What happened
On February 4, 2024, a Boeing 737-800, registration SP-ENW, operated by Enter Air, was conducting a passenger flight from EFET to EGCC. During the flight, the crew received a low fuel alert because the actual fuel consumption exceeded the figures calculated in the Operational Flight Plan (OFP). There were no indications of a fuel leak during the flight.
Upon landing at the destination, it was determined that the total fuel consumption was 802 kg higher than planned. Specifically, the hourly fuel burn for engine number 1 was 92 kg higher than anticipated. An investigation into 50 other flights by the same operator revealed a consistent trend where actual fuel consumption was approximately 3% higher than the OFP predictions.
The investigation
The investigation examined the discrepancy between planned and actual fuel usage. The analysis focused on the accuracy of the OFP and the performance of the aircraft's engines. The investigation also reviewed the software used to generate flight plans and evaluated wind forecast data used during the planning phase.
Findings
- The primary cause of the incident was increased hourly fuel consumption by engine number 1.
- The software used to generate the OFP failed to optimize flight plans effectively, as it did not account for increased fuel consumption under various aircraft configurations or when speed restrictions were applied below FL100.
- The OFP was prepared using outdated headwind components.
- A general discrepancy exists where actual fuel burn is approximately 3% higher than the OFP estimates.
Safety action
- A replacement for engine number 1 has been scheduled.
- A detailed analysis of actual fuel consumption versus the OFP is being conducted using data from various flights.
- Efforts are underway to optimize the OFP generation process.