History of the Incident
On Tuesday, February 14, 2017, an Airbus A330-343X registered as HS-XTC, operated by Thai Air Asia X Co., Ltd. (Aircraft A), was preparing for departure from Narita International Airport as scheduled flight 607. The aircraft carried 379 persons: a pilot in command (PIC), nine other flight crew, and 369 passengers. The PIC, age 49, held an airline transport pilot certificate and had 19,176 hours total flight time, with 1,931 hours on the A330. The first officer (FO), age 31, held a commercial pilot certificate and had 2,549 hours total time, with 222 hours on the A330.
While Aircraft A taxied on Taxiway B toward runway 34R, the Aerodrome Control Facility (the Tower) issued a landing clearance to a China Airlines Airbus A330-302, registered as B-18361 (Aircraft B), which was approaching approximately 15 nautical miles from the runway. Aircraft A reported ready for departure. The Tower instructed Aircraft A to hold short of runway 34R and advised of a six-minute delay due to departure sequencing, repeating the hold-short instruction. The PIC of Aircraft A read back the instruction.
The PIC then ordered the FO to turn on the Runway Turn Off Light on the nose landing gear to illuminate the right side when turning short of the Holding Position Markings (Stop Line) of Taxiway B9. The FO mistakenly activated the Strobe Light on the wingtip; the PIC pointed out the error, and the FO turned off the strobe and turned on the Runway Turn Off Light. During this, the PIC was distracted by the FO's switch operation.
At 20:15:31, the Tower observed on the Airport Surface Display System that Aircraft A appeared closer to the runway than usual. The system displayed a yellow warning indicating the aircraft had crossed the Stop Line. The Tower asked Aircraft A to verify holding short of runway. FDR data showed Aircraft A's ground speed became zero at that moment, and the crew read back "Hold short of runway." However, because the Tower judged safety was in doubt, it instructed Aircraft B to go around. Aircraft B, which was approximately 2,900 meters from the threshold on final approach, executed a go-around. The serious incident occurred at 20:16 on runway 34R.
Aircraft and Environmental Information
Aircraft A was an Airbus A330-343X (serial number 692, manufactured November 23, 2005) with a valid airworthiness certificate. Aircraft B was an Airbus A330-302. No injuries to persons were reported, and no damage to either aircraft occurred.
The aviation routine weather report at 20:00 indicated wind from 290° at 4 knots, visibility 10 km or more, few clouds at 3,000 ft, temperature 2°C, dew point -5°C, and altimeter setting 30.20 inHg.
Runway and Taxiway Configuration
The spacing between Taxiway B and runway 34R at B9 is narrow. Aircraft instructed to hold short of runway 34R stopped short of B9 on Taxiway B because the space before the Stop Line of B9 was insufficient for the aircraft to stop with its nose facing the Stop Line at a right angle. B9 is equipped with Stop Lines, Stop Bar Lights, and Runway Guard Lights to indicate the halt position. At the time of the incident, the Stop Bar Lights were not illuminated, but the Runway Guard Lights, which flash yellow, were on.
Recordings and Systems
Both aircraft were equipped with flight data recorders (FDR) and cockpit voice recorders (CVR). The FDRs recorded the incident. The CVRs were overwritten due to their two-hour capacity and continued operation after the incident. FDR and Multilateration System (MLAT) data, along with surveillance camera images, showed the stop position of Aircraft A relative to the Runway Guard Lights. The Airport Surface Display System, which uses MLAT, displayed a yellow warning when the system detected Aircraft A had crossed the Stop Line.