Just to address the Part 91 vs 135 for commercial flight: it is legal provided there are no revenue generating cargo or passengers aboard (e.g., zero people and

Just to address the Part 91 vs 135 for commercial flight: it is legal provided there are no revenue generating cargo or passengers aboard (e.g., zero people and a couple of lost bags = nope, because bags are freight). The carriers commonly make use of Part 91 for reposition flights to move equipment into place to resume original schedules following weather diversions or whatnot. (me: Licensed Aircraft Dispatcher)