A Boeing 737 took off from Canberra Airport with incorrect performance calculations after a data input error led to 51 of the passengers on board not being accounted for, an ATSB final report explains.
On 1 December 2024, a Qantas 737 operating a flight from Perth to Sydney diverted to Canberra due to bad weather.
Prior to its subsequent flight from Canberra to Sydney, an error was made within the Qantas departure control system that meant 51 passengers were incorrectly listed as not on board the aircraft.
A loadsheet was then issued to the flight crew with an aircraft weight that was 4,291 kg less than the actual weight of the aircraft, resulting in performance calculations generating take-off speeds 3-4 kt lower than they should have been.
“This increased the risk of degraded performance and handling characteristics during the take-off,” ATSB Director Transport Safety Dr Stuart Godley said.
“Fortunately, the flight crew elected to use the full length of the runway for the take-off, and did not apply the headwind component, which added an increased safety margin for take-off performance.”
While the flight took place without further incident, Dr Godley said the occurrence demonstrated how a small error can cascade when unusual situations are not proactively identified, addressed, or escalated by those involved in a safety system.
“The initial error made was by a Qantas staff member who inadvertently input a smaller aircraft type into the flight plan, resulting in the system automatically removing passengers from the flight,” Dr Godley explained.
The staff member recognised the aircraft code error and corrected it, but this did not automatically reallocate the passengers back onto the flight. The lower number of passengers went unnoticed.
Qantas airport personnel then used the erroneous planning data within the scheduling system to close the flight. After being made aware of offloaded passengers in the system by another staff member, they attempted but failed to onboard those passengers within the system. They then took no further action to address the issue, assuming load control would be aware of the error and resolve it.
“Qantas load control was not aware of the error,” Dr Godley said.
“While they had concerns about the validity of the data, after liaising with the system manager, they issued the final loadsheet to the flight crew because the previous closure of the flight by airport staff indicated to them that the data had been confirmed as correct.”
Shortly after the loadsheet was issued, but before the aircraft had departed, the load control manager identified there were offloaded passengers within the system, and tried to call the flight crew via mobile phone, which went unanswered.
The issue was then handed over to Qantas movement control at Canberra Airport, who attempted to contact the flight crew via radio. But this was also unsuccessful, as the flight crew had deselected the radio to reduce distractions while they entered the loadsheet data into the aircraft computer.
Qantas movement control then radioed the Qantas gate agent to pass on the message about the error to the flight crew.
“This was not in line with procedure, which stipulated the movement control officer needed to liaise directly with the flight crew about the error,” Dr Godley said.
The gate agent then did not inform the flight crew themselves, instead believing the aircraft cabin manager, who was next to them at the time, had overheard the radio call and would tell the flight crew.
“After the incident, the cabin manager could not recall either being advised of the issue, or overhearing the radio,” Dr Godley said.
The flight crew were therefore not made aware of the loadsheet error until they had taken off.
As a result of the occurrence, Qantas will amend its procedures to allow load control personnel to contact flight crews directly via the aircraft communications addressing and reporting system, when a loadsheet error is identified.
The airline has also amended procedures to require airport personnel to conduct a headcount when a passenger discrepancy is identified.
“This incident highlights that It is not sufficient to rely on downstream controls or other functions to intervene or trap errors,” Dr Godley said.
Nonetheless, Dr Godley reiterated the uneventful take-off demonstrated the value of prudent flight planning.
“The safety margins built into the performance calculations by the flight crew meant that the incorrect data did not lead to a more consequential outcome,” he concluded.
Read the final report: Passenger loading event involving Boeing 737-838, VH-XZK, Canberra Airport, Australian Capital Territory, on 1 December 2024
Image: Victor Pody