A single flight, bought from another operator, today.
A flight or a few days of cover when something has gone wrong and the schedule cannot wait for the fix. Fastest of the options to arrange, most expensive per hour, and the right answer when the alternative is cancelling on passengers.
Worth reading your own charter terms before you need them. Standard European conditions let the operator subcontract by default, and on unserviceability the usual remedy is best efforts to find a substitute plus a refund of the part not flown.
