Air crash investigators are trying to figure out why a Sydney Seaplanes pilot took an "inexplicable" turn into Jerusalem Bay shortly before his plane crashed killing all six people on board.
The Australian Transport Safety Bureau's preliminary report into the New Year's Eve crash reveals investigators have found no mechanical issues with the aircraft since retrieving it from the river earlier this month.
Their focus, now, is turning to why experienced pilot Gareth Morgan, 44, left his expected flight route to enter the bay which is bordered by steep terrain with no clear path out.
The ATSB likened the decision to enter Jerusalem Bay to turning into a dead end street instead of onto a freeway.
The DHC-2 Beaver plane, a kilometre off course, made a steep right-hand turn and dropped into the water before sinking, killing Mr Morgan and his five UK passengers.
Sydney Seaplanes chief executive Aaron Shaw said the Beaver was not supposed to be in the bay and the sharp turn before the crash was "totally inexplicable".
"It is not a route we authorise in our landing and take-off area register and the plane simply should not have been where it was," he said in a statement on Wednesday.
The ATSB said the final report is expected to be released toward the end of the year and has renewed their appeal for witnesses to the flight's final moments to come forward.
