Data sources

Publisher

Bureau of Transportation Statistics, US Department of Transportation

Database

Airline On-Time Performance Data, within the Air Carrier Statistics program (TranStats). Also referred to as the On-Time Reporting Carrier On-Time Performance table.

Legal basis

14 CFR Part 234, Airline Service Quality Performance Reports.

Coverage

Every domestic flight operated by carriers accounting for at least 0.5% of total domestic scheduled passenger revenue. Since the reporting rule was extended, mainline carriers must also report flights operated on their behalf by regional partners, which closed a significant gap.

Granularity

One row per flight. Scheduled and actual gate departure and arrival times, tail number, origin and destination, distance, cancellation and diversion flags, and delay minutes split across five causes.

Update cadence

Monthly, with roughly a two-month lag. A given month typically appears in the middle of the month after next.

Period used here

June 2025 to May 2026 — 12 complete months, 11,272,202 flights.

Licence

A work of the US federal government, in the public domain under 17 USC §105 and usa.gov/government-works. No permission is required to reuse it, and none was sought.

Access

transtats.bts.gov. Monthly archives are downloadable without registration.

Publisher

Federal Aviation Administration

Feed

National Airspace System status, nasstatus.faa.gov. Open, no key, no registration.

What it covers

Ground stops, ground delay programmes, general arrival and departure delay advisories, and airport closure notices. Airport level only: the feed says nothing about individual flights.

Update cadence

The FAA republishes continuously. This site reads it every few minutes and serves the result from its own domain, so your browser never contacts the FAA and no third party sees your visit.

Filtering applied

Two filters, both to avoid misleading readers. Closure notices that restrict only unscheduled private aircraft are dropped, because publishing them would read as an airport being shut when no airline flight is affected. Airports with no scheduled commercial service are dropped for the same reason. Recurring overnight maintenance windows are marked and listed separately from live disruption.

Staleness handling

If the last successful read is more than about twenty-five minutes old, the page shows nothing rather than presenting old conditions as current.

Licence

A work of the US federal government, in the public domain.

The BTS flight records carry three-letter airport codes and two-character carrier codes, not names. Two small tables checked into this site's repository supply the rest.

Airports. Names, cities and states follow the BTS Aviation Support Tables master coordinate files. Latitude and longitude come from the FAA's National Airspace System Resource aeronautical data, rounded to four decimal places. Used for display and for great-circle distances only; no figure on the site depends on a coordinate.

Carriers. Codes follow the BTS carrier lookup tables. The names used are the marketing names travellers recognise rather than the legal entity names, so "Delta Air Lines" rather than "Delta Air Lines Inc.". Where a carrier operates only under other airlines' brands, the site labels it a regional operator and says so on its page.

The pipeline downloads the twelve most recent complete monthly archives, parses them, and aggregates them into per-entity JSON. Aggregation is a set of plain SQL group-by operations: counts, sums, and one median. There is no modelling, no imputation of missing values, no smoothing and no seasonal adjustment.

Rows with a null origin or destination, and rows where origin equals destination, are dropped. Nothing else is filtered. Flights are counted under the operating carrier, which is how BTS files them.

Cached monthly archives are reused, so a routine refresh downloads only the one new month. The full definitions and thresholds applied during aggregation are on the methodology page.

BTS occasionally revises published months. When a revision lands, the next monthly refresh picks it up automatically, since the pipeline recomputes the full twelve-month window rather than appending to a stored total.

If a number here disagrees with your own computation from the same source, send the entity and the period to kaantokali1@gmail.com and it will be checked against the raw filings. Corrections are made to the pipeline rather than to individual pages, so a fix applies everywhere at once.