Live-sim robustness (pause, replay, repositioning)¶

Available now.

What it does¶

A live X-Plane session doesn't just fly a flight plan start to finish -- it gets paused, rewound to replay a landing, repositioned to a different spot, or restarted as a whole new flight, all mid-session. AtcEngine.on_tick checks for each of these before doing anything else, so none of them produce a bogus conformance callout, a stuck timer, or a flight stuck believing it's still where it was.

Pausing the sim¶

While AircraftState.paused is set, nothing advances: no conformance check runs, no timer ticks. The time spent paused is subtracted from every timer's clock once unpaused, rather than counting against it -- pausing for five minutes to answer the phone doesn't hand you a stale taxi clearance or an off-course call the moment you un-pause. A sim-time reload (time moving backwards) is treated the same way a pause reset is: every timer starts fresh rather than computing a bogus negative duration.

Replay¶

While X-Plane is playing back a replay (sim/time/is_in_replay), ATC does nothing at all -- the last live state is kept exactly as it was, so the flight picks up from there once the replay ends, and the replay's own time (which can run backwards, or jump) never reaches any timer. Live traffic snapshots are ignored during a replay too, since traffic advisories should reflect real other aircraft, not whatever the replay happens to show.

Repositioning¶

A position or altitude change too large for the aircraft to have actually flown in the elapsed sim time -- Location > Set Position, a teleport, a sudden reload -- is detected as a reposition, not a real deviation. The engine doesn't fault the aircraft for the jump itself: every conformance monitor resets, any pending readback or handoff is dropped, and the flight phase is re-derived from wherever the aircraft actually is now (the runway if it's lined up on one, the pattern if it's flying one nearby, DEPARTURE or ENROUTE if it's airborne near or far from the departure airport, PARKED otherwise) rather than staying stuck in whatever phase it was in before the jump.

Starting on a runway¶

X-Plane's own "start on runway" option (or a fresh session that just happens to begin lined up on one) is handled the same way as a reposition, even on the very first tick: the aircraft is treated as already cleared to line up and wait on that runway, not as an unauthorized runway incursion. An earlier version of this got that wrong for a new flight specifically -- a just-reset engine starting fresh on a runway got "hold position!" instead -- fixed so a reset flight's first tick is checked the same way a first-ever session's is.

A new flight¶

A different tail number or aircraft type, or a jump to the ground far from both the departure and destination airports, is treated as a genuinely new flight rather than a reposition: the engine resets itself completely (back to PARKED with a fresh clearance), the same reset the saved flight state is cleared for, so an old flight's leftover clearance or squawk can't leak into a new one that happens to share the same session.

Reset flight¶

The radio panel's Reset flight button (see Radio panel) does the same full reset on demand, without needing an actual new aircraft or a jump: drop the engine, rebuild fresh on the next tick wherever the aircraft currently is, and clear the saved flight state so a subsequent restart doesn't bring the old flight back.

Configuration¶

None -- all of this runs automatically on every live --live session; there's nothing to turn on or off.

Limitations¶

Anomaly detection only looks at up to a few seconds of sim time between ticks -- a longer gap (e.g. a dropped connection) is treated as missing data, not a jump, so a genuine jump that happens to coincide with a connection drop isn't specially detected.