A flight planning oversight resulted in a Boeing 737-300SF operated by Express Freighters Australia flying below the minimum permitted altitude after a missed approach.
The incident occurred in the early morning of 17 July 2016 above Launceston, Tasmania, says the Australian Transport Safety Bureau (ATSB) in its final investigation report.
The cargo aircraft, VH-XMO, had departed Melbourne at 00:55 local time. The two person crew was aware that Launceston was shrouded in rainy weather, with a forecast of low clouds and limited visibility.
Upon reaching Launceston, the crew conducted an approach briefing and attempted an instrument landing approach on runway 32L. The crew reached the minimum altitude for landing, but conducted a missed approach when they failed to see the runway, with the aircraft levelling off at 3,200ft.
While the captain spoke to a groundsmen at Launceston about the weather, the first officer conducted a left turn to circle back for another approach. The first officer observed the activation of the radar altimeter, which provides an indication of height above ground of up to 2,500ft, and told the captain that they should climb.
Although the crew climbed the aircraft, they still entered a 5,800ft minimum permitted altitude zone at an altitude of 4,400ft, prompting a warning from air traffic control asking them to climb. The crew advised ATC that they were climbing to 6,000ft.
Shortly thereafter, ATC issued another warning stating that the 737SF was entering an area with an even higher minimum sector altitude (MSA), and called for an immediate climb to 6,300ft or higher.
"The crew acknowledged the altitude requirement and advised ATC that they would be returning to Melbourne," says ATSB. "A short time later, as the aircraft had not yet reached 6,300ft, ATC reissued the instruction to climb immediately to 6,300 ft."
The crew then climbed to cruise altitude and returned to Melbourne.
The ATSB says that while the aircraft was not in immediate danger of flying into terrain, the incident highlights that crews need to be aware of the maneuvers necessary after conducting a missed approach.
In response, Express Freighters Australia has updated its procedures and training related to missed approach maneuvering and management.