What happened
On September 23, 2021, at approximately 09:14 JST, a privately owned Robinson R44 II, registration JA76EL, was involved in a serious incident at Nagasaki Airport. The flight, operated under visual flight rules for personnel transport, was scheduled to travel from Nagasaki to Kagoshima Airport.
During the departure sequence, the pilot was instructed by ground control to taxi to the runway holding point on Taxiway T2. Upon reaching the position, the pilot contacted the tower to report readiness for departure. The air traffic controller issued a clearance for take-off from the Runway 32 intersection at Taxiway T2. However, the pilot interpreted this instruction as permission to depart directly from Taxiway T2 itself.
As the aircraft began its ascent from the taxiway, the tower controller observed unusual movement and realized the aircraft was not using the runway. The controller immediately re-issued the clearance specifically for Runway 32 to correct the error. While the pilot initially failed to recognize the corrective intent of the second English-language clearance, the pilot eventually understood the warning after the controller provided instructions in Japanese. The aircraft then performed a left turn to join the proper runway path.
The investigation
The JTSB investigation focused on the discrepancy between the controller's intended clearance and the pilot's execution. Investigators examined the specific phraseology used by the tower, noting that the controller had followed standard procedures for an intersection departure. The investigation also reviewed the pilot's operational background and the infrastructure of the airports involved.
Crucially, the investigation compared the layout of Nagasaki Airport with Kagoshima Airport. At Kagoshima, a designated helipad is located on Taxiway T2, making departures from that specific taxiway a routine part of the pilot's experience. In contrast, Nagasaki Airport does not have a helipad installed on Taxiway T2.
Findings
- The pilot's error was driven by a reliance on familiar procedures from Kagoshima Airport, where taking off from the T2 helipad is standard practice.
- Because the takeoff clearance was issued promptly and included the phrase "T2," the pilot incorrectly assumed the controller was granting a flexible, non-standard departure from the taxiway itself.
- The pilot failed to distinguish between the specific ATC phraseology used for an intersection departure from a runway and the phraseology used for a departure from a designated helipad.
- The pilot misinterpreted the takeoff clearance, believing that departing from the taxiway was authorized.