Operations
How to calculate your true crew availability
True crew availability is the number of crew members who can legally and physically operate a given flight at a given moment. You obtain it by removing six successive layers from headcount: contract, flight and duty time limits, qualifications, existing commitments, positioning, and travel documents.
It is the most-used quantity in operations and the least often computed. At most operators, "who is available tomorrow?" is answered from the published roster, which amounts to an optimistic approximation.
Why does headcount on the roster tell you nothing?
A roster shows states: ON, OFF, leave, training. None of those answers the operational question, which is always more specific: can this crew member operate this flight, out of this airport, at this time, on this aircraft?
Three classic errors follow:
- Treating "on an ON day" as "assignable". Someone on an ON day may be hours from a rolling limit, awaiting rest, or not current on the aircraft in question.
- Counting availability without a flight attached. No crew member is available in the abstract; they are available for a particular flight, at a particular time and place.
- Reasoning in average headcount. "We have twenty pilots" says nothing about next Tuesday's coverage on a specific type.
Which layers do you remove?
The calculation is a funnel. Each stage removes a population.
| # | Filter | What it removes |
|---|---|---|
| 1 | Contract and status | Part-time, sick leave, leavers, restricted probation |
| 2 | Published roster | OFF days, approved leave, training, recurrent checks, standby already assigned |
| 3 | Flight and duty time limits | Rolling counters near a cap, rest required before or after |
| 4 | Qualifications and currency | Type rating, special authorisations, recurrent checks, medical |
| 5 | Positioning | Distance to the departure airport, feasibility and cost of getting there |
| 6 | Documents | Passport, visa, destination-specific authorisations |
Three points that decide whether the calculation is worth anything:
- The order of the filters hardly matters; skipping one is what hurts. A single omission (usually the fourth or the sixth) and the answer is wrong in the most expensive direction: optimistic.
- Filter 3 works in both directions. It is not enough to check that a crew member can operate the flight. You must check that operating it will not make them unavailable for a commitment already made downstream. Its thresholds are those of the applicable regime: ORO.FTL or, for air taxi, national rules.
- Filter 5 has a price tag. A crew member "available" 500 miles from the departure airport is not the same proposition as one on site, and the positioning leg itself consumes duty time.
The method is a framework for reading the problem: it does not replace the operations manual, which sets each operator's exact rules for every filter.
How do you compute it in practice?
Three maturity levels, in the order operators go through them.
Level 1: the manual list. The scheduler runs the six filters mentally, for a handful of crew. It works, it is slow, and it is not reproducible: two schedulers give two answers.
Level 2: the computed view. Roster, qualification and counter data live in one system, which shows the assignable crew for a given date. The answer becomes reproducible and defensible.
Level 3: availability per mission. The system answers the full question, trip by trip, including positioning and downstream effects. This is the level that lets you assign in minutes and quote without an artificial safety margin.
SkAI Tech operates at that third level, as an add-on connected by API to the operations system in place: data stays at its source, availability computation and optimised assignment sit on top, with full roster re-generation in 12 minutes on average when it is needed. That average is observed across SkAI Tech deployments in 2025-2026 and varies with fleet size and operating model.
Already running FL3XX, Cyberjet or Leon? See how SkAI Tech connects to your ops system.
Why does the number change from hour to hour?
Because it depends on counters that move. A departure twenty minutes late changes actual duty time, therefore required rest, therefore tomorrow's availability. A sick call removes one crew member and, by knock-on effect, weakens two others.
This is why availability "computed on Monday for the week" is indicative at best. The useful figure is computed on demand, at the moment the decision is made. A weekly projection remains valuable for a different purpose, though: spotting the days where coverage is critical before they arrive.
What do you do with the result?
Four uses, from the most immediate to the most structural:
- Answer commercial requests without an excessive safety margin. An operator that cannot verify fast enough ends up declining flights it could have operated.
- Spot critical days ahead of time: the ones where coverage rests on one or two crew members holding a given qualification.
- Size the standby reserve on data rather than instinct: how many trips landed outside the roster per week, on which aircraft, at what notice.
- Put numbers on the hiring question. If true availability is structurally below demand, the problem is headcount. If it is sufficient but badly distributed, the problem lies in the assignment method, and hiring will not fix it. See our article on the pilot shortage in business aviation.
FAQ
What is the difference between availability and assignability?
Availability describes a state over a period (an ON day, not on leave). Assignability describes a relation between a crew member and a specific flight, at a given time and place. Operational decisions turn on the second, almost never on the first.
Can true availability be computed in a spreadsheet?
Partly, and fragilely. Rolling flight and duty time windows recompute at every assignment, in both directions of the calendar, which is exactly what a grid does not show. See our Excel vs crew scheduling software comparison.
How often should it be recomputed?
At every decision, and at minimum whenever the plan or the actuals change. A figure computed yesterday is an indication, not a basis for a commercial commitment.
Should standby crew be counted in availability?
Yes, but separately: a reserve does not carry the same cost or the same response time as an already-rostered crew member. Adding them into a single number hides exactly what the number was meant to reveal.
Sources
- Regulation (EU) No 965/2012, Annex III, Part-ORO, Subpart FTL: cumulative flight and duty time limits over rolling periods (ORO.FTL.210) and minimum rest (ORO.FTL.235); Article 8(2) for the air taxi derogation to national rules.
- SkAI Tech KPIs (first-party data): average generation time observed across 2025-2026 deployments, varying with fleet size and operating model.
