Emergency services were called to Matron Porter Drive at Milton on Thursday afternoon after a head-on collision between a Volvo and a Subaru Forester.

The Subaru was driven by 36-year-old Hamid Mobarrez, an Olympian for Iran and the head swimming coach at an all-girls private school in eastern Sydney.

Mr Mobarrez was driving east with his wife, Tamara, and a five-year-old child when their car was involved in a collision with a westbound Volvo driven by the 39-year-old man about 3.50pm.

Mrs Mobarrez, 36, was unable to be revived and died at the scene, while Mr Mobarrez was trapped in the car, suffering multiple fractures and suspected spinal injuries.

He was cut out of his car and taken to St George Hospital, where he remained in a stable condition as of Saturday evening. The five-year-old child was flown to Sydney Children's Hospital in Randwick where he is in intensive care with head and facial injuries.

The Volvo driver was taken to Milton Hospital with minor injuries and underwent mandatory testing, before being transferred to St George Hospital for treatment.

He was discharged from hospital on Saturday, and taken to Kogarah police station where he was charged with dangerous driving occasioning death, two counts of dangerous driving occasioning grievous bodily harm, negligent driving occasioning death and negligent driving occasioning grievous bodily harm.

The man was given bail, and is due to appear at Sutherland Local Court on February 20.

Mr Mobarrez is the head swimming coach at Kincoppal Rose Bay School and Mrs Mobarrez worked in administration in the school's aquatic centre.

At the 2000 Sydney Olympic Games, he represented Iran in the men's 100-metre freestyle. In 2007, he held Iran's record for 100-metre butterfly.

In a statement, Swimming NSW described Mr Mobarrez as a "highly regarded" coach, and said the crash occurred "near Mollymook where Hamid was conducting a camp for his swimmers".

"Our love and deepest sympathy are with Hamid and Eli at this time and we offer our sincere condolences with the loss of their beautiful wife and mother," the organisation said.

Swimming NSW has established a GoFundMe page for Mr Mobarrez and the boy, to raise funds for convalescence. By yesterday evening, about $62,500 had been raised. Judy Brown, who arrived at the scene shortly after the crash, said it was a "sweeping bend".

Another passer-by, Lisa Elmas, had also pulled the Falkholt sisters from the wreckage of their family car following a separate, head-on crash on Boxing Day. Lars Falkholt and his wife Vivian died in the crash. Their daughter Annabelle, 21, died several days later, while their daughter Jessica, 28, has had her life support turned off.