Colgan 3407 Down in Buffalo

[ksu_aviator]

Latest Technical Data

Deice was turned on 11 minutes after departure, never turned off;

1 minute prior to end - Gear Down
Flaps 10 at 26 seconds prior to end

Full Power at 20 seconds

Pitch +31 followed by -45

Rolled Left 46 then right 105 as nose dropped

G-forces .75 to 2.0

At 250' agl heading 053, roll right 26 pitch -30 and 100 KIAS

From 1800 msl to 1000 msl took 5 seconds

 

[trainer8]

Is it me or is the media witch hunt beginning. They are saying the autopilot was on and that is against company regulations. Is that is in all icing or just severe icing.

They're wrong. AP is permissible. Q400 AFM says AP off in severe icing.

T8

 

[Singlecoil]

Deice was turned on 11 minutes after departure, never turned off;

1 minute prior to end - Gear Down
Flaps 10 at 26 seconds prior to end

Full Power at 20 seconds

Pitch +31 followed by -45

Rolled Left 46 then right 105 as nose dropped

G-forces .75 to 2.0

At 250' agl heading 053, roll right 26 pitch -30 and 100 KIAS

From 1800 msl to 1000 msl took 5 seconds

And the autopilot was never turned off?

Where were the throttles before full power was applied?

 

[ksu_aviator]

And the autopilot was never turned off?

Where were the throttles before full power was applied?

I'm sorry, I thought everybody already knew the autopilot was turned off.

I don't know where the power levers where before the event occurred, but I can imagine that they where at a point that set them up for the appropriate approach speed.

 

[VF45]

Surplus 1 said:

As the aircraft levels, the auto-pilot trims nose up to hold the altitude as the speed decreases. The nose up trim continues slowly unnoticed by the crew. The auto pilot is also inducing aileron trim at the same time – to keep the wings level - also unobserved. Airspeed decreases further. Glide slope is alive and the captain commands “gear down:” Airspeed is within limits and somewhat higher that intended approach speed. As the gear extends, drag increases, auto pilot inputs some more nose up trim. Flap speed is reached (upper limit).

What has occurred is what we call an upset. It happened when the aircraft was only 1500 ft agl. At that altitude, recovery is impossible – regardless of what the pilots may have done. Time from upset to impact – probably much less than 30 seconds. It takes much longer to write or read this than it does for the scenario to play itself out.

Could this accident have been avoided? YES – but not after the upset occurred.
hypothetical.[/QUOTE]

*****

Well thought out scenario..., doesn't even require any real effects from ice. Be interesting to see what the power setting was while decelerating, while the autopilot held altitude towards the FAF (did they decel into the stall driving in?) Didn't notice the decaying airspeed and approaching stall condition until the high AOA kicked off the autopilot just prior to stick shaker & upset? Full power on the engines hung from the wings (upon stick shaker as first warning to crew) cause initial pitch up?

ILS23 FAF at BUF just under 1500' AGL 4.4 miles from the threshold... upset the aircraft at that altitude and there is no recovery.

 

[joe_pilot]

Deice was turned on 11 minutes after departure, never turned off;

1 minute prior to end - Gear Down
Flaps 10 at 26 seconds prior to end

Full Power at 20 seconds

Pitch +31 followed by -45

Rolled Left 46 then right 105 as nose dropped

G-forces .75 to 2.0

At 250' agl heading 053, roll right 26 pitch -30 and 100 KIAS

From 1800 msl to 1000 msl took 5 seconds

Chilling

 

[MALSR]

Deice was turned on 11 minutes after departure, never turned off;

1 minute prior to end - Gear Down
Flaps 10 at 26 seconds prior to end

Full Power at 20 seconds

Pitch +31 followed by -45

Rolled Left 46 then right 105 as nose dropped

G-forces .75 to 2.0

At 250' agl heading 053, roll right 26 pitch -30 and 100 KIAS

From 1800 msl to 1000 msl took 5 seconds

What i want to know is whether the airframe deice selector was set to fast or slow. Depending on the FDR we may never know, except that is was just "on".

 

[ksu_aviator]

Surplus 1 said:

As the aircraft levels, the auto-pilot trims nose up to hold the altitude as the speed decreases. The nose up trim continues slowly unnoticed by the crew. The auto pilot is also inducing aileron trim at the same time – to keep the wings level - also unobserved. Airspeed decreases further. Glide slope is alive and the captain commands “gear down:” Airspeed is within limits and somewhat higher that intended approach speed. As the gear extends, drag increases, auto pilot inputs some more nose up trim. Flap speed is reached (upper limit).

What has occurred is what we call an upset. It happened when the aircraft was only 1500 ft agl. At that altitude, recovery is impossible – regardless of what the pilots may have done. Time from upset to impact – probably much less than 30 seconds. It takes much longer to write or read this than it does for the scenario to play itself out.

Could this accident have been avoided? YES – but not after the upset occurred.
hypothetical.

*****

Well thought out scenario..., doesn't even require any real effects from ice. Be interesting to see what the power setting was while decelerating, while the autopilot held altitude towards the FAF (did they decel into the stall driving in?) Didn't notice the decaying airspeed and approaching stall condition until the high AOA kicked off the autopilot just prior to stick shaker & upset? Full power on the engines hung from the wings (upon stick shaker as first warning to crew) cause initial pitch up?

ILS23 FAF at BUF just under 1500' AGL 4.4 miles from the threshold... upset the aircraft at that altitude and there is no recovery.

The scenario is plausible, but it just doesn't match this flight. I can't imagine an autopilot that would hold the aircraft level with that much up-force with the trim maxed out until the airspeed slowed. Maybe its possible. But if the aircraft was slowing just because of the power setting, wouldn't the aircraft pitch down when the AP disconnected?

The crazy pitch up suggests something less ordinary and more insidious.

 

[Lilah]

Why just "snap-shots" of the data? They may well be pertain to what happened, but it's hard to put them in context. If the graphs of the data were released, we could have a much more informed discussion.

If it's going to be released anyway, why not do it now, online? It's the NTSB's call, but isn't putting the information out in dribs and drabs just encouraging speculation?

Fly Safe,

Lilah


PS> What were the airspeed and power indications, that's my big question at the moment. A Dash flyer would quickly tell us if that's in the ballpark for the plane.

PPS> Wise man say "Nose heavy planes fly poorly, tail heavy planes fly once"....just another idea...

 

[belchfire]

Info from the NTSB

The crew discussed significant ice buildup on wind shield and leading edge of the wings.

Gear down one minute before end of recording

Flaps 15 which lead to severe pitch and roll changes

Ya know, the only airplane I ever flew where the flaps caused a roll change was a clapped out old Aztec freighter...flap extension only causes roll changes if something is wrong-like out of rigging, failure of the flap interconnect or drive systems and so on.

Asymmetric flap conditions have led to accidents in the past...most notably a DC-10 out of ORD.

 

[bailout]

As soon as the flaps extend the tailplane stalls and the autopilot disconnects. At the same time a wing drops – due to ice-induced roll that the autopilot was compensating for. The nose pitches up (due to the nose up trim input by the auto pilot). The captain initially counters the pitch-up with nose-down pressure, which agravates the tail stall.

The captain quickly recognizes the tail plane stall, commands “flaps up” and pulls on the yoke. At the same time he is countering the roll with extreme opposite aileron.

Now the wing stalls – shaker activates followed immediately by pusher. [Remember – attitude and AOA are two different things – a wing stall can occur at any attitude or airspeed.]. Pusher activation causes the tail to stall again. Recovery by nose up control input is attempted a second time, the wing stalls again and the pusher activates for the second time. Pitch and roll excursions are severe. In the process direction has changed by close to 180 deg. By this time 1200 ft of altitude has been lost – the aircraft drops off radar. Pitch attitude is 30 – 40 deg. Nose down.

.

Understanding question: If the tail stalled first, when the AP disconnected, why would it pitch nose up? Everything Ive seen on the subject says that nose would pitch down. I understand the trim issue, but it was keeping the airplane level with the weight of the ice so when the AP disconnects, wouldnt the tail stall cause the nose to drop first?

 

[satpak77]

I too am wondering why it would pitch up first.

I think there is more to the story than just "ice brought them down"

also, see these pics, if they landed bottom first (for lack of a better term), why is the gear so pristine?

I believe they landed inverted, flat, facing the other direction

http://www.cnn.com/2009/US/02/15/buffalo.plane.crash/index.html#cnnSTCPhoto

 

[belchfire]

Gear isn't pristine. Forward strut is bent...

 

[satpak77]

Gear isn't pristine. Forward strut is bent...

well its pretty darn pristine if we are under the belief they landed flat/pancaked in right-side up. Remember only one house was hit and a very localized area exists.

Maybe the strut was bent due to vertical impact forces

yes yes this is speculation and I do not claim to be correct, however it is worthy of discussion

 

[BVT94]

Do the flaps meet up to the ailerons on the Q400?

 

[ksu_aviator]

The gear is probably sturdier, more dense and they hit at 31 degrees nose down.

The data all points to a sudden pitch up resulting in a stall and probably a spin. The question is why?

 

[belchfire]

I could only see one of the main gear. My suspicion is that the one in the picture was sheared away from the wreckage and fire damaged areas by contact with the house, hence no dirt or debris on it.

 

[TOOL CRIB]

I thought the gear was on the way back up when they hit?

 

[172driver]

AP on, power back, configuring, slowing, anticipating GS intercept. GS doesn't capture or hasn't yet, deck angle rising, crew realizes they're getting slow, adds power but does not disengage AP and lower nose, stall, spin?

I hope there's more to the story.

 

[Singlecoil]

I wonder if the icing simply served to divert their attention the way it has all of us.
Power levers at idle, aircraft slowing and being configured on speed. Autopilot keeps rolling the trim back to maintain altitude as the aircraft slows until stick shaker. Stick shaker occurs, full power is applied, autopilot kicks off, nose rises steeply as the trim is all the way back with full power, stall occurs, stick pusher shoves the nose down hard.

There have been several instances when I have been the non-flying pilot and thought the autopilot was off because the flying pilot had his hands completely on the controls and was allowing his hands to be moved by them. I could see the FO in this case not being aware the autopilot was on as well.