By Robert Sumwalt
In June, the Board deliberated a runway overrun involving an American Airlines B-757 at Jackson Hole, WY. Fortunately, about the only thing hurt during the accident were the egos of the two pilots. Setting the stage for the incident were two separate and unrelated mechanical issues: the speedbrake did not automatically deploy, and the thrust reversers did not initially deploy when commanded. Although the speedbrake could have been deployed manually, this was not done – perhaps because both pilots now were engrossed with trying to deploy the thrust reversers.
At the end of the NTSB board meeting, the Board concluded the probable cause of the incident was a “manufacturing defect in a clutch mechanism that prevented the speedbrakes from automatically deploying after touchdown and the captain‘s failure to monitor and extend the speedbrakes manually. Also causal was the failure of the thrust reversers to deploy when initially commanded. Contributing to the incident was the captain‘s failure to confirm speedbrake extension before announcing their deployment and his distraction caused by the thrust reversers’ failure to initially deploy after landing.”
One learning point is that the captain called out “deployed” for the speedbrake and “two in reserve,” without actually verifying their deployed status. The NTSB concluded that “the captain’s erroneous speedbrakes ‘deployed’ callout was likely made in anticipation (not in confirmation) of speedbrake deployment after he observed the speedbrake handle‘s initial movement; after the ‘deployed’ callout was made, both pilots likely presumed that the reliable automatic speedbrakes were functioning normally and focused on the thrust reverser problem.”
In essence, he was looking but not seeing.
I suspect somewhere in my three decades of flying, I probably made the mistake of looking at something but not really seeing what I thought I was looking at.
Have you ever done that?
The NTSB has seen this in other accidents, as well. In the fatal July 2008 runway overrun accident involving a Hawker 800 at Owatonna, MN, the first officer called out “we’re dumped” to indicate the liftdump had deployed upon landing. Although he immediately corrected himself and said “we’re not dumped,” his initial callout was made in anticipation of the liftdump system activating, not by actually verifying it. The NTSB stated “the first officer most likely stated ‘we’re dumped’ as an automatic callout upon landing when he saw the captain move the airbrake handle aft” without actually verifying the deployment of the liftdump system (underlining for emphasis).
Another case of looking but not seeing occurred in 1988 when a Delta 727 crashed following an ill-fated no-flap takeoff attempt at Dallas-Fort Worth. When the second officer called out “flaps” on the taxi checklist, the first officer quickly replied “fifteen, fifteen, green light” – the standard takeoff flap setting for the 727. The physical evidence indicates that the flaps were retracted and not set for takeoff as stated by the first officer. The NTSB found that “because of the repetitive nature of checklist accomplishments, it is not uncommon for crewmembers to fall into a habit of answering to challenges by rote with the normal response without actually observing the appropriate indicator, light or switch… This can be particularly true if the respondent has a mindset that the action necessary to satisfy the indicator checklist has been completed.”
So, what have we learned from these accidents and incidents? Make sure what you are looking at is actually what you are seeing.
What measures can you take to make sure you not falling into the trap of looking but not seeing?
Robert L. Sumwalt was sworn in as the 37th Member of the National Transportation Safety Board on August 21, 2006. He is a frequent contributor to the NTSB blog.