Colgan 3407 Tailplane Icing?

[Lucas]

While I am not usually one to speculate about the cause of an airplane crash so many factors seem to point to tailplane icing. It looks like some information was released by the NTSB describing communication in the cockpit regarding ice buildup. 60 seconds before the crash landing gear was lowered, 15 second later flaps 15 were selected. Seconds later the plane experienced severe pitch and roll excursions. The crew was in the process of undoing the previous configuration changes when they impacted the terrain.

This video goes in depth describing tailplane icing-it is very interesting.
https://video.google.com/videoplay?docid=2238323060735779946

3407 ATC
https://event.liveatc.net/kbuf/KBUF-Feb-13-2009-0300Z.mp3

 

[user 13]

It seems that Icing will play some role in this accident, but it's been my experience that first calls are often incomplete, and incorrect. The NTSB is very good at finding out what went wrong.

I believe they have the FDR and CVR, Hopefully the can pull some information from the flight management computer memory.

 

[AKPilot]

The most important issue regardless of public/press percptions, the NTSB (sometimes delegated to the FAA) will get to the bottom is "why" it happened - not "what" happened. Sometimes people forget this.

For example, if it comes out the icing was "a" factor the question would still remain as to "why" it happened. Was the place deiced too soon, or was it deiced at all? And if it was too soon, or wasn't at all - why? Was there a delay in the system, were people too lazy, did the crew just call it off? And then why, again.

Using the 5-why theory, they'll find the first broken link in the chain.

 

[user 13]

Here is some more information:

https://www.flightglobal.com/articl...-aircraft-appears-to-have-landed-in-flat.html


It appears the flight was in a full stall/flat spin. It came in flat. Notice the small debris field. This supports the flat spin.

Once ice starts building bad things can happen fast. I have never flown a dash 8
but I have a few years flying a Shorts 330. Once while flying over England, we had the gear down for a maintenance ferry. We ran into some icing. Everything was great for about 4 min. We were controlling the wing/tail ice with the boots, but the gear was picking up ice. As the weight of the ice increased the autopilot started to increase the pitch of the aircraft to compensate. This exposed the underside of the aircraft to the ice. The entire
underside immediately iced over. The weight/drag made it impossible maintain altitude. We had to start a controlled decent to warmer air. We
started at 10000ft and ended at 4000ft. This was with moderate to heavy icing. I have no idea if anything like this happened to flight 3407 but it gives
an idea of how fast bad things can happen.

 

[user 13]

This just in from a large airlines safety department:


"Information has been received indicating it is possible to obtain a significant nose pitch up, in some cases as much as 30 degrees, if the glide slope is allowed to capture before established on centerline.

Pilots who are preparing to configure and land have the potential to experience abrupt pitch up, slow airspeed, and approach to stall if conditions present themselves in a certain manner.

This effect is the result of an earthen obstruction close enough to the ILS to affect the integrity of the glide slope signal. This has resulted in the issuance of an advisory given on ATIS which states that "the ILS Glide Slope for runway 23 is unusable beyond 5 degrees right of course." When attempting to intercept the runway 23 ILS from right traffic, the ILS glide slope indication may read full deflection down. Just prior to intercept it may then move up in such as manner as to enable approach mode to capture in such a way as to result in a nose up pitch and loss of airspeed.

XXXXXX Airlines has issued a notice reading: "Until further notice, when executing the KBUF ILS/LOC Runway 23, DO NOT select Approach Mode until established on the localizer inbound.""

No information that this is what happened to the -8, but interesting.