Ignition Override
First of all, this or any other airline crew, as you've suggested, should have looked at the "chart" to see if they could make the intended change in altitude. Perhaps this crew did, I wouldn't know. According to the "chart" this aircraft was capable of FL410 if it was flown as it should have been flown. It wasn't. They apparently used a zoom climb technique which is simply using airspeed to produce rates of climb to get you there. Unfortunately, at a cost. Airspeed. When they finally reached FL410, they were about M0.54 when they should have flown a constant M0.74. The complication at altitude is acceleration to the required cruise mach. Preferably one above the stall. M0.54 is a stall speed. Thrust is set to the 'carrot' for max CRZ (or MCT, which is likely to match CRZ at this point). Now the dilemma gets realized. At this max power setting you get the thrust the engine is capable of producing at FL410 and that thrust is insufficient to overcome the aerodynamic drag and allow the aircraft to accelerate to point 7 4 out of the stall region.
The CRJ has N1 'carrots' for all Max. power settings (including CRZ) and like it's CF6 lineage, the CF34 displays N1s and N2s separated by the ITTs. So it would be simple and straight forward enough for this crew to see what their maximum cruise N1 setting would be at FL410. The carrots automatically (reduce) adjust as you climb. The difficulty in attaining and maintaining the required cruise speed (M0.74) from the reported M0.54 speed at which they levelled off, would be virtually impossible as it is most probable they were at maximum TLA resulting in maximum CRZ thrust and nowhere near the required Thrust vs Drag to recover. Aerodynamic drag being greater than the actual thrust available from the engine at that altitude. Therefore, stalling was imminent.
Also, at that altitude, lowering the nose would have had to have been gentle rather than abrupt to avoid shaker. Based on the number of reported initial shaker and pusher events noted in the report, they might have been a little aggressive in stall recovery which in turn induced secondary stalls. It's also reported that the aircraft recovered at FL290. A substantial loss of altitude.
I wonder if the recent Tu-154 crash in the Ukraine might have been the result of an aircraft being too high for performance, stalling and entering a flat spin out of control. All in an effort to avoid Thunderstorms.
Willie
