AUSTRALIA'S crash investigator says that the Grumman G-73 Mallard that crashed into the Swan River in front of thousands of spectators celebrating Australia Day suffered an aerodynamic stall.
Father-of-three Peter Lynch, 52, and Endah Cakrawati, 30, died when the twin-engine Mallard stalled during a tight turn and plunged nose first into the river.
Mr Lynch had owned the plane since 2011 and had spent more than 120 hours at the controls.
But as a newcomer to Perth, he had never before attempted to land it on the river.
He has expressed concerns about the flying display he was take part in because of the lack of wind and the heat which would have impacted the plane's performance.
Those conditions required a higher speed and in this case deployment of the aircraft's flaps which increase the wing's lift.
However the flaps were not activated.
The ATSB said that the wind was about 20 km/hr from the south-west and the temperature was about 39 °C.
When the plane crashed it was travelling north-east so the 20km/hr south-west wind would have worsened the situation by affectively reducing his over-the-wing-speed by 20km/hr.
The ATSB said it found no pre-existing aircraft defects, which may have contributed to the collision with water.
However the ATSB has retained several items and components from the aircraft for further examination.
These include a fuel totaliser, a navigation unit and a mobile phone.
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