Accident
Last updated: 31 October 2014
Statuts:Enquête Officielle
Date:lundi 12 août 1985
Heure:18:56
Type/Sous-type:Boeing 747SR-46
Compagnie:Japan Air Lines - JAL
Immatriculation: JA8119
Numéro de série: 20783/230
Année de Fabrication: 1974-01-28 (11 years 7 months)
Heures de vol:25030
Cycles:18835
Moteurs: 4 Pratt & Whitney JT9D-7A
Equipage:victimes: 15 / à bord: 15
Passagers:victimes: 505 / à bord: 509
Total:victimes: 520 / à bord: 524
Dégats de l'appareil: Détruit
Conséquences: Written off (damaged beyond repair)
Lieu de l'accident:26 km (16.3 milles) SW of Ueno Village, Tano District, Gunma Prefecture (   Japon) show on map
Élévation des lieux de l'accident: 1530 m (5020 feet) amsl
Phase de vol: En vol (ENR)
Nature:Transport de Passagers Nat.
Aéroport de départ:Tokyo-Haneda Airport (HND/RJTT), Japon
Aéroport de destination:Osaka-Itami Airport (ITM/RJOO), Japon
Numéro de vol: 123
Détails:
JA8119 was a Japan Air Lines Boeing 747SR, a short range variant of the Boeing 747 Series 100. The was aircraft specifically configured for domestic flights with a high density seating arrangement.
On June 2, 1978 the aircraft operated on a flight to Osaka (ITM). It floated after touchdown and on the second touchdown the tail struck the runway. The aircraft sustained substantial damage to the rear underside of the fuselage. The rear pressure bulkhead was cracked as well. The aircraft was repaired by Boeing. Engineers replaced the lower part of the rear fuselage and a portion of the lower half of the bulkhead.
Seven years later, on August 12, 1985, JA8119 had completed four domestic flights when it landed at Tokyo-Haneda (HND) at 17:17. The next flight was to be flight 123 to Osaka (ITM). The aircraft took off from Tokyo-Haneda at 18:12. Twelve minutes later, while climbing through 23900 feet at a speed of 300 knots, an unusual vibration occurred. An impact force raised the nose of the aircraft and control problems were experienced. A decompression had occurred and the crew got indications of problems with the R5 door. In fact, the rear pressure bulkhead had ruptured, causing serious damage to the rear of the plane. A portion of its vertical fin, measuring 5 m together with the section of the tailcone containing the auxiliary power unit (APU) were ripped off the plane. Due to the damage, the hydraulic pressure dropped and ailerons, elevators and yaw damper became inoperative. Controlling the plane was very difficult as the airplane experienced dutch rolls and phugoid oscillations (unusual movement in which altitude and speed change significantly in a 20-100 seconds cycle without change of angle of attack).
The aircraft started to descend to 6600 feet while the crew tried to control the aircraft by using engine thrust. Upon reaching 6600 feet the airspeed had dropped to 108 knots. The aircraft then climbed with a 39 degree pitch-up to a maximum of approx. 13400 feet and started to descend again. At 18:56 JAL123 finally brushed against a tree covered ridge, continued and struck the Osutaka Ridge, bursting into flames.


CAUSE: "It is estimated that this accident was caused by deterioration of flying quality and loss of primary flight control functions due to rupture of the aft pressure bulkhead of the aircraft, and the subsequent ruptures of a part of the fuselage tail, vertical fin and hydraulical flight control systems.
The reason why the aft pressure bulkhead was ruptured in flight is estimated to be that the strength of the said bulkhead was reduced due to fatigue cracks propagating at the spliced portion of the bulkhead's webs to the extent that it became unable to endure the cabin pressure in flight at that time.
The initiation and propagation of the fatigue cracks are attributable to the improper repairs of the said bulkhead conducted in 1978, and it is estimated that the fatigue cracks having not be found in the later maintenance inspection is contributive to their propagation leading to the rupture of the said bulkhead."

Sources:
» Applying Lessons Learned From Accidents : Accident/Incident Summary Japan Airlines Flight 123, Boeing 747, Gunma Prefecture Japan
» Flight International 14.09.1985 (4-7)
» Job, Macarthur and Steve Swift. JAL 123: 520 Lost - It's 20 years since the world's worst single aircraft airliner accident. In: Flight Safety Australia. - Vol. 9, no. 4 (July, August 2005) page 28-33. [http://www.casa.gov.au/fsa/2005/aug/28-33.pdf]


Opérations de secours

FAA issued 6 Airworthiness Directives
NTSB issued 8 Safety Recommendations

Show all AD's and Safety Recommendations

Photos

photo of Boeing 747-SR46 JA8119
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Plan
Ce plan montre l'aéroport de départ ainsi que la supposé destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Tokyo-Haneda Airport et Osaka-Itami Airport est de 401 km (251 miles).

Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tels qui sont connus à ce jour.
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