AirAsia Flight QZ8501 climbed fast then stalled: Indonesia

[IDemo]

Source: Times of India

JAKARTA: An AirAsia plane that crashed into the Java Sea last month with 162 people on board climbed at a faster than normal speed and then stalled, the Indonesian transport minister said on Tuesday.

Flight QZ8501 went down on December 28 in stormy weather, during what was supposed to be a short trip from the Indonesian city of Surabaya to Singapore.

Indonesia's meteorological agency has said bad weather may have caused the crash, and investigators are analysing the data from the jet's black boxes before releasing a preliminary report.

Just moments before the plane disappeared off the radar, the pilot had asked to climb to avoid the storm. He was not immediately granted permission due to heavy air traffic.


Read more: http://timesofindia.indiatimes.com/world/rest-of-world/AirAsia-Flight-QZ8501-climbed-fast-then-stalled-Indonesia/articleshow/45956301.cms

[Blue_Tires]

1. The "coffin corner" strikes again?

[AtheistCrusader]

3. Like Tu-154 (Flight 05/09/06)?

Certainly can be.

Worse with the Flight Laws enforced by the airbus computers, and the additional possibility of lying instruments/sensors.

[AngryAmish]

4. Please explain....is that when a plane climbs too fast and stalls due to lack of airspeed?

I am not a pilot.

[Plucketeer]

5. It's not that simple

Believe it or not, a plane can "stall" (a stall being an incident when the plane's flying surfaces cease to perform as designed) with more than sufficient speed and/or power at hand. OVER-controlling - whether intentional or inadvertent - can push a plane beyond it's "flight envelope. The consequence can be physical breakage before corrective measures can be instituted.

[AtheistCrusader]

7. And that flight envelope gets narrower and narrower the higher you are.

[groundloop]

9. Actually a stall occurs when a flying surface exceeds a critical angle of attack

A stall can occur at any airspeed, all you have to do is increase the angle of attack. That's how aerobatic pilots do snap rolls, for instance - while flying at speed you yank back on the stick and stomp on the rudder.

In more normal, mundane circumstances, yes, if you fly too slow the plane will stall - but only because you have to keep increasing the angle of attack to provide enough lift to stay in the air and at some point you'll reach the critical angle of attack.

Now, as for this accident investigation - there are a number of causes that could fit in with these facts. One strong possibility is that the plane got caught up in a strong thunderstorm which certainly could have produced all of the effects seen. However, it's pointless to speculate until all the facts are known.

[AngryAmish]

13. Obviously something went very wrong

It seems fishy that the airline was oked on one end of the trip and not the other. And I don't mean the pilot crashed on purpose or another nefarious result like terror. Just seems that not everything was handled in the most professional manner. I can handle crashed being bad luck - suck enough birds into the engines then bad things happen. But if the pilot was told to go around the storm or wasn't told to go around the storm...that should not happen.

But as you say, the facts will come out hopefully.

[Blue_Tires]

16. That was an error on the airline's part

albeit a kind of serious one...Long story short, the airline was only allowed to fly 4 days out of the week, and tried changing one of the days to Sunday to take better advantage of the holiday traffic...

What isn't being said is that AirAsia's "unofficial" permission to fly on Sundays almost certainly involved some under-the-table cash to the Transport Ministry...

[Plucketeer]

15. How is that different

from what I'd said?

[Blue_Tires]

11. here:

In aviation, coffin corner (or Q corner) refers to the point at which the Flight Envelope boundary defined by a high incidence stall intersects with that defined by the critical Mach number. In other words, coffin corner occurs when, for a specific gross weight and G-force loading, the aircraft has climbed to an altitude where the speed differential between the onset of low speed stall buffet and the onset of high speed Mach buffet approaches zero.

As an aircraft climbs towards the altitude that defines its coffin corner, the margin between stall speed and critical Mach number becomes smaller and smaller until the Flight Envelope boundaries intersect. At this point, any change in speed would result in exceeding one or the other of the limits. In the most critical case, simply turning the aircraft could result in exceeding both limits simultaneously as, in a turn, the inside wing slows down whereas the outside wing increases speed. Likewise, encountering turbulence could result in a "beyond limits" change in airspeed.

In commercial and general aviation operations, flight at altitudes approaching coffin corner is generally avoided. Compliance with the aircraft manufacturer's charted maximum altitude, for the existing weight and temperature, will normally ensure that adequate buffet margins are maintained for both the high and low speed boundaries. In the event that turbulence is encountered or forecast, the cruising altitude should be reduced to ensure that buffet margins are not compromised.

http://www.airliners.net/aviation-forums/tech_ops/read.main/148333/
http://www.pprune.org/tech-log/332202-coffin-corner.html
http://airplanepilot.blogspot.com/2007/01/coffin-corner.html
https://www.boldmethod.com/learn-to-fly/aerodynamics/coffin-corner/
http://code7700.com/coffin_corner.html
http://en.wikipedia.org/wiki/Coffin_corner_%28aerodynamics%29
http://skybrary.aero/index.php/Coffin_Corner

[AtheistCrusader]

2. Fucking Airbus.

Who wants to bet this is another frozen pitot tube issue?

[Plucketeer]

6. I wouldn't bet on anything

until ALL the data and other evidence has been analyzed. Have you ever watched that program about air disasters on TV? Many times, "the obvious" has been proven to be wrong in the end.

[AtheistCrusader]

8. True, I'm basing that on a media report of one single data point.

There's a profile though. So far, all the evidence fits.

Probably not super-tasteful to be armchair quarterbacking an event that killed a lot of people though.

[mike dub]

10. non pilot here -- but I did fly with a friend who was a student pilot practicing stalls

in a single engine aircraft. When he put the plane into a stall on purpose, the nose dropped and he "simply" kept the nose down until we regained airspeed. Of course, he had several thousand feet in altitude before putting it into a stall.

I don't understand how an aircraft at 30-some thousand feet can stall, and not have enough altitude to push it downward and 'recover' from the stall.

Or does auto-pilot/auto-throttle and/or dark, stormy weather cause unawareness on pilots' part as to attitude (angle) of the aircraft?

Sad, tragic crash.

[yourout]

12. Death spiral....many planes go into a spin during a stall and on large aircraft spins are usually...

unrecoverable.

[mike dub]

14. ah, thanks for the insight, yourout

n/t

[FLPanhandle]

17. Going to take listening to the cockpit voice recorder to fully understand why

Was it some storm updraft? Emergency maneuver?

Night and stormy conditions did the pilots lose instruments and loss of orientation?

Faulty readings?