The Australian Transport Safety Bureau is ready to accept the possibility that missing Malaysia Airlines flight MH370 was in a controlled glide in the final moments of its doomed flight, almost two years ago, when it landed in the southern Indian Ocean.

If that was the case, and all the other fundamental assumptions are correct, the current priority search area might have to be three times as large as it is.

This concession by the Australia-managed search for the jet is made by the chief commissioner of the ATSB, Martin Dolan, in a paywalled interview with The Times.

The already extended priority sea floor search zone for the jet was based on the aircraft flying on a predetermined heading without further pilot input after first being deliberately diverted onto a westerly and then north-westerly course toward central Asia.

If, however, the captain was in control of the plane until very late in the flight, and it was deliberately made to glide even after the power to both engines stopped because of fuel exhaustion, it could have flown maybe 100 kilometres or more than modelled, vastly increasing the number of possible paths to an even larger area of the ocean than the 120,000 square kilometres that are being searched.

The Times report refers to the eventuality that Australia would publish a report explaining why the search had failed that would include recognition of the controlled end-of-flight scenario, should nothing be found in the defined zone.

The search partners, Australia, Malaysia and China, have agreed that the current ATSB-managed and Malaysia-instructed sea floor search will end on the exhaustion of this area, pending no material discoveries of sunk wreckage or credible new leads.

That end of the ATSB search is generally estimated to come by the end of May, subject to the sea state generated by the weather, which will deteriorate as the southern winter draws nearer.

The ATSB search has, in fact, contemplated controlled flight scenarios in the past. It took about a year of lobbying by UK pilot Captain Simon Hardy for his calculated end-of-flight scenarios, which involved ditching the jet while it had enough fuel left to deliver full control to a pilot, to be acknowledged.

Hardy’s optimal resting place for the wreckage was sonar scanned by the search late last year without result, although the calculations involved were accorded serious respect and consideration, and the margin for error is such that it might yet have come down within tens of kilometres of where he expected.

Unpowered gliding is another matter. The risk of loss of control toward the end of such a descent to the sea surface is considered very high, and the satellite ping data, as described by the ATSB last year, suggested that after both engines failed, one some minutes after the other, the Boeing 777-200ER began to fall out of control toward an impact, and that the jet might even have been inverted before impact, thus breaking the signal line-of-sight between a computer system antenna on the fuselage and an Inmarsat communications satellite parked in a geosynchronous location over the western Indian Ocean.

There is also the interesting question as to what China might do once the Australian search ends. It might continue the search rather than go home. Most of the victims of the loss of MH370 were Chinese nationals, and the derision with which Beijing held the conduct of the Malaysian authorities early in the saga is on the public record.

By coincidence or otherwise, The Times story came out at the same time as an unusually early release of the JACC/ATSB Wednesday search update.

This is what the very brief update says about the Chinese ship and its sharp synthetic aperture ultra deep water scanning sonar towfish.

“Dong Hai Jiu 101 has departed Fremantle to transit to the calibration range where the towfish will be trialed. It will then return to Fremantle to land personnel embarked only for the trials, before departing around 18 February for the first of three swings in the search area.”