What happened
On July 25, 2014, at approximately 16:46 PDT, a Eurocopter EC 130 B4 helicopter, registration N154GC, collided with a taxiing DeHavilland DHC-6 airplane at Boulder City Airport (BVU) in Nevada. The helicopter was operating an aerial sightseeing flight for Papillon Airways Inc., carrying a pilot and six passengers. The airplane, operated by Grand Canyon Airlines, was beginning a repositioning flight with a two-person crew.
The helicopter pilot was following established arrival procedures, descending along the centerline of taxiway Alpha and then west along taxiway Delta to land at a designated spot on the ramp. The pilot reported seeing the airplane on the ramp before the aircraft turned onto taxiway Delta. After the airplane crew announced their intention to taxi via taxiway Delta, the helicopter pilot radioed the CTAF to state he was "right above" the airplane. The helicopter pilot interpreted a "double click" on the radio as an acknowledgment that the airplane crew had him in sight and continued his descent.
As the helicopter pilot began a right pedal turn to land on the ramp, the helicopter's right horizontal stabilizer struck the airplane's vertical stabilizer. The airplane crew was initially unaware of the collision and continued their taxi until being recalled by company personnel. There were no injuries to the seven people on the helicopter or the two people on the airplane.
The investigation
Investigators examined the wreckage and found that the most significant damage occurred where the inboard trailing edge of the helicopter's right horizontal stabilizer contacted the leading edge of the airplane's vertical stabilizer. Damage was also noted on the underside of at least one helicopter main rotor blade and the top of the airplane's vertical stabilizer.
Radio transmissions from the CTAF were reviewed, confirming the sequence of position reports. The investigation also noted that the airplane's cockpit voice recorder (CVR) was recovered and analyzed. While the airplane's first officer was aware of the inbound helicopter via radio, the airplane's captain reported that he did not visually detect the helicopter during his turn onto the taxiway.
Findings
- The airplane's flight crew failed to exercise sufficient vigilance and did not yield the right-of-way to the landing helicopter.
- The airplane taxied onto taxiway Delta without stopping on the ramp to ensure the path was clear.
- The helicopter pilot continued his descent without confirming that the airplane was not a collision hazard.
- The airplane's position directly in the flight path of the descending helicopter significantly reduced the pilot's ability to avoid the collision.