Background
On 5 May 2018, two Robinson R44 Raven helicopters were involved in a ground collision at Cumbernauld Airport, North Lanarkshire. The aircraft, G-CTFL (manufactured 2008) and G-HYND (manufactured 2016), were both conducting training flights. Neither helicopter crew nor passengers sustained injuries.
History of the Flight
G-CTFL was preparing to depart for a trial lesson with its rotors turning. G-HYND had just returned from a sightseeing flight and landed on a grass area behind G-CTFL because both designated helipads were occupied. The pilot of G-HYND announced on the Air/Ground frequency that the helicopter was secure on the ground. One minute later, the pilot of G-CTFL obtained airfield information but was not alerted to the presence of the other R44. After acknowledging the information, he announced his intention to lift from the eastern helipad.
The pilot of G-CTFL felt constrained from moving forward or right due to a parked Robinson R22 and a stationary Cessna with its propeller turning. He decided to lift to a hover and move rearwards to taxi behind the R22. He did not turn his helicopter to check the area behind because of the nearby R22 and spectators near the buildings.
Collision Sequence
CCTV recordings showed G-CTFL lifting to a hover, approximately 6 ft above ground, then moving slowly rearwards and slightly right. G-HYND's main rotor blades were still turning slowly. As G-CTFL approached, one of G-HYND's blades struck the engine housing of G-CTFL below the left side of the tailboom.
The pilot of G-CTFL heard a bang and felt the helicopter pitch nose-up and right. He applied forward cyclic to return toward the helipad and lowered the collective. The helicopter then pitched nose-down; he moved the cyclic aft, but the tail struck the ground. The helicopter bounced forward off its skids toward the R22. Despite a left cyclic input, the rotor blades hit the ground, causing violent vibration. G-CTFL landed heavily in a nose-up attitude near the R22, with its tail on the ground.
CCTV analysis showed G-CTFL pitched to about 45° nose-down while maintaining height, then descended and pitched up, tail striking grass and skids hitting concrete. The helicopter bounced, swung, and struck the ground multiple times before coming to rest. Debris was thrown several metres.
Aftermath
The pilot of G-CTFL shut down the engine and electrical systems, applied the rotor brake, and evacuated via the left door. An employee helped the student and passenger escape. The pilot of G-HYND had removed his headset and turned off his radio during rotor slowdown; he saw the collision but his helicopter was unaffected and his passengers disembarked normally.
The helicopter operator's RFFS vehicle was available but not immediately deployed; the airport's Air/Ground operator activated the crash alarm and later drove the airport's RFFS vehicle to the scene, arriving within two minutes. No fire risk was identified, and local emergency services were not called.
Safety Actions
The helicopter operator implemented several changes: the northern helipad was extended eastward by 12 m; the grass area east of the helipads was extended; a mirror was installed at the hangar corner to improve rear visibility; reversing from helipads was prohibited; and procedures for avionics shutdown during R44 shutdown were to be reviewed. Additionally, the RFFS response was revised to ensure two trained employees are available during helicopter activity.