What happened
On 30 December 2017, at approximately 17:42 local time, a mid-air collision occurred at the Mutxamel aerodrome in Alicante, Spain, involving a Bell 412SP helicopter, registration EC-MMC, and a CASA 1131 biplane, registration N1950M.
The helicopter, operated by Babcock International Group PLC, was returning to the aerodrome after performing firefighting duties. The biplane was conducting a private flight and had been performing acrobatic maneuvers in the vicinity of the aerodrome pattern. During the final approach to runway 30, the biplane, which was positioned higher and further back in the approach, descended into the path of the helicopter.
The collision caused the biplane to strike the helicopter's tail assembly, resulting in the detachment of the helicopter's tail rotor and significant damage to its main rotor blades. The biplane lost its right wings and crashed to the ground in an inverted position. The pilot of the N1950M sustained fatal injuries. The crew and passengers of the EC-MMC managed an emergency landing; of the 10 occupants on board the helicopter, two sustained minor injuries.
The investigation
Investigators examined wreckage, flight tracking data, and eyewitness accounts. The investigation established that the helicopter crew had correctly followed the aerodrome's visual approach chart, reporting their position on the aerodrome frequency. However, the biplane pilot had not made any radio reports during his maneuvers or approach.
Analysis of the flight paths showed the biplane was executing a slip maneuver to position itself for the final leg, which caused it to descend rapidly into the helicopter's path. Environmental factors, specifically the position of the sun just eight minutes before sunset, significantly reduced visibility for the biplane pilot. Additionally, the open cockpit of the biplane likely contributed to high ambient noise, potentially hindering the pilot's ability to hear the helicopter's radio transmissions.
Findings
- The primary cause of the accident was the failure of the biplane pilot to detect the helicopter during the final approach to runway 30.
- The pilot of the N1950M failed to use radio communications to announce his intentions or position.
- The pilot of the N1950M failed to adhere to the standard aerodrome traffic circuit, instead performing acrobatic maneuvers within the pattern.
- Reduced visibility due to the sun's low position near sunset contributed to the lack of visual separation.
- The high engine noise in the open-cockpit biplane may have prevented the pilot from hearing the helicopter's position reports.