Pilots flying a Qantas plane that experienced a roller-coaster descent into Hong Kong two years ago struggled to respond to the incident because of a lack of training, an investigation has found.
The in-flight "upset" left four cabin crew and two passengers with minor injuries, and has prompted Qantas to retrain all of its Boeing 747 pilots and update training for its other Boeing pilots.
The Australian Transport Safety Bureau's final report into the incident, released on Wednesday, found the pilots at the controls of the 747-400 from Melbourne manually over-rode the flight computer's flight speed when preparing to enter a holding pattern around Hong Kong International Airport on April 7, 2017.
The pilots then failed to increase their speed when directed to enter the holding pattern at a higher altitude than expected. The ATSB said the aircraft slowed to below the necessary speed while descending but the flight crew did not notice because they were busy reading flight documents and looking out the window for other air traffic.
Shortly after, the aircraft started experiencing pre-stall buffeting. The pilot took recovery action to stop the buffeting, but failed to complete the full stall-recovery procedure.
This led to further "stick shaker" stall warnings – indicating the aircraft could be about to lose altitude. That prompted the pilot to force the plane's nose down several times, resulting in the violent oscillations that saw several crew and passengers hit the cabin's roof.
The ATSB found that while the pilots had been trained in stall recovery in low altitudes, they had not had instructions on how to handle the problem at higher altitudes.
"The opportunity for flight crew to practice their high altitude manual handling skills was limited," the report says.
As a result, the flight crew did not adequately respond to the initial buffet and probable stick shaker activation, leading to the in-flight upset."
Qantas has since updated its training for pilots across its fleet of 747s, Boeing 787 Dreamliners and Boeing 737s.
“We take these incidents very seriously and use them as an opportunity to reinforce procedures
and improve safety," a Qantas spokesman said.
"In correcting the aircraft’s path, the crew was very conscious they were operating in congested airspace and had limited room to manoeuvre, which added to the sense of turbulence in the cabin.“