Individually Owned: 150,657
Corporate Owned: 137,281
Narita International Airport
Aircraft Accident/Incident Report
Pacific Ocean, --
Monday, April 11, 2011 7:00 UTC
NTSB Narrative Summary Released at Completion of Accident
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.
NTSB Probable Cause Narrative
An inadvertent encounter with convective-induced turbulence upon entering cumulonimbus clouds.
Event Information
| Type of Event | Accident |
| Event Date | 4/11/2011 |
| Event Day of the Week | Monday |
| Time of Event | 700 |
| Event Time Zone | Coordinated Universal Time? Same as GMT |
| Event City | Pacific Ocean |
| Event State | -- |
| Event Country | -- |
| Zipcode of the event site | -- |
| Event Date Year | 2011 |
| Event Date Month | 4 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 355336N |
| Event Location Longitude | 1435218E |
| Event Location Airport | Narita International Airport |
| Event Location Nearest Airport ID | NRT |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 194 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 141 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Pilot |
| Time of the weather observation | 630 Coordinated Universal Time? Same as GMT |
| Direction of event from weather observation facility (degrees) | 267 |
| Weather Observation Facility ID | NRT |
| Elevation of weather observation facility | 141 |
| Distance of event from weather observation facility (units?) | 194 |
| Time Zone of the weather observation | UTC |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 3000 |
| Sky/Lowest/Cloud Conditions | Few |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 25 |
| Air Temperature at event time (in degrees celsius) | -38 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | 245 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 65 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Serious |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | 2 |
| Injury Total None | 227 |
| Injury Total Serious | 2 |
| Injury Total All | 4 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 29089 |
| NTSB Notification Source | NTSB Operations Center |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Oct 21 2011 8:44PM |
| User who most recently changed record | stam |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N766AN |
| NTSB Number | WPR11LA203 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | Yes |
| Damage | None |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BOEING |
| Aircraft Model | 777-223 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 32880 |
| Certified Max Gross Weight | 648000 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | 4 |
| Cabin Crew Seats | 12 |
| Passenger Seats | 247 |
| Total number of seats on the aircraft | 263 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | 33558 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | Unknown |
| Aircraft Owner Name | AMERICAN AIRLINES INC |
| Aircraft Owner Street Address | 4333 AMON CARTER BLVD MD 5569 |
| Aircraft Owner City | FT WORTH |
| Aircraft Owner State | TX |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 76155 |
| Operator is an individual? | No |
| Operator Name | AMERICAN AIRLINES INC |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | 4333 AMON CARTER BLVD MD 5569 |
| Operator City | FT WORTH |
| Operator State | TX |
| Operator Country | USA |
| Operator Zip code | 76155 |
| Operator Code | AALA |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Scheduled |
| Indicates Domestic or International Flight | International |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | -- |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | NRT |
| Departure City | Narita |
| Departure State | -- |
| Departure Country | JA |
| Departure Time | 625 |
| Departure Time Zone | UTC |
| Destination Same as Local Flt | -- |
| Destination Airport Code | LAX |
| Destination City | Los Angeles |
| Destination State | CA |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Oct 21 2011 8:44PM |
| User who most recently changed record | stam |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |