Boeing 737-322 N371UA

Summary

On 2 September 1999 at about 21:06 local time, a Boeing 737-322 registered N371UA, operated by United Airlines, Inc., was involved in an accident near Santa Barbara, California, United States. 113 people were on board and one was seriously injured, 14 had minor injuries. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

2 September 1999 at 21:06

Classification

Accident

Location

Santa Barbara, California, United States

Coordinates

Not recorded

Aircraft

Boeing 737-322

Registration

N371UA

Category

Airplane

Engines

2

Operator

United Airlines, Inc.

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Los Angeles → San Francisco

Aircraft damage

Minor

Weather

VMC

Light

Day

NTSB number

LAX99LA291

1 person was seriously injured.

The flight's encounter with wake vortices from a preceding heavy aircraft.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The flight had just leveled off at flight level 240 with the autopilot still engaged. The seat belt sign had been off for about 5 minutes, and the cabin crew was in the process of preparing a beverage service. The airplane was crossing a VORTAC when the flight encountered turbulence the crew categorized as 'severe,' with a rapid right roll and pitch excursion. The captain disconnected the autopilot and attempted to counter the excursions with control inputs. As a result of the aircraft motions, 1 flight attendant sustained serious injuries, and another flight attendant and 13 passengers sustained minor injuries. The airplane sustained minor damage, limited primarily to ceiling tiles and seats. A review of the meteorological data showed no evidence of any atmospheric phenomena in the area. A simulation study comparing the known airplane response to control inputs versus the motion of the airplane as recorded on the DFDR data showed that the flight controls alone did not cause the recorded motion of the airplane. Radar data established that the flight was in trail of a MD-11 by 11.5 nmi and 97 seconds when the upset occurred. The MD-11 had climbed through the flight's cruise altitude and was 600 feet above the flight at the time of the encounter. Wake vortex studies by NASA have documented vortex descent rates between 270 and 440 feet per minute.

Quoted verbatim from the NTSB record.