History of the Flight
On 19 May 2025, a Boeing 737-800 aircraft (registration 9M-MLL) operated by Malaysia Airlines was scheduled to depart from Singapore Changi Airport for Kuala Lumpur International Airport at 1635 LT. The flight crew consisted of a Pilot-in-Command (PIC) and a Second Officer (SO). The PIC was taxiing the aircraft while the SO communicated with Air Traffic Control (ATC).
At about 1649 LT, the aircraft was cleared to taxi via Taxiway T and Taxiway T2 to the holding point on Taxiway T2 (Holding Point T2) for departure on Runway 20C. While taxiing, the flight crew switched to the Runway Controller (RWC) frequency.
At about 1652 LT, an arrival aircraft had just landed on Runway 20C. The RWC asked if the flight crew were ready for departure, and the SO replied affirmatively. The RWC then cleared Aircraft A to line up on Runway 20C via Taxiway T2. The SO read back correctly, and the RWC switched off the red stop bar lights at Holding Point T2 via the Advanced Surface Movement Guidance and Control System (ASMGCS) to facilitate entry.
Shortly after, the flight crew realized the cabin crew had not yet reported the cabin ready. The PIC took over communication and informed the RWC they needed two more minutes. The RWC then switched on the red stop bar lights and instructed: “line-up clearance cancelled and report when ready.” The PIC incorrectly read back “cleared line-up and wait” and continued taxiing toward the runway.
The RWC noticed the incorrect readback and instructed “hold at Holding Point T2,” but only the portion “Holding Point T2” was transmitted to the aircraft. The PIC replied that they were lining up and wait, and continued. The RWC received a STOPBAR visual alert from the ASMGCS indicating the aircraft had crossed the red stop bar lights. The RWC considered instructing the aircraft to stop but decided against it, reasoning that the incursion had already occurred and she planned to have the aircraft line up anyway after they were ready.
Meanwhile, the arrival aircraft was taxiing slowly on Rapid Exit Taxiway T7. The RWC instructed it to turn onto Taxiway T to vacate quickly. Aircraft A eventually lined up on Runway 20C. At about 1654 LT, after the arrival aircraft had fully vacated, the RWC cleared Aircraft A for take-off. The RWC did not inform the flight crew of the incorrect readback or the unauthorized runway entry.
Injuries
No injury to any person was reported.
Personnel Information
The PIC, aged 38, held an Air Transport Pilot Licence issued by the Civil Aviation Authority of Malaysia, valid until 30 June 2025. His medical certificate was valid until the same date, with a requirement for corrective lenses for defective distant vision. He had 9,624 hours total flying time, with 2,378 hours on type.
The SO, aged 29, also held an Air Transport Pilot Licence issued by the Civil Aviation Authority of Malaysia, valid until 31 August 2025. His medical certificate had no operational provisos. He had 2,352 hours total flying time, with 2,186 hours on type.
Communications
The flight crew and RWC communicated via radio. The SO initially handled communications, then the PIC took over. The PIC misread the cancellation of line-up clearance, and the RWC's subsequent instruction was partially transmitted. The PIC believed he had been cleared to line up and wait, and informed the SO accordingly.
Flight Recorders
The investigation utilized flight data recorder and cockpit voice recorder information, though specific details were not provided in the summary.
Medical and Pathological Information
Toxicology tests were conducted; results were not specified in the available excerpts.
Conclusion
The occurrence was classified as an incident by the Transport Safety Investigation Bureau of Singapore.