What happened
In the early hours of 5 February 2024, a runway incursion occurred at Changi Airport involving two Boeing 787-9 aircraft. The first aircraft, a Korean Airlines B787-9 with registration HL7209, landed on Runway 02C at 0435 hrs. As the aircraft was exiting the runway via Rapid Exit Taxiway (RET) T6, the Runway Controller (RWC) issued a landing clearance to a second Boeing 787-9, operated by Scoot with registration 9V-OJH.
The clearance was issued under the assumption that HL7209 would clear the runway strip before the arriving aircraft reached the threshold. However, as the aircraft approached the bifurcation of the taxiway, the crew of HL7209 stopped the aircraft because there was insufficient space to complete the turn. At this moment, the Scoot aircraft was already over the runway threshold. Despite the presence of the stopped aircraft on the taxiway, the RWC did not instruct the arriving aircraft to execute a go-around, opting instead to let the landing continue. The Scoot aircraft subsequently landed and passed behind the stationary aircraft to exit the runway.
The investigation
The investigation focused on the actions of the Runway Controller regarding the issuance and subsequent management of the landing clearance. Investigators examined the Air Traffic Services Manual (ATSM) protocols, which allow for reduced separation if a controller has reasonable assurance that the preceding aircraft will vacate the runway. While the initial clearance for 9V-OJH was found to be consistent with established procedures, the investigation scrutinized the decision-making process once the incursion became apparent.
Findings
- The initial landing clearance provided to 9V-OJH followed standard air traffic service procedures.
- The RWC failed to cancel the landing clearance or order a go-around once it was known that HL7209 had stopped within the runway strip.
- The decision to allow the landing to proceed was based on the controller's assessment that the tail of the first aircraft was clear of the runway and that a go-around might pose risks such as a tail strike or runway overrun.
- This decision deviated from the ATSM, which mandates that controllers must instruct a go-around if a runway incursion or obstruction is identified.
- The presence of the stopped aircraft reduced the safety margin, as it created a hazard in the event that the landing aircraft had veered off the runway.
Safety action
Following the investigation, the air traffic service provider conducted briefing sessions for all controllers between 6 and 9 February 2024. These sessions were designed to share lessons learned and reinforce the requirement to instruct aircraft to go around whenever there is uncertainty regarding whether the preceding aircraft has fully vacated the runway.