Ontario International (ONT) on-time performance, September 2026

How we measure

On time means the aircraft took off within 15 minutes of its scheduled departure, after subtracting the departure airport's normal taxi time at ONT (FAA SWIM reports wheels-off, not push-back, so the median taxi time of the last 30 days is taken off every flight first). Average delay is the mean of that taxi-adjusted delay over all departures; early departures count as negative minutes, so an operator that routinely leaves early can show a negative average. 45+ min late is the share of departures that left 45 minutes or more behind schedule, the point at which most connections are at risk.

Scope: scheduled airlines only, the same set as the monthly State of the Sky report (operators with published routes; private, fractional and charter operators are left out), so the two publications give the same numbers for the same month. Departures are counted by scheduled day (UTC). Each day's flights are rolled up overnight and published the next morning; the newest day keeps filling in for a day or two and is only shown once it is substantially complete. Figures can differ by a few tenths of a point from the State of the Sky report for the same month: that report is frozen on the 2nd of the following month, while these pages are rebuilt from the live rollup, which recomputes each airport's taxi baseline nightly and re-rolls the last week of the month as late departure times arrive (September 2026 at SFO: 16,398 departures in both, 69.2% on time here against 69.5% in the report).

Source: FAA System Wide Information Management (SWIM) flight plans and departure times, processed by PlaneTrack. Free to quote with credit to PlaneTrack (CC BY 4.0).