The Australian Transport Safety Bureau on Thursday launched an investigation into a mid-air incident involving a "stick shaker" warning on a Qantas flight in which 15 people were injured.
A stick shaker is an aircraft mechanical warning system in which controls make noise and vibrate strongly to let pilots know that a loss of control is imminent and that action is required to prevent the plane from stalling.
A stick shaker activation occurred on April 7, during a Qantas flight from Melbourne to Hong Kong on a Boeing 747, according to the bureau.
It happened about 100 kilometres before reaching the destination and lasted about two minutes.
"The flight crew disconnected the autopilot and manoeuvred the aircraft in response," the bureau said on its website. "Fifteen passengers received minor injuries."
The flight landed normally in Hong Kong, where ambulances were waiting. One person was taken to hospital for assessment.
Qantas said it also has launched an internal review of the incident, triggered by an "unexpected in-flight turbulence."
"We notified the ATSB (Australian Transport Safety Bureau) of the occurrence, and our own teams are also reviewing the event," a spokeswoman said.
According to experts, a stick shaker warning is a rare and serious incident. It could occur due to severe weather conditions.