What happened
Following an arrival at Tamworth, the flight crew experienced a physiological distraction that persisted through their pre-flight preparations for the next departure. During this period, the crew misread the aircraft's fuel gauges, leading to the formation of an incorrect mental model regarding the amount of fuel on board. This inaccurate figure was subsequently recorded in pre-flight documentation and used for data entry tasks. Because of this error, the aircraft departed with incorrect load, take-off, and fuel management information.
The investigation
Investigators examined the crew's performance and the processes used during the pre-flight phase. It was determined that the crew's attention was degraded by a physiological response experienced during the arrival into Tamworth. Furthermore, the captain's limited experience on the De Havilland Canada Dash 8-Q300 meant that the crew had to perform manual mental calculations to determine the total fuel on board. This extra cognitive requirement, combined with the existing distraction, made it harder to detect the initial reading error.
Findings
- The crew's misinterpretation of the fuel gauges was likely caused by ongoing physiological distraction.
- The error was perpetuated because the incorrect fuel figure was used in subsequent pre-flight paperwork and digital inputs.
- The requirement for the crew to manually calculate fuel totals increased the likelihood of a calculation error.
- Reduced attentional focus led the crew to omit specific procedural checks that might have otherwise identified the discrepancy.
- The error remained undetected through the pre-flight and taxi phases, only being identified once the aircraft was in the cruise phase of flight during a routine fuel check.