The 42-year-old wrapped his body around his son's as they fell from the four-metre balcony.
A heroic father who leapt off a four-metre balcony to save his son's life was left fighting for his life in hospital after cracking his skull open on the concrete below.
Doctors couldn't believe Brad Lewis, 42, had survived the fall, when he arrived at intensive care.
The father of two was at a friend's house in Sydney's north on Saturday, August 4 when his eight-year-old son Oscar shot a few Nerf gun bullets at him.
When the bullets missed and went over the first-floor balcony, Oscar ran to see where they went and lost his balance, according to a Go Fund Me Page set up to support the family.
Mr Lewis saw what was happening and lunged to grab his son, but his speed and weight carried the two of them over balcony, tumbling towards the concrete below.
During the fall, the brave father — a former army officer and deep-sea diver — pinned Oscar to his chest and curled around him, taking the full force of the impact on his head.
"Are the kids OK? Don't let them see me like this, don't let me die mate," Mr Lewis told his friend Beau as he drifted in and out of consciousness after the fall.
Oscar was concussed, fractured his skull and suffered bruising on the brain.
The pair were treated by paramedics and a CareFlight team at the scene before Mr Lewis was flown to Royal North Shore Hospital in a serious condition, the Daily Mail reported.
Mr Lewis sustained major head and neck injuries — cracking his skull open, bruising his brain and fracturing his C6 vertebrae.
His recovery is expected to last for another six to 12 months, and he has now been moved from ICU to head trauma.
Oscar was taken to the same hospital and has since been released, but is still in shock and recovering slowly.
Annie Kendall, a friend of the family, wrote on the fundraising page: "He will not leave his mother's side and now sleeps with six pillows around him from fear of falling out of bed.
"While the family are still trying to come to terms with what happened, they are so incredibly grateful for the out pouring of support from their family, friends and the wider community — many of you they don't even know."
She also wrote that Oscar's mother Suz had taken leave from her new job to care for the family, "but the household bills and mortgage repayments keep rolling in".
So far almost A$30,000 has been raised of their A$150,000 goal.
"As the days go by, the realisation of this new reality and the financial implications it will have on the family are just beginning to set in," wrote Annie.
"The time has come for us to rally behind Brad and his family and give back just a taste of the goodness that he generously gives so many of us each and every day."