Every private flight runs on two clocks. One starts when the wheels leave the runway. The other starts earlier, when the aircraft first rolls out of its parking spot, and stops later, when it parks at the other end. The gap between them is usually ten to twenty minutes. At private jet hourly rates, those minutes are worth real money, which is why it pays to know which clock your quote is built on.
The two definitions
Flight time, sometimes called air time, runs from takeoff to landing. It is what most people mean when they say a trip takes two and a half hours.
Block time runs from the moment the aircraft moves under its own power for the purpose of flight until it comes to rest at its parking position after landing. The name comes from the wheel chocks, or blocks, that are pulled away before departure and put back on arrival. Block time therefore includes taxiing out, any wait at the runway holding point, and taxiing in.
Operators choose how to bill. Some price on block time. Some price on flight time and add a fixed taxi allowance per leg, commonly six to eighteen minutes. A few price on flight time alone. All three are legitimate; they just produce different totals for the same trip.
What the difference costs
The table shows what each extra slice of ground time adds per leg at typical light jet rates of $3,500 to $5,500 an hour, before the 7.5% federal excise tax.
| Ground time billed | Hours | Added cost per leg |
|---|---|---|
| 6 minutes | 0.1 h | $350–550 |
| 12 minutes | 0.2 h | $700–1,100 |
| 18 minutes | 0.3 h | $1,050–1,650 |
| 30 minutes, busy day or de-icing | 0.5 h | $1,750–2,750 |
On a round trip the effect doubles, and on larger aircraft it scales with the hourly rate. Eighteen minutes of ground time in a large cabin jet at $8,500 to $13,000 an hour is roughly $2,550 to $3,900 per leg.
A worked example: Teterboro to Palm Beach
The flight is about two and a half hours. Say the aircraft taxis for twelve minutes at Teterboro and six at Palm Beach, so block time is two hours and forty-eight minutes, or 2.8 hours.
- Billed on flight time: 2.5 hours at $3,500 to $5,500 comes to $8,750 to $13,750.
- Billed on block time: 2.8 hours at the same rates comes to $9,800 to $15,400.
The difference, $1,050 to $1,650 before tax, is the price of eighteen minutes on the ground. Neither number is wrong. What matters is that two quotes for the same trip are compared on the same basis.
Why short flights feel it most
Ground time does not shrink when the flight does. A thirty-minute hop from Boston to Nantucket with fifteen minutes of taxiing has a block time of forty-five minutes, half as much again as the flight time. In practice, short flights are usually governed by a daily minimum anyway, often one to two billed hours, so the minimum rather than the clock sets the price. We cover that in the minimum you pay on short flights.
Where ground time grows
Some conditions reliably add minutes between the blocks:
- Busy airports at peak times. Queues for departure at major business aviation airports can add ten minutes or more on a Friday afternoon.
- Winter de-icing. Treating the aircraft before departure adds ground time and is usually charged separately as well.
- Air traffic control delays. Ground stops and flow control hold aircraft with engines running or at the gate, depending on the day.
- Long taxi routes. Large airports with distant runways simply take longer to cross.
Fixed quotes versus actual time
Most on-demand charter quotes are a fixed price for an agreed itinerary, worked out from estimated times. If the day runs long because of a routine taxi queue, the price does not usually change. Changes to the itinerary itself, such as an extra stop or a later return, are another matter and are re-quoted. Programmes that sell hours in advance, such as jet cards, often deduct actual time flown plus a taxi allowance from your balance, and that is where the block-or-flight question matters most from trip to trip.
When comparing two quotes, ask the same three questions of each: is it priced on block or flight time, what taxi allowance is included, and is the total fixed for this itinerary?
Three questions to ask of any quote
- Which clock is it built on? Block time, flight time, or flight time plus a taxi allowance.
- How large is the allowance? Six minutes and eighteen minutes per leg produce noticeably different totals on a round trip.
- Is the price fixed for the itinerary? If it is, routine ground delays are the operator's risk; if it is billed on actual time, they are yours.
None of these questions is awkward to ask. Operators answer them every day, and the answers make two quotes properly comparable.
How we present it
We quote all-in. The billed hours are built in the way the operating carrier bills them, the 7.5% federal excise tax and segment fees are added, and the result is one total per aircraft option. If the operator bills block time, the quote says so; if a taxi allowance applies, it is inside the number. That way the comparison you make is between aircraft and operators, not between billing conventions.
If you want to see how much the billing basis moves a particular trip, the hours estimator lets you change the taxi allowance and watch the total respond.