Operations
What Is Block Time?
In short
Block time is the total time an aircraft is in motion under its own power, measured from brakes released at departure ('off-block') to brakes set at arrival ('on-block'), including taxi. Charter operators typically bill by block hour rather than pure airborne flight time, so ground delays add directly to the invoice.
How it works
Block time covers the whole period an aircraft is moving under its own power for a flight, not just the part spent airborne. It starts the moment the aircraft pushes back or taxis away from the ramp under its own engines, and ends the moment it comes to a final stop at the destination ramp. That includes taxi-out, any ground holding for departure sequencing, the airborne portion, and taxi-in at the far end.
This differs from "flight time" in the narrower sense some people assume, meaning wheels-up to wheels-down only. In practice the two terms are often used loosely and interchangeably in charter marketing, but a contract's definition of what is billed matters more than the label. Charter operators, jet card programmes and airlines alike generally record and bill against block time because it is what the flight actually occupies the aircraft and crew for, and it is verifiable from the aircraft's own systems rather than estimated.
In the United States, the FAA's own regulatory definition of "flight time" under 14 CFR 1.1 is written in block-time terms: it runs from the moment the aircraft first moves under its own power for the purpose of flight until it comes to rest at the end of that flight. That definition matters for crew duty and rest rules under Part 135 as well as for logging, and it is the position as of 28 September 2026. The UK CAA and EASA apply their own flight time limitation rules for crew duty purposes, under the UK Air Navigation Order and EU Regulation 965/2012 respectively, and this entry does not attempt to restate their detail; a reader operating under UK or EU rules should check the specific instrument rather than assume the US wording applies.
For a charter client, the practical point is that block time, not distance and not airborne time alone, is usually the unit an operator's hourly rate is multiplied against. A jet card or membership programme typically deducts block hours from a prepaid balance for the same reason.
Cost impact
Block time billing means every minute an aircraft spends taxiing, waiting for a departure slot, or being towed off a busy ramp is charged at the same hourly rate as airborne flying. This is a contract term set by the operator or jet card provider, not a fixed industry percentage, so the exact effect depends on the airports used and the specific agreement's wording on what counts as block time.
To size it: take an illustrative charter with 1 hour 30 minutes of airborne flight time between two regional airports, priced at an illustrative rate of $8,000 per block hour. If taxi-out and taxi-in together add 30 minutes, which is unremarkable at a congested airport, the billed block time becomes 2.0 hours rather than 1.5. That is a difference of $4,000 on the illustrative example, roughly a third more than the airborne-only figure would suggest. The extra amount appears as part of the flight-hours line on the invoice, or as extra hours deducted from a jet card balance, and it is borne by the client rather than the operator, since the operator's crew and aircraft are committed for that time regardless of how it is labelled.
The same mechanic interacts with a daily minimum flight time clause: on a short trip already close to the contract's minimum, extra taxi time booked as block time can be what tips a flight over that threshold, adding a further charge rather than merely a few extra minutes.
Example
Suppose, for illustration, a charter client books a return trip and the operator's contract bills at an illustrative $9,000 per block hour, with block time defined from brakes release to brakes set on each leg.
- Outbound leg: 5 minutes taxi-out, 55 minutes airborne, 8 minutes taxi-in, giving a block time of 1 hour 8 minutes.
- Return leg: 12 minutes taxi-out at a busier airport, 55 minutes airborne, 5 minutes taxi-in, giving a block time of 1 hour 12 minutes.
Total block time for the round trip is 2 hours 20 minutes, against 1 hour 50 minutes of airborne time alone. Billed at the illustrative $9,000 hourly rate, the round trip costs approximately $21,000 on a block-time basis, compared with approximately $16,500 if only airborne time were charged. The difference, roughly $4,500 on this illustrative trip, is attributable entirely to ground movement at the two airports, and it is the client who pays it.
Related terms
- Deadhead
A deadhead flight is a leg flown with the aircraft's crew aboard but no paying, revenue passengers, usually to reposition the aircraft before or after a paying charter. Charter clients are commonly billed for this leg, so a one-way trip often costs close to what a round trip would cost.
- Repositioning Cost
Repositioning cost is the charge billed to a charter client for flying an aircraft empty to or from a trip, covering positioning and deadhead legs when no fare-paying passenger is aboard. It appears as an added charge or is folded into the quoted price, and can substantially raise the cost of a one-way charter.
- Cabin Class
Cabin class is the industry practice of grouping private aircraft by cabin size, layout and range into categories such as light, midsize, super-midsize and heavy jet, used to price and compare charter, jet card and fractional aircraft. It is a commercial convention, not a government classification, and higher cabin classes carry materially higher hourly rates.
- Daily Minimum Flight Time
Daily minimum flight time is the minimum number of flight hours a charter contract bills for a single day, regardless of how few hours the aircraft actually flies. If a trip's actual flight time falls below this threshold, the client still pays for the minimum, so short trips can cost more per flown hour than longer ones.
- Light Jet vs Midsize vs Heavy Jet
Light jet, midsize jet and heavy jet are industry categories that group private aircraft by cabin size, passenger capacity and range, rather than a formal regulatory classification. Light jets are smallest and cheapest to charter; heavy jets carry more passengers over longer distances at a materially higher hourly rate.
- Range vs Payload Trade-Off
The range vs payload trade-off is the aerodynamic relationship by which an aircraft's usable range falls as the weight it carries — passengers, baggage and cargo — rises, because total weight cannot exceed its maximum takeoff weight. Fully loaded, an aircraft flies less far than its advertised maximum range, sometimes forcing an unplanned fuel stop.