What happened
On June 20, 2023, at Kohn and Aerodrome in Okayama Prefecture, a serious incident occurred involving two aircraft during training operations. A Cessna 172R, operated by Okayama Air Service Co., Ltd., was approaching the runway to perform a series of touch-and-go landings. The flight crew had received confirmation from the Kohnan Flight Service that the runway was clear.
Simultaneously, a Robinson R44, operated by Takumi Enterprise Co., Ltd., was taxiing. The helicopter was being piloted by a student pilot on their first solo flight, following the disembarkation of their instructor. The Flight Service had specifically instructed the helicopter to hold short of the runway due to the approaching Cessna. However, the student pilot misheard the instruction, mistaking the command to "hold short" for an instruction to "line up and wait."
Believing they had permission to enter, the Robinson R44 moved onto the runway. When the Flight Service observed the helicopter on the active runway, they immediately instructed the approaching Cessna 172R to execute a go-around. The Cessna pilot responded instantly, climbing to approximately 500 feet to avoid a collision. The two aircraft were separated by roughly 1.0 nautical mile at the time of the maneuver.
The investigation
The Japan Transport Safety Board (JTSB) examined the radio communications, the flight backgrounds of both crews, and the operational environment at the aerodrome. The investigation focused on why the student pilot failed to adhere to the holding instruction and why the error occurred despite previous successful radio simulations. The investigators also noted that the Kohnan Flight Service did not have a communication recording device installed, which limited the available audio evidence.
Findings
- The primary cause of the runway incursion was the student pilot's misunderstanding of the radio instruction, specifically confusing "hold short" with "line up and wait."
- The student pilot was experiencing significant mental tension due to the pressure of performing their first solo flight.
- The pilot was also heavily focused on managing the aircraft's flight controls, specifically compensating for crosswinds and the shift in weight and balance following the instructor's departure.
- The student pilot failed to monitor the radio traffic regarding the movements of other aircraft on the field.