This post is no judgement but expresses personal views about the CVR transcripts of Colgan flight 3407 which crashed near Buffalo. The investigation is not yet completed and the causes have not been established. There are however certain relevant points in these transcripts. This post focuses on the last seven minutes.
22:09:12: ATC clears Colgan 3407 down to 4’000 feet. The approach procedure for ILS 23 is started and “sterile-cockpit” rules shall apply. This means focusing on the approach to the exclusion of any other topic. No private conversations, no disturbance of any kind.
22:10:22: First mention of visible ice on the windshield.
22:10.57: The crew discusses about career and training.
22:11:39: The discussion goes on about experience.
22:12:05: The co-pilot is talking about ice again: “I’ve never seen icing conditions. I’ve never deiced. I’ve never seen any— I’ve never experienced any of that. I don’t want to have to experience that and make those kinds of calls. you know I’dve freaked out. I’dve have like seen this much ice and thought oh my gosh we were going to crash”
Reading from a transcript and hearing a person you work with is different and it’s hard to judge about the tone, but these remarks should have helped to re-focus the discussion on the present icing situation.
22:12:37: The Captain continues the previous discussion: “yeah uh I I spent the first three months in uh Charleston West Virginia and
uh flew…”
There is no further mention of ice, the conversation continues and the approach goes on normally. The transcript mentions “sounds similar to power increase” a couple of times. There is no mention of low speed or high pitch from the crew.
22:16:21: The crew extends the landing gear.
22:16:23: The Captain calls for flaps and before landing checklist. The approach seems to unfold in a perfectly normal way.
22:16:27: The CVR records the sound of the stick shaker for 6.7 seconds. This is a safety mechanism which alerts the crew about a too low speed and risk of stall. Almost at the same time, the auto-pilot disconnect alert sound is recorded, which lasts until the end of the recording.
22:16:35: The sound of the stick-shaker starts again, and is present until the end of the recording.
22:16:46: The co-pilot suggests to retract the gear and the Captain requests it.
22:16:53: End of recording.
The stick shaker is a quite aggressive mechanism, and it can hardly go unnoticed. This aircraft was also equipped with a second level of safety mechanism, known as stick pusher. If a stall occurs this mechanism pushes the control column to lower the aircraft’s nose and regain some speed. The transcripts makes no mention of it. Transcriptions of the flight data recorder (FDR) are not yet available but a lot of discussions are going on. It *seems* (read: not confirmed) that the Captain counter-acted the stick pusher, but this is both hard to do and to understand.
These transcripts raise many questions regarding the level of training and experience of the crew. I wrote questions and not that they were not up to the tasks. The particular environment in this cockpit could also be discussed but none of the crew survived and even CVRs can’t recreate the working atmosphere. I’m writing very carefully because I don’t have the competence to issue any judgment and I have only partial information. What I try to do here is to identify interesting points to be discussed, and to share the information I have. As always, any comment is welcome
On the same topic, Sam from FL250 wrote an interesting post, already on the 10th of May. He also posted later on with some details from the FDR.
The present post has also been indirectly fed by Twitter discussions between @TheGimliGlider (including a NASA video about tailplane icing, you can also check his blog) and @mickyl, who also posted on the same topic on her blog and also about Dash8, icing and autopilot.
Once again, this post only aims at highlighting interesting points, not to charge or blame anyone. Many pilots and aviation enthusiasts discuss this accident. Such discussions (particularly when incorrectly relayed by mainstream media) may seem cold and disrespectful to the victims, but their sole goal is to learn from this accident and improve the system. As always, any comment is welcome… as long as it goes in this direction. This accident is before all a human catastrophe for the victims (incuding the crew), their families and their relatives. Any disrespectful comment will be deleted.
{ 4 comments… read them below or add one }
Yes it’s totally understood that you’re just highlighting significant events that took place in the last 7 minutes of the flight and that you’re not blaming anything on anyone and it’s evident.
Thanks for explaining the difference between Stick-Shaker and Stick-pusher and what they do. i was having trouble with that.
http://www.twitter.com/mickyl ‘s blog can be found at http://comeletsflyaway.blogspot.com/ if you’re interested in adding that url to this blog post. Her blog is worth much more than mine given the qualification she possesses
@TheGimliGlider: thank you for the link to mickyl’s post. I updated and copied the link in my post. Regarding the stick pusher, I really look forward to the official report or any official intermediate update.
I’m not a pilot but I read the NTSB CVR Factual Report transcript. My dad was an Air Force Aircraft Accident Investigator and Editor-in-chief of the MAC Flyer USAF Flying Safety magazine, and I recall him telling me never to adjust my car’s seat while I was driving, and that it was particularly dangerous for pilots.
I noticed from the transcript that the Capt. adjusted his seat about 2 minutes before all hell broke loose, and just after they lowered the flaps.
I wonder if the Capt’s seat was not securely locked in place, and began sliding when he began to actively fly the plane, causing him to inadvertently pull on the yoke, causing the steep pitch up, causing the stall, causing the spin, causing the crash.
Have the investigators checked to see if the Capt’s seat was locked?
Ron, you make a good point. I don’t know about the Dash-8 seats, but the Airbus ones in example are electrically operated, so there is no way they could be unlocked. Adjusting the seat position while flying is may be not the best thing to do, but things are a bit different in the airline context. I don’t think the captain was at the controls at the moment he adjusted his sea: the autopilot was probably engaged or the co-pilot was flying. In these cases, adjusting a seat is no problem.