NTSB Identification: WPR09IA065
Scheduled 14 CFR Part 121: Air Carrier operation of Alaska Airlines
Incident occurred Wednesday, December 24, 2008 in Seattle, WA
Probable Cause Approval Date: 12/15/2009
Aircraft: BOEING 737-890, registration: N516AS
Injuries: 141 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

Airline personnel reported that the airplane pushed back from the gate with the auxiliary power unit running. As the push back sequence was completed, two deicing vehicles began deicing operations prior to the flight crew configuring the airplane for deicing. Shortly after, the cabin and flight crew noticed fumes within the cabin and cockpit area. The flight crew instructed the deice crew to discontinue deicing operations and the flight crew performed the smoke removal checklist as the deicing operation stopped. The flight crew started both engines and taxied back to gate N14 where the passengers and flight crew exited the airplane via the jet way. The captain reported that he did not clear the ground deicing crew to start their deicing operations. The driver of the primary deicing vehicle reported that he informed the flight crew of the fluid types, freeze points, and concentrations. He added that there was a lot of "radio chatter" and the bucket operator began deicing operations "after we received no objections" from the flight crew. Company deicing procedures state, in part, "prior to fluid application, Ground Deicing Crew member shall confirm with Flight Crew that the aircraft is configured for deicing." The flight crew gate deicing checklist states that the APU and engine bleed air switches are to be turned off prior to deicing. At the time, the APU and engine bleed air switches were still in the ON position when deicing fluid was sprayed on the airplane. This allowed the fluid to be introduced into the air supply lines leading to the cabin and cockpit.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

The failure of the deicing crew to follow company procedures by not receiving confirmation from the flight crew before beginning to deice the airplane.

Full narrative available

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