Contrary to conventional air ambulance staffing, it is on-call and contract rate. I am hoping to figure out a way to compare it with day-time part 91/135 contract rates for the same plane (also adjusted for cost of living location). Due to the nature of transplant surgery scheduling most of the flights are 2400-0600. One hopes for a premium for that but mostly because you'd be toast for any other income earning the following day.