Asiana 991, 28 July 2011
A cargo fire destroyed a 747-400F over the sea in 18 minutes, killing both crew and contributing to tighter rules on lithium batteries in air cargo.
On 28 July 2011, Asiana Airlines Flight 991 — a Boeing 747-48EF freighter, registration HL7604 — was destroyed by an in-flight fire and came down in the sea. Both crew members died.
The load
The aircraft was carrying 58 tonnes of cargo, mostly semiconductors and displays. Among it were about 400 kg of lithium batteries, paint and photoresist fluid.
Investigators established that a fire began in or near one of the ULD pallets containing dangerous goods in the rear fuselage. They could not determine exactly what started it.
Eighteen minutes
That is the figure that matters. From the first indication to the loss of the aircraft was around eighteen minutes — not enough time to reach a diversion airfield.
A main-deck fire on a freighter is a fundamentally different problem from a fire in a passenger aircraft’s belly hold. Class C cargo holds beneath a passenger cabin are sealed and fitted with suppression. A freighter’s main deck is an enormous open volume full of combustible packaging, and suppression at that scale is extremely difficult.
Lithium batteries
This accident, together with the loss of UPS Airlines Flight 6 in 2010, pushed lithium batteries up the agenda quickly. In 2012 ICAO began work on new standards for carrying them by air, and the rules have tightened repeatedly since: restrictions on quantity and state of charge, packaging and segregation requirements, and outright prohibitions on some categories aboard passenger aircraft.
The underlying problem is that a lithium cell in thermal runaway supplies its own oxidiser. Conventional suppression systems, which work by displacing oxygen, do not reliably stop it.
Why freighters carry the risk
Freighters fly the same routes as airliners, but their loads are dense, concentrated and often hazardous — and, as National Airlines 102 showed in a different way, what is in the hold and how it is secured can determine whether the aircraft survives.
That is the recurring theme across the 747 freighter accidents: the aeroplane was fine. The cargo was the problem.
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Boeing 747 accidents
The major Boeing 747 accidents, what caused them, and the changes to aviation that followed — from Tenerife to the end of production.
Tenerife, 27 March 1977
Two Boeing 747s collided in fog at Tenerife, killing 583 people. It remains the deadliest accident in aviation history, and it changed how crews talk.
Japan Air Lines 123, 12 August 1985
A faulty repair failed seven years later, destroying the tail and all four hydraulic systems. 520 died; four survived. The deadliest single-aircraft crash.
Pan Am 103, Lockerbie, 21 December 1988
A bomb in the forward hold destroyed a 747 over Lockerbie, killing 259 on board and 11 on the ground, and reshaped aviation security.
TWA 800, 17 July 1996
The centre fuel tank of a 747 exploded shortly after takeoff from New York, killing 230. It led to fuel tank inerting being mandated worldwide.
El Al 1862, Amsterdam, 4 October 1992
Two engines tore from the wing of a 747 freighter, which crashed into an Amsterdam apartment block. Fatigued pylon fuse pins were the cause.