What happened
On January 23, 2018, a mid-air collision occurred near the Speyer airfield during two separate training flights conducted under Visual Flight Rules (VFR). The first aircraft, an Airbus Helicopters EC 135 P2+ helicopter, was performing training maneuvers to obtain a type rating. After an initial landing, the crew departed the airfield to perform training procedures, which included flying an approach against the active runway direction (Runway 34) to simulate a tail rotor drive failure.
Simultably, a Piper PA 28RT was conducting a pilot training flight. The crew had recently changed their destination to Speyer, which increased their cockpit workload as they managed new frequencies and navigation. As the aircraft was in a constant descent toward the airfield, the helicopter was executing a right-hand turn to align with Runway 34.
At approximately 13:07 UTC, the right wing of the Piper PA 28RT struck the main rotor blades of the Airbus Helicopters EC 135 P2+. The impact severed the aircraft's wing, causing the Piper PA 28RT to crash. The collision also tore the tail boom from the helicopter, which subsequently caught fire and crashed. The collision resulted in four fatalities, as all occupants of both aircraft were killed.
The investigation
The BFU investigation examined radar data, FLARM data, and cockpit visibility limitations. Investigators analyzed the flight paths of both aircraft and the communication between the pilots and the Speyer air traffic controller. The investigation also reviewed the technical configuration of the collision warning systems on board the helicopter and the meteorological conditions at the time of the accident.
Findings
Several contributing factors led to the fatal collision:
- The helicopter was performing a specific training maneuver that involved approaching the runway against the active direction, which placed it in a difficult position relative to other traffic.
- The Piper PA 28RT was flying in a descent that placed the helicopter below the aircraft's horizon, making it extremely difficult to spot.
- Significant blind spots existed in both aircraft due to cockpit structural elements like door frames, windshield pillars, and sun visors.
- Both crews were experiencing high workloads due to their respective training objectives and the recent change in flight destination.
- The attention of both crews was likely diverted by a third aircraft, a Cessna 172, which had just departed the airfield.
- The helicopter's collision warning system was configured to only display traffic broadcasting FLARM data, meaning it failed to detect the Piper, which only transmitted Mode-S transponder signals.