A five metre fall from the roof he was spraying left a Blacktown man with serious head injuries at Kenthurst on Saturday.
Within an hour of a Triple 0 call which brought police, ambulance and CareFlight teams to the property the man was placed in an induced coma and flown to Westmead Hospital.
CareFlight landed at the Pitt Town Road property so the trauma doctor could team with ambulance paramedics treating the unconscious man.
The CareFlight doctor said the 37-year-old man fell onto concrete from a ladder.
The doctor placed the man in an induced coma as a pre-hospital start to intensive care management of the head injury then put him on a ventilator to control his breathing.
The man was flown to Westmead Hospital where he remained in a serious condition on arrival shortly before 11 am.