Colgan Air has submitted a report to the US National Transportation Safety Board saying it believes the fatal 12 February crash of one of is Bombardier Q400s was the result of a loss of situational awareness by pilots. Their failure to follow company procedures then led to loss of control, says Colgan.
The accident occurred as the aircraft was approaching Buffalo airport en route from Continental's Newark hub.
Subsequent NTSB hearings triggered scrutiny of US regional airline operations when questions arose over pilot training quality, extensive pilot commuting before duty, and fatigue.
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© PA photos |
The airline also notes that an NTSB simulation in a Q400 simulator demonstrated that if the accident flightcrew had performed according to Colgan training, the stall would have been avoided.
The Air Line Pilots Association (ALPA) notes the Q400 does not have a minimum manoeuvring low speed alert, which the union says would have provided the crew with an additional visual or aural warning of the aircraft's rapid deceleration.
ALPA says the only low-speed warning on the Q400 is on the airspeed display. The association comments: "Once the airspeed reaches that cue, the autopilot will disconnect and the stickshaker will activate, potentially leading to a surprised crew needing to handle an emergency situation."
ALPA believes Colgan's training was inadequate, arguing the airline's use of a NASA icing awareness video illustrating tailplane stall was misleading on its own, explaining: "There was no discussion of the fact that a stickshaker is only indicative of a wing stall, not a tailplane stall."
The aircraft was operating in icing conditions from shortly after take-off until the accident on final approach, says Colgan. ALPA says that Bombardier has added a new element to the Q400's stall protection system called the reference speeds switch, which is used when operating in icing conditions.
The switch is designed to increase the airspeeds at which the stickshaker and stickpusher are activated, by reducing the angle of attack threshold for stickshaker activation.
Colgan states the crew selected the reference speeds switch to the correct position for icing. The airline says that, ultimately, the stickshaker activated at a higher speed than was set, "which most likely surprised the crew". Bombardier was not immediately available for comment regarding Q400 speed alerts.
The carrier also highlighted "non-pertinent" conversation between the pilot and first officer on approach, reporting: "The accident crew flightcrew violated Colgan Air policy and FAA regulations by breaking sterile cockpit [procedure] during the descent to Buffalo."
Source: Flight International
