Autopilot level-off from a descent in an aircraft without autothrottles is a bit of a trap. Although I don’t know of any similar accidents, there’s beginning to emerge a story of a catalogue of similar frightening incidents on the Q400 where pilots have become preoccupied with resetting (or setting up ) the FMS and not noticing, whilst heads down, the body angle changing rapidly to nose-up (once below about 180kts the Q400 reputedly does this slowdown rather fast, iced up or not). The normal speeds for intermediate level-offs are 200 to 210 knots. It’s believed that Colgan 3407 slowed to as little as 134kts. Some of the anecdotes have both pilots heads down trying to resolve an FMS button-punching glitch and/or looking back at the special “wing inspection” lights illuminating the Q400 wingtips - to see if the ice is actually being dislodged.
Does the Q400 simply level off and start bleeding airspeed without any indications at all? Is setting this trap something that should be happening during high pilot workload on approach?
Should the autopilot instead be set to a descent rate and the altitude alerter set to clue the flight crew to do the level off manually - instead of the autopilot just capturing the altitude and slowing whilst awaiting the pilots setting of an appropriate thrust? At least then there would be an expected alerting chime or suchlike.
So did the "low time on type" Colgan Flt 3407 pilot respond to a sudden stick-shaker [and rapidly following stick-pusher] by raising the nose, cleaning up the gear and flap and attempting a go-round from a dangerously low speed (instead of taking the correct stall recovery action of adding power and lowering the nose?). At first glance, that possibility exists. Surprise can be quite a mind-numbing wake-up call. It’s called Instant Overload. It results from fatigue or loss of Situational Awareness (SA)
But why and how would he achieve 31 degrees nose up before the aircraft stalled and started spinning? Did he mean to? The logical response is “no, of course he didn’t”.
The simple answer is that that extreme nose-up pitch-up tendency would be the autopilot’s legacy to him after it kicked itself out due to reaching full nose-up auto-trim in pitch (in its attempt to maintain the set capture altitude against the added drag of ice, gear and flap - likely with something near idle power inadvertently LEFT set).
Once the autopilot kicked out and the panicky pilot added max power, the full noseup trim would be conducive to the aircraft looping the loop of its own accord. The pilot would be flummoxed by this setup and, after a confused pause, fighting hard against powerful nose-up trim forces to lower the nose. Adding max power at low IAS itself produces a powerful nose-up trim change. Add that to the already full nose-up trim state and they didn’t have a chance…… of avoiding a deadly stall/spin outcome.
I couldn’t imagine a nastier surprise. Fancy building in such a death-trap as an autopilot without autothrottle and an FMS that needs lots of head-down two-pilot trouble-shooting and reprogramming? His available solutions were:
a. Not to add full power, but just enough to keep it flying and, as per my flight school's SOP technique (see below)
b. Roll sufficiently (about 50 degrees bank) so that the fully back-trimmed airplane only pitched mostly into the turn - giving him a chance to wind the trim nose forward whilst minimizing the speed loss..
I had a similar situation (but not unexpected) tonight after a night take-off. The EFATO drill for a practice (or real) engine failure after take-off is for the front-seat student to raise the nose, simulate putting the throttle to “stop”, call Mayday on intercom and then he releases the stick after having run the pitch trim to full nose up (for his optimal survival seat-vector), places both hands on his left knee and calls “abandoning now” (simulating an ejection). The rear-seat instructor then takes over, banks into the circuit direction (turns “crosswind” essentially), to help the nose drop from around 25 to 30 degrees nose-up - all whilst running the elevator trim nose-down towards neutral and adding near to max power. It’s a silly drill (it’s like practising dying) but meant to be very realistic for the trainee - and it’s a requirement for him to do it prior to his NF3 night solo sortie. You wouldn’t want it to happen suddenly without warning however. It’d be a quite difficult recovery (particularly at night or in IMC).
Prima facie, and in light of all the similar anecdotes now emerging about turboprops with this cheap option (i.e.no autothrottles and a heads down FMS keypad), this would have been the scenario surrounding Flt 3407’s fate. For that Colgan pilot it would have all happened very fast. It’s a nasty setup just begging for a tech remedy.
Automation can be a half-baked bitch.