A former Qantas pilot and aviation expert says distraction is one many factors that could have played a part in a chopper crash near Sea World on the Gold Coast which killed four people and left three people fighting for life.
The tragic accident happened when two aircraft, both operated by Sea World Helicopters, collided at about 2pm AEST yesterday.
One of the helicopters, carrying seven people, plunged to the ground while the second, carrying six people, managed somehow to land.
Vision shows the accident happened when one of the helicopters was coming in to land and the other was taking off.
Richard de Crespigny, who has 45 years of flying experience, including 1000 hours of helicopter piloting, told Today there could have been many reasons why the pilots did not see each other before they collided.
"If you look at that video (of the crash) you can see the aircraft above the horizon, that looks fairly easy to see, if there are no distractions," de Crespigny said.
"But are there distractions?
"Is a passenger saying something? Is the aircraft misbehaving?
"Is something drawing the pilot's view inside and he can't look outside?"
Approaching aircraft could also play visual tricks on a pilot's eyes, de Crespigny said.
"An aircraft … will start as being a dot on the windscreen and it then gets bigger and bigger in the same position, until it hits you," he said.
"The eye is not designed to see objects that are still, especially if the aircraft has got a painted skin that makes it sort of camouflaged.
"Were there distractions? Were the aircraft camouflaged in the airspace below? All these questions are still to be answered."
Aviation authorities were helping pilots install equipment used to transmit position and altitude to big commercial aircraft, de Crespigny said.
However, choppers flying close to the ground relied on pilots seeing and avoiding other aircraft, he added.
de Crespigny praised the efforts of one of the pilots who managed to land their chopper on the ground after the collision.
Of the six in the helicopter which landed, five were taken with minor injuries to Gold Coast University Hospital and one person was physically uninjured.
"I think the pilot who landed that aircraft after that mid-air collision did an excellent job of landing on a hard surface safely and everyone got out.
"I think that looks like excellent piloting."