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

September 2025 to August 2026 — 12 complete months, 7,049,869 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.

Publisher

National Weather Service, NOAA

Feed

The public weather API, api.weather.gov. Open, no key, no registration.

What it covers

The latest observation from each airport's own automated weather station (temperature, wind and gusts, visibility, the lowest broken or overcast cloud layer) and the hourly forecast for the grid square over the airfield. Shown on airport pages and at both ends of each route.

Update cadence

Read every thirty minutes and served from this site's own domain, so your browser never contacts the Weather Service. Observations older than about two and a half hours are hidden, and the whole panel disappears if the file has not been refreshed for six hours.

How it is used

Conditions known to slow an airport (thunderstorms, snow or freezing precipitation, low cloud or visibility, strong gusts) are named in plain words. They describe the weather, not a flight: nothing on this site predicts whether a particular departure will be late.

Licence

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

No single dataset covers flights between Europe and the United States with times attached. The US on-time database is domestic only, and no European authority except the UK's publishes punctuality by route. The section therefore uses three sources, each for what it alone provides, and every page says which figure came from which.

US DOT International Report

Publisher

Bureau of Transportation Statistics, US Department of Transportation, as the US International Air Passenger and Freight Statistics Report on data.transportation.gov.

What it covers

Every flight and every passenger between a US airport and a foreign airport, by carrier and month, filed under 14 CFR Part 241 (T-100). Flights are counted in both directions together. No times, so no delays.

How it is used

The master list of which routes exist and who flies them. Freighters and business jets are dropped by a load test: a carrier counts on a pair only with at least 40 passengers a flight on average and a flight a month. A pair needs 100 flights over twelve months for a page.

Period used here

July 2025 to June 2026, the latest twelve months published. The report runs about four months behind.

Licence

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

UK Civil Aviation Authority punctuality statistics

Publisher

UK Civil Aviation Authority, caa.co.uk. Monthly CSV files, open, no registration.

What it covers

Every flight at 25 UK airports, by destination airport, airline, direction and month: flights matched to a planned time, cancellations, the share in each delay band from more than 15 minutes early to more than six hours late, and an average delay. Planned times come from the slot coordinator; actual times are gate (off-block and on-block) times, estimated from runway times where the gate time is missing.

Definitions

On time here means within 15 minutes of the planned gate time, early flights included, measured at the UK airport: departure delay for flights to the US, arrival delay for flights back. The CAA's average delay is across every matched flight with early flights counted as zero, which is not the DOT-style average of delayed flights only used elsewhere on this site, and the two are never mixed. Cancellation means a planned flight that did not operate, announced within 24 hours either side of its scheduled time.

Period used here

September 2025 to August 2026, the latest twelve monthly files. The CAA publishes about six weeks after the month ends.

Terms

The CAA asks that its statistics be credited when used and not sold on to third parties. They are credited on every page that uses them and are not sold.

EUROCONTROL Aviation Intelligence Portal

Publisher

EUROCONTROL Aviation Intelligence Unit, from Network Manager data, ansperformance.eu. Two workbooks, open, no registration, overwritten daily.

What it covers

For about 110 European airports: the share of arrivals and departures within 15 minutes of schedule and the share of scheduled flights operated, for yesterday, the last seven days and the year to date; and air traffic flow management delay per arriving flight, the minutes the network held flights on the ground elsewhere because of conditions at the airport. Whole-airport figures: every airline, every destination.

How it is used

As the departure airport's own record on every Europe-to-US page, and as the ranking on the section's front page. Because the workbook carries no history, a daily job on this site's server keeps one snapshot a day; month-by-month series appear on an airport's page once enough days have accumulated.

As of

21 October 2026 in this build; refreshed with each weekly rebuild.

Terms

EUROCONTROL permits reproduction with the source credited and for non-commercial use of the content itself; the figures are quoted with attribution and the workbooks are not redistributed.

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.

European airports. A third table maps the European airport codes in the DOT report to names, cities, countries, coordinates and the ICAO codes EUROCONTROL uses. It is built from the OurAirports dataset, which is public domain, with display names set by hand for the airports that have pages. The CAA files name airports and airlines in words rather than codes; a hand-checked table maps those names, and a name not in it is left out and logged rather than guessed.

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.