Colgan 3407 Down in Buffalo

[The Prussian]

Suppose all the Capt. had on his brain was ICING. He's seen the video or been briefed on tailplane icing in this and other aircraft. As they approach the marker, they get configured and slow rapidly. He's new to the airplane, and fairly unfamiliar with the aircraft's stall logic. Suddenly the stall warning sounds, combined with A/P kickoff and rapid nose down pitch over. For someone new to the aircraft, it has the look and feel of tailplane icing. Looks like he recovered for tailplane stall rather than wing stall. I don't fly this aircraft, so I may be missing something, but I'm wondering if the two different recovery methods weren't confused in his head...

 

[Oakum_Boy]

Well, the aggressive pitch-up could be explained in that if he was overriding the stick pusher with brute force, then remembering the SP/AP button on the yoke, suddenly the pusher is gone and all that muscle coming back on the yoke...

 

[JAKEFAC]

There is a delay, albeit a short one, between shaker and pusher. That's where the correct recovery has to be made. Once the pusher activates - it activates for a reason - using the yoke button to override it -in my opinion, is counter-productive. When the pusher activates, the airplane needs to fly itself out of the stall via an unloaded wing.

 

[Britpilot]

Suppose all the Capt. had on his brain was ICING. He's seen the video or been briefed on tailplane icing in this and other aircraft. As they approach the marker, they get configured and slow rapidly. He's new to the airplane, and fairly unfamiliar with the aircraft's stall logic. Suddenly the stall warning sounds, combined with A/P kickoff and rapid nose down pitch over. For someone new to the aircraft, it has the look and feel of tailplane icing. Looks like he recovered for tailplane stall rather than wing stall. I don't fly this aircraft, so I may be missing something, but I'm wondering if the two different recovery methods weren't confused in his head...

Well in a tail stall there would be no shaker/pusher. That's the fundamental difference between the two stall types.

 

[ImbracableCrunk]

How about this:

They get slow, shaker and then pusher comes on.

At some point, the throttles are jammed forward.

The elevator, which was attempting to maintain altitude, is trimmed most of the way, if not all the way nose up.

The initial pitch down is commanded by the pusher and A/P disengagement, but the pitch up is the result of going from <30% Torque to >100%.

In other words, couldn't this just be a trim stall?

 

[The Prussian]

Well in a tail stall there would be no shaker/pusher. That's the fundamental difference between the two stall types.

Yeh...I know what you're saying. I'm thinking it's been a long day, and he's got "tail stall due to ice" on the brain. A/P kicks off, he's got yoke going forward, and in the heat of battle, disregards the shaker, knowing full well that in a tail stall, he's gonna have to come in with a gut load of back pressure...
Tired....spring-loaded in the wrong direction...thinking loss of hundreds of feet within seconds...

 

[sinkrate]

If this captain pulled hard on the yoke when the shaker went off - it probably follows he was trained to do just that.

EXACTLY RIGHT A number of posts here have talked all around the subject of how to recover from a stall. Any pilot that has worked as a sim instructor or sim check airman in a 121 carrier's program can tell you two things. One - how a pilot responds to something in the sim is how he will respond to it in an aircraft. 'If he does it in the sim he will do it in the aircraft'. Two - when faced with a surprise in an airplane his immediate response will be exactly the way he was trained in the sim. It sounds simplistic but it has been demonstrated time and time again.

In a 121 training program the way you recover from a stall, and the required performance, is dictated by the FAR's. Appendix F of FAR 121 specifically states the three stalls you will be tested on (clean configuration, take off configuration and landing configuration) and the performance requirement - no loss or gain of altitude and clean up on a specific schedule. It is a constant altitude maneuver. The FARs require you to hold a lot of back pressure on the yoke and power out of it. That is the only FAA acceptable way to complete a Proficiency Check that a Captain must pass every six months. Since that is the requirement to pass a checkride that is the way hours and hours are spent training the maneuver. ​

There is a school of thought that claims this is 'negative training'. Some swept wing, T tail jets with aft body mounted engines are 'deep stall' AC. There is no recovery from a fully developed stall because all five flying surfaces are stalled. In these AC at altitude (no thrust left to accelerate with) the only 100 percent successful way to recover is give up altitude. There is a similar school of thought that emphasizes these maneuvers are simply a 'proficiency demonstration' that you would never actually use in an aircraft. The problem, if these schools of thought are correct, and emphasized in training, is now we provide no useful training for the situation. And that means there will be no telling what each pilot will do when faced with the situation.​

Now add to this discussion the issue of an icing induced tail plane stall that is unique to AC with fixed horizontal stabilizers (most turbo props and no swept wing jets). The immediate response to one is exactly opposite the response to a wing stall. Reduce thrust and pull full aft yoke to move the airflow stagnation point back to where the ice is. Then the tail will start flying again. When pitch authority is regained relax the yoke before you enter an accelerated stall. Fortunately this problem has been well documented for decades and engineers have known for decades how to design tails so they do not have this problem. There are no turbo props in service in the US that are known to have the problem. The A model SF3 was the last AC known to have this problem but they were all modified years ago to eliminate it. The 'B' model SF3 has an entirely different empennage.​

 

[Newf Dog]

If "icing," tailplane or otherwise, was such a great concern to the crew don't you think airspeed awareness would be among your top priorities, if not your number one priority.

Regarding tailplane stalls, flying faster only exacerbates that situation with increased flap deployment. You shouldn't get a tail stall at only flaps 10, ice or not. Plus the switch which increases Vref by 20 knots gives a big margin with only a flaps 15 landing assuming you keep the wing flying which would be no problem even if you flew a little below Vref.

I'd like to think the crew had something else going on besides "significant" ice concerns or mere lack of airspeed awareness and nobody pushed the power up. (By the way even if that's all it is, I'll wager most of you have been part of a crew where somebody did an "oh sh***" and pushed up the power or some other type of mistake. Mistakes happen. They shouldn't but they do and if it hasn't happened to you yet then it will. If you doubt that please let everyone know so we can avoid flying with you.)

I agree with Surplus1's original comments. Something doesn't seem right about this NTSB alleged "stall recovery" by the Captain unless it was a panic reaction. There has to be more to it (I hope). Maybe even the "5 cent light bulb theory" which someone else mentioned. Classic example.

Like everyone else I eagerly await more "actual facts and data" so we can learn from it.

 

[q100]

EXACTLY RIGHT A number of posts here have talked all around the subject of how to recover from a stall. Any pilot that has worked as a sim instructor or sim check airman in a 121 carrier's program can tell you two things. One - how a pilot responds to something in the sim is how he will respond to it in an aircraft. 'If he does it in the sim he will do it in the aircraft'. Two - when faced with a surprise in an airplane his immediate response will be exactly the way he was trained in the sim. It sounds simplistic but it has been demonstrated time and time again.

In a 121 training program the way you recover from a stall, and the required performance, is dictated by the FAR's. Appendix F of FAR 121 specifically states the three stalls you will be tested on (clean configuration, take off configuration and landing configuration) and the performance requirement - no loss or gain of altitude and clean up on a specific schedule. It is a constant altitude maneuver. The FARs require you to hold a lot of back pressure on the yoke and power out of it. That is the only FAA acceptable way to complete a Proficiency Check that a Captain must pass every six months. Since that is the requirement to pass a checkride that is the way hours and hours are spent training the maneuver. ​

There is a school of thought that claims this is 'negative training'. Some swept wing, T tail jets with aft body mounted engines are 'deep stall' AC. There is no recovery from a fully developed stall because all five flying surfaces are stalled. In these AC at altitude (no thrust left to accelerate with) the only 100 percent successful way to recover is give up altitude. There is a similar school of thought that emphasizes these maneuvers are simply a 'proficiency demonstration' that you would never actually use in an aircraft. The problem, if these schools of thought are correct, and emphasized in training, is now we provide no useful training for the situation. And that means there will be no telling what each pilot will do when faced with the situation.​

Now add to this discussion the issue of an icing induced tail plane stall that is unique to AC with fixed horizontal stabilizers (most turbo props and no swept wing jets). The immediate response to one is exactly opposite the response to a wing stall. Reduce thrust and pull full aft yoke to move the airflow stagnation point back to where the ice is. Then the tail will start flying again. When pitch authority is regained relax the yoke before you enter an accelerated stall. Fortunately this problem has been well documented for decades and engineers have known for decades how to design tails so they do not have this problem. There are no turbo props in service in the US that are known to have the problem. The A model SF3 was the last AC known to have this problem but they were all modified years ago to eliminate it. The 'B' model SF3 has an entirely different empennage.​

Great post. I've never liked this approach to stall "training" and believe it to be a proficiency test at best.

 

[Indy319FA]

Chealander is a loose cannon. He is the same guy that showed up at the SWA 1294 press briefing after the MDW accident and proceeded to treat it like it was a fact finding mission when in fact it was to announce the findings. He made some comments about the pilots that were not at all supported by the text of the NTSB report.

I think that he is WAY out of line wrt this Colgan accident. Speculating and proposing theories to the press. I've never seen an accident investigation handled this way and find it disturbing and unprofessional. He needs to find another line of work and the NTSB needs to get back to their job of determining the causes of accidents and away from the job of feeding the press monster with regular, poorly thought out speculations.

Because I live in LEX and knew some of the folks involved in the 5191 crash, I watched the entire NTSB hearing on 5191. From his remarks and demeanor in the hearing I think Chealander has a real disdain for regional pilots. Chealander spent most of his career with the Air Force, and was a Chief Pilot at American.

Bio:http://www.ntsb.gov/Abt_NTSB/Bios/chealander.htm