Passengers on a tourist seaplane that crashed into the ocean moments after takeoff escaped the sunken aircraft through an air pocket, it has been revealed.

The Cessna 208 Caravan 675 was carrying seven people when it slammed nose-first into the water and sank at Rottnest Island, off the coast of Perth, on January 7.

Pilot James Wong, 34, killed along with two passengers. Four other passengers survived — a Swiss man, 63, Danish woman, 58 and Western Australians Jeremy and Patricia Connor aged 63 and 65.

A preliminary report released by the Australian Transport Safety Bureau on Thursday provided details of the crash. It gave no findings on its cause, which will be revealed in its final report.

After hitting the water, the seaplane remained partially afloat, with  all cabin doors submerged, it stated.

“Survivors and other witnesses recalled the aircraft remained partially afloat in a perpendicular orientation, with the aircraft nose resting on the sea floor,” said the report.

The rear windows were not submerged.

Four passengers moved into a pocket of air in the rear cabin and one opened the top section of the rear right door, where they and another passenger exited.

“The coxswain of the tender vessel broke the rear left aircraft window, and two passengers recalled escaping through this broken window,” the report said.

Wong and the two other passengers remained in the aircraft, which later sank. Their bodies were later pulled from the wreckage, eight metres below the water’s surface.

Three of the four survivors were injured and taken to Fiona Stanley Hospital and Royal Perth Hospital. One passenger was completely unhurt.

Key locations in Thomson Bay on Rottnest Island. Source: Google Earth, annotated by the ATSB

The safety bureau report says Wong had complained about windy conditions before takeoff.

One of the directors of Swan River Seaplanes texted Wong at 3.11pm to ask about winds, the report says.

He replied that conditions were “OK but rough”. He said the swell was “not too bad” closer to shore, noting the aircraft would be “pretty light” for the departure.

The aircraft’s earlier flight to Rottnest Island carrying Wong and 10 passengers was labelled uneventful.

Six passengers boarded its return flight to South Perth and were fitted with life jackets.

“Passengers described conditions onboard the vessel and pontoon as rough and windy,” the report said of the return flight from the island.

The engine was switched on at 4pm and the plane travelled along the surface of the water for 32 seconds.

It became airborne with a high-nose attitude as it approached the western tip of Phillip Rock and rolled rapidly to the left and hit the water.

The aircraft had been brought to Perth from NSW for scenic flights over the city and Rottnest Island, arriving on New Year’s Day and making several flights before the crash.

Wong had more than 1900 hours of aeronautical experience, including almost 1400 hours on floatplanes and over 2600 water landings.

-with AAP