What the scheduler checks
The seven operational gates every schedule is checked against, live and with exact reasons: traffic rights, range, runway, slots, curfew, rotation, and the maintenance window.
Behind every schedule in PlaneSim sit seven operational gates, and they are checked live. As you edit in the schedule wizard, each change runs against the real engine; a checklist shows pass, fail or pending per gate, and every failure carries its exact reason. Violations are surfaced the moment they exist, on the screen where you caused them, which is where an ops controller would want them.
The set, in brief:
| Gate | What it checks | Typical rejection |
|---|---|---|
| Traffic rights | Your nationality may legally fly each leg | Cabotage inside a foreign country; both endpoints foreign with no treaty |
| Range | Each leg is within the aircraft's ferry range | Sector longer than the type can fly at all |
| Runway | Both airports' runways fit the type | Runway shorter than the type's requirement |
| Slots | Hourly movements at each airport fit capacity | An hour bucket already full across all airlines |
| Curfew | Departure and arrival local times avoid night closures | 23:40 arrival into a 23:00 to 06:00 curfew |
| Rotation | The tail's whole week chains cleanly | Turnaround too short; aircraft ends up at the wrong airport |
| Maintenance window | Enough qualifying ground time each week | Rotation too dense to maintain the aircraft |
Traffic rights run first
This is the hard regulatory gate, and if it fails the remaining gates are not evaluated. Domestic legs are yours only in your home country, or inside a bloc that grants cabotage. Legs touching your home country are default-granted in most worlds; hard-mode worlds are restrictive. A leg between two foreign countries needs a fifth-freedom treaty and a rotation anchored at home. Nationality comes from your home airport, so this gate is the one you chose at founding.
Range has a soft edge
The range gate looks binary and is not. Beyond the type's full-payload range, a sector still flies with restricted payload, and the wizard shows the percentage of seats you can actually sell. Only beyond ferry range is the sector impossible. In practice that gives you two lines: a commercial one you can trade against, and a physical one you cannot.
Runway is the simple sibling: both airports' runways must fit the type, full stop.
Slots and curfew
Slots counts every movement per airport per hour, yours and everyone else's, against the airport's declared capacity. Worlds with a slot ledger add a second, stricter test based on slot ownership per 15-minute bucket, and a dry bucket answers with a counter-offer naming the nearest free time. Curfew checks your departure at the origin and your arrival at the destination, in local time, including windows that wrap past midnight. The 23:40 arrival into a 23:00 curfew is the classic write-up.
Rotation treats the week as one tour
The rotation gate is the reason a schedule holds together physically. It treats the tail's full week as a single closed tour: each flight must depart where the previous one arrived, with at least the type's minimum turnaround between them, and a newly assigned rotation must pass through the airport where the aircraft is currently parked. Aircraft do not teleport, and the gate declines to pretend otherwise.
The maintenance window
A rotation must leave enough qualifying ground time: stops of at least 2 hours each by default, adding up to 12 hours per week by default, with your world free to differ. One long overnight stop satisfies it; so do several shorter ones, at any airport. A rotation too dense to maintain the aircraft fails here, which is the engine's way of saying the utilization you scheduled was never real.
Numbers in the pool
A flight number created without an aircraft is checked only against traffic rights and departure curfews at creation. The equipment gates, meaning range, runway, slots, arrival curfews, rotation and maintenance, run when you assign the number to a tail. Round-trip pairs are validated as a single unit throughout, because one direction alone can never close a weekly tour.
The gate-by-gate reference, with each default spelled out, is the Scheduling gates article on the wiki.