Qantas
Flight 72 (QF72)
was a scheduled flight from Singapore Changi Airport to Perth Airport on
7 October 2008 that made an emergency landing at Learmonth
airport near
the town of Exmouth, Western Australia following
an in-flight
accident featuring
a pair of sudden un-commanded pitch-down
manoeuvres that resulted in serious injuries to many of the occupants. The
injuries included fractures, lacerations and spinal injuries.
Aircraft Details
VH-QPA
was delivered new to Qantas on 26 November 2003, initially as A330-301.
It later had a change in engine type fitted and was re-designated as an Airbus
A330-303 in November 2004.
Flight Details
The accident began at 12:40:28 WST.
The aircraft was travelling at around 37,000 feet (11,000 m) when pilots
received an electronic message warning them of an irregularity with autopilot
and inertial reference systems. The autopilot disengaged automatically, and the
aircraft climbed 200 feet (60 m) under manual control. The autopilot was re-engaged
when the aircraft returned to the prior selected flight level before the
autopilot was disengaged for the remainder of the flight. At 12:42:27 the
aircraft made a sudden un-commanded pitch down manoeuvre, recording -0.8 g,
reaching 8.4 degrees pitch down and rapidly descending 650 feet (200 m) in
about 20 seconds before the pilots were able to return the aircraft to the
assigned cruise flight level. At 12:45:08 the aircraft then made a second un-commanded
manoeuvre of similar nature, this time reaching +0.2 g, 3.5 degrees pitch down and
descending 400 feet (120 m) in about 16 seconds before being returned to
level flight. Unrestrained passengers and crew as well as some restrained passengers
on board were flung around the cabin or crashed on overhead luggage
compartments. The pilots stabilised the plane and declared a state of alert (a PAN-PAN is broadcast), which was later updated
to a MAYDAY when
the extent of injuries was relayed to the flight crew. Forty minutes later, the
plane made an emergency landing at Learmonth airport.
Investigation
The
ATSB investigation was supported by the Australian Civil Aviation Safety Authority (CASA), Qantas, BEA (France) and Airbus. Copies
of data from the aircraft's flight data recorder and cockpit voice recorder were sent to the BEA and Airbus.
The
aircraft was equipped with a Northrop
Grumman made ADIRS,
which investigators sent to the manufacturer in the US for further testing. On
15 January 2009 the EASA issued an Emergency Airworthiness Directive to address the above A330 and A340
Northrop-Grumman ADIRU problem of incorrectly responding to a defective
inertial reference.
The Australian Transport Safety Bureau (ATSB) identified in a preliminary
report that a fault occurred within the Number 1 Air Data Inertial Reference Unit (ADIRU) and is the "likely origin
of the event". The ADIRU (one of three such devices on the aircraft) began
to supply incorrect data to the other aircraft systems.
The initial effects
of the fault were:
§ False stall and overspeed warnings
§ Loss of attitude information on the Captain's primary flight display
§ Several Electronic Centralised Aircraft
Monitor (ECAM) system
warnings
About two minutes
later, ADIRU #1, which was providing data to the captain's primary flight
display, provided very high (and false) indications for the aircraft's angle of
attack, leading to
§ The flight control
computers commanding a nose-down aircraft movement, which resulted in the aircraft pitching down to a maximum of
about 8.5 degrees,
§ The triggering of a
Flight Control Primary Computer pitch fault.
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