'Bring my little man back': Father's plea

The father of a 10-year-old Sydney boy fighting for his life, after two helicopters collided in mid-air on the Gold Coast killing the child's mother and three others, has asked for prayers for his son.

"I do ask that if everyone can please say a prayer for Nicky, so he can wake up and make a good recovery," Simon Tadros posted on social media on Tuesday night.

"He is in an induced coma on a life support machine to help him breath (sic). He is in a very serious and critical state. I'm asking for all your prayers to bring my little man back to me."

Mr Tadros' wife Vanessa Tadros, 36, also known as Vanessa Geagea, died after the two Sea World Helicopters aircraft hit each other in mid-air on Monday afternoon.

The crash near the Sea World amusement park also killed British-born pilot Ashley Jenkinson, 40, Ron and Diane Hughes, 65 and 57, from Liverpool in the UK.

One of the choppers, which was carrying six people including the four who died, lost its main rotor blades and crashed heavily onto a sandbar.

The survivors, nine-year-old Leon De Silva and his mother Winnie De Silva, from Geelong, remain in hospital.

Ms De Silva's husband, Neil, said on an online fundraiser, which had raised more than $16,500 by Wednesday morning, that the family had been on a quick holiday to Queensland.

"Thankfully they are both alive but have a lot of surgery ahead of them which means the family will need to stay here on the Gold Coast and I won't be able to return to work," Mr De Silva said.

The 52-year-old pilot of the second helicopter, Michael James, and four of his five passengers suffered shrapnel wounds when the cockpit was struck by the main rotor of the other aircraft.

Three of the six people from the second helicopter, including the pilot, are still in hospital, a Queensland Health spokesperson confirmed.

That second helicopter's passengers included a West Australian woman and two New Zealand couples in their 40s who were travelling together.

The Australian Transport Safety Bureau is probing the crash, and in particular what was happening inside the two cockpits at the point of impact.

ATSB Chief Commissioner Angus Mitchell said Mr Jenkinson's aircraft had taken off and was in the air for less than 20 seconds before its main rotor blades hit the cockpit of the second helicopter, which was coming in to land.

"Now, exactly whether that was the very first point of impact we're yet to determine," he told reporters on Tuesday.

"But that in itself has led to the main rotor and the gearbox separating from the main (Mr Jenkinson's) helicopter, which then had no lift, and has fallen heavily to the ground."

Both helicopters were salvaged on Tuesday.