FlyerIntel

How on-time performance is counted

A flight that lands 14 minutes late counts as on time in every official statistic, and one that lands 15 minutes late does not. This guide explains where that line comes from, what it is measured against, and what happens to cancelled and diverted flights, so that an on-time percentage on any page can be read for what it is.

The 15-minute rule

The line is written into federal regulation. Under 14 CFR Part 234, which governs the service quality reports that US airlines above the reporting threshold file with the Department of Transportation, a flight is on time when it arrives less than 15 minutes after its published arrival time. A flight that arrives at the gate 15 minutes or more after that time is late. The measure is the arrival at the gate, not the touchdown on the runway.

A flight scheduled to arrive at 2:00 PM is therefore on time at 2:14 PM and late at 2:15 PM, and a flight that arrives early is on time. The threshold is a convention. The passenger who landed at 2:14 and the one who landed at 2:16 had almost the same afternoon, but they sit on opposite sides of the statistic. When two airports or two airlines are only a point or two apart, that is worth remembering: the gap is made of flights that fell either side of the same line.

Scheduled time against actual time

Both sides of the comparison come from the airline’s own records. The scheduled time is the arrival time the carrier published. The actual time is when the aircraft reached the gate, which the carrier records and files each month with the Bureau of Transportation Statistics (BTS), the part of the DOT that publishes the data. FlyerIntel reads that public file and does not add timing of its own.

Because the measure is relative to the schedule, a flight that is given more time on paper is more likely to arrive on time without being any faster. A timetable with slack in it and a timetable without it can describe the same aircraft flying the same trip. This is one reason FlyerIntel shows the median delay and the share of flights that arrive an hour late alongside the on-time rate.

The measure is also about arrival. A flight that leaves the gate 20 minutes late and makes up the time in the air arrives on time. Departure punctuality is reported separately, as on-time gate departures divided by flights that departed. And the rate on an airport page counts flights leaving that airport, judged on when they arrived at their destination. A late landing at the far end counts against the airport the flight left.

Cancelled and diverted flights

Part 234 defines a cancelled flight as one that was not operated but was listed in the airline’s reservation system within seven calendar days of its scheduled departure. A flight removed from the schedule earlier than that is called discontinued and is not counted as cancelled. A diverted flight is one that flew from its origin to a point other than its scheduled destination.

Neither kind has an arrival at the scheduled destination, so neither can be 14 or 15 minutes late. FlyerIntel leaves both out of the on-time rate and reports them as rates of their own. Across 17,884,589 scheduled departures from the covered airports, July 2023 – July 2026, 265,507 were cancelled (1.48%, or 1 in 67) and 47,023 were diverted (0.26%). That leaves 17,572,058 completed flights, the base of the on-time rate. Of those, 13,724,842 arrived on time (78.1%) and 3,847,216 arrived 15 minutes or more late (21.9%).

Leaving them out has a cost. An airline that cancels a lot can post a respectable on-time rate on the flights that remain. For that reason a FlyerIntel page prints the cancellation rate next to the on-time rate, and the reliability score gives cancellations a weight of their own (20% of the total). If every cancelled and diverted flight were counted as not on time instead, the same network would stand at 76.7% rather than 78.1%. That figure is arithmetic on the counts above, not a DOT statistic. Other sources may count cancelled flights in the denominator, so check which one a published on-time percentage is using before comparing it with another.

What a single percentage leaves out

An on-time rate counts flights, not minutes, and it treats a 16-minute delay and a six-hour delay alike. Of the completed flights, 1,348,844 (7.7%) arrived 60 minutes or more late. That is 35% of all the arrivals that were late at all. The airport, route and airline pages therefore also give the severe-delay rate, the median arrival delay and the average delay among flights that were late. The median describes the typical flight. At all 64 covered airports it is below zero, so the typical flight landed early and the on-time rate reflects a minority of long delays.

Looking up your own case

The same definitions apply wherever a rate appears on the site. To see your own case, start with the airport you are leaving from, where the reliability section gives the on-time rate, cancellation rate, median delay and the count of flights behind them. A route page does the same for one pair of airports, and a flight-number page for a single flight. To see how a particular day and hour have gone, use When to fly or the trip planner. The rates for every covered airport, airline and route are also available as downloads on the open data page, so they can be checked against a spreadsheet.

What this is based on

The figures in this guide are totals for departures from the 64 airports FlyerIntel covers, July 2023 – July 2026, added up from the same airport records that fill the airport pages. The definitions are on the methodology page.

An error in a figure or a definition can be reported on the corrections page. How FlyerIntel decides what to publish is set out in the editorial policy.