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Air Asia Indonesia Lost Contact from Surabaya to Singapore

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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Old 24th Jan 2015, 04:32
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It seems that the radar plot is not too accurate
Time and location does not match the speed
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Old 24th Jan 2015, 04:35
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Nice find training wheels.

I don't see anything inconsistent with a spin, particularly a flat spin which would likely develop after a couple of turns of spin entry gyrations. The wreckage location makes sense also if you consider a current from the NW moving the wreckage to the SE. Even the earlier pictures of the radome seem to confirm a flat water entry with the radome attached and no forward speed.
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Old 24th Jan 2015, 04:36
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Debris fieds

Fuselage and tail are 1,5nm apart, this is quite considerable distance. AF447 debris field is about 600mx300m (deph 3900m).
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Old 24th Jan 2015, 04:45
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About engine stall

FWIW this old explanation re what can happen may be of some interest re recovery from wrong moves

China Airlines Flight 006 - Wikipedia, the free encyclopedia

1985 and a 747 - a miracle the plane stayed together from a major upset

here is official report

seems that "HAL" almost did them in

http://www.rvs.uni-bielefeld.de/publ...r/AAR8603.html
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Old 24th Jan 2015, 05:50
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Originally Posted by _Phoenix
It seems that the radar plot is not too accurate
Time and location does not match the speed
The only speed you are talking about is GS in the horizontal plane.

Just consider that the vertical component could be at terminal velocity - or there about!
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Old 24th Jan 2015, 06:16
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Stall Spin training for Ab Initio Pilots

This incident prompted China airlines to require 12 hours of unusual attitude/aerobatic training for all their AbInitio trainees. Some didn't enjoy those hours but, at completion, they all knew how to avoid AND, if need be recover from, every possible kind of stall and spin. (In aerobatic aircraft...) Gulf Airline's Ab Initios, also trained at the University of North Dakota's "Specturm" program, followed the same syllabus.


http://www.rvs.uni-bielefeld.de/publ...r/AAR8603.html
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Old 24th Jan 2015, 07:25
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At long last someone is prepared to stop the rot....my course in 1970 was one of those with very little aerobatic training...since then those in "the British Isles" have cut it to virtually zero.
Of course those who make these decisions never carry the can.
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Old 24th Jan 2015, 07:57
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@roulishollandais - yes the post link was wrong but I think the intended link may have been China Airlines B747SP Loss of Power and Inflight Upset
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Old 24th Jan 2015, 09:01
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seems that "HAL" almost did them in

http://www.rvs.uni-bielefeld.de/publ...r/AAR8603.html
That was nothing to do with HAL, the autopilot did what it was designed to do....the Captain however did not!
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Old 24th Jan 2015, 09:36
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A goodly portion of the spin recovery problem goes right back to ab-initio training. The UK CAA removed spin training from the PPL sylabus several years ago, followed by several others, so modern pilots have never experianced a spin.
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Old 24th Jan 2015, 09:56
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Originally Posted by Stabilo31
Fuselage and tail are 1,5nm apart, this is quite considerable distance. AF447 debris field is about 600mx300m (deph 3900m).
The ocean currents in AFR447 were negligible in the doldrums under the ITCZ and the wreckage was a lot deeper falling to the ocean floor at 13,000ft. The currents in the Java Sea in comparison are very strong running at up to 6kts in a shallow sea with a silty bottom. (The divers were clinging onto ropes and 'flying like superman' to quote one report.) So let's assume a light piece of aircraft wreckage slowly sinks then gets pushed along the bottom till it sticks in a way that the current no longer moves it how long would that take 20 minutes or 30 minutes? 1.5 nm is only 15 minutes at 6kts. After 2 weeks if the currents were always in the same direction (which they aren't) in theory wreckage that is bowled along the sea floor or floats with some drag in the water could travel well over a thousand miles with a 6kt current.

When AFR447 fin was found floating on the surface and the wreckage of the aircraft was not immediately beneath it, the same claims were made in the AFR447 thread that the reason for the crash was the fin detaching as with the New York A300. It wasn't.
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Old 24th Jan 2015, 10:08
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Agreed spin recovery training is good. It should at least be demonstrated at abin itio level, where just closing the throttle and hands and feet off the controls to effect recovery. Depending on c of g of course. No control input is better than the wrong control input. Glider pilots should be taught spinning and recovery. If caught in extreme turbulence in mountain wave a spin initiation maybe the only action to stop the wings being "pulled off". A spin of course is the one maneuver where roll, yaw and pitch are simultaneous and the speed is keep relatively low. In a stall situation the wings must be "unloaded" somehow. Whether that be pushing the stick forward or roll to 90 degrees bank as this will get the nose lowered.

Last edited by Sop_Monkey; 24th Jan 2015 at 11:15.
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Old 24th Jan 2015, 10:43
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Radome

as someone has commented that looks like it was forced off the metal support ring by a huge internal positive pressure forcing the radome to pull through the rivets.

Where did this pressure come from is a sudden change of atmospheric pressure (very low) capable of creating that differential that or a very high RoC.

Or would it require a front pressure bulkhead failure.?

What pressure differential would be required to force the radome material over the rivets?

Has it been confirmed it is from the aircraft? any pics of cockpit seen yet. Finally I suppose it is possible that depending on the attitude etc at impact that could have caused front bulkhead to go

Last edited by oldoberon; 24th Jan 2015 at 10:47. Reason: add last line
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Old 24th Jan 2015, 11:18
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Debris field

So let's assume a light piece of aircraft wreckage slowly sinks
What do you call a "light piece of aircraft"? The tail section which has been recovered is weighing at least several hundreds kilograms and probably more than a ton. Once this kind of piece has sunk (less than 30m deph) in the mud and due to the shape of this part (asperity), I doubt that it could have been dragged along the bottom even with a 6kts stream.
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Old 24th Jan 2015, 11:39
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Quote:So let's assume a light piece of aircraft wreckage slowly sinksWhat do you call a "light piece of aircraft"? The tail section which has been recovered is weighing at least several hundreds kilograms and probably more than a ton. Once this kind of piece has sunk (less than 30m deph) in the mud and due to the shape of this part (asperity), I doubt that it could have been dragged along the bottom even with a 6kts stream.
What are you suggesting?
The tail section has a large surface area which would have been exposed to the current. Kind of like a sail. Therefore in a six knot current it would not take long for it to be moved some considerable distance away from other wreckage. Like the center section which is far heavier and less likely to be moved by the currents.
The pictures we have seen all point to the break up of the aircraft upon contact with the surface in a more or less level attitude.
The radome does not from what we have seen so far appear to have separated prior to this. However I have not seen all of it, and nothing should be dismissed yet.
With a six kts current and something as light as it is I am not surprised it has travelled so far!
Rudder and fin separation, did not occur as they are still attached to the rear fuselage. This "complete package" seperated on impact.
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Old 24th Jan 2015, 11:53
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Originally Posted by Stabilo31
What do you call a "light piece of aircraft"? The tail section which has been recovered is weighing at least several hundreds kilograms and probably more than a ton. Once this kind of piece has sunk (less than 30m deph) in the mud and due to the shape of this part (asperity), I doubt that it could have been dragged along the bottom even with a 6kts stream.
Aircraft are made to 'fly' their structures are not solid and many are deliberately honeycombed. Some parts of the structure like engines are denser. If you drop something into water that is moving fast then it will be carried along dependent on its density and aspect ratio. The engines if disconnected are likely to fall to the bottom. Lightweight aluminum and composite structures are far less dense with a large surface area to weight ratio will be carried a long way. They are MADE to be carried a long way in the air after all. Aerodynamic forces are strong on flat panels hydrodynamic forces are hugely stronger.
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Old 24th Jan 2015, 11:56
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Originally Posted by Stabilo31
The tail section which has been recovered is weighing at least several hundreds kilograms and probably more than a ton. Once this kind of piece has sunk (less than 30m deph) in the mud and due to the shape of this part (asperity), I doubt that it could have been dragged along the bottom even with a 6kts stream.
Weight is not a problem. Thanks god we have buoyancy, so multi-tons objects can float. (in water: immersed 1 cubic meter = 1000kg buoyancy)
In my opinion in this particular case, vertical stabilizer worked as kind of a parachute for this part of fuselage (because it contained some empty spaces or foam-filled) making the resultant force less. Not enough to float but sufficient to substantially reduce speed of decent. Add strong currents and mystery is solved.

Last edited by klintE; 24th Jan 2015 at 12:09.
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Old 24th Jan 2015, 12:19
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Indonesia salvage teams fail to float AirAsia fuselage

Indonesia salvage teams fail to float AirAsia fuselage - Channel NewsAsia
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Old 24th Jan 2015, 12:24
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Originally Posted by island_airphoto
FYI - if ice plugs the pitot tube quick enough to trap the air in there, the speed may not go down. If the airplane gains altitude the "speed" goes UP because the difference between the trapped pitot and static air gets bigger.
Could this phenomena triggers the high speed protection (in an ALT mode without alpha prot.) creating a diverging / self amplifying control loop (small NU input => hiher alt. => higher spd => high spd prot. => higher nose up => even higher alt. => even higher spd, whereas it is the opposite in reality) with a skyrocketing altitude out of the flight enveloppe ? (a moderate NU input would translate as an ever increasing altitude)

If the high vertical speeds put forward are derived from radar data measured at range limit (just before the track is lost), meaning derived from noisy altitude measurements at low SNR, are they reliable ?

Last edited by Hyperveloce; 24th Jan 2015 at 12:41.
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Old 24th Jan 2015, 13:23
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Hydrodynamic forces

There seems to be a widespread lack of any understanding of the scale of hydrodynamic forces in many posts here. Water is about 800 times the density of air, which means that 6kt of current generates forces similar to about 28 (I.e. approx square root of 800 ) times 6 or 168 kts airspeed. Even ignoring buoyancy effects, I doubt any pilot will not appreciate that a 168 kt wind would be able to keep that tail section on the move until it gets seriously snagged on something that can hold it!
This calculation also shows why these are hugely challenging conditions for those brave divers.
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