Colgan 3407 Down in Buffalo

[LowlyPropCapt]

I agree either lots of toilet paper or a clean break is the only way to go! :laugh:


not picking on you cornholio just saw an opportunity to lighten the mood a little with my strange sense of humor.......

Got a little beer on my keyboard with that one. Nice comic relief!

You can send my new keyboard to SBY, care of Chief Pilot Shirl.

 

[Captzaahlie]

Got a little beer on my keyboard with that one. Nice comic relief!

You can send my new keyboard to SBY, care of Chief Pilot Shirl.

I was cleaning up my den the other day and came across two of them not being used.

I think I still have your latest address and phone number, let me know and I'll send you an old keyboard...... send postage and a case of beer first though! (just to verify the correct address).

 

[surplus1]

It really isn't true that 'bridging' doesn't exist. That depends on the design of the airfoil and the boot.

On older aircraft with 'thick' wings bridging is quite possible.

On modern thin-wing (higher speed airfoil) aircraft with new technology boots bridging does not occur.

One must use the procedures that apply to the type of aircraft/airfoil being flown.

 

[goodgig]

when the NTSB releases the investigation results I am going to relink that thread to my original post. You will all see that I am 100% accurate.
Have a nice day! And believe what you want, I KNOW the truth and having nothing to lose by "leaking" it.

So, does the microsoft flight sim for the dash have a wing heat switch?

 

[great cornholio]

I agree either lots of toilet paper or a clean break is the only way to go! :laugh:


not picking on you cornholio just saw an opportunity to lighten the mood a little with my strange sense of humor.......

I have the same messed up sense of humor. I thought that was pretty classic. And thought it was a nice change of pace to bring some happiness to a sad conversation and did so without disrespecting the crew or pax.

 

[surplus1]

Just want to make sure I got this right. To counteract a stall of the tailplane, one has to pull back on the yoke (according to the video).

You got that right.

Now, the NTSB is saying that the stick shaker and STICK PUSHER activated shortly before impact. Seems to me there's a flaw in the design. Why would anyone want to have to fight a stick pusher during a tailplane stall, when the proper reaction is to pull back?

You’re thinking and the thinking is good. One would not want to fight a pusher during a tailplane stall – but one might have no choice.. Now lets think some more with relation to the specific accident and see if you can answer your own question..

Hypothetical Scenario

The aircraft is approaching the terminal area. The pilot requests a descent to 6000 ft and is cleared. During the descent the aircraft enters icing conditions. Anti-ice and de-ice systems are activated (correctly) and are functioning (assumed – we don’t know yet).. The crew observes ice accretion and comments about it.; confirms that anti/de-ice is on. Shortly thereafter the aircraft is cleared to 4000 ft and then to 2300ft and for the approach. The aircraft is being flown by the auto pilot.

During the descent from 4000 to 2300 the aircraft enters a localized zone of heavy icing. The aircraft reaches 2300 ft shortly before the outer marker. Altitude is captured and held by the auto pilot. The leading edges are relatively clear of ice – boots working – but a great deal of ice has been accumulated on un-protected areas and behind the boots (due to run-back or flow-back). The crew cannot see this ice and is unaware of its existence. It is both snowing and raining and the temperature is below freezing. The weight of the aircraft has also increased significantly above the calculated landing weight – due to the ice accretion. There is some SLD in the area the aircraft is crossing. The ice accretion is mixed (some rime, some clear).

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).

Unknown to the flight crew, the AOA on both the horizontal stabilizer (neg.) and the wing are each very close to critical. There is turbulence and the yoke is moving back and forth quite a bit. Subconsciously the yoke movement is attributed to the turbulence – but its actual cause is tailplane icing. Glide slope captures and the captain commands “approach flaps” (whatever that might be). The auto pilot is still flying – this is a coupled approach.

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.

The aircraft breaks out – perhaps a bit earlier. Wings are now level but sink rate is 2500 fpm or more. The pilot is still flying but now sees the terrain. Both pilots pull as hard as they can. The aircraft flattens in pitch and strikes the terrain in a level attitude with an extremely high sink rate.

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.

Fate is the Hunter.

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

Probable cause? Draw your own conclusions. The above scenario is only hypothetical.

 

[Captzaahlie]

You got that right.



You’re thinking and the thinking is good. One would not want to fight a pusher during a tailplane stall – but one might have no choice.. Now lets think some more with relation to the specific accident and see if you can answer your own question..

Hypothetical Scenario

The aircraft is approaching the terminal area. The pilot requests a descent to 6000 ft and is cleared. During the descent the aircraft enters icing conditions. Anti-ice and de-ice systems are activated (correctly) and are functioning (assumed – we don’t know yet).. The crew observes ice accretion and comments about it.; confirms that anti/de-ice is on. Shortly thereafter the aircraft is cleared to 4000 ft and then to 2300ft and for the approach. The aircraft is being flown by the auto pilot.

During the descent from 4000 to 2300 the aircraft enters a localized zone of heavy icing. The aircraft reaches 2300 ft shortly before the outer marker. Altitude is captured and held by the auto pilot. The leading edges are relatively clear of ice – boots working – but a great deal of ice has been accumulated on un-protected areas and behind the boots (due to run-back or flow-back). The crew cannot see this ice and is unaware of its existence. It is both snowing and raining and the temperature is below freezing. The weight of the aircraft has also increased significantly above the calculated landing weight – due to the ice accretion. There is some SLD in the area the aircraft is crossing. The ice accretion is mixed (some rime, some clear).

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).

Unknown to the flight crew, the AOA on both the horizontal stabilizer (neg.) and the wing are each very close to critical. There is turbulence and the yoke is moving back and forth quite a bit. Subconsciously the yoke movement is attributed to the turbulence – but its actual cause is tailplane icing. Glide slope captures and the captain commands “approach flaps” (whatever that might be). The auto pilot is still flying – this is a coupled approach.

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.

The aircraft breaks out – perhaps a bit earlier. Wings are now level but sink rate is 2500 fpm or more. The pilot is still flying but now sees the terrain. Both pilots pull as hard as they can. The aircraft flattens in pitch and strikes the terrain in a level attitude with an extremely high sink rate.

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.

Fate is the Hunter.

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

Probable cause? Draw your own conclusions. The above scenario is only hypothetical.

Good description and again why I never liked the auto pilot on approaches..... gusty or icy.

Calm , down to tiny rvr numbers, and very early in the morning before I had that sixth cup of coffee.... I loved the A/P.

Watching a newbie watch the auto pilot control (?) the A/C on a really gusty day always made me silently groan. ( i feel better now thanks... Once again, good description on your post :beer: )


moms calling me I better go to bed...

and only 9000 more posts to go to catch Genital Lee!

 

[great cornholio]

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.

Forget where I heard it, and it might not even be true, but from what I heard time from gear down till impact was just about 1 min. Time from initial wobble at beginning of the upset to impact approx 04 as in 1...2...3...4 seconds.

 

[EdAtTheAirport]

Tail Stalls: I am not an aero engineer, nor did I watch the video, but but I have experienced a tail stall in icing conditions in the BA31. Actually it was three stalls, much like a PIO porpose. We were trying to climb with fairly good airspeed (the low end of what would be "normal"). The tail stalled, nose immediately dropped due to reduced "lift" from the tail. (I felt the yoke go dead in my hand in a way that you don't feel during a wing stall). My instinct was to reraise the nose; stalled again. Two more times, until I finally gave up on trying to climb. It took like 5 seconds for these three cycles. (15,500' BTW).

The tail is mounted upside down. It "lifts" downward and raises the nose. If the tail stalls, the nose drops, reducing both tail and wing AOA. (The Ercoupe was designed with a limited amount of tail lift/ up elevator, so that there would never be a wing stall.) BTW a stick pusher would lower the AOA of both the wings and the tail simultaneously.

But since they got a stick pusher, it would seem that this does not have much to do with tail stalls anyway, since I doubt that the stall warning system is tied to tail AOA.

The real question, with what was revealed today, is why did the shaker/pusher activate? Can it sense airflow disruption due to icing? What activates it in the Q, exactly? Anybody?

 

[Flyin2low]

Look at my post (138) and you will find the answer. I'm sure icing had something to do with it as well.