What happened
On June 25, 2006, two helicopters operated by Heli Service Belgium were preparing to provide aerial coverage for a cycling race in Antwerp. The aircraft involved were an Agusta Bell AB206A, registered OO-SKE, and a Eurocopter AS355 F1, registered OO-HSH.
While positioned at the D’Herbouville Kaai federal police heliport, the OO-HSH began its departure. The pilot of the OO-HSH broadcasted the intention to take off on the company radio frequency but received no reply. Assuming the other pilot was still performing pre-flight checks, the pilot proceeded with the takeoff. Simultaneously, the pilot of the OO-SKE, who could not see the trailing aircraft due to its position, also initiated takeoff to clear the way.
During the initial climb, the OO-SKE drifted slightly to the right, causing its main rotor to strike the tail boom, vertical fin, and tail rotor of the OO-HSH. The impact caused the OO-HSH to spin uncontrollably and strike a building wall before crashing onto the ground. The impact caused the OO-HSH's engines to catch fire, though the ground crew managed to extinguish the flames. The OO-SKE was able to perform an emergency landing safely. The collision resulted in two serious injuries and two minor injuries.
The investigation
The AAIU(Be) investigation focused on the communication protocols and the coordination between the two crews. Investigators found that the briefing prior to the mission was inadequate, leaving the takeoff priority and specific radio procedures ambiguous. While three different frequencies had been discussed, it was unclear which channel the OO-SKE pilot was monitoring during the critical moments of departure.
Furthermore, the investigation examined the organizational structure of the operator. Both pilots held management roles within the company, specifically in operations and ground operations. The investigation noted that the pressure to adhere to the race schedule may have led the crew to prioritize timing over established safety and communication procedures.
Findings
- The primary cause of the accident was a lack of situational awareness by the pilots during simultaneous take-offs.
- Communication failures occurred because the pilots were using different radio frequencies during the departure phase.
- The briefing held before the mission was poor and failed to establish clear takeoff sequences or unambiguous radio protocols.
- The pilots were operating under time pressure to meet the race schedule, leading to a disregard for standard radio contact procedures.
- There was an absence of effective coordination or guidance from the ground crew during the takeoff sequence.