With underwater technology company Ocean Infinity’s search nearing the end of its 90-day mission, the senior aviation figures say there is no hope of any discovery being made, based on advice from the Australian Transport Safety Bureau.

Captains Byron Bailey, of Australia, Simon Hardy of the UK, and New Zealand-born Mike Keane all have the same theory that Captain Zaharie Ahmad Shah hijacked his own plane, depressurised it to kill everyone else on board while using the pilot’s long oxygen supply and continued to fly it before ditching it.

If the pilot was still in control, that means he could have flown the aircraft further than if it was on autopilot. This includes gliding it when fuel supplies ran out.

Captains Bailey and Hardy and some other airline pilots think the missing plane lies not far behind the southern boundary of where the ATSB conducted its original search.

Last year, the ATSB led a failed underwater search of 120,000sq km, a target zone identified by its “ghost flight” theory that the pilots were incapacitated at the end of the flight and the aircraft flew on auto­pilot until it ran out of fuel and crashed.

“Four of us came up independently with a ditching locations 60 to 100 nautical miles south of latitude 38 degrees south, and if searched in that location MH370 has a high probability of being found,” Captain Bailey told The Australian.

He said it was “ridiculous” Ocean Infinity was searching more than 1000km north of 38 South on instructions from ATSB.

The new search plan is based on where the ATSB predicted would be the next best place to look.

Captain Keane, who was a fighter pilot and intelligence officer in the Royal Air Force, this week accused the Australian Government of being complicit to a crime if it sticks to its “ghost flight” theory and doesn’t publicly admit it was wrong.

Captain Hardy also believes the pilot deliberately flew the plane over his hometown of Penang for an “emotional goodbye”.

While most aviation specialists agree that evidence points to the plane having been intentionally steered into the ocean, nobody has been able to come up with a motive.

Ocean Infinity, the US company searching for the plane, hasn’t ruled out a further mission related to new theories.

It is coming to the end of its “no find, no fee” deal with the Malaysian Government which was to be carried out in 90 days, receiving up to $AU93 million if the wreckage is discovered.

Spokesman Mark Ateleme said the search was “agnostic” when it came to ATSB’s ghost flight dive theory or the ditching idea.

He said Ocean Infinity had based its search on CSIRO drift modelling, as well as models by the University of Western Australia.

Both studies came back with a position more north than the first search zone.

“We’re not closing the door on future MH370 searches but will not go straight into anything,” he said.

In his book MH370: Mystery Solved released this week, former Senior Investigator with the Transportation Safety Board of Canada, Larry Vance, said even without the certainties of the unpiloted aeroplane theory, there were too many variables to allow realistic calculations about where to look.

“The good news is that we do not need to find the aeroplane to solve what happened,” he writes.

“Fortunately, the pilot’s plan to make the aeroplane disappear was not perfect. Satellite communication technology, and drift modelling, provided the means to discover that the aeroplane went to the southern Indian Ocean.

“Fate gave us the exact wreckage pieces required to prove that the flaps were extended during a pilot-controlled ditching.

“With that, we have all the evidence we need to solve the mystery of MH370.”

He said the event was not caused by a defect in the aeroplane, or by some unknown intervention.

“We know that the pilot took it, and we know how he took it, and we know where he took it, and we know it was all deliberate and well planned,” Vance said.

“There is no longer any mystery about what happened to MH370. With this book, the mystery of MH370 is solved.”

The search is about a week or two from completion, with the crew needing to move on because difficult winter sea conditions were closing in.

They will then return to other projects.

Joint Agency Coordination Centre, responsible for informing the public on MH370 updates from a whole-of-Australian Government perspective, has not answered any questions from news.com.au this week, only referring inquiries back to Malaysia.

The media section on the government’s website has not been updated since 2016, with the last post on its homepage written in January this year about the search.

It can only be contacted via email.