Boeing Co 747-312, VH-INH

A Boeing 747, while en-route from Kansai to Brisbane at Flight
Level 370, encountered unforecast clear air turbulence, which
lasted for about 10 seconds. One flight attendant and 16 passengers
suffered minor injuries. The aircraft sustained minor damage to
internal ceiling panels in the rear cabin. A number of panels which
contained the passenger overhead lighting and air vent controls
were dislodged. However, the overhead cabin baggage lockers
remained intact during the event.

An examination of the aircraft flight data recorder indicated
that the turbulence had been preceded by a period of smooth air,
which lasted for 40 seconds. The data revealed that during the
event, the aircraft had sustained a positive G-loading of about
1.55, and a negative loading of about 0.21. The aircraft also
deviated 250 ft above, and 30 ft below, its assigned flight level.
No anomalies were recorded that might have suggested a malfunction
of the aircraft systems.

A forecast for the area indicated no significant weather,
although a subsequent analysis of relevant satellite images
revealed isolated cumulo-nimbus clouds. A report by the Bureau of
Meteorology suggested that turbulence above those clouds may have
been responsible for the occurrence.

During the flight, the pilot in command had recommended that the
passengers, when seated, should keep their seatbelts fastened. The
pilot in command subsequently advised that prior to the turbulence,
flight conditions had been smooth. The night was dark, and the
aircraft weather radar did not indicate adverse weather.
Consequently the crew did not illuminate the seatbelt signs.

A flight attendant reported that, at the time of the occurrence,
a number of passengers did not have their seatbelts fastened and
were injured when they were thrown from their seats. Some of those
passengers had refused to fasten their seatbelts when seated. One
of the passengers was injured when a piece of ceiling panel fell on
him. A flight attendant was injured when she was thrown to the
ceiling and then to the floor. Five passengers admitted to hospital
were later released the same day.

In order to alert other crews in the area, the airline's
standard operating procedures required the crew to report severe
turbulence to air traffic services. However flight service records
indicated that this did not occur.