What happened
On November 2, 2010, at 19:25 UTC, a Bell 212 helicopter, registration EC-GID, operated by INAER – Servicios Aéreos de Mantenimiento de Aeronaves, performed a precautionary landing in Alcochete, Portugal. The flight originated from Badajoz, Spain, and was en route to Salemas, Portugal, for a scheduled major inspection.
The pilot departed with approximately 1,150 pounds of fuel, which was estimated to provide 1 hour and 40 minutes of flight time for a journey expected to take 1 hour. After 50 minutes of flight, the 'Fuel Low' warning light illuminated for the left tank. At that time, the total fuel indicated was approximately 450 pounds, while the warning threshold is 140 pounds. Due to uncertainty regarding the accuracy of the fuel gauges, the pilot decided to divert to the planned alternate airport, Lisbon (LPPT), and notified Lisbon Approach of the intention.
Five minutes later, while overflying the Sporting Clube de Portugal football academy in Alcochete, the 'Fuel Low' warning light illuminated for the right tank as well. Adhering to the manufacturer's 'Land ASAP' checklist requirement for low fuel warnings, and fearing the aircraft might run out of fuel before reaching the alternate, the pilot decided to land in a nearby illuminated football field. The pilot informed air traffic control that the landing was precautionary due to suspected insufficient fuel but did not declare an emergency. The landing was completed safely with no injuries and no damage to the aircraft or third parties.
The investigation
The GPIAAF investigation focused on why the fuel low warning lights activated while the total fuel quantity indicated was still well above the warning threshold. The investigation considered two primary hypotheses: an error in the fuel quantity indication system reporting a higher value than actually present, or a redundant electrical failure causing both warning lights to illuminate despite sufficient fuel.
Findings
- The pilot followed the established manufacturer checklists by performing a precautionary landing immediately after the second warning light illuminated.
- The decision to land in a field was made to avoid the risks of an unplanned forced landing at night over densely populated areas or crossing the Tagus River.
- The investigation concluded that the probable cause of the incident was an error in the fuel quantity indication system on the Bell 212, EC-GID.