What happened
On May 22, 2023, an Aerospatiale AS355F2 helicopter, registration JA6718, operated by Aero Asahi Corporation, was performing a personnel transport flight from Yao Airport to Chubu Centrair International Airport. While operating under visual flight rules, the crew approached the airport and requested landing instructions from the tower control.
During the approach, the pilot provided a position report before actually reaching the designated visual reporting point. Observing this, the air traffic controller, assuming the pilot was unfamiliar with the airport's layout, decided to clear the helicopter to land on the runway rather than the helipad to make the landing point more visually recognizable. At 09:01, the tower issued a landing clearance for Runway 36, specifically noting the touchdown point near Taxiway A8.
The pilot responded with a readback that incorrectly referenced a different taxiway, and the crew failed to notice the specific touchdown point instructions. Instead of following the runway path, the helicopter crossed the runway and proceeded to the T Helipad, where it landed at 09:03. The air traffic controller realized the error and notified the pilot that they had missed the runway and were landing at the helipad.
The investigation
The Japan Transport Safety Board (JTSB) investigated the incident, focusing on the communication between the tower and the crew. The investigation examined the pilot's prior knowledge of the airport, the specific phraseology used by the air traffic controller, and the crew's internal assumptions during the flight.
Investigators found that the crew had previously consulted other pilots and operated under the incorrect assumption that aircraft at this airport are always cleared to land at the T Helipad rather than the runway. The investigation also noted that the pilot failed to seek clarification when the instructions were difficult to understand, and the crew did not recognize the specific ATC phraseology used for runway clearances versus helipad clearances.
Findings
- The pilot's primary error was an incorrect assumption that the landing clearance was for the helipad, driven by prior misinformation obtained from colleagues.
- The crew failed to recognize the difference in ATC phraseology, where runway clearances begin with the runway number, whereas helipad clearances begin with the field name.
- The pilot did not request a repeat of the transmission when the instructions were unclear, which could have corrected the misunderstanding.
- The flight operation assistant on board also misinterpreted the controller's instructions as a directive to cross the runway toward the helipad.
Safety action
Following the incident, Aero Asahi Corporation implemented training measures for all pilots. This included education on the specific ATC phraseology required for helicopter landings at non-runway fields and training sessions based on similar historical incidents to prevent errors caused by incorrect assumptions.