What happened
On 2 June 2025, a Boeing 777-300ER operated by KLM Royal Dutch Airlines, registration PH-BVO, was taxiing toward Runway 20C at Singapore Changi Airport. The crew, consisting of a captain and first officer, had been instructed to hold at the runway holding position on Taxiway T1 (RHP T1). While approaching the holding point, the stop bar lights were illuminated, indicating that entry onto the runway was prohibited. However, the flight crew perceived the lights as off, likely due to glare from the setting sun behind the aircraft.
At 17:00:50 local time, the Runway Controller issued a landing clearance to an approaching aircraft with a similar callsign structure. The KLM first officer, monitoring the frequency, misinterpreted this transmission as a take-off clearance for their own aircraft. Believing they were cleared and that the stop bar lights were inactive, the crew increased engine thrust and crossed RHP T1 onto the runway strip. This action triggered an audio alarm in the Advanced Surface Movement Guidance and Control System (ASMGCS).
The controller immediately corrected the error, stating the clearance was for the other aircraft and instructing the KLM crew to hold position. The approaching aircraft executed a go-around. The KLM 777 came to a stop on Taxiway T1 after receiving further clarification from the tower. No injuries or damage were reported.
The investigation
TSIB examined the flight recorders, air traffic control recordings, and statements from the crew and controllers. The investigation focused on why the crew entered a protected runway area without explicit clearance and with illuminated stop bars. Key factors included the similarity of callsigns between the KLM aircraft and the approaching plane, the visual conditions affecting the perception of the stop bar lights, and the communication dynamics during the critical moment.
The analysis highlighted that the crew had not stopped to seek clarification despite perceiving the controller's speech as fast or unclear. The investigation also noted that the controller's correction included both callsigns, which may have contributed to confusion among the parties involved.
Findings
The primary cause of the incident was the flight crew mistaking a landing clearance for another aircraft as their own take-off clearance. Contributing factors included:
- Misperception of Stop Bar Lights: The crew believed the red stop bar lights were off, likely due to sun glare masking the illumination.
- Assumption Bias: The crew assumed the runway was exclusively for departures at that moment and expected the next instruction to be a take-off clearance.
- Procedural Non-compliance: The crew did not adhere to operator procedures requiring them to stop and seek clarification when instructions were unclear.
- Communication Clarity: While the controller's speech rate was considered normal for an urgent situation, the inclusion of multiple callsigns in the correction transmission may have added to the confusion.
Safety action
Following the incident, the Air Navigation Service Provider (ANSP) conducted runway safety briefings for all air traffic controllers to reinforce situational awareness and operational consistency. The ANSP also briefed controllers on the risks of including multiple callsigns in a single instruction to reduce human-factors related confusion.
Additionally, the ANSP shared lessons learned with operators through Runway Safety Team meetings, emphasizing strict adherence to ATC instructions, proper runway entry protocols, and the immediate execution of go-around instructions. The KLM operator conducted a study on runway incursions and is reviewing its procedures against global industry standards for preventing such events.
TSIB issued two safety recommendations to the KLM operator: to remind flight crews to seek clarification if ATC transmissions are unclear, and to verify the status of stop bar lights with controllers if environmental conditions make their perception uncertain.