Two 737 passenger flights landed at Darwin Airport in September 2021 with unnecessarily reduced landing distances available to them after their flight crews misinterpreted NOTAMs detailing that a displaced threshold was in place due to runway works.
The incidents occurred on two flights operated by Virgin Australia Boeing 737-800s: the first on 3 September 2021, from Melbourne to Darwin, the second on 19 September 2021, from Brisbane to Darwin.
On both occasions, during pre-flight briefings, flight crews misinterpreted a NOTAM (notice to airmen) for Darwin Airport. The NOTAM stated that runway 29 (for landing from the east) had a displaced threshold of 765 metres due to works in progress and that the eastern end of the runway was not available due to the works.
Landing from the west on runway 11, however, did not require using the displaced threshold, although the landing distance available, due to the runway works at the eastern end, was reduced to 2,670 metres.
“On both occasions, the flight crews misinterpreted the NOTAM and conducted unnecessary displaced threshold landings, reducing the available runway for their landings.”
Both aircraft landed without incident.
“These incidents highlight the critical importance that operational information in a NOTAM can have for the planning and conduct of a flight,” ATSB Director Transport Safety Stuart Macleod said.
“Misinterpretation of NOTAM information can significantly affect flight safety.”
In addition, Mr Macleod noted correct and complete readback of air traffic control clearances are important to confirm information has been received and understood.
“Readbacks provide a valuable defence to detect and correct errors such as occurred during these incidents,” he said.
“Flight crews are also encouraged to seek clarification from air traffic control when there is uncertainty or ambiguity about the condition of a destination, such as a displaced threshold.”
After the first incident, Virgin Australia updated their Flight Crew Operational Notice for Darwin Airport. It then modified it further after the second incident, to specifically highlight the displaced thresholds.