What happened
On the night of September 3, 2008, a Bell 212 helicopter, registration A6-ALV, was performing a scheduled night transfer flight from Dubai International Airport to various locations, including the Maersk Resilient drilling rig. The aircraft was carrying two crewmembers and five passengers, along with a small amount of freight.
After landing on the drilling rig's landing area, the crew unloaded the cargo and prepared for departure. Once the helideck crew signaled that the aircraft was cleared to take off, the helicopter lifted off vertically to a height of approximately two meters. The pilot then initiated a 180-degree left turn to position the aircraft into the wind. During this maneuver, the helicopter began to climb while simultaneously traveling backward.
As the aircraft moved in reverse for approximately 50 meters, the main rotor blades struck the vertical crane of the drilling rig. The impact caused the helicopter to break into two major sections. The cabin area caught fire and was consumed by flames, while the cockpit section separated and fell through the center of the rig's rear jackup leg, eventually becoming submerged in the water. All 7 occupants on board were fatally injured.
The investigation
The GCAA Accident Investigation Team examined the wreckage, the flight path, and witness statements from the rig's deck crew. Investigators analyzed the aircraft's maintenance history, the flight crew's training and experience, and the mechanical integrity of the rotor systems. The investigation also included laboratory examinations of the aircraft components and simulator tests to understand the flight dynamics during the reverse movement.
Findings
- The primary cause of the accident was the collision between the main rotor blades and the drilling rig's vertical crane during a backward flight maneuver.
- The helicopter was operating in a reverse flight path while climbing, which led it into the path of the rig's structure.
- The impact forces were sufficient to separate the fuselage into two distinct pieces.
- The aircraft was totally destroyed due to the high-energy impact and the subsequent intense fire.