Ask an owner what a flight hour costs on his aircraft. The answer usually comes fast, and it is usually too low, because it answers a different question: what the fuel for the flight hour costs.
The complete calculation is less pleasant and far more useful. And it has a second half almost nobody does: what the hour the aircraft doesn't fly costs.
The two cost families
Variable cost is what only exists when the aircraft flies: fuel and oil, hourly maintenance reserves (the engine moving toward overhaul, components with life limits in hours and cycles), navigation and landing fees, and the wear each cycle charges.
Fixed cost is what comes due with the calendar, flying or not: hangar, insurance, crew, the calendar inspections of the maintenance program, data and software subscriptions, administration, and depreciation, the cost nobody sees on the statement and everybody sees at resale.
This separation isn't accounting pedantry: it is what makes the one calculation that matters possible:
Dilution: why the hour of someone who flies little costs more
Variable cost per hour is reasonably constant. Fixed cost is not: it is an annual amount divided by hours flown. And that division produces the effect that changes decisions:
An aircraft with a high annual fixed cost that flies 200 hours spreads that cost over 200 slices. The same aircraft flying 50 hours concentrates the same cost in 50 slices, with each hour carrying four times as much fixed cost. Whoever flies less pays more per hour, the opposite of the intuition that flying less saves money.
This math underpins structural decisions: sharing among owners (splitting the fixed cost among those who dilute together), chartering during idle hours, or, in the opposite direction, the honest conclusion that below a certain annual usage, chartering from third parties costs less than owning.
The calculation nobody does: the idle aircraft
An aircraft in the hangar seems not to cost anything. The reality:
Fixed cost runs in full. Hangar, insurance, crew, depreciation: the calendar's meter has no pause button.
So does the maintenance calendar. Calendar inspections come due with the date, not with usage. The aircraft that didn't fly reaches the inspection all the same, paying the same and having delivered zero.
Sitting damages. An engine that doesn't turn accumulates the problems of inactivity: internal corrosion, dried-out seals, contamination. The aircraft that is "resting" is, in practice, slowly deteriorating, and the bill shows up at the next intervention.
Capital has a cost. The value tied up in the idle aircraft would earn returns anywhere else. This opportunity cost appears on no invoice, and it is just as real.
Adding up the items, an executive-class aircraft costs per month, sitting idle, what many operators estimate it costs flying. The phrase "I'm not spending, I didn't even fly this month" is the most expensive in business aviation.
How to build the real cost per hour
The method matters less than the discipline, but the outline is this:
- Capture every expense tied to the aircraft, from fuel to licensing, with no "small stuff" left out of the calculation (small stuff added up is a relevant component);
- Classify fixed × variable at the time of entry, not in a year-end reconstruction;
- Provision for what comes due slowly: overhaul, life-limited components, paint and interior. The per-flight-hour reserve exists so the big bill is not a surprise;
- Divide by actual usage, not planned, and recalculate as the year goes on.
The result unlocks the decisions that intuition blocks: whether or not to accept sharing, pricing a charter, replacing or keeping, and, above all, seeing the idle hour as the cost it is.
How Alis handles this
Alis expense control is born tied to the flight and the aircraft: the expense entered in the context of the operation, not in a spreadsheet reconciled months later:
- Expense per flight, per aircraft and per category, with the cost per hour emerging from real data, not from hangar-talk estimates;
- Maintenance talks to cost: the same CTM (Maintenance Tracking) that controls expiries feeds the view of what's coming, so provisioning stops being a guess;
- For aircraft managers and fleets, separation by aircraft and by owner is native: each owner sees his own account, with no manual split.
The aircraft is probably the most expensive asset the owner has, and often the only one without its own management accounting. Closing that gap doesn't require becoming an accountant: it requires the data to be born in the right place.
This article is informational and does not constitute financial or accounting advice. Cost structures vary by aircraft type, operating regime and context. Build your calculation with your own data.