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a330pilotcanada
30th Dec 2010, 11:03
Good Morning All:

Although this is not really relevant to Canadian aviation as it happened in AMS it does show a very good example of the "Swiss Cheese" error method. As one watches this you can see where the initial error message on the F.M.A. (Flight Mode Annunciation) led not only to confusion but to the incident.

Not being that well versed in the B-737-NG series of aircraft maybe our "Teal" friends in CYYC can expand on this for everyone's edification.


Turkish B-737 Accident (video animation)

Nine passengers and crew including the three pilots were killed in this accident which highlights the ancient truths of fly the aeroplane and remain in the loop. -8 ft would be the nose wheel compressed ground reading for the Radio Altimeter.

http://www.tarpa.com/fdo-bcy/turkish2009.html (wlmailhtml:{A40A0873-FB43-4B35-A641-39511F3AABEB}mid://00000022/!x-usc:http://www.tarpa.com/fdo-bcy/turkish2009.html)

WJAPilot
10th Jan 2011, 04:58
Heres what we have been told over here regarding the issue - on all NGs not just the -800.

The auto throttle is linked to the captains Rad Alt - not the first officers even if the autopilot is running under command B ( f/o flying)

During normal operations on any given landing if the Captains rad alt reads less that 26ft AGL then the auto throttle retards to idle.

The idea being that the system assumes that you are in landing mode and have simply forgotten to disengage the auto throttle system.

We dont see this usually because SOP dictates that on normal landing with the exception of Auto land - we must disengage the auto throttle thru 50ft (above the 26ft trigger).

While I cannot explain the lack of cues this crew missed - ie airspeed - abnormal pitch indications - we know that many times "mode confusion" is the cause of many accidents.

It is not also abnormal on certain days to capture the path from above - the key however is that as a safety check in our (teal) system that if we are not stabilized by a 1000 AGL meaning on speed on target stable with engine spooled up then we go around -

If Turkish air had had this check - that last cross check of stable appch at 1000AGL and had the pilots adhered to it then maybe it might have saved lives - but thats alot of maybe's.

I know that this was not the only NG to have had this issue and it has occurred on at least two other occaisions - both times however the pilots caught the error and disengaged the autothrottle themselves and advanced thrust levers as necessary with no other deviation to flight path.

Regards

J

a330pilotcanada
20th Jan 2011, 22:53
Good Evening WJAPILOT:

Thank you for your response and sorry for the late reply as I was out of the country

Willie Everlearn
21st Jan 2011, 14:21
This accident has brought to light a problem with those -800 Rad Alts. It seems the failure rate is higher than originally thought. In fact, it extends to other aircraft types.Boeing is investigating as are other OEMs.
Stay tuned.

Willie

clunckdriver
21st Jan 2011, 14:52
So let me see if Ive got this, {1} The Rad Alt is MEL, crew are aware of this. {2} Power comes back on apch as crew are doing an auto throttle Apch even though the MEL is quite clear on restrictions. {3} Crew {three of them} sit with their minds in neautral as airspeed falls , fail to disconect auto thrust and push those two big levers forward. {4} Aircraft mushes into the ground with a last second intervention by one of the pilots, sadly they paid with their lives but dear God where are the basic/fundemental flying skills? Way back when a four engine piston aircraft was thundering down 28 in Dorval, the FE noting all the hash in his Chinese Television, {Ignition scope to those post pistons} reached up to reduce the MP, Captain responds with, "Dont touch those, they make it go!" It really is that simple folks, automation cant think, thats the pilots job.

greywings
21st Jan 2011, 22:54
How very true!

When using the automatics the story about the way things are going is shown on the mode annunciator panel. Despite the rushed approach and maybe even the extra workload sometimes confronting the (training) captain when there is a trainee in the right seat, it seems inconceivable that none of the three noticed the abnormal indication, or, presumably, bothered to investigate the warnings that had been given.

It would be most interesting to see the CVR matched to the video to see what really transpired.