Overworked Yuletide Loading Error
The Australian Transport Safety Bureau (ATSB) report into a loading incident during a busy-pre Christmas period on an Airbus A320 highlights the effect of high workload on data input errors, as well as the importance of system feedback of incorrectly entered data.
On 21 December 2016, Jetstar A320 VH-VGI was being loaded at Melbourne Airport, Victoria. At 05:00 Local Time, a clerk at a freight organisation commenced their shift say the ATSB.
The organisation recently introduced a new processing system, however a decision was made to use the old system due to the amount of freight for processing and [technical] system issues.
The team was short one person. The replacement clerk was starting work at 0700. Until then, the clerk was responsible for processing freight on all narrow-body flights from Melbourne.
The clerk spent about 20 minutes on the radio, and processed freight for 9 or 10 flights over half an hour. During this time, the clerk identified two pieces of freight (flowers and meat) to be sent to the Sunshine Coast [VH-VGI's destination], weighing a total of 93 kg. The clerk put the freight in a unit loading device (ULD) and wrote the ULD number on the same page with the details of a ULD destined for Adelaide.
The clerk entered the ULD as going to the Sunshine Coast in the office. However, they inadvertently put the Sunshine Coast freight card on the ULD (containing medical goods, weighing 245 kg) destined for Adelaide. This ULD was subsequently loaded on the Sunshine Coast flight.
The clerk realised the error when the ULD destined for Adelaide could not be located. The clerk who commenced at 0700 noticed the ULD on the Sunshine Coast flight paperwork.
Once the error was detected, the clerk rang the Sunshine Coast freight office. They were informed the incorrect container had been sent and provided them with details of the freight so the ULD could be sent back to Melbourne, then to Adelaide.
The aircraft remained within weight and balance limits. However the ATSB comment that:
The same error involving heavier weights could have a significant impact on the handling and performance of an aircraft.
The clerk provided the following comments:
- They felt very busy. Within the first hour, they would have processed freight for about 9 to 10 flights, which was double the usual workload.
- They had to process all flights to Adelaide, Brisbane, Canberra, Alice Springs, and Townsville, as well as all other narrow-body flights. Normally this role would be divided between two clerks.
- If there is a person unable to work their shift, they try to find a replacement. They had done so in this case, but the replacement could not start until 0700.
- Normally at Christmas time, they would have extra staff rostered, but that year they did not.
- On the day, they felt under stress due to the busy time of year.
In the old manual system, the same ULD number can be entered twice and the ATSB found that in this case both ULDs had the same ULD number.
In the new system, this would result in an error feedback. Without the error feedback, the clerk would not have known that the same container was entered twice. Furthermore, this data cross check is completed by the same person who entered it, making it difficult to detect any errors, particularly if they are experiencing a high workload.
The operator issued a revised loading instruction to prevent a recurrence of this type of event. The instruction stated after weighing the ULD or barrow [a frame used for holding ULDs] immediately record the weight on the appropriate ULD or barrow card and immediately insert in the ULD/Barrow pocket. Then close load in the Cargo system and move the ULD/Barrow to the designated staging area away from build-up areas.
The ATSB’s identified two prior cases of incorrect loading information processing when staff were under high workload:
- On 16 May 2010, an Embraer ERJ 190 aircraft was operated on a positioning flight from Adelaide, South Australia to Brisbane, Queensland (ATSB investigation AO-2010-034). The pilot-in-command reported that the load and trim sheet for the aircraft was inaccurate due to items being counted twice. It was found that the error occurred when the airport movements coordinator inadvertently selected the incorrect aircraft configuration in the company’s computerised load and trim system during a high workload time.
- On 8 September 2016, an Airbus A320 aircraft was being loaded at Sydney Airport, New South Wales to Brisbane, Queensland (ATSB investigation AO-2016-119). The leading hand assumed that the freight handler had inadvertently transposed the numbers on containers, amended them and continued loading (against protocol). The leading hand noted that the short turnaround time and the flight was the last one of the day led to procedures being bypassed.
One of the ATSB’s SafetyWatch priorities is data input errors.