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Old 9th Sep 2012, 12:32
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Tee Emm
 
Join Date: Jun 2006
Location: Australia
Posts: 1,160
But the right power lever (no. 2 engine) remained in take-off power setting. It took no. 1 power lever 42sec to move to idle power. During these 42 seconds an asymmetric thrust situation developed. The aircraft by then had past the 'OTR'-beacon and the crew had, according to SID procedures, begun a 25 left turn onto a 327 heading for the Strejnic 'STJ' VOR/DME beacon. Due to the thrust asymmetry the nose-up pitch of 18 decreased to 0. The aircraft rolled through 170 laterally and finally crashed into an open field and exploded on impact.
For some reason the pilots did nothing to correct the asymmetric thrust situation that occurred to the autothrottle system where one throttle came back to idle while the other remained at high power. A similar accident happened to a Chinese operator in a Boeing 737-300 a few years ago. In that accident the crew seems dumbfounded at why the huge split in the throttles and did nothing to fix the problem by switching off the autothrottles and controlling them manually.

In the simulator we have seen the same thing happen when one autothrottle clutch motor was failed by the instructor during flap and gear extension on an ILS with a 737-300. As the drag cut in intercepting the glide slope and the thrust increased to mainatin vref + five, the left throttle remained at idle (which was the throttle setting when the instructor failed its clutch motor) while the No 2 throttle increased to 75%N1 to maintain the selected speed. The autopilot was engaged at the time and the control wheel was well over to one side trying to maintain the localiser. NEITHER PILOT TOOK ANY CORRECTIVE ACTION despite both being aware of the unusual throttle split and control wheel position.

Eventually the autopilot disengaged itself and the 737 rolled to the left beyond the vertical and the nose dropped. The captain called for the engine failure checklist when there was nothing wrong with the engine. The aircraft crashed in a spiral while the first officer was still trying to find the engine failure page in his QRH. NEITHER PILOT HAD A CLUE WHAT TO DO. I suggest a similar defect happened to TAROM and from the tragic result the crew also didn't have a clue what to do for something as simple as an AT defect. It's the old story of simulator training. For some airlines if it is not in the syllabus of training, then a head in the sand approach is adopted and lessons from past accidents are disregarded.

Last edited by Tee Emm; 9th Sep 2012 at 12:37.
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