A Singapore Airlines Boeing 777-300ER landed very low on fuel after declaring ‘Mayday Fuel’ and aborting three attempted landings at a diversion airport in Indonesia.
The occurrence took place on 22 October 2022 after the aircraft (9V-SWH) operated a service from London Heathrow, according to a final report by Singapore’s Transport Safety Investigation Bureau (TSIB).
The aircraft, with 280 passengers on board, had departed London with 106,604L (28,100USgal) of fuel. At the time, no large weather system was anticipated in Singapore.
At 16:05 local time the crew was preparing to land on Changi airport’s runway 20R when they learned that a tailwind and heavy precipitation would delay arrivals.
The weather was also poor at the two primary diversion airports, Singapore’s Paya Lebar Air Base and Senai International airport in Malaysia. However, conditions at Indonesia’s Batam airport appeared fine.
The Changi arrival runway was presently changed to 02L and as the 777 flew a holding pattern the weather continued to deteriorate.
At 16:29 the 777’s crew learned that the weather at Batam remained fine. They also informed arrival control that they could perform only one hold at waypoint SAMKO, at which point they would be down to emergency fuel.
Completing the first hold over SAMKO at 16:36, the crew asked for an update about Changi and were informed that there was no change. Nonetheless, they informed arrival control that they could perform one more hold before diverting to Batam.
At 16:42, at the end of the second hold, the crew opted to conduct an orbit over SAMKO – at this point the diversion to Batam had yet to be cleared.
At 16:53 the crew declared “Mayday Fuel,” which was shortly followed by priority to land at Batam. By this time, however, weather conditions at Batam had deteriorated as well, with heavy rain and winds.
PREFERENCE FOR CHANGI
In its analysis, the TSIB questions the crew’s apparent preference to land at Changi, noting an earlier diversion would have enabled a landing in better conditions at Batam.
“With the decision taken to stay in hold as much as possible in hope that the scheduled arrival airport starts to accept arrivals again, the trade-off for any flightcrew is the reduced safety margins available to them when the decision to divert is eventually made and should they need to perform more than one landing attempt due to unforeseen events such encountering windshear during short finals that requires a go-around to be performed,” says the TSIB.
SIA, however, suggests that the crew lacked insufficient information to divert earlier.
What followed were a missed approach and two go-arounds at Batam. The first approach, to runway 22, was discontinued owing to a tailwind of 14kt (28km/h), gusting up to 30kt.
The second approach, to runway 04, resulted in a go-around when the crew received a “No Autoland” message, and released that “the aircraft was away from the centreline and glidepath for the runway.” The go-around was executed at an altitude of 132ft.
As the crew repositioned for another attempt at runway 04, they learned that visibility for runway 04 was down to 500m (1,640ft), while at runway 22 it was 6,000m. The pilot flying, however, informed controllers that there was insufficient fuel to reposition for runway 22 and stressed the next landing attempt on runway 04 “had to be successful.”
“According to the pilot flying, when the aircraft broke cloud cover on the second approach to runway 04, the aircraft was above the glidepath and offset to the left of the extended centreline of the runway,” says the TSIB.
“The pilot flying increased the descent rate in an attempt to position the aircraft on the glidepath and extended centreline of the runway. However, the Ground Proximity Warning System generated a warning for excessive sink rate when the vertical speed exceeded 1,400ft per minute.”
In response to the GPWS warning, the pilot initiated a go-around at an altitude of 212ft.
The crew then decided to land on runway 22 despite a 15kt tailwind.
“The pilot flying was aware that the aircraft’s tailwind certification limit was 15kt for landing and the operator’s procedure was not to land with a tailwind exceeding 10kt,” says the report. “Considering that the remaining fuel quantity had reached critically low level, the pilot flying decided to proceed with the approach to land on runway 22.”
The aircraft landed at 17:19 and taxied to a parking bay. At touchdown, the “fuel remaining was significantly below the [final reserve fuel] of 3,024kg.” The investigation does not disclose the precise amount of fuel remaining.
In the wake of the event, SIA has conducted a review of the incident with all pilots, and updating training around fuel management.
“The operator and air traffic services provider have initiated efforts to explore possibilities to expedite the coordination process with nearby alternate airport and consider setting up a team for real-time operations management during inclement weather,” adds TSIB.
There was no damage to the aircraft, and no injuries to those aboard. The 55-year-old captain had total flying time of 14,400h, while the 31-year-old first officer had 2,300h.