The Australian Transport Safety Bureau (ATSB) has discontinued its three-year investigation into multiple passenger overloading events involving Jetstar Airways.

The investigation focused on five separate occasions between 2015 and 2017 where Jetstar Airbus A320 and A321 aircraft were loaded with incorrect passenger distributions or with incorrect passenger numbers used to determine the aircrafts’ weight and balance.

“This placed increased operational pressure on flight and cabin crews and, on at least one occasion, adversely affected aircraft performance during take-off,” according to a notice posted on the ATSB website last week.

“Records show that there were other flights where erroneous passenger loading was discovered before pushback.”

Four of the occurrences followed Jetstar’s introduction of a new type of mobile boarding manager (MBM) device used to scan passenger boarding passes and tally the passengers as they boarded.

In each case, the ATSB found that technical faults and/or erroneous operation of the MBM led to incorrect passenger loading information being provided to flight crews.

On two of those occasions, passenger seating allocations were erroneous after a late change of aircraft type.

However, the ATSB noted that Jetstar’s organisational context has significantly changed in the three years since the investigation began, likely making some of the organisational aspects of the investigation no longer relevant.

Jetstar has also conducted internal safety investigations into the relevant occurrences, and has taken action to address those issues in regular consultation with the Civil Aviation Safety Authority.

“Based on the available information, the risk controls currently in place and the operating context, the ATSB considers any undetected passenger loading problem associated with the identified limitations were very unlikely to have a significant operational impact,” the report said.

“Consequently, the ATSB has discontinued this investigation, and will communicate all additional provisional safety issues and learnings to the operator to reduce future risk.”

Commenting on the ATSB’s investigation, Jetstar head of safety Matt Franzi said the airline had several instances of weight and balance discrepancies caused chiefly by a fault with the devices its crew use to scan boarding passes.

“This fault meant that the number of people on board was misreported on some flights,” he told Travel Weekly.

“We investigated these discrepancies immediately and implemented new technology and extra safeguards, which has led to the ATSB discontinuing their investigation.

“There have not been any instances of faults with boarding devices since these incidents.”