Methodology & data sources
Transparency is the core of our E-E-A-T: this page documents where our flight data comes from, how it is computed, how often it is refreshed, and the limits of each figure.
How "on-time" is defined
We use the US DOT standard: a flight is on-time if it arrives at the gate fewer than 15 minutes after its scheduled time and is not cancelled or diverted. On-time departure uses the same 15-minute threshold at the origin gate. Average delay is the mean of positive and non-negative delay minutes as reported by carriers. Taxi-out is the time from gate push-back to wheels-up.
Data sources
| Source | Refresh cadence | License |
|---|---|---|
| US DOT BTS — Airline On-Time Performance (TranStats) | monthly | U.S. Public Domain (federal government work) |
| FAA — Aviation System Performance Metrics (ASPM) | monthly | U.S. Public Domain (federal government work) |
| BTS — Airline Baggage Fee statistics | annual | U.S. Public Domain (federal government work) |
How the figures are computed
The route and airport pages are generated from structured JSON in our data layer. Airport
on-time departure and arrival rates and cancellation rates are real figures taken from the
US DOT Bureau of Transportation Statistics Airline On-Time Performance record for full-year 2024,
the latest complete reporting year. The "average delay" figure is the BTS average length of delay
among delayed flights, not the mean across all flights. Average taxi-out time is a labelled
estimate (the exact figure lives in FAA ASPM). The committed-data refresh path — downloading the
monthly BTS On-Time Performance ZIPs from PREZIP, streaming the CSV and re-aggregating — is
documented as comments in scripts/fetch-data.mjs and run out-of-band (the source is
large bulk CSV) rather than at every site build.
How the route figures are derived
Published on-time statistics for specific origin–destination airport pairs are not broken out in the standard BTS consumer tables, so the per-route figures here are estimates derived from the endpoint airports' BTS on-time performance (origin departure reliability and destination arrival reliability) for full-year 2024, with delay and cancellation rates interpolated from the same endpoints. They indicate the likely reliability of a route, not a measured per-route statistic; always verify against the primary BTS source for a specific carrier and date range.
Current status & limitations
Airport on-time and cancellation figures are real BTS statistics for full-year 2024 (latest complete BTS year). Per-route figures are labelled estimates derived from the endpoint airports, and taxi-out time is an estimate. Baggage fees reflect the airlines' published 2026 schedules (including the April 2026 increases) but change several times a year and vary by fare class, route and payment timing; note that Spirit Airlines ceased all operations on 2 May 2026 and is therefore no longer listed. Always verify a specific number against the primary source before relying on it. See our disclaimer.
Last updated: 2026-06-13