Some years ago in the 737 simulator the instructor failed one throttle clutch motor during idle decsent leading to an ILS. The aircraft was being flown with autopilot and autothrottles engaged. The crew did not notice it because there was nothing to indicate clutch motor failure while the throttles were closed.
It was only when the aircraft was established at 10 miles on the ILS and flaps and gear was extended that power went up to maintain programmed airspeed. But with a clutch motor inoperative only one throttle opened up. The yaw caused by one throttle at idle and the other throttle at 75% N1 was counteracted by the automatic pilot which was flying the ILS. The autopilot used 50% aileron to maintain semi directional control. If the crew noticed this, no words passed between them, although both pilots presumably would have watched with increasing interest; each wondering what the other pilot would do about it.
There was no attempt by either crew member to disengage the automatic pilot which was struggling to maintain the localiser and glide slope. Cultural mores forbade the PM from dropping a hint to the PF who, following company SOP's, still had both hands on his knees unsure what to do.
Suddenly the autopilot disengaged as it had reached beyond its tolerance. The simulator was in simulated IMC so no outside view. The instruments showed the aircraft rolling sharply past 70 degrees angle of bank as all directional control was lost and the aircraft emtered a spiral dive still with one throttle closed and the other at high power. It was only then that the captain who was PF called "Engine failure - checklist." yet still failed to take any physical action.
Astonishingly, both his hands were firmly on his knees at all times. There was nothing wrong with both engines of course. An alert pilot would have earlier seen the offset control wheel and split throttles and taken immediate appropriate action to regain stable flight. The first officer was still diving to find the QRH when the instructor decided to " freeze" the simulator as GPWS warnings sounded and autopilot disengage warning siren sounded.
From the instructor point of view, there was little to be gained by prolonging the embarrassment and cultural loss of face. What shook him was the total stunned horror displayed by the captain as the aircraft was about to crash. The first officer simply stared straight ahead disbelievingly and at no stage did he support the captain with any words of warning. From the first officer's point of view it was the captain's problem - not his. This crew were like robots; totally automation dependent from the time the gear was retracted after takeoff, right to the end. Both pilots were experienced on the 737 but apparently had never seen a thrust lever clutch motor failure in the simulator - a sad indictment on their training. Theirs was total disbelief at what was happening.
Last edited by Centaurus; 18th Jan 2021 at 11:55.