What happened
On March 1, 2017, an S-76C helicopter, registration PR-MEY, operated by OMNI Air Taxi S/A, was performing a transport flight from Farol de São Tomé Aerodrome to the P-37 offshore platform. The flight was carrying two crewmembers and eight passengers.
During the final approach to the P-37 helideck, the aircraft experienced an excessive sinking rate. This led to an abrupt landing on the helideck, which caused the aircraft to overturn. The impact resulted in substantial damage to the helicopter, including the main rotor, tail rotor, landing gear, and internal engine components due to the sudden stoppage of the rotors. The helideck itself sustained damage to the floor and non-slip netting.
Of the occupants on board and one person on the platform, the Second in Command, seven passengers, and one person on the platform sustained minor injuries. The Pilot in Command and one passenger were uninjured.
The investigation
CENIPA's investigation focused on the environmental conditions and the technical specifications of the landing site. Investigators examined meteorological reports from the P-3 and nearby maritime units, noting that while the official helideck report indicated favorable conditions, subsequent reports from other aircraft suggested wind gusts of up to 40 knots in the region.
Crucially, the investigation identified a discrepancy in the known height of the helideck. While information from the operator's website suggested a height of 34 meters, the official Helideck Limitation List (HLL) recorded the height as 19 meters. Furthermore, the investigation found that the helideck reports provided by maritime units did not consistently include specific helideck height information.
Findings
- The abrupt landing and subsequent overturn were driven by the physical characteristics of the P-37 platform, which created turbulence during the approach.
- There was a lack of specific landing envelope limitations (such as wind or payload restrictions) to mitigate the risks of landing on a helideck subject to such turbulence.
- Inadequate managerial oversight led to a lack of effective risk mitigation mechanisms in operational planning.
- The helideck's position at the stern of the platform, below the superstructure, contributed to the aerodynamic instability during the approach.