Passengers on a Jetstar flight from Melbourne to Perth were forced to move seats during the trip so their off-balance plane could land safely.
Photo: AFP
The incident occurred on 29 October and is now the subject of an Australian Transport Safety Bureau (ATSB) investigation.
During takeoff from Melbourne, the crew noticed the plane was "nose-heavy" as they attempted to get the Airbus A-321 off the ground.
The pilot said it was necessary to pull back almost completely on the controls in order to lift the nose off the runway.
After takeoff, flight attendants were asked to count the passengers and report back on their seating locations.
After entering the data into their flight management computer, the pilots realised they should not have taken off because there were too many passengers seated towards the front.
"Passengers were relocated within the aircraft cabin to return the aircraft to within allowable limits for the remainder of the flight and landing," the ATSB said.
Head of Aviation at the University of NSW, Professor Jason Middleton, said it was essential that any aircraft was correctly balanced.
"If the aircraft is loaded too far forward, then the control surface isn't enough for the pilot to actually lift the nose up," Professor Middleton said.
"You don't want to have all your heavy rugby league types up the front and all your dancers up the back, or vice versa."
Second flight being investigated
ATSB will also examine another Jetstar flight 10 days earlier, which took off with 16 more passengers than the pilots knew about.
As a result, the flight from Brisbane to Melbourne was more than 1300kg heavier than the crew was anticipating.
Professor Middleton said the issue could "absolutely" cause a concern.
"Depending on where [the extra passengers] were located in the cabin, that could make a significant difference to the balance.
"Loading the correct takeoff weight into the aircraft's flight management computer is crucial in modern jets," he said.
"There are implications for takeoff distance required and landing distance required."
After discovering the error during the flight, the pilots reprogrammed their computers and the plane landed safely.
Jetstar pilots and ground crews will be interviewed as part of the investigation.
A Jetstar spokesman said the airline was investigating both events and working closely with the ATSB to assist with its inquiries.
"Since these incidents took place in October, we have put additional measures in place to check our flights have been loaded correctly and that aircraft weight and balance is properly accounted for," the spokesman said.
"We've had no flights operate with this type of error since we introduced these measures."
- ABC