Investigators have found that the “safety margin” was reduced in a runway incursion incident between two Boeing 787-9s at Singapore’s Changi airport.
The incident, which happened on 5 February, involved a Korean Air and Scoot aircraft, both of which were landing at Changi, says the Transport and Safety Investigation Bureau (TSIB) in its final report.
The Korean Air jet (HL7209) had touched down on runway 02C at around 04:35 local time, and was exiting the runway via rapid exit taxiway T6.
It had not vacated T6 when the Scoot 787 (9V-OJH) was about to land about a minute later. This was because the flight crew of the Korean Air aircraft assessed there was insufficient clearance for it to turn into the exit assigned.
“Even though the runway controller was aware that [the Korean Air 787] had come to a stop and was unable to vacate [T6], the runway controller did not cancel the [Scoot 787’s] landing clearance and instruct it to go around,” the TSIB states.
According to the final report, the controller took into consideration that the Korean Air jet’s tail was clear of the runway and “there was no immediate obstruction” that would affect the Scoot jet’s landing.
The Scoot jet was “already over the threshold of Runway 02C”, according to the runway controller, and “it would be safer to allow [it] to continue landing instead of instructing it to go around”. It landed on Runway 02C without incident, and exited on a rapid exit taxiway further along the runway.
In its analysis, the TSIB found that while it would be “ideal” for the entire runway to be clear of any traffic when an aircraft touches down, there were existing provisions in case of high traffic volume.
In the incident, the runway controller’s decision to issue a landing clearance to the Scoot 787 was in line with procedures.
However, it found that the decision not to call off the landing despite the runway incursion was “not in line” with procedures.
“Had [the Scoot 787] experienced a runway excursion during the landing and veered off the left edge of the runway, the presence of [the Korean Air 787] on the runway strip would constitute a hazard,” the TSIB states.
It adds: “While it is not common for a landing aircraft to overshoot, undershoot or veer off the runway, the landing phase for an aircraft carries the highest risk in an aircraft’s flight operation. The landing aircraft may take on an unintended path.”
The TSIB stresses that it was crucial for air traffic controllers to “keep in mind” that the purpose of having the runway strip free of other aircraft or obstacles is “to reduce the risk of damage should an aircraft undershoot, overrun or veer off the runway”.
To this end, the air traffic services provider at Changi has briefed air traffic controllers to review the incident and share the lessons learnt.
