I was alerted by TheGimliGlider through Twitter today of this great video on tailplane icing. Watch
I remember, actually, seeing this video a couple years ago, whether it was at Embry-Riddle or during my CAL internship. And it's definitely worth a watch, especially if you're a pilot.
What I came away with is a definite feeling that the Captain and First Officer on Colgan 3407 felt that they were experiencing a tailplane stall. This, I believe, is evidenced by the CA's response to the stall by increasing back pressure against the stick-shaker and stick-pusher, which is a warning system used to prevent and correct a stall situation.
The FO's first response was to bring up the flaps and prompt the CA to see if he wished for landing gear retraction. This is part of the recovery procedure for tailplane icing, as the configuration change (specifically the lowering of flaps) usually causes the tailplane stall to finally occur.
According to the previous video, tailplane icing is evidenced by extreme nose-down pressure. Perhaps the CA mistook the stick-pusher for this control pressure? I'm still not sure as to why he ignored the stick-shaker in the first place, but due to the icing already observed by the crew (as stated in the CVR) it was a sensible assumption to believe that they were encountering a tailplane stall.
This brings me to the use of autopilot during the flight. I've spoken to a few Dash8 pilots, and all of them said that autopilot should never be used during icing conditions. This is reaffirmed by the video. AP prevents you from noticing the increased use of trim (since when activated, the AP assumes this function as well) and the lightened forward control pressure.
It's always said that an accident never has just one cause, it's a result of a chain of errors and events that ultimately lead up to the accident. As pilots we're charged with breaking this chain of errors, which could have started with us, or started with an airline policy or culture.
Safety is everyone's highest priority. The tragic events of Colgan 3407 remind us that we always have to be on our toes, we constantly have to educate ourselves and must consistently be on the lookout for that chain rattling at our cockpit door.