Why would a glider have water ballast? If it is trying to stay aloft without an engine, wouldn't it be better to be as light as possible? So I was looking at the description of a ASW 27 B glider and ran across this statement:

  Two water tanks in the wing plus a further 35 liter tank in the
  fuselage enable the ASW 27 B to carry more water ballast than any
  other 15 m glider and also give it the widest range of wing loadings

If a glider is trying to stay aloft as long as possible, wouldn't it be better to be light?  Why would you add ballast and be able to dump it?

Mass doesn't affect the maximum distance, only the maximum endurance.

For example, image two identical planes A and B: A weights 50kg less than B. Assuming no wind (horizontal / vertical) and speed of best glide, both gliders will land at the exact same spot.

The lighter airplane A however will arrive later than B, as the speed of best glide is less than for B. In conclusion you can say, that additional mass only increases cruise speed, but not the travel distance.

Glider competitions are most of the time a route you have to fly in the shortest time possible. So that means, if you have a higher speed of best glide, you can fly faster in competitions.

The only downside to having a higher weight is, that your liftrate in thermals will be decreased and due to the higher speed it is harder to center the thermals.

It is to some extend also possible to shift the Centre of Gravity (CG) with the added load. The further it is to the aft limit, the higher your maximum distance is. This is because you will have less down-force from the stabilizer required. (If the CG is at the front limit, you will need to pull the control stick in order to fly level, therefore you have more drag). However I think this is rather a positive side effect and most of the time the water is used for flying faster.

Source: I am a glider pilot and currently doing my ATPL training.

One point not explicitly mentioned in other answers is that on a strong soaring day, no one flies at best L/D.  Suppose the lift is strong and climbing is no problem.  Ballast up to max gross. Cruise between thermals at 100 knots. The sink rate at the same airspeed will be much higher if no ballast is carried.

You can easily see this by checking the polar diagrams provided in this related answer.  Look at the second diagram-- the graph of sink rate versus airspeed for three different wing loadings.  100 knots is about 180 kph.  At the heaviest loading, the sink rate at this airspeed is 1.8 m/sec, and at the lightest loading the sink rate at this airspeed is 3 m/sec.  That is a 66% higher sink rate.

When flying at some given airspeed that is well above best L/D speed, ballast does in fact increase the distance made good for the same loss of altitude.


Can a civilian aircraft pilot see a missile coming? Can a civilian aircraft pilot see a missile coming?

By "civilian aircraft," I mean planes that were not equipped with flares that fire when rockets approach  or any similar anti-missile systems.  If these missiles can be detected, can the pilot take any evasive measures?

Visual detection

To take one example, a vehicle-launched ground to air missile system (e.g. the SA-11) that can reach the cruising altitude of airliners travels at several thousand miles per hour and takes perhaps 30 to 40 seconds from launch to reach its target.

Pilots don't have an especially good view of the ground immediately below and would have a very hard time spotting a missile travelling at those speeds.

Electronic detection

Civilian airliners are equipped with a collision avoidance system called TCAS. However this relies on radio signals from transponders which are fitted to other aircraft. Naturally, anti-aircraft missiles do not have a transponder and do not advertise their presence.

Missile Countermeasures

Anti-missile systems that are available (example) are mainly intended to protect against small infra-red seeking man-launched air-defense missiles (MANPADs) rather than larger more sophisticated radar-homing systems.

Even these systems are not fitted to all civilian airliners, probably only to those that operate into airports where there is a current known risk of MANPAD use by terrorists or other armed factions.

Evasion

Civilian aircraft are not designed for high-G evasive maneuvers and in any case, the missile does not have to strike the aircraft, it detonates nearby based on a proximity fuse and the resulting explosion and high velocity fragments will do enough damage to result in the destruction of the target.

Missles are way too fast for a commercial jet to take evasive maneuvers even if it was capable of it.  Korean Air 007 in 1983 is a perfect example of pilots not knowing about missiles.

They strayed into Soviet Airspace (unknowingly) and the pilot that shot the plane down suspected it was a commercial plane built by Boeing but shot it down anyway.  He fired two missiles 2 seconds apart.  The detonated 50m from the rear of the aircraft. The first one tore through 3 of the 4 hydraulic systems.  The plane was still flyable (as the data recorders prove), the second missile tore through the fuselage causing a decompression (not explosive decompression).  One of the flight crew was able to radio that they had decompression.  Unfortunately, because the plane was already crippled with the hydraulics being out it spiraled down into the ocean in Russian territory.

It wasn't until 1993, after the fall of the USSR, that the truth finally came out.

There is absolutely no way a commercial jet aircraft has any chance of evading a SAM of any kind.

The MH-17 was hit by a Soviet-built missile, however, Malaysian Airlines KNEW the area was a conflict zone and should have flown around it, not through it (like the other airlines were doing).


Is it OK to move a light aircraft by pushing or pulling the propeller? It's very common to see pilots moving a light aircraft by pushing or pulling on the prop, either because there's no tow bar available or simply out of preference or convenience. Is this a reasonable thing to do or can it damage the prop or engine in some way?

A couple of my CFIs have asked me to help them park the airplane (in absence of a tow bar) when I was pushing the airplane by putting one hand on the hub and the other on the propeller near the hub, and them (the CFIs) pushing the tail down and nose wheel elevated. But according to AOPA, it is not a good thing:

  ... never push or pull on the prop blades. Forget what anyone has told
  you about pulling near the hub or the strength of the propeller.
  Aluminum blades can bend, and it doesn’t take much to put the blades
  out of track with one another.

This PDF says the same thing:

  Avoid pulling the airplane around by the prop. Yes, this seems the
  perfect solution to a vexing problem of how to change the airplane’s
  position without having to walk around and get the tow bar, but it’s
  worthwhile to make the extra effort. Neither the engine nor the prop
  particularly benefit from the loads imposed by horsing the whole
  airplane around.

Regarding "it must be ok to pull the plane by the prop because the prop pulls the plane through the air"...
Yes....through the air. The air is much less sticky than the ground.
Also, the propeller doesn't pull the plane through the air, it pushes air behind the plane creating a lower pressure area in front of the plane and a high pressure area behind it. This "pulls" the plane into the low pressure area.


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

Looks like a CJ-6. Popular as an affordable "warbird" type of aircraft, without the rarity.

Various other images of the CJ-6 that seem to match up to what you posted.

It is in fact a Yak-52, Soviet era trainer aircraft.
It indeed looks nothing like the T-34.

See Wikipedia for more information


Who is the owner of the world's only private Boeing 787 Dreamliner? I have just stumbled across this video and I was wondering, if anyone knows who is the owner of this particular airplane (world's only private Boeing 787 Dreamliner)? I mean a man or a company -- an actual user or property owner. Not an airline / operator, because it seems to be Deer Jet.

The video itself does not reveal plane's registration or serial number, so I cannot look it up in any aviation database.

I've tried to locate it in Flightradar 24 database, based on airline / operator -- Deer Jet -- but it lists Gulfstreams and Dassault Falcons only for this operator. Neither Boeing 787 nor any other Boeing.

The registration number of this aircraft is well visible in the video: 2-DEER.
According to Planespotters, this B787 was first leased by Jet Aviation Flight Services from 2014 to 2016. During this time it was registered as N28MS.
In 2016, the plane was bought by Deer Jet, a company owned by HNA and received the registration number 2-DEER. The video was published in 2017. That means 2-DEER was not privately owned, but available and furnished for private charter clients. The video title is a tad misleading.
Deer Jet was trying to sell it for 300 million US$ in 2018 (source).
In February 2020, 2-DEER was spotted still in Deer Jet livery. It appears that they couldn't find a buyer.
The registration number starting with 2- might look unfamiliar to most of us. A company called 2-REG offers these personalised registration marks. Here is an advertising text from www.weareguernsey.com that summarizes it:

2-REG is an ICAO (International Civil Aviation Organisation) registry,
well-recognised around the world for accommodating all aircraft
categories, including commercial aircraft, business jets, helicopters,
and general aviation. In 2015, 2-REG began to issue Aircraft Operating
Certificates (AOCs), and six have been issued so far.
Run by the Dutch company SGI Aviation, 2-REG pays royalties to the
Guernsey government on operating income. The registry has built its
reputation by being extremely responsive and customer-focused,
offering its worldwide coverage coupled with competitive fees, making
it the most successful registry within the aircraft leasing sector.

A second B787 was converted to Business Jet classification at Moses Lake Washington State in US in 2018. It flew to Westover KCEF in Chicopee, Massachusetts where it has been for over a year. It is owned by Korean Air and it was for sale. It is a B787-800 N507BJ


Why is it necessary to fly in visual conditions to certain unmanned airstrips? I have come across certain unmanned airstrips where only VFR flight is allowed not IFR? I wonder what can be the possible reasons for that?

Two reasons:

1) It takes time and money to create an instrument approach procedure, and possibly not enough people have requested that one has been created.

2) A certain amount of obstacle clearance is required, if for some reason the required safety cannot be guaranteed using instruments, the FAA can simply not create a IFR approach

Instrument approach relies on beacons and transmitters on the ground like VOR/DME or ILS.  That's unlikely to be in place.  Furthermore, even if this was in place, a manned tower would be needed for ground movements in IMC conditions, to avoid runway incursions.


Why does the BAe 146 have higher maintenance costs than other comparable jet aircraft? In many discussion(1)(2) it is stated that the BAe 146 has higher maintenance cost and higher cost of operations in compare to other jets due to its complexity.

  Quoting IslandHopperCO (Reply 21): The PSA (then USAir) BAe-146s were
  parked in the desert in 1991 due to high maintenance costs according
  to USAir. More likely was that USAir couldn't turn a profit on the
  western routes that PSA used to make money on, because those routes
  were dropped when the plane were parked.

  No that is pretty much correct...PSA also had major problems with
  reliability. In fact BAE provided them with a spare because they broke
  down so much. Who knows if they would have gotten rid of them because
  of that. They were kinda ugly but in a cute way....that smile really
  did it!

Why are the maintenance and operating cost higher?
Why is it more complex than other jets?

higher maintenance cost and higher cost of operations in compare to other jets due to its complexity.

That seems ironic considering what Wikipedia says

According to the BAe 146's chief designer, Bob Grigg, from the very start of the design process, making the aircraft as easy to maintain as possible and keeping operator's running costs as low as possible were considerably high priorities.
Velupillai 1981, pp. 1245-1246, 1253.

Why is it more complex than other jets?

Because it has four engines? I believe short-haul airliners of similar capacity mostly have only two.

Why are the maintenance and operating cost higher?

Wikipedia says of the original Lycoming engines used:

The ALF 502 has experienced multiple issues. Its internal electronics could overheat, triggering an automatic shutdown of an engine with no option of in-flight restart, and certain rare atmospheric conditions could cause a loss of engine thrust due to internal icing.[29] Additionally, the BAe 146 experienced aerotoxic syndrome due to leakage of tricresyl phosphate (TCP) into its bleed air; this has been blamed on problems with leaking engine seals. Exposure to these toxic fumes is a dangerous health risk

Note: the above is speculation, you'd have to ask an airline maintenance manager.
There are interesting maintenance anecdotes / whinges at pprune

High price of spare parts.
Accessibility of some components.
N1 harness that goes through engine fan strut.
Quick release fastners needed on engine core covers.
FADEC harness (RJ) can't be changed without dropping the donk.
Lower engine power cables that freeze full of moisture.
Corrosion issuse with the gear bay longeron strut.
The nose landing gear steering lube leaks out and the internals corrode
Air con pacs are unreliable.
Honeywell apu's are unreliable, Garrets better.
Fuel tanks need proper draining off every day to get rid of moisture.
Tri-wing fasteners often fail on removal.

Because it was a pain in the a*** to work on. The only benefit the aircraft had was it's ability to operate in noise curfew limited airports (yes, it had an attribute, it was very quiet). Maintenance manhours were very high compared to other aircraft. Engine changes, too many, compared to other aircraft, engine issues, too many, cockpit design, antiquated, spar issues, the list goes on.


How do planes descend for landing? I fly occasionally  on a pretty short route on a turboprop (DHC-8). When the airplane descends for landing, I can look through the window and see the ground below getting closer over time. However I can't really tell what the pilots do to achieve that. I know that turns make you lose altitude, but it's very clear to me when the airplane makes a turn, so let's count that one out. So we're basically left with:

Slight nose-down attitude
Reduction of engine power
Combination of both

The reason I'm asking this is that during descent I do get this sensation of going down. However, during that time I cannot really see what the pilot did to achieve it. The nose-down attitude might be too minor for me to actually notice (I do not notice a slight nose-up cruising attitude to be honest). I hear a slight reduction in engine power a few times during a descent, but the feeling of going down and the audible noise reduction are separated in time. Is it that it takes time for an airplane to reduce speed (and as a result, descend) when you reduce engine power?

One additional question: I guess that with all the electronics in the cockpit pilots just set a target altitude or rate of descent, and then the airplane systems apply the correct measures to achieve this. How does the airplane know how much to reduce engine power and/or pitch to achieve this exact rate of descent?

If the pilot reduces the airspeed while he increases the rate of descent, you will not notice any change in pitch attitude when the aircraft descends. With jets you should be able to hear a change in engine pitch when thrust is reduced. Turboprops run their engines at constant speed, and a reduction in power here means a reduction in propeller pitch. This causes the propeller noise to change, but this change is harder to discern. With a little practice you should be able to hear the slight drop in propeller noise which signals the begin of the descent, though.

Gliders control their sink rate by flying in rising or sinking air, and additionally by flying slow (and near their minimum sink rate) or fast. To descend quickly, they can open speed brakes and/or sideslip. My favorite for a fast descent is to spin the aircraft, but airliners do not use this option.

In order to produce the necessary lift to keep the aircraft in the air, the pilot picks a combination of speed and angle of attack at which lift equals weight. Other combinations would result in an accelerating vertical speed and are only used in transitions from one flight state to the next.

To arrive at the aircraft's pitch attitude, you need to add the flight path angle to this angle of attack. If the plane descends with a flight path angle of -3° and the pilot reduces speed such that he needs to increase the angle of attack by the same 3° to produce the same lift, the resulting pitch angle of the aircraft would stay the same.

Normally, the correct answer to your question is 2. Reduction of engine power. But the other answers are also correct: If the speed is held constant, the attitude has to be reduced by the desired flight path angle change. Note that this is achieved by reducing thrust alone. If the pilot wishes to descend really fast, he might move to answer 3. Combination of both as in this answer.

In one important sense, the pilot doesn't need to do anything to descend: gravity takes care of that all by itself.

A plane descends when its wings produce less lift than it weighs

In order to keep the plane aloft, the pilot needs to keep overcoming gravity - in physics terms, ensure that the aircraft produces more lift than the aircraft weighs.

A wing produces lift when it moves through the air

An airliner produces lift when air flows around its wings, which happens when the aircraft moves forward through the air. By changing the shape of the wings (for example, by extending flaps) or changing the attitude (angle) of the aircraft in the air, the pilot can adjust how much lift the wings produce.

More power = more speed = more lift

One very simple way to descend therefore is to reduce power. This will slow the aircraft down, so the wings produce less lift, and the plane slowly falls.

Why pointing the aircraft down (or up) isn't the way altitude is controlled

Another would be to point it firmly at the ground, but this would not be pleasant or safe, so airline pilots rarely do that.

Although it would seem intuitive that raising the nose will cause the aircraft to climb, and lowering it will cause it to descend, that doesn't necessarily follow.

Other things being equal (i.e. if the thrust produced by the engines does not change) pointing the nose down somewhat will cause the plane to descend, but it will also cause it to go faster.

This is for two reasons:

the potential energy (height) of the aircraft has to go somewhere, so it becomes kinetic energy (speed)
less of the engines' thrust is converted into lift, and more of it contributes to the plane's speed

This extra speed, other things being equal, will in turn cause the wings to generate more lift! Depending on how the controls are set, lowering the nose won't actually cause the plane to descend for very long.

The reverse applies when lifting the nose. Eventually of course if the nose is lifted far enough, although the aircraft will climb rapidly at first, soon it will lose so much speed that the wings fail to produce enough lift to keep it in the air, and it will plummet in what's known as a stall.

So the key overall is engine power, thrust. Smaller and more momentary adjustments will be achieved by moving the aircraft's control surfaces and controlling its angle of attack, but on the whole, a descent involves keeping the plane comfortably level and allowing it to fall very slowly through the sky - as far as possible, so that the passengers don't even feel it.


What are the advantages and disadvantages of a delta wing compared to a swept wing? What advantage does a delta wing have over a swept wing with high AR for supersonic flight? And what disadvantage does a delta wing have over a swept wing with high AR for transonic flight?

The Concorde is made to cruise at supersonic speed--delta wings.

Most commercial airliner--swept wing with high AR.

Would you design a supersonic airplane with the conventional airliner swept wings? On the other hand, would you design a transonic flight with delta wings?

Benefits of a delta wing:

Due to the large root chord, a delta wing combines low relative wing thickness with a sufficiently thick wing spar for a lightweight structure. Since a low relative thickness keeps wave drag down (a drag component which occurs only in supersonic flow), this makes delta wings especially attractive for supersonic aircraft.
The large root chord gives the delta wing a high internal fuel volume even at a low relative thickness.
The large root chord also provides it with a large surface area which helps to bring the minimum speed of the aircraft down.
With sufficient leading edge sweep, a delta wing produces vortex lift, so flow separation can be turned into a means of increasing lift.
A delta wing is naturally stable in pitch, therefore it does not require a separate tail surface.

Drawbacks of a delta wing:

The large wing area causes more viscous drag for the same amount of lift compared to a high aspect ratio wing. Swept wings have a better lift-to-drag ratio (L/D) than delta wings.
High-lift devices like fowler flaps are hard to integrate into delta wings. The higher relative thickness of regular airliner wings allows to integrate large flaps more easily, and the rearward location of the trailing edge of a delta wing will produce intolerable pitching moments if such flaps would be deflected.

Generally, the moderately swept high aspect ratio wings of subsonic airliners are ideal for flight at high subsonic Mach numbers. Delta wings are superior only in supersonic flight, and due to their good low speed characteristics they offer the best overall compromise for supersonic aircraft.

North American XB-70 in flight, a classical delta wing design (picture source). Note the canard wing, which has little sweep and a low aspect ratio: This kind of wing is ideal for supersonic flight, provided it has a low relative thickness. The main wing of the XB-70 is a delta wing to keep the take-off and landing speeds relatively low and offers the best compromise of low and high speed characteristics. Also, the wing tips could be deflected downwards to improve directional stability at supersonic speed and to improve L/D by using the waverider effect.

The wings of both the Boeing 787 (top, picture source) and the Airbus A350 (bottom, picture source) show their powerful high-lift devices in these pictures, which allow them to fly with less than half the wing area of a comparable delta wing aircraft. Also, the lower surface area translates into lower drag at high flight speed, and the higher possible wing span helps to reduce induced drag, making those wings far superior for efficient flight at high subsonic speed.

Delta wing advantages

Can fly at high angles of attack, which that's why fighter jets use a delta wing to fly at very high angles of attack
Provides good amount of drag for landing. On landing you need drag and that's the purpose of flaps is to increase drag and lift and you can make the flaps a little bit smaller

Delta wing disadvantages

Lots of drag, which is caused by vortex lift that a delta wing uses instead of conventional lift. Instead of just suffering drag from a wing tip vortex you suffer even more with 2 extra vortices that form on a delta wing.

With a swept wing you reduce drag by decreasing the lift. The problem with that type of wing at supersonic speeds is that you surfer from wave shock drag. Wave shock drag forms when air on top of the wing exceeds the speed of sound. Even at subsonic speeds that a 787 travels at you suffer from wave shock drag. Air is moving so fast on top of the wing at subsonic speeds that it causes the air to break the sound barrier. If you try to fly a swept wing at supersonic speeds your aircraft is really going to suffer from wave shock drag and any faster speeds could result in the whole plane splitting apart and is very serious. A delta wing doesn't have a slope on top of the wing like a swept wing does so the air doesn't travel any faster than the aircraft does. The reason airliners use swept wings is to reduce the lift to reduce the amount of high pressure air that can rotate around the wingtip. The swept wings reduce wake vortex and wake vortex can actually decrease an aircrafts lift and you want as much lift as possible. The major companies that build airliners main focus is to decrease drag. With a supersonic aircraft your main focus is to reach supersonic speeds and aren't designed to reduce drag. So you wouldn't design a supersonic aircraft that has swept wings, but you would design it with delta wings.


How do people smuggle stuff with private airplanes? I get it, the question seems as if I'm reaching out for answers from experienced smugglers! But no. As a matter of fact, I'm trying to get answers on air surveillance & security.

Love it or hate it, these kind of smuggles are being done all over the world. However, recently I heard a story from a retired soldier stating that he used to know people who knew people who smuggled jewelries, hard drugs, guns and even people from middle eastern countries to Europe, specifically, Germany! Via planes!

In fact, he said some stuff was too valuable for them to "risk it" by land transports. He added that the pilots were experienced World War II pilots who specialized in flying at high speed in very low altitudes to make deliveries for infantry units on distress, making them unnoticed on radars and unstoppable for air defense systems.

So that's for World War II, which ended on 1945, so the question is, how can people still do this considering all the enhancements and improvements or even inventions (which some boldly have "foolproof" labels attached to their names) implemented on radar and satellite technologies? Especially on a country like Germany, with superb defense and military status?

There are lots of ways to smuggle goods with planes and it depends what you are smuggling and the aircraft on which you are smuggling it. Smugglers often bank on the fact that most countries do not have or allocate the resources to search every aircraft throughly enough from top to bottom before every flight as that is simply impractical on some level. Some times all you need is a good audio equipment road case.

Generally you need to get past customs which happens on the ground and is its own set of issues. In the USA the Customs And Border Protection takes care of a lot of the searching. Smuggling sometimes happens on commercial aircraft and there is plenty of info on it here on the CBP website. In this case the goods are smuggled on aircraft that are very much on radar and flying at assigned ATC speeds. Sometimes they are even loaded by official personal. On occasion even the head honcho is involved, moving some strange things.

It is possible to "fly under the radar" but that also depends on where you are going and what their radar coverage is. Steps have been taken over the years to combat this issue. It seems that some of the smugglers have once again resorted to small aircraft.

Barry Seal, the inspiration for the movie American Made was historically a pretty prolific smuggler. The movie takes some poetic license but is based on some facts.

  Seal used his knowledge of aviation to become the infamous smuggler he
  was. Once in U.S. airspace, Seal would drop to 500 feet and slowed to
  120 knots to mimic, on radar screens, helicopters which frequently
  flew from oil rigs to the coast.

  Within U.S. airspace, Seal would have people on the ground monitor for
  any signs his planes were being tailed. If they were, the mission was
  aborted. If not, they would continue on to drop sites over the
  Louisiana bayou, where duffel bags full of cocaine were dropped into
  the swamp. Helicopters would pick up the contraband and take them to
  off-loading sites, and then on to Ochoa distributors in Miami by car
  or truck.

Smugglers are still attempting to move product in older, but fast, biz jets with fake or missing registrations. To avoid being discovered they are apparently destroying the planes after they use them sometimes.

There is a great article on some of the history of air smuggling here. Which dates back to the early days of aviation.

This is a fairly interesting story...

Just remember, aviation smuggling is Illegal very illegal

People smuggle with private instead of commercial because when boarding a private plane, the security checks are less thorough and very breif. Sometimes, they don't even get checked!

But on commercial jets on whatnot, the security is held to very high standards. That should answer your question.


Can a MEI CFI give a valid flight review in a plane for which he is not endorsed? A friend of mine is working towards his initial CFI.  I'm helping him work through regulatory, weather, and other knowledge stuff when time permits.  During our most recent ground session he asked me a question that I had never been asked.  Here's the setup...

A CFI with a freshly minted MEI (airplane, land) is asked to conduct a flight review for a customer in the customer's own Cessna 421C, a pressurized piston twin certified to >30,000'.  This CFI has only flown one type of twin (pick a common training twin, doesn't really matter).  He has no time at all in a 421 of any sort or any other twin aside from the trainer in which he trained for his commercial-multi and MEI.  Our MEI is otherwise current in all categories and classes for which he is certified, holds a complex endorsement gained during his commercial training, and holds a First Class with no limitations.

The customer is current in all categories and classes for which he is certified, is within the 24mo flight review window, and has a First Class.  In short, the customer is fully qualified to be PIC for the flight portion of the flight review.

What's obvious:

The five hour rule does not apply since a flight review is not
instruction given for a certificate or rating.
Our MEI cannot act as PIC of the customer's 421C because the MEI is missing a high altitude endorsement and a high performance endorsement even though he is category and class certified for airplane multi land.
A CFI does not need to be PIC, or even hold a medical, in cases where the student/customer is able to act as PIC.
Edit: it's a really bad idea to do fly an aircraft type with which you are not familiar.

The question is this:
Can our fresh MEI give the customer a valid flight review in the customer's 421C?

The flight instructor is limited to give training in the category and class ratings of their pilot and instructor certificates, not by make and model.

Per §61.193 and §61.195 the flight instructor is authorized to train and issue endorsements for a flight review so long she or he holds a pilot certificate and flight instructor certificate with the applicable category and class rating.

Furthermore, per §61.51(e)(3), the flight instructor may log pilot in command flight time for all flight time while serving as the authorized instructor in an operation if the instructor is rated to act as pilot in command of that aircraft.

The instructor is advised according to Advisory Circular: AC 61-98C,  Section 4-2 Paragraph e. Instructor Qualifications:

  Instructors should also consider their own experience and
  qualifications in a given make and model aircraft prior to giving a review in that model... ...To conduct a flight review in a multiengine
  airplane, the instructor must hold an airplane multiengine rating on their pilot and flight
  instructor certificates. For aircraft in which the CFI is not current or with which he or she is not
  familiar, he or she must obtain recent flight experience or sufficient knowledge of aircraft
  limitations, characteristics, and performance before conducting the review. In any case, the CFI
  must observe the rating limitations of § 61.195.

So, yes.  An appropriately rated flight instructor (whether or not they should) is authorized to conduct the flight review.

What's more, even if the instructor is not qualified to act as PIC (e.g. does not have a high-performance training endorsement), that instructor will still log pilot-in-command time as instructor because he or she is appropriately rated to do so.

In a flight review, the instructor is supposed to evaluate the pilot flying simulated IMC, which may also include unusual attitude recoveries.  The point is that the pilot being evaluated is under the "hood" and the CFI would need to be capable of acting as PIC.  This means a current medical as well as any aircraft requirements.

As near as I can determine the only loophole possibility is if the flight were conducted under IFR, in which case the CFI would not be needed as a crew member because of the flight rules.

So lack of medical (and the requirement to have one to act as PIC during hooded pilot operations), combined with high altitude endorsement, time in the C421, all work to make the administration of a flight review a no-go.

Tangentially, a safety pilot for IFR practice must also have a valid medical.


What turbine blade alloy did the Jendrassik Cs-1 use? Wikipedia says that the first turboprop aircraft engine was the Jendrassik Cs-1 invented in Hungary by György Jendrassik.

It says it was supposed to run at 1000 hp but "combustion problems" limited it to 400 hp.

I would like to know what turbine blade alloy it used. Could not find this info online. I have a feeling the blade alloy limits were what limited the engine power, since that is the main limiting factors on gas turbines in general.

Note: The Hungarian version of the wikipedia article says the turbine ran at 550 C, and...

  A turbinalapátokat 50% reakciófokú csavart, szárnyprofil keresztmetszetű hőálló acélból gyártották precíziós öntéssel, és speciális beerősítéssel szerelték a rotorba.

Google translate:

  The turbine blades are made of 50% reactive twisted, heat-resistant steel with wing section cross-sections, and are specially mounted in the rotor.

Don't know what that means. 50% steel? Then what is the other 50%? Also, there is no citation for it.

Jendrassik's own patent from 1939 does not go in-depth into the alloys. However, for the turbine blade legs he mentions "austenitic [stainless] steel" as preferable (see PDF page 3).

From that era, a Swiss patent from 1937 on the materials of gas turbine parts also discusses austenitic steel, in particular (translated from German):

  Alloy of an austenitic steel containing 25 to 35% of chromium, 25 to 35% of at least one of austenite-forming metal [e.g. nickel], 1 to 4% of titanium and 0.3 to 0.8 (preferably 0.4 to 0.6%) containing carbon, optionally up to 3% silicon and up to 10% molybdenum.

It is close to the composition of the 316 stainless steel (source), which has a mechanical maximum temperature of 590°C (source).

What is the time frame ? Vitalium ( cobalt + chromium + Mo ) was one of the first turbine blade materials. Otherwise 50 % iron is not unusual ; for example the Incoloy group. But most of the high temperature materials have nickel as the major element . And contain Cr, Mo, Co , W , etc , and 1 to 20% iron.  A temperature of 550 C / 1022 F is certainly not very hot in the turbine world so an alloy like  Incoloy 800 H  with 45 % iron plus 34 Ni, 21 Cr,1 Al, etc  is reasonable. The relatively low temperature suggests an older design : So actually "steels" are a possibility. Stainless 310 ( 25 Cr , 20 Ni , balance iron ) and the high carbon cast version HK . And even stainless 309 ( 25 Cr, 12 Ni , balance iron ) , cast as HH. These alloys are used in great quantity as petrochemical furnace tubes at temperatures to 1700 F +. I believe I examined failed 310 blades or vanes from a mid-eastern stationary gas turbine in about 1970.


Why haven't quadcopters been scaled up yet? Why are quadcopters not flown by human pilots yet?

Wouldn't they be more stable and easier to control than helicopters?

Wouldn't they be more stable and easier to control than helicopters?

No, they would not.

Quadcopters don't have any special inherent stability. When you increase power of one of the rotors to pitch, the increasing pitch will not do anything to the power difference and therefore the pitching moment.

The advantage of quadcopters is that the rotors can be fixed pitch while single (or double) rotor helicopter needs complex control mechanism. While this is huge advantage for the small scale devices where each rotor can be powered by its own simple electric motor, the complexity of either additional engines or long transmission shafts would outweigh any advantage from the simpler rotors in full-scale vehicle.

And why can't full-scale helicopters use electric motors like the small ones? The reason is that when you scale an airfoil up, the lift it produces increases with its area, which grows with the second power of size, but its weight increases with volume, which grows with the third power of size. Therefore models have much more lift for weight and can afford simple but relatively heavy batteries while full-size aircraft need propulsion systems with higher power density.

And then there is also the factor of safety. In case of power failure, helicopters can still glide to the ground and still land vertically using autorotation. But since the rotor rotating speed can't be changed without power, controlling the helicopter during such manoeuvre requires variable pitch rotor. So there goes the main advantage of quadcopters.

I think that both single rotor than quadcopters will cohesist, at least for some time. The reason for creating manned quadcopters are countless. A quadcopter could be driven like a car, while real helicopters need hundreds of flight hours for a pilot to master. this will lead to mainstream production and lower manufacturing prices to make them available to the mass.
about usefullness: a quad copter can have the blades ENCLOSED inside protecting structures, making their flight viable for cramped areas, where trees, buildings and poles would otherwise destroy normal helicopters. this makes a quadcopter much a better choice for rescue operations.
probably normal helicopters will stay a better choice for long range operations and speed.


Who has authority to close a runway/airport? In the recent runway excursion at LGA, visibility was bad, and an airport ops vehicle called the tower to inform them of the excursion and that runway 13 was closed, and then that the airport was closed.

The tower is in charge during normal operations. Who has the authority to close a runway/airport? Is this codified somewhere?

This also applies on a smaller scale, as I've heard of such things as chunks of taxiway pavement going missing.

Generally two groups have authority to close a runway (or airport) for an incident/emergency, and if either says it's closed, it's closed:

The airport owner/operator/management.
It's their facility, so if they say it's closed, it's closed.
Specifically it's the persons authorized to issue NOTAMs for the airport who can close a runway (by issuing the NOTAM saying it's closed), but the chain of command for making this decision may vary from airport to airport.
Runways may also be closed by airport administration without issuing a NOTAM (this happens frequently at Brookhaven airport (KHWV) - "Closed Runway" X's will be put out on the crosswind runway when the banner tow operators are set up for pick-up/release on that runway). Often there's a blanket NOTAM about "banner tow ops" or similar that sort-of covers this situation (basically "Expect strange things to be happening because the banner tow people are doing...whatever it is they do".)
The control tower (if one exists).
Whether or not they have the administrative authority to "close" a runway, they certainly have the practical authority to do so by denying anyone clearance to take off/land from it or to enter it, and by issuing NOTAMs indicating that a runway is closed/unusable for some reason.

At an airport like LaGuardia where you have both an FAA Control Tower and a robust airport operations/management group (The Port Authority of New York & New Jersey) a Memorandum of Understanding (MOU) or similar agreement is likely in place to ensure that everyone knows who is authorized to do what when, but in cases like this where an aircraft has a runway excursion the course of action is pretty obvious and nobody is going to want aircraft to be moving around on the ground until the situation is under control and safety can be assured.

This is kind of a gray area, but there is a procedure...

Theoretically, the way a runway is closed is that the airport or airfield operator notifies, in writing, the FAA thirty days ahead of time that a publicly-accessible runway will be closed. The FAA then issues a NOTAM about the closure and the airport puts big X's on the runway at either end. The runway is then closed.

In the event of accident, you obviously cannot "close" a runway this way. The best you can do is warn pilots off it. Since there is no way to "close" a runway on a short-term basis, what happens is that they "close" the entire airport, which is what happened at La Guardia. There is no NOTAM or forewarning during the initial response, so small aircraft can potentially still arrive and they have to be warned off.

Unfortunately, a lot of police and firemen do not understand this, so they try to "close" a runway just by ordering the tower to close it. Often, they do not even do this; they just rush onto the tarmac without even waiting to get permission or calling anyone. Obviously this creates incredibly dangerous situations. The tower (if there is one) reacts to this irregular action by notifying ATC and making constant do-not-land-here warnings on the common channel(s). If there is no tower, hopefully there are people on the ground with radios who do the same thing.

Just as an example of how dangerous this can become: once I was at an airfield with no tower and an aircraft landed short in the trees, getting hung up in some branches. A bunch of state police cars and fire engines literally drove down the runway to get to him like it was a road or something. The danger here is that many smaller aircraft or ultralights (etc) may not have (working) radios or may be on the wrong frequency so they have no idea what is happening. They could have just landed on one of the cop cars and blown up killing everybody. After it happened we called the police and told them how to drive on side of the airfield (not down the runway !!!) and provided them with emergency route maps, but at a certain level it is whistling in the dark, because most emergency personnel do not read these materials.


Why does XKCD say that autogyros will crash if the pilot reacts to a stall as in a normal airplane? This recent XKCD comic is all about autogyros.

Image is copyright XKCD, licensed under CC 2.5 BY-NC

The note at the bottom is what got my attention

  Extremely safe, unless you do the one thing you instinctively do to escape a stall in a normal airplane, in which case it will crash immediately

So what is that one thing, and why does it not work in autogyros?

That one thing is to unload the rotor too much (i.e. "push on the stick"):
From explainxkcd:

... Unfortunately, as soon as the rotor stops spinning, the whole aircraft falls like a brick and the rotor may be impossible to restart in flight. This is a situation that should be avoided at all costs.
Normally it is not a problem since the weight of the aircraft keeps the rotor spinning. However, if the weight becomes too low or even negative, the angle of attack will become negative, and the rotor will slow down and eventually stop. It can happen when the pilot "pushes on the stick" and dives.
Unfortunately, "pushing on the stick" is also how you escape a stall in a fixed wing (normal) airplane as it is a way to regain airspeed. This is actually a counter-intuitive maneuver but because a stall is an emergency, pilots are trained to do it instinctively. It can trick a pilot trained in fixed wing aircraft into doing the one thing that shouldn't be done on a gyro.

I believe what the comic is referencing is Mast Bumping. Rotor blades are very flexible, and for a bunch of reasons, are free to pivot around the mast.(The shaft the blades are spinning around) In normal flight, the blades are held taut by centrifugal forces and the weight of the rotor craft they are supporting. If a pilot were to suddenly push down on the Cyclic, you can create a low G, Zero G, or even a negative G situation. The blades are not having to support the weight of the aircraft anymore and the blades can potentially pivot so much as to strike the mast, tail, and even the fuselage.

So if an Autogyro pilot got into into a high angle of attack situation, and reacted by suddenly pushing the nose down into a zero G situation, the rotor blades would float weightlessly along with the aircraft. Its usually the next action that causes mast bumping. The pilot, out of his high AoA predicament, now pulls up to level off. The blades, still weightless, pivot without any resistance and strike the aircraft. This is rarely a survivable situation.


What is the use of saw-teeth present on the nacelle outlets of modern turbofans? I've noticed that there are saw-teeth on modern jet engines such as the GEnx and the Rolls Royce Trent 1000. What is their purpose?

These "saw-teeth" or "chevrons" or even "acoustic liners", are there to help reduce noise generated from the operation of the engine.

As hot air from the inner core of the engine mixes with the other, cooler air, it generates noise. These "saw-teeth" are there to help smooth that mixing, thereby generating less noise which is the result of turbulence. These are seen on the Boeing 747-8 (as seen in your picture) and the Boeing 787.

The reduction of sound generated means that less noise insulation is needed for use in the fuselage of the airplane. Less insulation means less weight. Less-weight equals less fuel burn, which means that chevrons are great for passengers, and economics.

There's only one difference from your picture. As much as we would like them to blow kisses to everyone, that's not what they are there for. :)

To quote from the Wikipedia article on the subject:

  In aerospace industry, chevrons are the sawtooth patterns on the
  trailing edges of some jet engine nozzles[1] that are used for noise
  reduction. Their principle of operation is that, as hot air from the
  engine core mixes with cooler air blowing through the engine fan, the
  shaped edges serve to smooth the mixing, which reduces noise-creating
  turbulence.[1] Chevrons were developed with the help of NASA.[1][2]
  Some notable examples of such engines include GEnx and Rolls-Royce
  Trent 1000.

Banke, Jim (2012-12-13). "NASA Helps Create a More Silent Night". NASA. Retrieved January 12, 2013.
Zaman, K.B.M.Q.; Bridges, J. E.; Huff, D. L. (17–21 December 2010). "Evolution from 'Tabs' to 'Chevron Technology’–a Review" (PDF-1.34 MB). Proceedings of the 13th Asian Congress of Fluid Mechanics 17–21 December 2010, Dhaka, Bangladesh (NASA Glenn Research Center. Cleveland, Ohio). Retrieved January 29, 2013.


What regulations or procedures address runway-taxiway interference for aircraft with large wingspan? Are there cases of airports where a large wingspan aircraft on a taxiway can interfere with another aircraft on the runway?

Or do the airport design parameters take care that the largest wingspan aircraft on a taxiway will still never infringe on a runway's safety zone?

How about taxiway-to-taxiway interference? Is that precluded by design itself for worst case combinations or can there be cases where two large wingspan aircraft on two taxiways may interfere?

If so, is it the pilot's duty primarily or the tower's  to ensure that interference does not occur due to conflicting wingspans of aircraft on different taxiways?

Are taxiways with potential for such interference separately indicated on the airport taxi charts?

Yes this can and has happened with what is considered a "super-jumbo" like the A380 or the 747-8 (Aircraft Design Group VI aircraft).

The FAA must issue waivers to airports to legally accept these types of aircraft due to spacing rules that are in place. A lot of larger airports built quite a few years ago didn't have the foresight to handle aircraft of this size, so special precautions have to be taken when handling those types of aircraft. For class VI aircraft, an airport must have taxiways that are 100' wide and runways that are 200' wide. Note though that an A380's wingspan is 262', so even on a 100' taxiway, the wings hang over 81' on either side.

Usually ground controllers get special training to handle the larger aircraft and maintain separation, but its even a problem for the ground crew before talking to ground control because there are quite a few notable incidents of aircraft being backed into other aircraft.

Here are some interesting reads:

Miami International A380 Preparations
Los Angeles LAX A380 Operational Plan

Well, runway-taxiway interference would not exist because the airports are designed with enough buffer space in between to keep the aircraft separated. The only place that that might occur is when at least two of those aircraft land at an airport that is not designed for them (Like that would happen anyways).

Taxiway-taxiway interference is very similar to the one above, and only very rare occasions would have that occurring.

Basic answer then: No, it would not occur. However, if need be, the airport does issue warnings and prohibitions on what airplanes can use a certain taxiway like on the top right corner on the diagram of KATL Airport


Did the XF-84H Thunderscreech really cause "900 sonic booms per minute"? The Republic XF-84H, known as the "Thunderscreech" was an experimental version of the F-84F Thunderstreak. It was intended to be a supersonic turboprop fighter.  Even at idle, the prop tips rotated at supersonic speeds and the plane is often claimed to be the loudest ever built, supposedly audible 25 miles away.

Most sources describe a continuous sonic boom due to the supersonic prop tips. However, a fairly common claim on the internet is that they caused "900 sonic booms per minute."

Is there any truth to the claim that the plane caused 900 sonic booms per minute?

One's first thought should be, "no": because the prop tips are continuously above the speed of sound, they emit a continuous sonic boom (as most sources claim), not 900 separate ones per minute.  However, since the prop tips were supersonic and the roots were not, it follows that a section of the prop's length would be in the transonic range. Any change to the wind or propeller RPM would cause more or less of the propeller to be moving supersonically.  I suppose that, say, an appropriate oscillation in the turbine engine could cause the continuous boom to be modulated by some 15Hz (900-per-minute) component.

I think it is a matter of where you stand (literally).

From the front or the rear the shock waves from the propeller tips would hit your ears continuously, and the result would be constant noise.

When standing laterally, the propeller tips would move towards and away from you and produce a variation of noise intensity of the frequency produced by the product of propeller RPM and blade count.

It seems that the design RPM of the XF-84H propeller was 3000, and since the propeller had three blades, the frequency should have been 9000 per minute, not 900. The airframe could be split ahead of the cockpit to allow the installation of several nose sections with their own gearbox and propeller. Several gearboxes and propellers were prepared with propeller design speeds between 2100 RPM and 3000 RPM, but the test program was ended prematurely, so most of the planned variations were never flown.

I can only judge from the little information available online and count myself lucky not to have witnessed a power-up of the XF-84H (for me personally, the loudest aircraft is still a Sukhoi 22M-4 – you think "man, this afterburner is loud!" and only then the pilot switches the afterburner on), and it seems that the 900 per minute figure must have lost a zero on its way of becoming an internet meme.

Note that I only speak of a variation of noise – as Jon Story writes, a sonic boom is what arrives at your ear, not what is produced by the propeller.

A sonic boom is technically the same concept as thunder... It's air that moves over the aircraft and crashes together behind it resulting in the sound. I do highly doubt the XF-84H make 900 sonic booms a minute. I have done extensive research on it and one of the big misconceptions is they were trying to make a supersonic propeller driven aircraft when that's not the case. This goes a little off topic but in fact early jets were not that great and they wanted jet performance out of props, which is doable to an extent. Jets take time to accumulate their power where a prop is instantaneous with the use of variable pitch props. The engine on the Thunderscreech was in fact ran at full throttle all the time and the prop was adjusted to generate the needed power which was instant compared to a jet. I'm linking this article so I don't go too much into a huge chat about this, it's my favorite plane of all time... But read this, it's the most informative article I've read and it's got people from the project actually talking about things I've mentioned. https://www.airspacemag.com/how-things-work/zwrrwwwbrzr-4846149/


Why on weather surface charts high pressure is blue and low pressure is red? Is there any relation with the temperature of the air or is it just a standard procedure?

Red/blue for pressure is in no relation to surface temperature. Storms develop where the pressure is very low. Red being associated with danger is a good color choice for low pressure.

  Storms are created when a center of low pressure develops with a system of high pressure surrounding it.

Low pressure is also associated with decreased aircraft performance, both lift and engine power. See below and find the strongest storm system.

(Source)

Blue for cold and red for hot is used for coloring the weather fronts:

(Source) 1. cold front 2. warm front 3. stationary front.

Wouldn't it be an appropriate analogy to equate low pressure with lower frequency light color (red) and high pressure with higher frequency light color (blue)?  Also, more energy in higher frequency wavelengths (blue) than lower (red)...


Regular procedure followed by the pilots before takeoff? What are the list of procedures (checks) followed by A320 and A380? Are these procedures decided by the airlines and (or) the manufacturer, or by the Civil Aviation Regulatory Authority of the respective country?

Try to search "Before Takeoff Checklist". Manufacturer will provide standard checklist but airlines can modify it.


Is there a maximum airspeed to deploy a ram air turbine? Is there any airspeed limit for deploying a ram air turbine? Can airspeed be determined from the rate of its propeller rotation? Could that data be used to determine altitude?

Is there a maximum airspeed to deploy a ram air turbine?

The ram air turbine (RAT) can be extended and used at any speed above a minimum speed, because under this minimum speed, power is difficult to generate.

Generated power may be decreased below 130 knots, and extension is prevented below 100 knots because of additional drag produced for nearly no power obtained.

The RAT can be extended automatically (loss of engines or pressure) and manually, e.g. logic for RAT extension on A330 (note the inhibition by airspeed below 100 kt and by on-the-ground sensor:

Source: Airbus A330 FCOM - Hydraulics

  Can airspeed be determined from the rate of its propeller rotation?

No, the RAT turns at constant speed to produce a constant AC frequency or hydraulic pressure or both. The rotational speed is stabilized by a governor which adjusts the angle of attack of the blades according to airspeed.

If the governor fails to maintain the speed, there is a security to prevent overspeed and blade damage/release.

Emergency Airplane RATs, Michael J. Zolidis, Hamilton Sundstrand, 2006.

A ram air turbine from Hamilton Sundstrand has a mechanical speed governor to vary the RAT blades angle according to the airspeed, and maintain a constant rotational speed.
At low speed, the blade angle is maintained near-perpendicular to the airflow to extract the most energy possible. When the ram speed increases, the angle is progressively reduced.
HS seems to measure the RAT power at 130 KEAS (Knots Equivalent Air Speed), e.g. the A380 RAT is 62” (1.57 m) diameter and delivers 85 HP (63 kW) at 130 KEAS. This mean at 130 KEAS or above, the full power is delivered.

Uncommanded Ram Air Turbine (RAT) extensions - Airbus

The RAT auto-deploys when both engines fail, or manually from a panel overhead. It's prevented to deploy on the ground, and below 100 KCAS
The speed value is provided by the ADIRU.
The RAT is able to be extended in all flight envelope conditions.

Embraer 190 - Airplane Operations Manual

There is no maximum altitude or speed for RAT deployment
Deployment occurs whenever AC buses are not powered or manually.
RAT deployment takes 8 seconds.
RAT has its full capacity at 130 KEAS or above.
Below 130 KEAS, only the AC bus is powered. DC buses are powered by the batteries, as well as the standby AC bus through a DC/AC converter.

ETOPS CAA

For ETOPS, three electrical power sources are required. If the RAT is one of them, it must be demonstrated as reliable (extension and generation).
The extension mustn't rely on engine power :-)

The most popularized RAT use may be for AC143 Gimli Glider, with a dual engine loss.

More:

RAT article on Wikipedia.
A320 RAT extension and retraction on Youtube.

Bombardier BD700-1A11 Global 5000 (source)
Airbus A320 Flight test (source)
Bombardier CRJ700 (source)
US Navy T-45A (source)
Airbus A330 (source)
Boeing B747-8 (picture by Gregor Schläger, source)
Boeing B777, RAT extension switch (source)

The rate of spin of RAT in the no-load condition is closely related to TAS, so by comparing this to IAS, you can calculate altitude, or at least density altitude.


Could an electric engine provide the same performance as jet engines on current aircraft? I have looked at various questions on this SE site regarding this topic but I have not really found a satisfactory answer. Some comments here regarding torque and power in electric motors vs gasoline engines were helpful. Additional info also found here.

Underlying my question is the assumption that battery technology will considerably advance from what is available commercially now. Simply assume that providing the electric motor with enough power is not an issue and that the weight of the battery is equal to fuel.

Is it possible to build an electric aircraft engine that would allow current commercial airplanes the same capabilities as jet engines available today do?

Not yet.

To look at a medium-range aircraft, let's base the engine on the CFM56 or the IAE V2500. Those engines produce between 100 and 150 kN static thrust. In cruise, their thrust is considerably lower due to the low density in cruise altitude and due to them moving at Mach 0.8. Let's use a value of 25 kN - this is enough so that two of them will comfortably push an A320 class airframe through the thin air at altitude.

The power to produce such an amount of thrust is force times speed. The speed when flying with Mach 0.8 in 35.000 ft is 240 m/s, so the power produced by one engine is 6.0 MW. Now let's look up how big and heavy an electric motor has to be to produce 6 MW continuously. As you can see from the linked Wikipedia page, the results are all over the place. Big, industrial motors come in at less than 1 kW/kg, so our motor would weigh more than 6 tons. The smaller motors for electric airplanes are pushing 10 kW/kg, the power-to-weight ratio of the GE90 turbofan, but will lose some of that when scaled up to size. Remember, even at 98% efficiency the motor will generate 120 kW of heat - this needs to be removed, and operating in thin air doesn't make this easy.

With current technology the motor could achieve maybe 2 to 3 kW/kg - this means the motor driving our hypothetical engine comes in at 2 to 3 tons. Add to this the fan and the fairing of the jet engine (we will not need the high-pressure part and all the turbines), but double the fan weight because we need to compensate for the missing high-energy core flow. This will maybe weigh 50% of the CFM56 / V2500, so we need to add another 1.2 tons.

The electric motor will be twice as heavy as the parts it replaces. There is still some work to do before it can gain an advantage over current jet engines, but it has some potential because it does not dump half of the energy supplied to it overboard in a hot, fast-moving, noisy gas stream.

EDIT:

Since so many people get excited about me omitting the energy density aspect of electric propulsion, even though the question did expressly desire to leave this out, here are two things to consider. Energy density is only half of the problem of electric storage.

The energy density of jet fuel is around 43 MJ/kg, while Lithium polymer batteries achieve not even one MJ/kg. But this comparison is linear thinking - realistically, the current will be produced either by a high-efficiency turbine-generator combination, or by fuel cells, burning hydrogen at twice the efficiency of a conventional jet engine. Since hydrogen packs 142 MJ per kilogram, at twice the efficiency the electric airliner would need only 162 kg of hydrogen for every ton of kerosene in a conventional jet. Yes, I know, even then its volume will still be a problem.
If any form of batteries is used, the fact that empty batteries weigh as much as full ones is the final nail in the coffin of battery-powered flight. While your average long-range jet lands at 60% of its take-off weight, the battery-powered jet would need to schlepp those heavy batteries all the way to the final destination. To be competitive, those hypothetical batteries would need to have twice the energy density of kerosene.

Battery and motor technologies aside, there is one major problem with the application of electric engines on commercial aircraft and that is recharge time. Commercial aircraft only make money when they're loaded with revenue paying passengers and in the air; when they're on the ground, it's extremely costly.   Conventional chemical fuels not only pack a great deal of energy density but are also extremely easy  to replenish the supply of. Refueling a passenger plane takes a matter of minutes - in some cases as long as a half hour for say an A-380 or a 747.   Batteries currently takes hours to recharge so this would have a huge implication on the delay a passenger or cargo flights.

Personally, I  don't see an electric powered commercial aircraft as a viable alternative to current jet engines. Probably the cleanest form of air travel would be current high-efficiency jet engines powered by a carbon neutral bio diesel fuel.


What is this old US Air Force plane? What model of plane is visible in this image?

Based on the unique 6x pusher-prop configuration, this looks like a derivative of the Convair B-36 Peacemaker. Looking up the Wikipedia article for the B-36 and scrolling down to the variants section, this seems like an XC-99 (or, more aptly, the XC-99):

Public domain image via United States Air Force - USAF photo via, Joaobsen, Wagner, Greer (1980), B-36 Peacemaker in action - Aircraft No. 42, Squadron/Signal Publications; 1st edition, ISBN-10: 0897471016

This was to be a passenger variant of the airframe, with a passenger capacity of up to 400 people. Beyond the prototype, it didn't enter service.

XC-99, o e was built and was on display for years at Kelly AFB, Texas and later moved to the Air Force Museum.


Can one become a CFI with a sport license? Under FAA can a sport pilot get a cfi endorsement for LSA category only? If so do they need a medical?

Same questions for glider pilots.

Yes.

FAR 61.403.

  To be eligible for a flight instructor certificate with a sport pilot rating you must:

    (a) Be at least 18 years old.

    (b) Be able to read, speak, write, and understand English. If you cannot read, speak, write, and understand English because of medical reasons, the FAA may place limits on your certificate as are necessary for the safe operation of light-sport aircraft.

    (c) Hold at least a sport pilot certificate with category and class ratings or privileges, as applicable, that are appropriate to the flight instructor privileges sought.

A CFI never needs a medical certificate.  It is not required for the operation of that certificate.

A medical certificate may be required if the CFI has additional roles.  For example, the CFI also is acting as the legal pilot in command.  A sport pilot acting as the legal pilot in command does not need a medical.

FAR 61.23(b)

  (b) Operations not requiring a medical certificate. A person is not required to hold a medical certificate—

    (1) When exercising the privileges of a student pilot certificate while seeking—

      (i) A sport pilot certificate with glider or balloon privileges; or

      (ii) A pilot certificate with a glider category rating or balloon class rating;

    (2) When exercising the privileges of a sport pilot certificate with privileges in a glider or balloon;

    (3) When exercising the privileges of a pilot certificate with a glider category rating or balloon class rating in a glider or a balloon, as appropriate;

    (4) When exercising the privileges of a flight instructor certificate with—

      (i) A sport pilot rating in a glider or balloon; or

      (ii) A glider category rating;

    (5) When exercising the privileges of a flight instructor certificate if the person is not acting as  pilot in command or serving as a required pilot flight crewmember;

    (6) When exercising the privileges of a ground instructor certificate;

To answer your questions.  A sport pilot or CFI will never need a medical because the operation does not require a medical but a valid driver's license.

A glider pilot or CFI never needs a medical or drivers license, if I am reading the regulation correctly.

A sport CFI does not require a CPL as does a regular CFI. The CPL requirement is found under part 61 subpart H

  Subpart H—Flight Instructors Other than Flight Instructors With a Sport Pilot Rating

    §61.183   Eligibility requirements.
    To be eligible for a flight instructor certificate or rating a person must:

      (c) Hold either a commercial pilot certificate or airline transport pilot certificate with:

But subpart H specifies Other than Flight Instructors With a Sport Pilot Rating. The rules for sport CFI are found in subpart K where no such requirement is found. (see 61.403 above)

It does not relieve the pilot or CFI from adhering to FAR §61.53 Prohibition on operations during medical deficiency though.

Interesting.  However you would not be able to do flight instruction with a sport pilot in training for monetary compensation.  That would require a commercial pilot certificate and a Class II or above medical.


Was the adoption of conventional tailplanes as 'everyday aircraft' inevitable, or are there other designs that can be just as good? I originally asked a variant of this on Worldbuilding.SE, but they didn't seem to like it. So I apologize if it's out of place even here.
I ask, because I've been forming in my head an alternate history or two that would logically involve a completely fresh start to aviation; no Wright Brothers, no Otto Lilienthal -- the entire world looks slightly different on a political map.
Because the world is different, it would be lazy of me to just import elements of our timeline without understanding why things developed the way they did. Our world, in general, appears to have rolled with canard planes and later adopted the tailplane for just about every conceivable function for fixed-wing aircraft.
That alone seems to imply that the tailplane is the superior choice to any other design, but is it really? Or was it just a case of technological and economic inertia?
Since 'superior' can be subject to opinion, I'll try to narrow down some criteria:

The design has comparable advantages in stability, lift production and maneuvering.
The design has comparable economic advantages; it doesn't necessarily require more time and resources to build and maintain.
The design does not (necessarily) incorporate concepts that require an advanced and well-developed understanding of fixed-wing aerodynamics. These would be among the early aircraft designs, or at least a short time into successful flight, so things like vortilons, fly-by-wire, etc. would not be present.

There are definitely plenty of wacky creations like Burt Rutan's Quickie, the V-173 and Miles M.39, but I'm sure there are good reasons none of them ever became popular...right?

If you write an optimizer which modifies the wing spans of a virtual aircraft, you will end up with a big wing in the middle and a smaller one at the tail if your goal was to achieve good performance, a wide cg range and docile behavior. So yes, a concurrent evolution would also result in a conventional layout.

Why no canard?

The forward wing is more highly loaded for stability. Adding control surfaces there would reduce the possible control effectiveness. Putting them at the large rear wing will result in higher stick forces and higher lift changes for the same pitch moment changes.
For the same reason, the wing cannot utilize its full lift potential because the canard has to stall first.
Since the wingspan of the canard is smaller than that of the wing, the wake of the canard will hit the wing and disturb the lift distribution over span there.
For directional stability a tail is still needed, even though it is only used for vertical surfaces. Alternatively, the canard wing can be swept and winglets be used for directional stability, but adding sweep will reduce the efficiency of the wing.

This all puts the canard at a distinct disadvantage. It works, but comes at a price.

Why no flying wing?

Flying wings have low pitch damping and a very limited center of gravity range.
They often cannot have trailing edge flaps for extra lift during slow flight, so their take-off and landing speeds are higher than those of a comparable tailed aircraft. Or the wing loading has to be made lower, which hurts at high speed.
Even though a good flying wing design has sweptback wings, they are poorly suited to high transonic speeds. Their wing airfoils cannot have rear loading, so the critical Mach number at the same lift coefficient is much lower than for conventional configurations.

That alone seems to imply that the tailplane is the superior choice to any other design, but is it really? Or was it just a case of technological and economic inertia?

A bit of both. And beside the technological features discused in other answers, one should not forget about history here. The tail plane/front engine has its disadvantages, but at the same time an incredible development advantage due WW2. Standard setup planes allow very agile configurations, something fighters depend on. And while many other configurations have been tried during the war, most attention was given to standard ones. As a result knowledge for their construction was widespread after the war and used for civil developments.

It's a bit like the question why the once leading electric car was put out of business by petrol cars - again, WW1  played the major role. While loading batteries isn't a hassle in a developed civil environment, it becomes almost impossible under war conditions - here petrol holds an incredible logistics advantage as moving a few barrels of petrol is easy done, in contrast with setting up power generators to load batteries.

It's not always the war, as economic scaling works as well - like why our modern computers almost all reassemble at the core simplified mini computer constructions - and huge efforts are now added to 'de-simplify' them again.


What climb rates can the Airbus A320-200 achieve and which climb rates are commonly used for normal flight operations? In relation to AirAsia flight QZ8501 officials have been quoted as saying:

  "It is not normal to climb like that. It's very rare for commercial planes, which normally climb just 1,000 to 2,000 feet per minute. It [climbing at 6,000 ft per minute] can only be done by a fighter jet."

Two parts of that statement struck me:

The rate of 1,000 to 2,000 feet per minute is stated as "normal", not "maximum"
The claim that only fighter jets can climb at 6,000 feet per minute.

My question is then:

What is the maximum climb rate that an AirBus A320-200 such as the one involved in this incident could achieve with out stalling? (Including configurations and operations outside of "normal")
If it is less than 6,000 feet per minute on the A320-200 can any commercial passenger carrying aircraft in operation today exceed 6,000 feet per minute? (I'd assume Concorde could, but that's no longer in operation)

There's a lot of nonsense being banded about regarding this flight.
First up, we are not talking about sustained, powered climb rates. If you're travelling at Mach 0.85 and pull up vertically, in theory (if your plane didn't break) you'd climb at an initial rate of nearly Mach 0.85 (your original speed minus the airspeed loss when pulling up).... That's near enough 57,000 feet/minute.
If you're at high speed and willing to trade speed for altitude, an Airbus A320 is physically capable of climbing at much higher rates than 6000 feet per minute.... At least until it runs out of airspeed.
A fighter is the only aircraft which would be likely to perform a sustained 6000ft/minute climb rate in normal use, but they're also capable of much higher rates of climb.
The maximum rate of climb you'd see in an A320 in normal use is in the 2000 ft/min range, but that's because it's the highest reasonably efficient rate of climb. That's not the maximum the aircraft is capable of under power (which is more in the region of 4000 ft/min), and is absolutely no indication of that maximum unsustained climb rate.
It would eventually stall at any unsustainable rate of climb, but then again, so would any aircraft even at a sustainable rate... Keep climbing and before too long you run out of atmosphere.
Either way, there is nothing to say that climbing above the sustained climb rate for an aircraft is unsafe or, necessarily, unusual. You trade airspeed for altitude, sure, but if you need to be higher at that moment in time, there's plenty of time to accelerate again later.
From Airlines.Net:

The three are roughly the same at 10,000', at about 2500 fpm. (Maybe a bit more for a light A319, and less for a full A321)
Normal climb rates from 10,000' to about 30,000 are as follows:
A319, 3000 fpm to about 1500 at 30,000'
A320, 2200 fpm to about 1000 at 30,000'
A321, 1400 fpm to about 500 at 30,000'

TL;DR - The official is spouting nonsense s/he doesn't understand. A fighter is the only aircraft likely to be able to (or wish to) climb at a 6000 ft/minute SUSTAINED climb rate, but almost any aircraft can climb at that rate for brief durations in a zoom climb - converting airspeed/momentum to altitude

Considering the Vne of an a320 is about mach 0.9, theoretically if you were travelling at Vne and were to pull back in to the vertical and still be pushing mach 0.75 by the time you reached the vertical, a climb rate of 50,000 feet per minute is momentarily possible.


Why do airplanes start descending when we initiate a left turn? Today I watched a video about the Fly-by-Wire (FBW) system (see below) and at 3:20 there is a left turn initiated in a Cessna 152. Then it is shown that with a left turn (only by ailerons), in aircraft with a mechanical flight control system, it will start a descend (and a slip).
I understand why the aircraft starts flying a slipping turn, but I don't understand why it start descending. Because gyroscopic effect would make the aircraft to pitch up in a left turn.
It is also said that each aircraft with mechanical flight control system, either little Cessna or Boeing 737, will have that tendency. Can somebody explain that descending tendency?
My guess is that the turn is initiated without power increase, so to stay with the same indicated airspeed the aircraft must be pitched down, but I'm not sure of that.

This is because when you roll left (or right), the lift changes from pushing up to pushing up + left. This is what makes you turn. Since some of that lift is being used to the left, not as much is pushing up, causing the plane to lose a bit of altitude. On FlyByWire aircraft, since it is computer controlled, the computer automatically compensates for this by adjusting elevators to pitch up slightly.

Most conventional aircraft are designed so that their Center of Gravity (COG) is forward of their Center of Lift (COL). When an aircraft banks for a turn, weight and centrifugal force combine to increase the Load acting through the COG. In order for the Aircraft not to lose altitude, the vertical component of Lift must continue to be equal to weight. The horizontal component of Lift must be more than the centrifugal force in order to affect a turn. The combined load on the aircraft in a 60° bank coordinated turn can be twice the normal weight of the aircraft.
In straight, level and unaccelerated flight, the aircraft acts similar to a lever with the COL acting as a fulcrum. The moment of the COG toward the front is counterbalanced by a downward force on the tail created by the negative lift of the horizontal stabilizer. This negative lift is created by the airspeed of the relative wind against, and the angle of attack of the horizontal stabilizer.
In a normal banking turn without an increase in power, airspeed remains constant or slightly decreases with an increase in induced drag. When the force of the COG and the force of the COL increase with no corresponding increase of the force on the horizontal stabilizer, the airplane will pitch nose down around the COL.


Why are magnetized materials dangerous goods? I was reading about Dangerous Goods, and came across the fact that magnetized materials are classified as Dangerous Goods (item 12 in the linked page). We all see magnets every day, and they seem harmless.

Why are magnets dangerous to airplanes and require more careful handling?

98% percent of magnets - the everyday ones - are completely harmless. I believe the concern is with super-strong rare-earth magnets, where they can be problematic. Aside from Simon's valid point on interference to compasses:

Getting stuck to things, such as other bags or the infrastructure itself, in the baggage system.
Attract themselves to other packages and content, possibly damaging these. Think of hard drives and electronics.
Being a nuisance and safety concern should somebody decide to open it, such as customs or security. You can get your hand crushed in the process if you open the box and the thing springs out.

Be aware they do not appear to be banned - just regulated in that they have to be properly labelled and packaged for safe transport. More curiously in that list are 'First Aid Kits' and 'Seatbelt Pretensioners'.

Airplanes have many sensors which are sensitive to electrical noise. And moving magnets can cause an electrical flow, hence electrical noise. As you can not estimate who is carrying how strong magnets it is safer to forbid them in life-critical environments like airplanes.

And about compass, it is only needed for an initial heading estimate, and it replaces GPS heading after moving a few meters in aircraft. So the compass is not a big deal as long as GPS is available.


What happens when a pilot has no Instrument Rating and visibility drops? Note: I'm not a pilot, so I don't have much basic knowledge of how the pilot licence ratings work

If a pilot doesn't have an Instrument Rating, and the weather conditions drop below VMC; what do they do?

Presumably you can't instantly land, but nor can you safely continue to fly without sufficient visibility?

I know the basic licence includes some instrument training, but is this enough to fly and land without visibility? I was under the impression that was the entire point of gaining an Instrument Rating... To train the pilot to fly on instruments alone

It is very rare for weather to go IMC unexpectedly.

A responsible pilot should see that weather is deteriorating, and begin planning for the nearest available landing.   If they cannot find a landing, they should contact ATC while still in VMC, declare an emergency, and begin working with ATC to get down safely.

In some cases, a pilot may inadvertently enter IMC unexpectedly.   The standard procedure is to execute a standard rate 180° turn, and fly equal time in the opposite direction.  That should get them back to VMC conditions.

If that doesn't work, unfortunately inadvertent flight into IMC is a leading cause of GA accidents, especially CFIT (Controlled Flight into Terrain - i.e. 'aircraft flew into the ground').   Because of that, even basic private pilot training includes more basic instructions on instrument flying (BAI) than it used to.

A pilot must have a very good kinesthetic sense : his or her position in the air, in the space. When you have that natural quality; training helps but it is natural, it is much easier to have the same feeling for you plane. Early pilots did not have any kind of instrument and they crossed very long distances. Bleriot, the French pilot, went over he Channel in the 1920s. Some veteran pilots are more competent than now a days when some feel over confident in their electronic system. The pleasure of piloting is feeling safe and confident in its own abilities. Piloting is a vocation; you have to have natural predispositions for it. When you have them, you like the job. You are less stress. Kinesthesie is the senses of a human being measuring motion in space, so in the air too.


How hard would it be to convert a glider into an powered electric aircraft? How hard would it be to convert a glider into an powered electric aircraft?
I'm thinking something that looks like this:

Would it be as simple as mounting two electric motors and props to the wings and plugging it into power the electronics and a battery system?
Any thoughts?

"Hard" is a matter of opinion. But installing an electric motor on a glider is quite doable. You don't want to put motors on the outside, though. Would make more sense to do what most manufacturers do, put the motor on a retractable pylon behind the cockpit, with doors that open and close as needed.

Unless you can put the complete propulsion system in the back seat of a two-seat glider, you will have to redesign the whole aircraft to take account of the changed mass distribution.

But if "replacing almost everything" counts as "conversion" then … yes, you could do it.


Safety regulations for take off spectators around airports? In a Greek island, an A320 blasted a child ten meters away, during take off. It was with his family outside the airport (Greek src).

I wonder what are the regulations, if any, for how much people are allowed to approach the airport (I intended to say runway, but some people might not be able to identify it).

I don't expect from a common person to be aware of the dangers that occur at these situations. The airport should protect them, that's why I ask, if there are any regulations that define the min. allowed distance of people outside the airport?

If yes, it would make sense for the airport to have it's fence at that distant, not any closer.

Most airports are intentionally built away from other areas because of practical problems like noise and potential structures getting in the way. There's also the rather significant requirements to build a runway itself (long, relatively flat and level). But there doesn't seem to be any hard minimum safety distances. It seems to be left up to the airport itself to determine safe distances.

One of the best examples I can think of (with limited clearance around the airport) is Princess Juliana International Airport in St. Maarten. The runway approach passes directly over Maho Beach, a road, and then you have a 7000ft runway (the largest flat spot the island can muster). In the picture below, the fence marks the end of the airport.

It produces some spectacular videos of planes passing less than 100ft over the beach and people watching on the beach are impacted by the blast of jets, who must stop at the end and bring their engines up to speed before starting their roll.

The incident mentioned happened at Skiathos Airport, which is also an island airport with limited land for a runway (shorter than St. Maarten at 5300ft).

So it seems to be that if you have a long, flat, and relatively level spot to build a runway, there's nothing to prevent you from building an airport there.

From the article:

A serious accident occurred at noon in Skiathos, as a 12-year-old child was injured by the airborne aircraft taking off.
The child, together with their parents, watched from a short distance the take-off of a TUI Airbus 320 to London.
However, the power of the gases from the engines of the airplane expelled the 12-year-old at a distance of more than 10 meters.
The unfortunate child was initially transferred to the health center of Skiathos and then to the Achilopouleio hospital of Volos.
According to the doctors, the 12-year-old is at no risk.

It does seem like there ought to be at least a sign near the end(s) of the runway.  There are plenty of videos of the airport at St Martin where folks get sandblasted by the blast of engines of the airliners.  I believe they have a warning sign. Even a lowly Cessna/Piper/etc with 180HP engine can kick up quite a wind.
There are no regulations on the distance from the end of runway/runoff areas to nearby roadways.


Why isn´t TOGA thrust always 100% N1 or N2? It makes sense to me, that under normal circumstances the engines shouldn´t be pushed to their maximum, to reduce wear and tear. But why isn´t TOGA thrust, which is the maximum selectable thrust setting, not corresponding to the maximum possible thrust, thereby 100% N1 or N2 whichever is the limiting factor.(In the picture TOGA is limited to 88.9% N1)

TOGA thrust is not always 100% N1 (or N2), because TOGA thrust is actually not about delivering the absolute maximum thrust that can be provided. Rather, it's about delivering a guaranteed large amount of thrust, to ensure the performance of the aircraft is what the pilot expects, and what the flight manual states will occur. The level of thrust needs to be predictable. So it's got to be the same with a new aircraft, as one 5 years old (for example), and the engines are about to be overhauled.

To achieve this, engines are "flat rated". See What is a Flat Rated Engine?

To repeat that answer a bit, a flat rated engine, produces a constant, or the same amount of thrust, up to a certain ambient temperature. This is achieved by having a margin (gap) between the maximum thrust the engine provides, and what it can really produce. This also results in a temperature margin between the engines actual turbine temperature, and the red line temperature. This means as the engine degrades, it can increase its operating temperature without hitting the red line (until it has degraded a lot), and so still provide the same level of thrust.

When a gas turbine's engine control is designed to produce the same thrust at different ambient temperatures, it means N1 speed will be higher on a hot day, than a cold day. See how in the figure, for a constant thrust, N1 is increasing as ambient temperature goes up? N1 has to go up as ambient temperature increases, because hotter air at the intake is less dense than colder air, so the engine needs to run at a faster RPM to make up for the lower density.

Many pilots confuse 100% N1 as max thrust or 100% thrust.Although N1 always corresponds to a certain valve of thrust, In gas turbines 100% N1 means that the turbine is operating at or close to 100% efficiency.

5


How does the dihedral angle work? I've been looking for this topic on the internet but I don't have enough concrete answers. Suppose we have a plane with dihedral and it has a suddenly swinging to the right (watching from the nose of the plane), so the right wing goes down. I'm trying to understand why the right wing generates more lift than the left wing when it has a sideslip. I have seen in some sites that the sideslip induces a flow from the tip to the root and this makes the right wing increase locally the angle of attack, hence the lift of this wing increases too.

But, why the right wing increases the angle of attack? I think it couldn't be possible because the sideslip flow is in a different plane respect the mainstream.

Basically, dihedral effect is that during banking, the 'lower' wing will experience a higher angle of attack compared to the 'higher' wing, and a result, a greater lift. The resulting net force and moment reduces the banking angle, reducing stability.
Consider a wing with a dihedral angle $\Gamma$ with a forward airspeed of $u$. If the sideslip angle is $\beta$, the wind due to sideslip is $u \cdot \sin\beta$. From geometry, the normal velocity induced due to dihedral, $v_{n}$ becomes $u \cdot \sin\beta \cdot \sin\Gamma$.

Image from Stability and Control of Aerospace Vehicles
Note: The notations are different in the figure; but the principle is the same.
For our purposes, we can take the sideslip velocity ($u \cdot \sin\beta$) as $v_{y}$. Now, consider two sections from the wing - one each from the 'lower' and 'higher' sides. The induced velocity is of the same magnitude in both the sides, while the direction differs, as can be seen from the above figure.

Image from people.rit.edu

Image from Stability and Control of Aerospace Vehicles
For small angles, $v_{y}$ is nearly equal to $u \beta$. The induced angle can be given as,
$\Delta \alpha = \frac{v_{n}}{u}$.
From the earlier relations, we have,
$\Delta \alpha_{1} = \beta \cdot \sin\Gamma$, and $\Delta \alpha_{2} = -\beta \cdot \sin\Gamma$.
Because of these induced angles, the lift on the downgoing wing increases by $\Delta L$, while of the other one decreases by $\Delta L$. The net result is that the 'lower' wing experiences an increases lift, causing a rolling moment, which causes the banking angle to reduce.

Image from Stability and Control of Aerospace Vehicles

This is a very exaggerated diagram of a fuselage with dihedral wings.

When the plane is flying normally (top), both wings produce the same lift vectors.

When the airplane is disturbed in the roll axis, and one wing goes higher than the other (bottom), the vertical lift vectors are different, with the "down" wing producing more vertical lift than the "up" wing. This increased vertical lift on the down wing and decreased vertical lift on the up wing, pushes the down wing up, and helps right the airplane.

Note: everything in this diagram is schematic and is not meant to indicate any specific mathematical or physics laws or formulas.


I want to be an airline pilot. Would becoming a NON-COMBAT Air Force pilot be a good way to become one? I know that becoming a fighter pilot is highly competitive, making it a difficult route, but would becoming a pilot for an Air Force cargo aircraft or something of the like be a good way to reach my final goal of piloting for an airline?

It depends on which part of the world you're in.

Airlines based in a country with a healthy General Aviation scene will probably prefer civil pilots. If there General Aviation scene is limited then it would make military pilots an attractive source.

I'm not saying that Military pilots are any worse/better but there have been airlines where the safety record was quite poor as a result of poor CRM from the military pilots, China Airlines and Korean Air are examples. These airlines have recognised and rectified the problems and today are up to industry levels in terms of accidents/incidents.


What precautions are taken to avoid bird strikes? According to this Wikipedia page on bird strike,

  The International Civil Aviation Organization (ICAO) reported 65,139
  bird strikes for 2011-14, and the Federal Aviation Authority counted
  177,269 wildlife strike reports on civil aircraft between 1990 and
  2015, growing 38% in 7 years from 2009 to 2015. Birds accounted for
  97%.

What precautions are taken so that birds are not killed by aircraft?
Is the pilot held responsible or does the pilot pay some penalty in case innocent animals are killed?
Are there any planes which have been designed specifically focusing on bird safety (or have there been any efforts in designing planes focused on bird safety)?
Where can I get reports on the number of bird strikes per year on an international level?

Note: This question does not concern the damages the airline suffers from bird strikes.

Update In Addition To Other Answers

Why jet engines are NEVER protected in the front?!

Humans are more important than animals by "most" societal standards. Therefore, bird safety is secondary to human safety (pilots and passengers). However, there are certain areas (in US) that are designated as protected areas for certain types of birds, such as in California where I have seen protected areas for the California Condor which requires pilots to fly at a certain altitude above that area. On VFR Sectional Charts the special conservation areas are depicted as indicated here:

These conservation area restrictions are mostly to avoid disturbing the birds, but I assume it also reduces the risk of a bird strike by requiring the aircraft to fly higher over these areas.

One of the most important precautions is for pilots to remain vigilant and see and avoid, but that is not always possible when a flock of thousands of birds takes off near an airport when airplanes are landing and taking off.

Some airports use various methods (see links provided) to scare flocks of birds away such as using hawks, noise, and other methods.

I don't know of any aircraft that are designed for the safety of birds. I believe this is a very low priority in aircraft design.

Try checking the Audubon Society website, they have a lot of information on risk to birds and statistics on such risks.

How Airports keep birds away?
Most airports combine a lot of methods
to keep birds away, such as Standing Lasers, Pyrotechnics, Propane
Cannons, Visual Effects, Natural Predators (i.e. Falconry), Traps and
even adjusting the height of the grass at the airfield.
How does pyrotechnics work at airports to keep birds away?
The key of using pyrotechnics is combining sounds and visual effects to create a
stimulus that attracts birds primary instincts. This can be done with
a variety of pyrotechnics of varying range, colours, and blasts that
can make birds fell that the place is not safe to stay. However, the
correct training of bird controllers is also essential. A true
specialist knows there is not a “silver bullet” in airport bird
control. A complete toolbox and well-trained professionals are needed
for a successful Wildlife Control Program.
What is a birdstrike?
It is a collision between a bird and an aircraft
which is in flight or on a takeoff or landing roll. The term is often
expanded to cover other wildlife strikes.

from: https://airportbirdcontrol.com/airport-bird-control-6-most-asked-questions-and-answers/