XPLM_API void XPLMScheduleFlightLoop( XPLMFlightLoopID inFlightLoopID, float inInterval, int inRelativeToNow);
This routine schedules a flight loop callback for future execution. If inInterval is negative, it is run in a certain number of frames based on the absolute value of the input. If the interval is positive, it is a duration in seconds.
If inRelativeToNow is true, ties are interpretted relative to the time this routine is called; otherwise they are relative to the last call time or the time the flight loop was registered (if never called).