The Flying Doctors (1986) : 5x17

Nick's father, Jim, and Nick are out driving. Nick is a bit worried, the rumour says his dad takes amphetamine. Nick is asleep, when Jim suddenly can't see properly. He crashes into the Broken Hill bus! There are a lot of victims, and everybody is called in. Nick thinks they crashed because his dad was high, but an x-ray showed he had a braindamage. He goes to Sydney for treatment as soon as they found out.