The student pilot and an instructor in the second small plane walked away from the collision unscathed when they landed at Bankstown airport, as the other chartered plane, a Piper Cherokee, piloted by a father, his wife and two teenage children spiralled to the ground nearby.

The family, from Sydney’s west, were returning from Wagga Wagga at the time of the accident. A spokeswoman for the charter company, Clamback and Hennessy, said the father was an experienced pilot.

Death scene: Firemen inspect the wreckage of the plane lying in a factory carpark in western Sydney after the mid-air collisionPicture: Jeff Herbert; Photo: DiagramMapPhoto

INVESTIGATORS began piecing together last night how two light planes about to land under instructions from air traffic controllers could, on a sunny afternoon, collide in mid-air above suburban Sydney, leaving a family of four dead.

The student pilot and an instructor in the second small plane walked away from the collision unscathed when they landed at Bankstown airport, as the other chartered plane, a Piper Cherokee, piloted by a father, his wife and two teenage children spiralled to the ground nearby.

The survivors, who radioed in a mayday call before making their emergency landing, were last night at Bankstown police station.

A police spokesman said the pair were giving statements but were not being charged. “They are very shaken,” he said.

It was unclear last night who had control of the second plane. A spokesman for the Civil Aviation Safety Authority said: “Nine times out of 10 it would be thestudent doing a practice landing but whether that was necessarily the case this time round we don’t know.”

“It’s possible that it wasn’t. But you would think normally, on an instructional flight, the main things you do are takeoffs and landings.”

The CASA spokesman said the cause of the accident was unknown. “Somehow they’ve collided,” he said.

“It’s impossible to say, at this stage, where the error has occurred. The errors you’re searching for are air-traffic control, pilot error or mechanical error.”

The family, from Sydney’s west, were returning from Wagga Wagga at the time of the accident. A spokeswoman for the charter company, Clamback and Hennessy, said the father was an experienced pilot.

The Piper spun out of control, according to witnesses, missing nearby houses by about 100m, before coming to rest next to a boat parked between two factories in Violet Street, Revesby. The plane did not explode.

One witness, Ken Holden, said one of the planes appeared to do a “gentle barrel roll” as debris apparently came from its tail section.

“There was blood every where. The pilot, his arm was hanging out, it looked almost severed.”

Investigators from the Australian Transport Safety Bureau were travelling to the scene from Canberra late yesterday.

Bankstown airport is Sydney’s second-busiest after Kingsford Smith and is home to several flying schools.