Wheels-up time
Wheels-up time is the moment the aircraft leaves the runway, as distinct from the departure or block time when it starts to taxi. Operators and air traffic control plan around it: a slot at a coordinated airport, an oceanic clearance, or an arrival before a curfew is usually expressed as a required wheels-up time, and the crew will ask you to be at the FBO 15–30 minutes earlier so that boarding, doors closed and taxi can happen in sequence. On a jet card contract the phrase is often used loosely to mean the departure time you book; on an operations sheet it is precise, and being ten minutes late can cost the slot.