all?

Of course getting a job is another matter, but I just want to know if I could theoretically fly for a living (or even just a side job) while accepting my colour deficiency as opposed to continually trying to fight it. I'm originally from the UK, but I'm interested in opportunities all around the world - in fact, I'm planning on spending the next few years in Australia, New Zealand and possibly Canada using the temporary visas they offer to UK citizens.


texts: What are L/D ratio of famous WWII fighters?

texts:
I'm looking for L/D ratio of old warbirds. I'm particularly interested by the P-51D, the Supermarine Spitfire Mk.VII and the Mitsubishi A6M3 Zero, but I'm also quite curious about other warbirds that flew during this period.

What are L/D ratio of those warbird? The answer may include L/D ratio of other WWII fighters.


texts: What‘s the diameter of the engines of the Airbus E-Fan?

texts:
does somebody know the diameter of the E-Fan‘s engines ?
To me the look like around 80cm or what do you think ?
Also, with more and wider blades and 60 kW motors instead of 30 couldn‘t they get much more thrust out of them than 75 kg ?

Thanks for your answers!

Simon


texts: On Airbus aircraft, can the pilot control the aircraft when the autopilot is active?

texts:
I am looking at the schematics of computerized control for Aibus aircraft and I do not understand the relation between the various control law and the autopilot.

Under "normal law" can the pilot control the aircraft while the autopilot is engaged, or will control input from the pilot disconnect the autopilot automatically?

What is the meaning of "alternate law" for the autopilot? Will the autopilot be disconnected when shifting to alternate law?


texts: Can I display the route which I have created with skyvector.com on google maps?

texts:
I really appreciate skyvector.com as a tool for initial route planning and providing me with a good lookout to the upcoming VFR flight, but honestly I'm not very satisfied with the FAA Sectional charts.

Using these charts navigation in some more congested areas is tough work especially as I'm not very familiar with the area yet. Its often useful to have a satellite picture of these areas to identify some helpfull landmarks, which might not be shown on the sectional.

Does anyone know how to transfer the skyvector route to Google Maps, or know an alternative to achieve a similar result?


texts: Does a Boeing 747-830 exist and if it does, is there any difference to a 747-8 (748)

texts:
Two years ago I've uploaded a video of the Lufthansas Boeing 747 "D-ABYA" to Youtube. I am currently receiving some angry comments on that video because the title reads "747-830 with new Lufthansa livery performs low pass at Hanover Airport". Many people are angry with the label "747-830", telling me that no such thing exists and that the featured airplane is a 747-8 or a 748.
Back when making the video, if I recall correctly, I looked up the type on Jetphotos. It reads "Boeing 747-830". The same is true on Flightradar24. airframes.org tells me the type is B748 and the model is 747-830. However, I could not find a reference to "747-830" on boeing.com.
What are the differences between type and model? Is a type 747-8 always a 747-830? Or are there other models with a similar name (747-8xx)? Am I correct in saying that the airplane is a 747-830?


texts: What are these criss-cross patterns close to Cambridge Airport (UK)?

texts:
To the immediate south of the runway at Cambridge airport, there are a large number of possibly-concrete things embedded in the grass.

I'm not sure whether they are have any aviation-related function, but they are mostly either parallel or perpendicular to the runway.

The question is - what are they?

Aerial view here.


texts: Moment Coefficient Variation with Angle of Attack

texts: looking at the moment coefficient for certain NACA profiles, I noticed that their graph changes with AoA and is not a constant horizontal line as I would expect (pure moment independent of the AoA). This seems to imply that the moment and the associated moment coefficient is measured relative to a point $P$ (maybe the leading edge $LE$?) that is not the aerodynamic center $AC$ (otherwise the moment would be independent of Aoa) but I am not sure what that reference point may be. The figure below illustrates what I discussing...


texts: Why is the battery turned off for checking the voltage on the A320?

texts: Preliminary cockpit preparation section requires BAT check for 25.5V with BAT off (The beginning step). Since BAT indicator always show respective voltage, why they must be switched off?


texts: Viability of Magnetically started engines

texts:
I am working on a school project of mine which involved testing the viability of a magnetically started jet engine. By magnetically started, I mean that there are magnets which accelerate the main shaft to speed to start the engine. The point of this is to remove the need for an APU, saving space and cost on airliners and military jets.

To provide intake air to the engine to allow it to start up without an APU, there would be a system on the bottom of the engine with small electric fans to push air to the wet section of the engine to start combustion. During the flight the electric fans would be turned off and the intake section would be used like a RAM air intake for the wet section of the engine. The magnets would be powered by the battery in the aircraft, and the small electric fans would be powered by a separate battery in the engine itself.

With all that in mind, would this be viable in a commercial or private environment? Or does the APU do its job too well to replace it?


texts: What type is this aircraft, appearing in the movie "Kingsman"?

texts:
In a scene of the movie Kingsman: The Secret Service the young aspiring agents have to skydive from an airplane. I didn't recognise it: which airplane is it (assuming it actually exists)?

I could only find a picture from inside and one from below.


texts: How many active Cessna 172 aircraft (or any other make/model) are there in the United States?

texts:
I define "active" in accordance with the FAA's definition: "An active aircraft is one that flies at least one hour during the year."
The Bureau of Transportation Statistics (BTS) provides a summary of aircraft registered based on aircraft configuration (fixed wing, rotorcraft, single/multi engine, turbo-prop, jet, etc.) and GAMA has a report on the annual shipments, but not the totals of active aircraft.
The FAA's downloadable aircraft registration database is cryptic to the point where I can't figure out what a specific entry means, and the online search interface returns data for one search at a time.
Is there a data source that provides the count of a given make and model across the active fleet of aircraft in the US?
(PS: If there is some trick to decrypting the FAA registration database that would be be great to know as well!)


texts: What is the record length of time for single-occupant flight?

texts: What is the longest flight time for a single pilot alone in an aircraft?


texts: Was there any progress in ramjet-powered helicopters after 1960?

texts:
It seems in 1950's some countries investigated production of helicopters powered by ramjet engines on rotor tips - examples include American Hiller YH-32 Hornet or Polish JK-1 Trzmiel. The enthusiasm was short-lived - high fuel requirements, a significant load to the power transmission system, noise and high visibility on battlefield were significant disadvantages that ended the research programs which I know of.

Still, that's over half a century ago, and the technology has progressed quite a bit since then so maybe some technical problems of that epoch are now past? - The ramjets are small, lightweight and quite simple in construction, so despite the disadvantages the technology doesn't seem like a total dead-end. Was this line of helicopter propulsion investigated further? Could someone provide a progress report - if there is anything to report? Or is this research branch still dead, with no attempts to revive it?


texts:
Forgive my ignorance in my wording of this question.

I assume the weapons control in a military aircraft cockpit are colored differently from other instruments the pilots has to look at considering U.S. military pilots are not allowed to be colorblind, Why do some Air Forces not allow Color Blind Pilots?

If that is correct, what color are the weapons controls?

Please add any appropriate tags I missed.


texts: I'm designing an airport of a flight simulator. One of the runway settings is Runway End Identifier Lights (REIL). Is there a way I can see if a runway at a US airport has REIL via the internet, and whether they are Omnidirectional or Unidirectional REIL?


texts: Is it true that the pilot and co-pilot are required to eat different meals?

texts:
I was watching a documentary about a Lufthansa A380, and they said that the pilot and co-pilot are required to eat different meals; why is that?

Is it a country-specific requirement, or airline-specific?


texts: How can critical angle of attack of the wing of an an aircraft exceed even when the pitch angle is zero?

texts: Normally one would expect that if the pitch angle is zero, that is the aircraft is level on the artificial horizon, how would the wing present itself to the relative wind at such high angle that it exceeds the critical AOA.?


texts: What exactly happens when I try to maintain the flare when coming to a hover?

texts:
I've been considering this question.  I believe myself to be an average pilot but I'm embarrassed to say that I could not figure out the answer to the following question:

I flare and use power to maintain height, for example coming into the hover.  As I slow, I must keep increasing power.  I have enough power to hover out of ground effect.

If I attempt to continue maintaining the flare, attempting to come to a stop, I will sink and if I don't do anything about it, I will hit the ground. Why?

I've been trying to think through all of the key aerodynamic effects but keep hitting a brick wall.

P.S.  Fixed wing pilots - if you don't have a good understanding of helicopters, please try to resist the temptation to guess.  A helicopter in this flight regime is similar to a fixed wing in that it's a powered, heavier than air flying machine. End of list.


texts: Does lateral stability decrease during transonic flight? If so, why?

texts: I haven't got much more to explain other than the title of the question itself. This question was written down in my notes that I took while studying Principles of Flight for my EASA commercial license.


texts: Is it legal to land in bad visibility conditions without ILS?

texts:
Korean Air Flight 801 crashed during bad visibility conditions in Guam because the ILS was out of commission and the pilot thought it wasn't.

My question though is why he even tried to land there in the first place. Wouldn't an airport be closed during bad visibility conditions in that scenario? Or is it possible to land without ILS in bad weather conditions?

I seem to remember someone talking about a step-chart or something like that as an alternative to ILS, is that what would be used in a case like that?


texts: Descending on a given glide slope (e.g. ILS) at a given airspeed-- is the size of the lift vector different in headwind versus tailwind?

texts:
We had a discussion with friend and we were talking about if the airplane is on approach and the one is landing with tailwind and the other one is landing with headwind, so both have the same value of IAS but the different value of ground speed. Will the airplanes produce the same value of lift in both cases or will be the value of lift be different? He said that value will be still the same and I was argueing that if you have tailwind you will have to increase angle of attack which means that parasite drag will increase so the value of lift will have to increase.

EDIT: Question is: If two same aircraft are on same glidepath (descending on ils glide slope) with same IAS but different ground speed, because of headwind acting on one aircraft and the tailwind acting on the other aircraft, will the amount of lift produced by one of the airplanes be different or will be both two values be the same?


texts: Why doesn't a single engine airplane rotate along the longitudinal axis?

texts: As far as I know, the tail rotor in helicopters prevents the aircraft from turning in the opposite direction that the main blades turn (due to Newton's third law). On the other hand, torque in single-engine airplanes makes them drift away from the center of the runway during take-off (which must be compensated by using the rudder). Now, my question is: once in the air, why doesn't this torque make the whole aircraft spin along the longitudinal axe? Perhaps the engine's power isn't enough to exceed the resistance of the wings against the air?


texts: Is there a list of CASA prohibited medications which would disqualify a pilot from flying or obtaining a Class 1 medical?

texts:
Is there a list of medications which would disqualify a pilot from flying or obtaining a Class 1 medical?

Prior to having my medical I want to know if any medication I am likely to take will disqualify me, so that I can make enquiries about switching to an approved alternative.

A link to a list of prohibited or otherwise troublesome medications or similar online resource would be ideal.


texts:
I believe that all aircraft must be controlled under ATC's instructions to fly safely especially when take-off and landing. And, most ATC instructions are conducted by ground radar which controllers use.

But I know that the stealth aircraft (including B-2, F-22 etc.) aren't captured on radar display owing to their stealth ability. If so, how does a controller give instructions like radar vectors to stealth aircraft?

I know that there's are primary and secondary target when using radar, and the controller must use primary target to vector aircraft. I guess stealth aircraft can be captured by secondary radar but not primary target.


texts: How do the Beech Bonanza's ruddervators work? When the yoke is pulled completely back, is it possible to use rudder?


texts: Why did my transatlantic flight meander off the great circle?

texts:
I recently flew commercial to Scotland and was tracking our progress on my iPad using Foreflight. I made a direct-to line that followed the great circle route, but noticed that we meandered off of it quite a bit.

The only explanation I can think of is that the crew was trying to take advantage of favorable tailwinds by following the jet stream. Is this assumption correct?

And if so, can an autopilot be programmed to follow a route dictated by a winds aloft forecast?


texts: How useful are the AOA Indexers and indicators for jet pilots and civillians?

texts:
I dont see them neccessary unless you are landing on a aircraft carrier.

I just don't know a lot about them. I understand what they do but they just dont seem neccessary unless you are landing a jet to an aircraft carrier where every bit of precise information is neccessary.

And now I see them on the Cessna 172SP planes.

Long story short. How important they are for aircraft carrier pilots and Cessna students/pilots?


texts: Will the ATC be in constant communication with aircraft?

texts:
When a passenger aircraft travels at higher altitudes will it be in constant touch with air traffic controller?

Are the altitudes or flight levels assigned by ATC or does the pilot file them as part of flight plan?

While flying over regions with no radio communication, how does one ensure that there are no other aircraft nearby?


texts: Why would one want to slow to V2 following an engine failure during takeoff?

texts:
Reading about the crash of American Airlines Flight 191, the proximate cause of the final loss of control was the pilots' reduction of the aircraft's airspeed to V2, in compliance with the published procedures for a single engine failure after V1 during takeoff in a DC-10-10; unbeknownst to the pilots, the damage caused when the #1 engine separated from the aircraft had caused the left wing's outboard slats to retract, decreasing the left wing's stall angle, with the result that decelerating to V2 required the aircraft to fly at an angle of attack at which the left wing stalled.

But why would one even want to slow to V2 in the first place?  Even if we, like McDonnell Douglas, ignore the possibility of an engine separating from the airplane and damaging it to the process, there are still good reasons to go faster, not slower:1

If an engine has failed, there's no way to immediately know whether it's a contained or an uncontained failure; if it's an uncontained failure (which is, unfortunately, a common enough occurrence to demand consideration when designing an aircraft), there's a very good (or bad) chance that the exploding engine (especially if it's a wing-mounted engine, like the DC-10's #1 engine) has damaged the aircraft's flight control systems, in which case you'll want to be flying as fast as possible in order to maximise the control authority of the surviving controls.
If there's a chance that whatever caused the first engine to fail could also take out the remaining engines (for instance, contaminated fuel or a flock of birds), you'll want to get as much speed reserve as possible, so that, if the remaining engines do fail, you'll be able to zoom-climb and reach your best-glide speed at the highest possible altitude, thus giving you the most time and space to do something.

What good reason could there possibly be for eroding your already-degraded safety margins yet further by slowing to V2 following an engine failure?

1Not that doing so was justifiable of their part (it wasn't, as the NTSB accident report makes clear).


texts: May a pilot legally fly an ILS approach to ILS minimums with an inoperative Attitude Indicator without declaring an emergency?

texts:
A seasoned pilot told me the other day that if the vacuum system fails while on final approach leaving the Attitude Indicator (AI) inop, the pilot must use localizer minimums even with both glideslope and localizer needles functioning normally.

Is this accurate, or did I misunderstand?


texts: Can helicopters perform the Split S maneuver?

texts:
In the animation movie "Planes 2" we see the helicopter (Blade character) performing first a 180° roll (getting inverted chassis up and rotor down) and then the U-shaped half loop down into the normal orientation. From Wikipedia it looks like the Split-S.

Are helicopters actually capable of doing this? The concerns are

An inverted wing still may provide a lift upwards, but the inverted rotor will pull downward. Hence the inverted orientation seems risky.
Wings provide air support while making the sharp U-turn. Can the helicopter rotor do the same?

If a helicopter would manage this figure, would it trade altitude to speed as the fixed wing planes do?

If the model is important, the helicopter looks somewhat like Augusta Westland.


texts: Why does Qatar Airways fly over Syria and Iraq?

texts: I saw on Flightradar that Qatar Airways still fly over Syria and Iraq. Why do they think that airspace is safe? I dont want to have to worry about my plane being shot out of the sky on my trip.


texts: Why is colour of aircraft access panel outlines darker than the rest of the aircraft?

texts:
I've seen that in nearly every photo of a dark-coloured aircraft (especially prominent in military jets) its panels have a darker colour compared to the rest of the aircraft.

What is the reason for this?


texts: What did Fiji have to do when it incorporated GPS into its aviation system?

texts:
I'm reading the BBC's How Fiji changed the way we travel; The little Pacific island nation was the first to incorporate GPS into its aviation system – and in doing so forever changed the way we get from Point A to distant Point B..

The article (and photos!) are quite interesting and worth a read. I'll quote just one paragraph below:

  Fiji approached the US and its Federal Aviation Administration (FAA) to volunteer as the testing ground for GPS navigation. The FAA agreed to fund the upgrade, supplying equipment and technical support in return for the knowledge it could take away from the trial. It would take well over a year to get the system ready; in addition to the installation of the equipment, new flight routes had to be charted, manuals developed and pilots and crew trained.

and later:

  Fiji proved that GPS could improve aviation in myriad ways, making it faster, more efficient and safer. In the quarter century since Fiji adopted GPS navigation for its domestic flights, the technology has been adopted around the globe, often with the direct help of Fiji’s new experts.

I'm having trouble understanding what exactly Fiji did when it "incorporate(d) GPS into its aviation system". Does this refer to installing GPS receivers on domestic Fiji Airways planes and training only, or were there any hardware or procedural changes on the ground as well?


texts:
I am wondering who makes the 757 avionics? Is there a glass cockpit upgrade? What is the name of the avionics suite?

Thanks in advance


texts:
I logged into my flying club's online scheduling website today (May 19, 2015) and it was warning me that my Flight Review was about to expire (on May 31, 2015). My last flight review was on June 7, 2013.

According to 14 CFR 61.56 (c), the look-back period runs from (my emphasis added):

  ... the beginning of the 24th calendar month before the month in
  which that pilot acts as pilot in command ...

So am I right in calculating that my last Flight Review is actually valid through June 30, 2015?


texts: In Raymer diagram "Take off parameter- Take off distance", what is the difference among "balanced field length", "over 50 ft", "ground roll"?

texts:
Raymer in his book suggests a method to find wing loading W/S (for example we consider jet with 2 engines) (starting from specific thrust $\frac TW$, $CL_{to}$, density/reference density etc.).

In step 1:  he suggests to use graphics "Fig. 5.4 Takeoff distance estimation": you enter takeoff distance (in ordinate), so .. in abscissa you can determine Takeoff Parameter ("TOP")

Step 2: From "TOP" you can find $\frac WS=TOP\cdot \sigma \cdot CL_{to} \cdot \frac tW$

The questions are: in figure 5.4 you can find many diagrams: takeoff distance for:

a) "Balanced field Length"
b) "over 50 ft"
c) "ground roll"

Which one I have to use?
What is the difference among them?
Which curve you have to use, in order to calculate "take off parameter"?

Source: Daniel P. Raymer, Aircraft design: a conceptual approach. Chapter 5 Thrust-to-weight ratio and wing loading, paragraph 5.3 Wing Loading, sub-paragraph Takeoff Distance, page 88-89 and "Fig. 5.4 Takeoff distance estimation".


texts:
What (if any) sort of pilot authentication systems do fighter jets have?

Could anyone with the required skills simply take the aircraft or is a key or authorization code required?


texts: What was this mystery flash on an airport runway?

texts:
Recently I was onboard a commercial airliner and we had just landed and were headed for the gate. I cannot remember exactly which airport but it was either Schiphol(Amsterdam Airport) or Bristol. As we were taxiing I was looking out of the window and saw an object(?) fall vertically into my eyeline from about 10 m up. This object was maybe 50 m away and was at the edge of an intersecting adjacent runway/road and the grass. I noticed it because it had a faint trail of smoke emanating from it. At around 3 m above the ground it ignited, there was a short white flash and it made a small white cloud of smoke that lingered for a short while.

Does anyone know what this might have been? It was almost like a flare/firework (which makes no sense at an airport) so is there another explanation?


texts: Is AD compliance ever physically verified when maintaining an aircraft?

texts:
As we all know around here, national aviation authorities put out Airworthiness Directives mandating certain changes be made to aircraft during their service life so that the aircraft can stay airworthy.  The paperwork for these ADs is part of the aircraft logs, and thus stays with the aircraft for the life of the aircraft.

However, just because an AD is marked as complete and closed out in the paperwork does not necessarily mean it has actually been completed.  This was a causative factor in the Omega flight 70 mishap, where an engine fell off a 707 shortly after rotation and damaged the plane to the point where it could not climb out.  The investigation revealed that although the applicable ADs were marked complete, the upgraded part required to be installed to close the ADs out had not been installed on the mishap aircraft.  Instead, a prior owner had marked the AD at the time complete when it had not actually been fully closed out.

How can an aircraft owner ensure that the ADs that the paperwork says have been closed out on an aircraft have actually been closed out and not simply pencil-whipped?  Are such verifications ever performed during maintenance or inspections (including pre-/post-sale inspection), or is the paperwork trusted absolutely?  Furthermore, how can an inspecting mechanic accurately determine the completion status of ADs?  (For the 707 AD in question in the Omega 70 mishap, this could be done with a small template and some mechanic time inside the pylon, but I suspect some ADs aren't that easy...)


texts: How do I determine holding pattern entry and direction in this example?

texts:
I need help with this question for the IFR written test: "A pilot receives this ATC clearance: '...CLEARED TO THE XYZ VORTAC. HOLD NORTH ON THE THREE SIX ZERO RADIAL, LEFT TURNS...' What is the recommended procedure to enter the holding pattern?"
Why is the answer on the left the correct visualization? It doesn't say if I should hold left or right of the radial. Both answers are left turns. Both answers are holding north. What am I missing?

Thank you all for your help. My 150 arrow was wrong and I was confusing myself. Also, it's helpful to know that the inbound leg terminates at the fix (which entirely makes sense now). So, my new answer is direct entry and here is my new visualization:


texts: How were the graveyard spiral and other sensory illusions discovered?

texts:
The graveyard spiral has an infamous reputation for killing even experienced pilots which only have visual flight experience. What the wikipedia article does not mention is how and when the spiral and other dangerous sensory illusions were discovered.

Essentially it means that pilots in the beginning years would be found inexplicably killed by seemingly harmless weather with visual impairment (fog, night). Someone must have survived such an experience and lived to tell the tale. Is there any information about the hunt for the cause of early crashes and when they identified the culprit?


texts: pre-departure sequence, how to increase number of flights in the sequence

texts:
If I have number of flights ready to depart (valid TOBT) if I want to increase the number of flights in the queue by adding flights in the gaps between any 2 flights whats the minimum seperation that should be taken into consideration?

example:
suppose I have 2 flights the first one is already included in the sequence and it has CTOT. the second flight is still not included in the sequence and has no CTOT(the origin and the des airport not in Europe) and I would like to add it before the first flight since I have time between its TSAT and its TOBT.
whats the minimum seperation time that allow me to add another flight?

TOBT => Target Off Block Time (when flight is ready to push back)

CTOT => Calculated Take Off Time (given by the European control management its the slot when the flight should depart (CTOT -5/+10 min))

TSAT => Target Start up Approval Time, when ATC give permission to aircraft to start bush back from its stand

EXOT => Estimated Taxi Out Time


texts:
Why do modern fighter jets use 20mm guns? Is the armor of a modern jet that thick? Does, for example, .50 (12.7mm) ammunition lack velocity to be effective?
I'm just curious on why is that 20mm is so widely used in air-to-air guns.


texts: How can a Boeing 747 take off from Princess Juliana 7,546 ft runway?

texts:
I recently read this article that talks about 747s taking off from Princess Juliana International Airport in Sint Maarten.

The Princess Juliana runway is only 7,546 ft, but according to Wikipedia, the 747 needs more than 10,000 ft of runway for take-off.

How can the 747 take off from Princess Juliana?


texts: What are the effects of crosswind on glide angle?

texts:
When gliding what are the effects of a crosswind on my glide path angle?

If I have head-wind, the minimum flight path angle (usually called gamma) will be lower than the one without crosswind and with an attitude with a larger lift coefficient  Cl than lift coefficient of max efficiency with no wind?

On the other hand, if I have tailwind gamma will be greater and the Cl will be lower than Cl of max efficiency. Briefly if I have tailwind without engine I can glide much longer, is it right?


texts: Why does the CFM LEAP have so many LPT stages?

texts:
With the core power being similar, intuitively, the higher the number of turbine stages, the more energy is absorbed, the higher the RPM. But the PW1000G vs CFM LEAP (both engines have similar thrust and power the A320neo) throws a wrench in that logic:
The N1 shaft of the PW1000G (before the gear) runs very fast (max 10,047 RPM), and I thought: high RPM in, high torque out, for the geared fan. But as the comparison below shows, it is the LEAP engine (max 4,586 RPM) with the greater number of turbine stages.

Source: Pratt & Whitney via airinsight.com

LPT = low pressure turbine


texts: How do modern turboprops avoid slow spool up of early jets?

texts:
I was reading about modern crop dusters that are blessed with 600 or more horsepower
turboprops and have seen them do amazingly effortless high angle of bank turns near the ground.

It seems that a slow rate of power increase would make this type of flying much more dangerous. I had imagined using air bleed gates to close and raise combustion chamber pressure instantaneously, along with more fuel.  This would involve an overdesigned compressor.

Is this how it is done?


texts: Why do airlines have intermediate stopovers with no passenger boarding?

texts:
I fly regularly KLM 573 from Amsterdam to Dar es Salaam. This flight does a stop over in Kilimanjaro International Airport and no passengers are boarded, but passengers are disembarked.

There are also other flights of other airlines that I know of that do this (Turkish airlines, Swiss International).

Why is this done? Wouldn't it be more of an advantage to pick up some more passengers in a short intermediate flight in order to maximize profits?

Or does the hassle of loading/unloading luggage and passengers make it less viable?


texts: Is there a limit for which vision can be corrected to 20/20 vision for being a pilot?

texts:
I have 20/400 vision and can be corrected to 20/20 vision with glasses.
Does having 20/400 vision disqualify me from getting a pilot license?
Would it prevent me from getting the required medical certificate?


texts: Why is crushable-block EMAS the only overrunning-aircraft-stopping system in wide civilian use?

texts:
Because runway overruns often end badly, and many runway ends (especially older ones) don’t have enough clear space available beyond the runway end for a full-size runway safety area (RSA), EMAS has come into wide use (at least in the U.S.) for quickly stopping overrunning aircraft within a smaller-than-normal RSA.  An EMAS system consists of a bed of crushable pavement blocks (usually cellular concrete or foamed silica) which collapse when an aircraft runs over them, causing the aircraft’s landing gear to sink into the EMAS bed and drag through it, slowing the aircraft quickly to a stop.

However, EMAS is far from the only conceivable system for slowing and stopping overrunning aircraft:

One option would be a simple bed of sand or gravel (like the runaway truck ramps ubiquitous on steeply-inclined highways), which would slow an aircraft down through exerting drag on its landing gear; although not as effective as a full-blown EMAS, it would be capable of handling small aircraft that wouldn’t be heavy enough to crush the paving material of an EMAS, and would also be far less expensive, making it ideal for smaller general-aviation airports.1
In a similar vein to the sand/gravel arrestor bed, a thick bed of tall, stiff bristles would also slow aircraft fairly quickly through landing-gear drag (like how it takes a lot more effort to walk through waist-deep grass than on bare dirt).
Another possibility would be a large retractable net, similar to the nets aircraft carriers carry to stop aircraft if need be.  Although aircraft-carrier nets are, admittedly, usually used for aircraft considerably smaller than your average airliner, the aircraft more than make up for this by landing at very high speeds compared to an airliner and by travelling a much shorter distance (and, thus, having much less time in which to slow the aircraft by braking) between touching down and hitting the net than an airliner at a land-based runway would, and the aircraft do have the ability to handle the considerably-larger aircraft that sometimes land on aircraft carriers; additionally, nets were formerly used at emergency landing sites for the space shuttle orbiters, which were about the size of a DC-9, but much heavier and having landing speeds over twice as fast, strongly suggesting that similar nets would be capable of handling even large airliners.

So why is the crushable-block EMAS the only system widely used for stopping overrunning aircraft?

1: One airport does have sand-filled arrestor beds at two of its four runway ends; however, this airport serves aircraft large enough that it should have a full EMAS instead, the sand beds being woefully inadequate for stopping aircraft of these sizes, as was spectacularly demonstrated in 2010.  Sand/gravel beds are far better suited to stopping smaller general-aviation aircraft that aren’t heavy enough for an EMAS to be effective.


texts: Why were there pneumatic headphones on airliners in the 70's and 80's?

texts:
I remember listening to the on-board program with headphones that consisted of hollow hoses as a kid. You plugged them into small holes in the arm-rests. The program was the same for everybody.

Why was the system in place? Why was it phased out?


texts: How does a vertically higher center of gravity affect handling?

texts:
Much of the discussion of the center of gravity of the aircraft is focused on the longitudinal axis, i.e. front and back. How does the vertical position of the CG affects the handling characteristics?

For example, the Boeing Dreamlifter and the Airbus A300-600ST both have their cargo stored in the upper portion of the airframe. Are these aircraft easier to "flip over"?


texts: Which system is in place which gets data from all the flights on a terminal and display them every where like Airport Screens, Websites, different Apps etc?


texts: How are antennas integrated into stealth aircraft?

texts:
In Hephaestus Aetnaean's answer to this question, it is mentioned that the F-117 had no radar detection equipment because at the time it was developed the designers had not figured out how to integrate the antennas into the body without increasing its radar profile. How is this done on newer stealth aircraft?

And what about things like air speed sensors? Do they use something other than a pitot tube?

As a related question, obviously if this was the case they apparently were not able to place radar detection inside the cockpit as you can with police radar detectors. Is the cockpit glass in the F-117 somehow opaque to radar or is there another reason?


texts:
One episode of the BBC series "Engineering Giants" featured a BA 747 undergoing a multi-week "D check". Here the inside of a fuel tank was surprisingly clean and dry (to me):

since elsewhere I've read of technicians having to wear respirators and protective overalls. Presumably the lighter fuel fractions can be driven out with forced ventillation, but is a specific cleaning process required to remove less volatile compounds?


texts: What is the transient bleed valve in a gas turbine engine?

texts: What is a transient bleed valve and what's its purpose ? Also, can you explain the purpose of bleed valves in general?


texts: What is the approximate accuracy of ASDE-X?

texts: Can anyone suggest some ballpark figures for estimating the tracking accuracy of ASDE-X systems at airports? Specifically, I'm trying to get a sense of the error (± x meters) that can be expected from ASDE-X when fixing the position of an aircraft.


texts: What is the airfoil used in the SB13 flying wing?

texts:
(Source)

What airfoil is used for the wing of this aircraft?


texts: How does stall depend on angle of attack but not speed?

texts:
Everyone says that the angle of attack is what determines a stall, not the speed. I understand the theory and understand that it is separation of the airflow that matters for stalling.

However, I don’t understand in a practical sense. Let’s say you’re in a Citabria going at 100 knots. If you pull up extremely fast, you can get a high angle of attack, beyond what you’d need to stall at 60 knots, yet you wouldn’t stall straight away. If you stayed at that angle of attack, you’d quickly slow, then stall. But if I’m right that you wouldn’t stall straight away, then it seems like the angle of attack is not the only thing that matters.

What am I missing? What’s wrong in my argument?


texts:
Everyone I know knows about DUATS and Flight Service weather briefers, but you almost never hear about TWEB and TIBS.  They have something to do with telephones and recorded weather information...are they the same thing?

What's the difference between TWEBs and TIBS?  When is it appropriate to use each?


texts: How is a type rating administered for aircraft that do not comply with 91.109?

texts:
Let's say you have a demilitarized A-10 (this isn't too farfetched an idea, as this SDSM&T proposal for a replacement thunderstorm research aircraft demonstrates).  With an empty weight twice the 12,500 pound limit, it clearly requires a type rating; however, there was only one two-seat A-10 (the YA-10B) ever built, and it likely isn't airworthy any longer.  (It is on static display at Edwards AFB.)

So, how would you train a civil pilot to get their A-10 type rating?  Would it be a simulator-only exercise, or a long ground school followed by a solo signoff?


texts: How can a designer deal with a strict requirement when designing an aircraft?

texts:
I'm working on designing an aircraft with some specific requirements (Vstall, Vmax, Ceiling, Payload, Range, RoC, Slanding/takeoff etc).
I'm following Anderson's and Raymer's ways (trying to find the best for me).
Right now I'm stuck at the step of estimating for the first time the Wing Loading (W/S). Doing the calculations about the W/S constraints (Vstall, Landing distance from Anderson) I found that the Stall constraint is very strict. The result that I get is a W/S = 24 lb/ft2 for a twin turboprop with a estimated gross takeoff weight of 16k lbs. The constraint of landing distance gives a W/S of 62.
Looking at historical data (and some similar aircraft) and Raymer's/Anderson's tables the W/S = 24 is way off the ordinary values. I do understand that it is just an estimation.
What would you suggest to do so I can satisfy the requirement and be able to get a higher W/S?
I thought about changing the flaps that I used (Split Flap) but I don't know if it's possible and realistic to have "Double Slotted Flaps and Slats" for a simple twin turboprop that has a simple mission.
edit: After the comment, here are the equations about the Vstall and Landing Distance.

and


texts: Why is the minimum runway length non-linear in relation to the landing weight?

texts:
The graph below shows the landing runway length requirements for a Boeing 747-8.

(taken from the Boeing 747-8 Airplane Characteristics for Airport Planning)

Considering the fact that the kinetic energy and impulse are directly proportional to the mass, I would have expected this graph to be linear – but clearly that's not the case. What is causing the non-linearity here?


texts: What free online educational resources should pilots in training be aware of?

texts: Obviously this website is great as is boldmethod and several of the aviation youtube channels. Also the FAA wings website is great as is all the FAA handbooks and advisory circulars. I also like to use the ASA study guides for the oral exams. Are there any other high quality sources of information that pilots should be taking advantage of, preferably free or low cost?


texts: Identify an USAF transport aircraft in Greenland around 1960

texts:
Could anybody help me identify this aircraft?
It was photographed in Greenland around 1960.
Thanks in advance.


texts: Can ATC tell if aircraft is being flown manually?

texts:
Was wondering if ATC can detect if aircraft is being flown manually vs. autopilot and if that affects their clearances given out for surrounding aircraft?

More specifically, can they tell through ADSB signal or just by observation (holding flight level, turn rate, correction for wind, etc)?

I would imagine that in high winds/bad weather non-AP operation would need to be better isolated from other aircraft?


texts:
In AW189, B787 and few other aircraft/helicopter, the physical breaker has been replaced by virtual breaker, which can be controlled by the MFD (Multi-Function Display).

I tried to google the answer, but I could find nothing about it: how does a virtual breaker physically work? I know how you control it, but what really happens when you press the breaker switch button on the MFD?


texts: Aircraft Carrier Launches: ABE Checks and Signals

texts:
Somehow I got hooked on videos of aircraft carrier flight deck operations, and have been binge-watching over the last couple of days. (Glad it's a long weekend...)

I've been able to understand many of the hand signals from the Aircraft Signals NATOPS Manual (NAVAIR 00-80T-113), but I'm missing a lot of the context of what I'm seeing, because much of the video footage focuses rather narrowly on specific individuals and tasks rather than showing the "bigger picture."

I actually have many more questions than I will put down in this first post, and I will likely post more later. But here I will start off with just a few questions about the "Aviation Boatswain's Mate - Equipment" (ABE) rating, because it looks the most interesting to me.

All questions reference this video, which has some pretty clear shots of ABEs at work. (Parenthetically, I assume that the reason there are two ABEs working the catapult attachment task is that the "hands-on" one is under instruction, and his work is being checked by the other one. Have I got that right?)

At 0:27 the two ABEs appear to be waiting for some kind of go-ahead signal from someone out of frame (to whom they are pointing?), before signaling for the aircraft to be brought forward to position the launch bar in front of the catapult shuttle. Who are they pointing at, and what condition needs to be satisfied before they can proceed?
At 0:38, before signaling for catapult tension, they go through what appear to be a series of visual check-ins with three (or maybe four) separate individuals out of frame:

ahead of the aircraft;
behind the aircraft on the near side;
ahead of the aircraft again (same individual as before?);
behind the aircraft on the far side.

These checks happen quickly enough that I believe they can only be looking
for simple thumbs-up signals. What are the roles of the specific individuals they are looking to, and what, specifically, are those individuals verifying that make it okay to proceed with catapult tensioning?

When tension is finally applied at 0:44, they make a final check of the holdback bar before getting clear. What possible failure modes of the holdback bar are they looking for, specifically?
At 1:01, when the catapult officer signals “launch,” the deckedge catapult operator (center of frame, with hands raised overhead to signal “final ready”) turns his whole body first left, then right, before actuating the catapult. Is he checking something (what?), signaling something (what?), or both?


texts: Can any land-based plane be made to land on water?

texts: Can any land-based plane be converted to a seaplane by installing skids? For example, is it possible to convert a Boeing 747 to one that is capable of landing and taking off on water using pontoons or planing hulls?


texts: Why is ditching speed higher than stalling speed?

texts:
I was looking for a checklist for the Cessna 182 and I stumbled upon this one. When I looked at the speed-table, I found an interesting entry. It says "Ditching" with a speed of 65 KIAS:

Everything I read and watched about ditching so far told me to ditch at the lowest speed possible.

Why should I ditch with 13 knots more than I could (Vso is 52 KIAS)? I can think of no reason I would like to do that.


texts: Why was the Iraqi airspace closed on 12 Mar 2020?

texts:
I was onboard BA105 on March 12, 2020 (London LHR to Dubai DXB), which was rerouted (I hope this is the correct term) to fly over Egypt. See the inflight map photo below:

Close to arrival, the crew informed us that we had changed course because of an Iraqi airspace closure, bit didn't give any additional info.

How would I find out more details about what happened (I couldn't find anything through a basic online search)?


texts: What is the minimum distance allowed between planes in flight, in Europe?

texts:
What is the minimum vertical and horizontal distance allowed between aircraft operating in European airspace?

(This linked question is the US-specific equivalent of what I am asking about European regulations for ease of reference)


texts: Why are ambient pressure and burner can pressure always the inputs on a hydromechanical fuel controlling system?

texts:
I worked on several of these older systems using a hydromechanical fuel control. I've noticed that the inputs at the fuel control are for the most part the same. Power lever angle, N2(N1 on a single spool), ambient pressure (usually Pamb or whatever the manufacturer calls it), and burner pressure (sometimes Pb4, again depends on manufacturer). My question specifically pertains to the pressures.

Why is it always ambient pressure and burner can pressure that are inputs? Why not compressor discharge pressure and turbine exhaust pressure or some combination of other pressures in the engine?


texts: What kind of problems can a flight have if passenger weight is miscalculated?

texts:
There was a widely reported news story about a TUI Boeing 737 flight, where a bug in reservations system caused 38 passenger on the flight to be allocated a 38kg standard weight as opposed to the correct figure of 69kg. In total, this caused the report to state that the weight of passengers was 1200kg lighter than it actually was.
My question is - how serious of a problem is that? Would the pilot notice this discrepancies? What kind of problems could appear due to pilots using the wrong passenger weight in calculations and flight configuration?


texts: Why is A320's CG optimum position at 25% MAC?

texts:
I have read a320's optimum CG position is 25% MAC. But, the aerodynamic center is also at 25% of chord.
So since CG and aerodynamic center at the same position, there would be no moment arm of lift, so what will be the use of tail plane?
Also, as fuel burns,
the CG shifts rearward,
in that case aerodynamic center will be in front of center of gravity.
wouldn't that mean center of gravity is behind the center of pressure?
I have read center of gravity is ahead of center of pressure in airliners, so wouldn't this be a violation.
Please explain my two questions.,


texts: Can ramjets reach higher thermal efficiencies than gas turbines?

texts: Since a ramjet isn't constrained by turbine inlet temperature like a gas turbine is, it seems to me that it should be able to achieve a higher thermal efficiency, given that it's operating at a speed that results in a comparable compression ratio. Is this true?


texts:
Question:
Is there any internationally accepted definition for what an "unsafe airline" is based on objective criteria (e.g. fatalities per million passengers) ?
Or is there an international standard or worldwide blacklist ?

All I was able to find are regional lists:

the list of air carriers banned in the EU, AKA the EU Air Safety List and
the International Aviation Safety Assessment for the US.

I'm hoping to receive answers in a similar vein as those for the question What is a “Major Airline”?.


texts: Where can I find more information about my grandfather's crashed B-18a bomber on Mt. Redoubt Alaska?

texts:
My father and I have chartered a plane for late August to search for the remains of my grandfather's B-18a bomber, which crashed in the summer of 1942 in Mt. Redoubt Alaska.

I am specifically interested in advice from pilots who have flow around Mt. Redoubt:

A Saturday Evening Post article mentions the accident site is at 7500 feet MSL, on the southwest side of the mountain.  The accident report OTH, says the southeast side.  Questions:

What is the terrain/glacier situation at this location?
Is landing possible at this location?
Has anyone seen an accident site at this location?

I've posted additional details and pertinent material in this blog post.

Also, I would think the USAAF would have more detailed records of the rescue, which again, is detailed in the Saturday evening post article.  Perhaps even a dispatch to the rescue crew with a specific location.  Does anyone know where I might find such records?

Update, July 21st, 2017 (One month till departure)

Since I've offered a bounty, I guess I should iterate what I've done so far:

I've posted this to an Alaska bush pilot's forum.  I was surprised to not get a better response from this.
I've ordered (and received) a full sized topo map of the area from mytopo.com. The detail is pretty darn good.
I've scoured over multiple satellite photos.  Note, the obvious photos on google maps/earth are pretty iffy.  I found the photos at zoom.earth to be better.


texts: How long is spin training good for in the USA?

texts: Written tests are only good for 24 calendar months before they must be applied to a certificate (or lost).  Spin training is a requirement of the flight instructor certificate.  Does the required spin training have the same limitation of life as a written test?  Or, is it like an endorsement where it's good "forever"?


texts: What is the FAA's definition of "for hire"?

texts:
(note: references to specific FAA documents or cases are always appreciated!)

This is a general question and might best be considered as open-ended.

It is, however, posed for clarification of a few specific regulations:

91.205(c)(4) "if the aircraft is operated for hire, one electric landing light..."

91.409(b) "...no person may operate an aircraft carrying any person for hire .... unless within the preceding 100 hours..."

91.205(b)(12) "if the aircraft is operated for hire over water and beyond vliding distance from shore, approved flotation devices..."

There may be others regulations that reference the term in Pt 91.

The point is: do these regulations imply that neither landing lights, life jackets, nor any current 100 hr inspection are required for e.g. (1) a solo rental, (2) a rental with $\leq$ pro-rata contributing friends, (3) a checkride ? It is my understanding that none of these are not "for hire" flights but perhaps there is clarification otherwise.

i.e.1) what flight scenarios/activities are conducted under for hire circumstances and therefore must comply with the above regs?

i.e. 2) Does the term for hire describe the airplane or the pilot?


texts: Is it possible to fly a B-24 under Bixby Bridge?

texts:
If that sounds like a ludicrous question it's because I believe it is, but here is why I'm asking.

My grandfather flew B-24s in WWII and there was something of a local legend that he once flew a crew-laden Liberator under Bixby Bridge (near Big Sur along the CA coast). Here is a short video of the bridge:

I say no way. Aside from the the idea of a trained military aviator so recklessly risking crew lives (not to mention court martial, etc.) straining credibility, I think such a feat is physically impossible for an aircraft of that size. But then, I'm not a pilot - I just pretend to be one on X-Plane. I have relatives (also not pilots) who are convinced the story is true. Those of you who fly IRL, what do you think?

Unfortunately my grandfather passed before I was born so short of breaking out the Ouija board there isn't really a convenient way to ask him!


texts: If I recall, in America there were several "Prohibited Access" airspaces and others required permission, via radio, to enter in a typical aircraft. But, what if I'm gliding over a restricted airspace? (Say, over the Capitol?). Would I be shot down (or fined, sued, etc.)?


texts: What is the longevity and replacement schedule for turbine engine blades?

texts:
I'm trying to understand how frequently hot section turbine engine blades are changed out. Is this a calculation based on flight hours, material, engine size or maybe something else?

Apologies if this is an obvious question, conducting some research for work and do not have any prior background in this area.

Thanks.


texts: Does 3D Thrust vectoring (TVC) provide improved maneuverability over 2D TVC?

texts: What are the additional capabilities that 3D thrust vectoring (TVC) provides over 2D thrust vectoring?


texts: What are some symptoms of a clogged fuel filter?

texts: I can certainly imagine one of the symptoms could potentially be engine fuel starvation. If the fuel flow to the engine isn't totally blocked, how can one recognize a clogged fuel filter?


texts: What is the need for twist along a wing?

texts: Why should a wing even have a twist towards its outermost chord? How did that even come about? Why can't it be straight and aligned as it usually is?


texts: What is the correct procedure in case of vertical stabilizer failure?

texts:
What is the correct procedure in case of vertical stabilizer failure in cruise?

Am I correct in guessing that one should descend to a lower altitude and decrease speed?