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Debris, Bodies Recovered From AirAsia Flight 8501 132

Searchers have found traces of the crashed AirAsia Flight 8501, which lost contact with ground controllers shortly after requesting a weather-related course change. Reuters reports that both debris and some passenger remains have been recovered off the coast of Borneo, in a search complicated by waves "up to three meters high." From the report: About 30 ships and 21 aircraft from Indonesia, Australia, Malaysia, Singapore, South Korea and the United States have been involved in the search. The plane, which did not issue a distress signal, disappeared after its pilot failed to get permission to fly higher to avoid bad weather because of heavy air traffic, officials said. It was travelling at 32,000 feet (9,753 metres) and had asked to fly at 38,000 feet, officials said earlier. Pilots and aviation experts said thunderstorms, and requests to gain altitude to avoid them, were not unusual in that area. ... Online discussion among pilots has centred on unconfirmed secondary radar data from Malaysia that suggested the aircraft was climbing at a speed of 353 knots, about 100 knots too slow, and that it might have stalled.
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Debris, Bodies Recovered From AirAsia Flight 8501

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  • I'm not anything close to an expert, but wouldn't a stall be easily recoverable at 32,000+ feet? If a plane fell from this altitude without any radio contact I would think it would be some kind of catastrophic structural or mechanical failure.
    • I'm not anything close to an expert, but wouldn't a stall be easily recoverable at 32,000+ feet?

      Depends what caused the stall. If the engines ingested a tremendous amount of hail and water and flamed out then the crew may not have been able to start them again. They could still have gotten out of the stall into a glide, but with no power there would have been nowhere to go...

      • Yeah, but they would have a controlled descent in this scenario and would have radioed for help, wouldn't they?
      • Re:Stall? (Score:4, Informative)

        by sycodon ( 149926 ) on Tuesday December 30, 2014 @12:19PM (#48696983)

        Modern Engines are designed to ingest tremendous amounts of water and still run.

        A Qantas airliner suffered a catastrophic engine failure ad returned to the airport. After landing, the engine was still running and spewing fuel everywhere. They poured foam and water directly into the engine for 30 minutes before it finally quit running.

        You can watch a documentary on it here. [youtube.com]

      • by Anonymous Coward

        At 38,000 feet the difference between overspeed and underspeed (stall) can be as little as 10-12 knots. Many airplanes behave similarly in both conditions however recovery procedures are very different. There have been a number of accidents due to pilots not being able to tell the difference. For more information see: https://en.wikipedia.org/wiki/Coffin_corner_%28aerodynamics%29

    • Re:Stall? (Score:5, Interesting)

      by tlhIngan ( 30335 ) <<ten.frow> <ta> <todhsals>> on Tuesday December 30, 2014 @12:24PM (#48697029)

      I'm not anything close to an expert, but wouldn't a stall be easily recoverable at 32,000+ feet? If a plane fell from this altitude without any radio contact I would think it would be some kind of catastrophic structural or mechanical failure.

      Or a cumulonimbus (CB) cloud. Pilots are generally advised to stay 20 miles AWAY from storm clouds because of intense up and down drafts.

      It's likely the pilot was trying to do that when denied by ATC - and towering CB can go up to the stratosphere (literally - it's why they get their anvil shape).

      No plane can outfly the up or downdrafts which can be several thousand feet per minute. Fly into it and 32,000 feet can be gone in just a few minutes. Never mind wind shear which can basically rob an airplane of all airspeed.

      Embedded CBs are even scarier.

      • It should be noted that the Pilot is responsible for the safety of everyone on board and has the very last word on it.

        Assuming that the pilot was trying to avoid a dangerous thunderstorm that he had reason to believe would imperil the aircraft and passengers, he could have and should have changed course and/or altitude and tell ATC to fuck off, but keep them apprised at the same time so they can move others out of the way.

        • by jrumney ( 197329 )
          So had sycodon been pilot, we would have been picking up the remains of two plane loads of passengers right now, due to a mid-air collision between his plane and the one that was flying an intersecting course at 34000 feet at the time air traffic control denied permission to climb from 32000 to 38000 feet.
          • by sycodon ( 149926 )

            Declare the Emergency, advise ATC of your intentions, and they move everyone out of the way. That's the way it works.

    • by ai4px ( 1244212 )
      Air France Flight 447 stalled at 38,000 feet with an attitude between 35 and 45. If they'd known that their airspeed as below stall, they could have simply dipped the nose and gained airspeed. But the pilots seemed confused the whole way to the sea. Same may have happened here.
    • by jbwolfe ( 241413 )
      Stalls in swept wing aircraft at high altitude are difficult to recover from. It takes time and patience to avoid secondary stalls, and usually a significant loss of altitude. AF447 was flyable all the way to impact but improper recovery technique complicated by confusing systems failures were big links in the chain of events.

      I have no doubt the FDR's will be found and I think the similarities between these two events is significant.

    • I'm not anything close to an expert, but wouldn't a stall be easily recoverable at 32,000+ feet? If a plane fell from this altitude without any radio contact I would think it would be some kind of catastrophic structural or mechanical failure.

      Base on the reports of the weather I've been reading, it was about as bad as it gets for turbulence. They suspect the craft got hit by multiple lightening strikes as well. I've been on a plane when lightening has struck it before and while not immediately dangerous it's like being inside a flashbulb going off. It's terrifying. I couldn't imagine it happening multiple times while getting thrown around by turbulence.

      Imagine being on a roller-coaster, inside a paint shaker while someone repeated shown

  • by spacefight ( 577141 ) on Tuesday December 30, 2014 @12:17PM (#48696973)
    Lufthansa went through a 4000fpm rate of descent incident a couple of weeks ago. The loss of altitude had been caused by two angle of attack sensors having frozen in their positions during climb at an angle, that caused the fly by wire protection to assume, the aircraft entered a stall while it climbed through FL310.

    http://www.aeroinside.com/item... [aeroinside.com]
    • Yes, there is an Airworthiness Directive [caa.co.uk] (caution:pdf) about that little issue. For some some reason, Airbus won't give the pilots an angle of attack indicator either. It is one of the most basic and important things to know when flying a fixed wing aircraft.

    • There was a very similar crash involving frozen/jammed angle-of-attack (AOA) sensors with another A320 back in 2008, XL Airways flight 888T:
      https://en.wikipedia.org/wiki/... [wikipedia.org]

      In this case it was caused by aircraft maintenance personnel not covering up the sensors properly when repainting the livery, causing paint-related or cleaning chemicals to fill the gaps inside the AOA sensor housing and later freeze in-place once the aircraft was airborne - which caused confusion among the pilots when the aircraft's fli

  • What I find somewhat puzzling is how this happened in daylight. In AF447 and others where pilots lost control or were confused by conflicting instrument readings, it was during night or poor visibility and they lost reference to the horizon. This was at 7am Singapore time, and although there were storm clouds, I would have thought that at least for some portion of the incident, the horizon would have been visible?

    This of course assumes that the problem was a loss of attitude control due to instrumen
    • Day or night is irrelevant if the aircraft was in IMC (Instrument Maneuvering Conditions) - exterior view is useless for attitude control when you're in the soup.
    • by bledri ( 1283728 )

      What I find somewhat puzzling is how this happened in daylight. In AF447 and others where pilots lost control or were confused by conflicting instrument readings, it was during night or poor visibility and they lost reference to the horizon. This was at 7am Singapore time, and although there were storm clouds, I would have thought that at least for some portion of the incident, the horizon would have been visible? This of course assumes that the problem was a loss of attitude control due to instruments.

      They were likely in clouds (remember they were trying to avoid a thunderstorm.) They probably had extremely poor visibility.

  • by 140Mandak262Jamuna ( 970587 ) on Tuesday December 30, 2014 @01:03PM (#48697455) Journal
    West Caribbean was flying an older plane, MD-80 I think. The pilot had turned on de-icers which bleed hot compressed air from the engine. That resulted in engine having less power/thrust. The plane was nearly at its service ceiling at that time. Turning on the de-icers reduced the service ceiling to FL310 and the plane was at FL330 or so. Plane was flying through severe storm, vertical gusts stalled the plane. The plane went into a stall, the co-pilot correctly diagnosed it and reported it to the captain. But captain tried to climb to FL350, way above the service ceiling with de-icers. Plane stalled and fell to the ground.

    This Air Asia plane was asking permission to climb to FL380 from FL310 in a storm. But as others have noted, Air Bus has issues with pitot tubes icing over and the flight control computers getting confused.

    • I belive you are thinking of flight 708 [wikipedia.org] which crashed in Aug 05. The captain was very fatigued since the crew had not received regular paychecks in several months, and the captain had reportedly been forced to moonlight as a bartender to provide income for his family.
    • by fnj ( 64210 )

      Any pilot who can't recover from a stall in 10,000 vertical metres is not even worthy of the job description. It is incomprehensible. Even in zero visibility in a piece of video game garbage like an Airbus, he's got an altimeter, right?

  • "radar data from Malaysia that suggested the aircraft was climbing at a speed of 353 knots, about 100 knots too slow, and that it might have stalled. "
    I thought climbing too quickly stalls an engine. Why would climbing slowly in denser air that can run the engines better cause it to stall? Any pilots know what they're talking about? (or do they mean it was going too slow while climbing as opposed to climbing at too low of a rate).
    • I think that 353 knots refers to forward airspeed... meaning that more airspeed is required to climb without stalling... such speed might be appropriate for lower altitude, like a landing profile, but not for climbing while at altitude. I'm not a pilot though, this is just my understanding.

      • by Anonymous Coward

        Yes. A rate of climb at 353 kts (vertical speed) would mean reaching 30000 ft in about 50 seconds. Rate of climb is typically given in feet/minute (typical values up to +/- 5000 ft/min).
        The thrust / power generated by the engines is used to overcome drag, accelerate, and climb. Normally, at higher speeds more power is needed to overcome drag, leaving less power to climb. Except when reducing speed so much that the lift generated no longer is sufficient, and the engine output is creating the remaining lift (

    • Re:what? (Score:5, Informative)

      by danheskett ( 178529 ) <danheskettNO@SPAMgmail.com> on Tuesday December 30, 2014 @03:11PM (#48698727)

      The engines will never stall given fuel and clear path. Any angle, underwater practically, throw a frozen goose through it. The stall being talked about is an aerodynamic stall, where the flow of air over control surfaces generates insufficent lift, and the plane ceases to be a plane and becomes an object falling the sky.

      Recovering from a high-altitude stall takes some skill. Depending on factors, you may need to scare the living s*#! out of your passengers, put your nose down to regain enough speed, and then gradually level off.

      Apparently there were really nasty weather problems at the time of the incident. Some serious weather clouds can have drafts that can almost instantly stall a plane, removing all of it's airspeed. Going from 350+ kts to single digits knots all of a sudden can be very dangerous, as you would imagine.

      • there is compressor stall. [wikipedia.org] and the FAA does have air worthyness directives to cover specifically A320/321 aircraft regarding problems with compressor stall. Until they recover the flight data and cockpit voice recorders all of the information being put out there is speculative.

      • by Anonymous Coward

        "throw a frozen goose through it."

        That will result in a sudden loss or significant reduction of power. The engine will not keep trucking.
        The frozen goose test is about ensuring that the engine does not suffer an un-contained engine failure. That is, no shrapnel leaves the engine pod, where it can further damage the aircraft. I'm unaware of any modern turbo-fan engine that can survive a frozen goose and keep on trucking. (Severe hail can do the same thing). This is why (still) so many aircraft incidents

    • by ceoyoyo ( 59147 )

      Engines don't stall, wings do. If your wings aren't passing through the air fast enough or are at too high an angle of attack (or both) the airflow over them becomes turbulent and the amount of lift the wing generates drops abruptly.

      In aircraft with straight wings that can result in you being screwed. Aircraft with swept wings are generally designed so that the inside, further forward part of the wing stalls first. That means that a stall drops the nose, lowering the angle of attack and increasing airspe

      • Engines can stall, especially turbines, compressors etc. The mechanism for stalling a turbine is the same as stalling a wing, flow and pressure imbalances prevents the blades from pushing air. They have been known to stall in the past but it's painfully obvious when they do, they make a really loud bang repeatedly several times a second and start shaking the wing.

    • by ceoyoyo ( 59147 )

      PS: a speed in knots indicates airspeed, not climb rate. Climb rates are in feet per minute or, rarely, m/s.

  • It's probably not the (only) reason for the crash, but I don't understand why they want to climb in this situation. The Air France flight did the same IIRC.
    They can't hope to outclimb a CB and at FL390, the difference between stall speed and VNE gets pretty damn small.
    Maybe it was too late to do anything else, but then they really need to improve their weather forecast in the area.

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