What happened
On December 5, 2008, at approximately 11:48 UTC, a near-collision occurred at Helsinki-Malmi Airport between a Robinson R22 helicopter, registration OH-HMZ, and a Valmet L-90 TP Redigo aircraft, registration RG-9.
The Robinson R22 was conducting a training flight and was performing a low-level hover taxi. Simultaneously, the RG-9 had just landed on runway 36 and was taxiing toward the apron via taxiway C. As the RG-9 turned onto taxiway T, the crew observed the helicopter approaching them head-on. The helicopter was moving sideways and backward, which prevented the crew from seeing the approaching aircraft. The crew of the RG-9 immediately stopped and issued urgent warnings over the radio, stating the aircraft were only about five meters apart. The helicopter pilot, realizing the danger, maneuvered the aircraft onto a grass area to avoid a collision. The minimum separation between the two aircraft was estimated to be approximately two meters.
The investigation
The investigation examined radio recordings, air traffic control (ATC) logs, and operational manuals. Investigators also reviewed audit reports from the Finnish Civil Aviation Authority and training records from Avia College. The investigation looked into the specific clearances provided to both aircraft and the visibility conditions at the time, which were deteriorating due to twilight and weather.
Findings
- The primary cause of the near-collision was that the helicopter crew failed to maintain adequate lookout for other traffic while performing a hover taxi.
- The air traffic controller provided a taxi clearance to the RG-9 without verifying the presence of other active traffic on taxiway T.
- There was a significant misunderstanding between ATC and the helicopter crew regarding the scope of the provided clearance; the controller believed the helicopter was restricted to a specific pattern, while the clearance actually allowed movement over taxiway T.
- The helicopter was performing a hover taxi without specific permission to use taxiway T, partly due to an established local practice driven by overgrown vegetation in the designated helicopter area.
- The helicopter crew was maneuvering in a manner (sideways and backward) that made it impossible to maintain the required lookout.
- ATC failed to provide necessary traffic information to the aircraft and did not issue a safety report following the incident.
- Declining visibility and twilight conditions may have hindered the controller's ability to visually observe the conflict.