American B772 over Pacific on Dec 16th 2014, turbulence injures 12

Last Update: March 31, 2016 / 16:29:44 GMT/Zulu time

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Incident Facts

Date of incident
Dec 16, 2014

Classification
Accident

Cause
Turbulence

Airline
American Airlines

Flight number
AA-280

Departure
Seoul, South Korea

Destination
Dallas Ft. Worth, United States

Aircraft Registration
N751AN

Aircraft Type
Boeing 777-200

ICAO Type Designator
B772

An American Airlines Boeing 777-200, registration N751AN performing flight AA-280 from Seoul (South Korea) to Dallas Ft. Worth,TX (USA) with 240 passengers and 15 crew, was enroute at FL340 at around 13:00Z about 2 hours into the Pacific crossing northeast of Japan when the crew decided to turn around and divert to Tokyo's Narita Airport (Japan) after having encountered turbulence causing injuries to 12 people on board. The aircraft landed safely at Narita Airport about 2.5 hours later. One cabin crew and a passenger received serious, two cabin crew and eight passengers received minor injuries. The injured were taken to hospitals.

Japan's Ministry of Transport reported 10 passengers and 4 crew received injuries believed to be minor.

Passengers reported the upset involving several serious terrifying bumps lasted for about 45 seconds, loose items went flying within the cabin and impacted the cabin ceiling.

On Dec 18th 2014 Japan's TSB reported the aircraft was maintaining 8200 meters/FL270 out of Seoul, when in the "sky between Ishikawa and Ibaraki Prefecture" just about northwest of Tokyo, the aircraft experienced an upset. Later the aircraft changed destination to divert to Tokyo Narita, where the aircraft landed on Dec 17th 00:55L (Dec 16th 15:55Z) about 6.5 hours later. 3 cabin crew received injuries, one of them a left should fracture (serious injury), 9 passengers received injuries, one of them a cervical spinal fracture (serious injury). An investigation has been opened.

Radar data show the aircraft climbed to FL270 initially reaching FL270 about 50nm east of Seoul, still over South Korea, and continued at FL270 over a distance of about 600nm until about 70nm north of Tokyo, when the aircraft climbed to FL340. While overflying the mountain ridge at Nagano (Japan) at FL270 at approximately 10:27Z (19:27L) the radar data show the aircraft at 27050 and 26950 feet, while otherwise the aircraft showed altitudes consistently between 26975 and 27000 feet. At about 10:37Z the aircraft left FL270 to climb to FL340.

On Mar 31st 2016 Japan's TSB released their final report concluding the probable cause of the accident was:

In this accident, it is probable that the aircraft was fiercely shaken because it unexpectedly penetrated the airspace with CAT, causing the passenger and the cabin attendant were seriously injured.

It is probable that the unexpected penetration to the airspace with CAT was because the PIC and the dispatcher could not predict the occurrence of the CAT which could interfere with the flight, this is because it is somewhat likely that the method for utilization of weather information in the Company was involved.

The JTSB reported the aircraft had levelled off at FL270 initially after departure. The automation was engaged, and the fasten seat belt signs were turned off. The captain (60, ATPL, 28,395 hours total, 1,297 hours on type) noticed however, that the thrust levers were pulled back by the autothrust system, which is a common prerequisite of turbulence encounters, and turned the fasten seat belt signs on again. About 13 minutes later the aircraft was cleared to climb to FL340 and was climbing between FL270 and FL290 about north of Tokyo when the aircraft encountered severe clear air turbulence producing vertical accelerations between +1.8G and -0.88G, with just thin clouds visible outside and no radar returns being painted by the weather radar. The turbulence caused serious injuries to a passenger and a flight attendant as well as minor injuries to 8 passengers and 2 flight attendants. The turbulence continued for the next 20 minutes with decreasing tendency as the aircraft climbed, with the flight crew attempting to get cleared for an even higher flight level. About one hour after the onset the aircraft, now enroute at FL350, entered calmer air and the turbulence subsided. About 94 mintes after the onset of the severe turbulence encounter the crew decided to divert to Tokyo, requested priority and medical services to meet the aircraft upon landing.

The JTSB reported a severe turbulence warning was issued by Japan's Met Office for the time of the flight expanding from FL260 to FL340 and included area that the flight was planned to still remain at FL270, this weather warning however was not used by the airline. The used information included a severe turbulence forecast for FL260-FL340 as well. However, neither dispatcher nor crew recognized from this information that the area of severe turbulence up to FL340 expanded into that segment of flight at FL270 and believed, that the aircraft would avoid that area of turbulence by climbing at FL350 later on. Quite the opposite, the captain in preparing the flight believed the flight's trajectory would result in a smooth flight.

In addition, the captain continued to maintain FL270 past the planned point of climb to FL350 as the flight so far had been entirely smooth.

The JTSB analysed: "It is probable that the aircraft was flying to glaze thin clouds near the top of the cloud over Japan. In addition, according to the ground weather radar, there was developed cloud near the point where the aircraft encountered the fiecre shake. However, the clouds at the flight altitude were weak in rainfall intensity and there was no cloud which can cause big shake on airborne radar display of the aircraft. However, it is probable that these were thin cloud. After encountering the shake, the aircraft ascended to a high altitude to avoid the developed clouds; however the fierce shake still continued. In addition, the aircraft was flying for a long time in the airspace where severe CAT was expected according to FBJP; the jetstreams were diverted in the airspace; therefore, it is probable that the occurrence of CAT was expected."

The JTSB reported following safety action was taken by the airline: "Upon the occurrence of the accident, the Company has strengthened Internet environment in order to enable the flight crewmembers to acquire necessary weather information with portable terminals in all airports which the Conpany flies into in the same mannar as hub airports."
Aircraft Registration Data
Registration mark
N751AN
Country of Registration
United States
Date of Registration
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Manufacturer
BOEING
Aircraft Model / Type
777-223
Number of Seats
Aqj Subscribe to unlock
ICAO Aircraft Type
B772
Year of Manufacture
Clbj Subscribe to unlock
Serial Number
Gm jj Subscribe to unlock
Aircraft Address / Mode S Code (HEX)
Jim Ae Subscribe to unlock
Engine Count
K Subscribe to unlock
Engine Manufacturer
Blfdinedkh Subscribe to unlock
Engine Model
DnhqqjglkkdAj Subscribe to unlock
Engine Type
Glhn ikck Subscribe to unlock
Pounds of Thrust
Dmneb Subscribe to unlock
Main Owner
pmmgcqqqjAAcblAickn kgclcgiAmk qjA nchjnApdpgm Amhnnjhmkkdibgipqqj djAk bkhdAq Subscribe to unlock
Incident Facts

Date of incident
Dec 16, 2014

Classification
Accident

Cause
Turbulence

Airline
American Airlines

Flight number
AA-280

Departure
Seoul, South Korea

Destination
Dallas Ft. Worth, United States

Aircraft Registration
N751AN

Aircraft Type
Boeing 777-200

ICAO Type Designator
B772

This article is published under license from Avherald.com. © of text by Avherald.com.
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