Air taxi sells something the airline doesn't: availability. The customer calls today to fly tomorrow, changes the departure time twice, adds a leg and asks you to wait at the destination. That service is what justifies the price.
The problem is that crew duty time doesn't care about the customer's schedule. It runs on the law's clock, and the law's clock doesn't renegotiate.
What the law sets, and what it leaves to you
Law No. 13,475/2017, the Aeronaut Law, which replaced Law No. 7,183/1984, sets in art. 37 duty limits that vary with the crew composition in non-scheduled services, the category air taxi falls into:
| Composition | Duty limit |
|---|---|
| Minimum or simple crew | 11 hours |
| Augmented (composite) crew | 14 hours |
| Relief crew | 18 hours |
Notice what these numbers really are: single-day ceilings. They say nothing about the next day, which is the job of the minimum rest between duty periods. And they say nothing about the month: that is what flight time limits are for, which under the law vary with the aircraft category, with different values for jets, turboprops and helicopters.
So there are four clocks running at the same time on the same person:
On top of these four there are still monthly days off, standby and reserve, which the law treats as regimes of their own. Standby is not time off: it has rules, it has a count and it affects what comes after.
Where the air taxi roster really breaks
No operator exceeds duty limits because it doesn't know they exist. It happens for three very specific reasons, and all three are about information, not intent.
The rolling window is not the calendar month. Thirty days counted back from today change every single day. A spreadsheet organized by month closes nicely on July 31 and hides that July 25 through August 24 added up to more than allowed.
The flight that changes after it was rostered. The customer moves it up by two hours; the report time moves with it; so does the cutoff. The roster was built with the old time and nobody recalculated, because recalculating by hand, for everyone, at every change, is not realistic.
The extra leg accepted in the air. This is the most expensive pattern. The crew is already en route when the additional sector that "fits" comes up. It fits the aircraft and it fits the fuel. The question nobody can answer at that moment is whether it fits the duty period, and the cost of finding out wrong shows up later, in reconciliation.
In all three cases, the necessary data existed. It just wasn't available at the moment of decision, which is the only moment when it would be worth anything.
Why "warn" beats "block"
This is a product opinion, and it is deliberate.
When we built Alis's duty engine, the decision was that the system warns, but never locks the roster. It sounds counterintuitive on a regulatory subject, and there are three reasons:
- Not every operation follows the same regime. Public safety operators have their own rules; flight schools have a different reality. Software that locks by the general-law standard would be wrong for part of its users.
- Roster authority belongs to the manager. There are provided-for situations in which the limit changes, and whoever answers for them is a person with a name, not a rule in code.
- Locks become workarounds. A system that prevents the inevitable teaches users to record outside it. Then you lose both things: compliance and data.
That is why limits in Alis are configurable per company (duty, rest, hours in 30 and in 365 days) and come from the Aeronaut Law defaults when the company doesn't define its own.
What the system does is what the spreadsheet doesn't: it calculates the four clocks for each crew member while you build the roster, and shows the warning on the screen where the decision is being made. In rostering and the schedule, the number shows up before the commitment to the customer, not in next month's audit.
The five-second checklist
Before saying yes to the next request, five questions. If all five have an immediate answer, your operation is in control:
- Does this crew member close the day within the duty limit, considering the actual report time and not the flight time?
- Was the rest before this report time met, and does the rest after it still fit what is already rostered for tomorrow?
- Where is he or she in the 30-day window today, not at month close?
- And in the 365-day one, which is the one nobody tracks until it runs out?
- Are the month's days off still possible with this roster, or did you just spend the last one?
Whoever answers all five by looking at a screen negotiates better with the customer, because they can offer the alternative (another crew, another time, another aircraft) instead of simply refusing or, worse, accepting and finding out later.
The closing point
Duty time is not an HR matter: it is operational capacity. Each crew member has a stock of hours that renews slowly, and the roster is how you spend that stock.
An operation that sees the stock sells with confidence. One that doesn't sells in the dark, and the price of discovery comes as a flight refused at the last minute, a crew member unavailable on the worst day, or an unpleasant conversation with the regulator. It is the same reasoning that applies to the technical control of the aircraft: the limit you don't track doesn't stop existing. It just arrives without warning.
This article is informational and does not replace reading the applicable rules or legal advice. The limits cited come from Law No. 13,475/2017 (the Aeronaut Law); specific regimes, collective agreements and the regulations applicable to your operation may change what applies in your case. Confirm in the official publications and with your operations department.