Boeing 777-223 N766AN

Summary

On 11 April 2011 at about 07:00 local time, a Boeing 777-223 registered N766AN, operated by American Airlines Inc, was involved in an accident near Pacific Ocean, United States. 231 people were on board and 2 were seriously injured, 2 had minor injuries. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 April 2011 at 07:00

Classification

Accident

Location

Pacific Ocean, United States

Nearest airport

Narita International Airport (NRT)

Coordinates

35.8933, 143.8717

Aircraft

Boeing 777-223

Registration

N766AN

Category

Airplane

Engines

2

Operator

American Airlines Inc

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

Narita → Los Angeles

Aircraft damage

Not recorded

Weather

VMC

Light

Day

NTSB number

WPR11LA203

2 people were seriously injured.

An inadvertent encounter with convective-induced turbulence upon entering cumulonimbus clouds.

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

Read the full NTSB narrative

As the airplane was climbing, the flight crew observed a small weather buildup in front of them. They requested a deviation around the weather, but the air traffic controller requested that they stand by. After entering the weather, they received clearance to turn; however, about 24,000 feet, the airplane encountered about 11 seconds of moderate, and then severe, turbulence. During the encounter, two flight attendants received broken ankles while conducting work in the aft cabin area. The digital flight data recorder revealed that during the encounter vertical acceleration forces went from 2.2G to 0.6913G within 1 second, to a minimum of 0.496G about 5 seconds after the 2.2G maximum. A weather study conducted by a National Transportation Safety Board meteorologist revealed a frontal wave over the Japanese coast with a warm front extending eastward in the vicinity of the turbulence encounter. A gale force wind was expected. The region of the turbulence encounter also contained low to mid-level clouds with cloud tops near 14,000 feet; cumulonimbus cloud development, with tops up to 26,000 feet, was slightly upstream from the turbulence encounter. Review of the weather package given to the flight crew found no forecasts for turbulence and no Significant Meteorological Information advisories (SIGMETS) were in effect for the route of flight. At the time of the occurrence, there were no reports of turbulence from pilots ahead of the accident flight and the flight crew saw no indication of turbulence on their weather radar.

Quoted verbatim from the NTSB record.