Wednesday, March 25, 2009

Colgan Air Flt. 3407 crash near Buffalo: New info from NTSB

NTSB logoEarlier today, the U.S. National Transportation Safety Board (NTSB) released new information from their ongoing investigation of last month's crash of a Colgan Air Dash 8-Q400 near Buffalo. Readers will recall that the aircraft, operating as a Continental Connection flight between Newark and Buffalo, crashed during an instrument approach to runway 23 at the Buffalo-Niagara International Airport on February 12, 2009, killing all 49 people on board, and one person on the ground.

We'll get to the new factual information about the aircraft, etc., in a minute, but first, I want to point out something that immediately jumped out at me when I read through today's news release from the NTSB, in which the Board also announced plans to hold a public hearing in Washington regarding this accident. The hearing, which is scheduled for May 12-14, 2009, "will cover a wide range of safety issues including: icing effect on the airplane’s performance, cold weather operations, sterile cockpit rules, crew experience, fatigue management, and stall recovery training," says the NTSB.

Whoa, whoa, whoa! Sterile cockpit rules? What the heck was on that Cockpit Voice Recorder (CVR)? Nothing about the CVR's content -- not even a partial transcript -- has been revealed publicly to date. I can't imagine that they would specifically mention 'sterile cockpit rules' unless there was a reason.

Fatigue management? That phrase gave me a start as well, as did the mention of crew experience and stall recovery training. In fact,I can't help but notice that the "wide range of safety issues" actually is loaded with a wide range of human factors issues. Are you thinking what I'm thinking?

Now, about the aircraft. Today's NTSB update provides the following factual information about Flight 3407:
A preliminary examination of the airplane systems has revealed no indication of pre-impact system failures or anomalies. Investigators will perform additional examinations on the dual distribution valves installed in the airplane’s de-ice system. The de-ice system removes ice accumulation from the leading edges of the wings, horizontal tail, and vertical tail through the use of pneumatic boots. The dual distribution valves, which transfer air between the main bleed air distribution ducts and the pneumatic boots, were removed from the airplane for the examination.

The airplane maintenance records have been reviewed and no significant findings have been identified at this time.

The ATC group has completed a review of recordings of controller communications with the flight crew during the accident flight and conducted interviews with air traffic controllers on duty at the time of the accident. The group has no further work planned at this time.

Further review of the weather conditions on the night of the accident revealed the presence of variable periods of snow and light to moderate icing during the accident airplane’s approach to the Buffalo airport.

Examination of the FDR data and preliminary evaluation of airplane performance models shows that some ice accumulation was likely present on the airplane prior to the initial upset event, but that the airplane continued to respond as expected to flight control inputs throughout the accident flight. The FDR data also shows that the stall warning and protection system, which includes the stick shaker and stick pusher, activated at an airspeed and angle-of-attack (AOA) consistent with that expected for normal operations when the de-ice protection system is active. The airplane’s stick shaker will normally activate several knots above the actual airplane stall speed in order to provide the flight crew with a sufficient safety margin and time to initiate stall recovery procedures. As a result of ice accumulation on the airframe, an airplane’s stall airspeed increases. To account for this potential increase in stall speed in icing conditions, the Dash 8-Q400’s stall warning system activates at a higher airspeed than normal when the de-ice system is active in-flight to provide the flight crew with adequate stall warning if ice accumulation is present.

Preliminary airplane performance modeling and simulation efforts indicate that icing had a minimal impact on the stall speed of the airplane. The FDR data indicates that the stick shaker activated at 130 knots, which is consistent with the de-ice system being engaged. FDR data further indicate that when the stick shaker activated, there was a 25-pound pull force on the control column, followed by an up elevator deflection and increase in pitch, angle of attack, and Gs. The data indicate a likely separation of the airflow over the wing and ensuing roll two seconds after the stick shaker activated while the aircraft was slowing through 125 knots and while at a flight load of 1.42 Gs. The predicted stall speed at a load factor of 1 G would be about 105 knots. Airplane performance work is continuing.
Further to the crew issues, the NTSB said:
Since returning from on-scene, the Operations & Human performance group have conducted additional interviews with flight crew members who had recently flown with and/or provided instruction to the accident crew, as well as personnel at Colgan Air responsible for providing training of flight crews and overseeing the management and safety operations at the airline. The group also conducted interviews with FAA personnel responsible for oversight of the Colgan certificate, which included the Principal Operations Inspector (POI) and aircrew program manager for the Dash 8 Q-400. The team has also continued its review of documentation, manuals, and other guidance pertaining to the operation of the Dash 8 Q-400 and training materials provided to the Colgan Air flight crews.

The Operations & Human Performance group continues to investigate and review documentation associated with the flight crew’s flight training history and professional development during their employment at Colgan as well as prior to joining the company.
By the way, there was some good news about the crew. Toxicology reports were negative for alcohol and illicit drugs for both pilots.

RELATED: Click here to view all posts about Colgan Air Flt 3407 on Aircrew Buzz.