Accident McDonnell Douglas MD-83 N943AS,
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Date:Tuesday 25 December 2007
Time:10:18 LT
Type:Silhouette image of generic MD83 model; specific model in this crash may look slightly different    
McDonnell Douglas MD-83
Owner/operator:Alaska Airlines
Registration: N943AS
MSN: 53018
Total airframe hrs:55606 hours
Engine model:Pratt & Whitney JT8D
Fatalities:Fatalities: 0 / Occupants: 114
Aircraft damage: None
Category:Accident
Location:Ontario, CA -   United States of America
Phase:
Nature:Passenger - Scheduled
Departure airport:Seattle/Tacoma International Airport, WA (SEA/KSEA)
Destination airport:Ontario International Airport, CA (ONT/KONT)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
Two flight attendants were seriously injured when the airplane encountered severe turbulence while descending for landing. The turbulence was likely the result of strong easterly winds interacting with the rough terrain in the area (mechanical turbulence). The flight data recorder data indicates that the airplane experienced a vertical acceleration of 0.4 G to 1.9 G, or 1.5 G total change, which corresponds to severe turbulence. The National Weather Service forecast the severe turbulence in Significant Meteorological Advisory (SIGMET) Victor 2, which was issued before the flight departed. The weather company that provides weather information to the operator did not forecast severe turbulence for the area. The content of SIGMET Victor 2 was available to the flight's dispatcher. However, this information was not provided to the flight crew. The two flight attendants who sustained injuries were both standing, completing final cabin duties in preparation for landing, and were knocked to the floor during the turbulence encounter.

Probable Cause: The lack of turbulence forecasts available to the flight crew, which resulted in the flight attendants not being seated when the flight encountered severe terrain-induced turbulence. Contributing to the accident were the terrain-induced turbulence, the failure of the company that provided the flight's weather briefing to forecast severe turbulence, and the failure of the dispatcher to provide the National Weather Service severe turbulence forecast to the flight.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: SEA08LA050
Status: Investigation completed
Duration: 1 year
Download report: Final report

Sources:

NTSB SEA08LA050

Location

Revision history:

Date/timeContributorUpdates
25-Mar-2024 08:29 ASN Update Bot Added

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