Airlines With Worst Delays: How Official U.S. Data Ranks Them

What “airlines with worst delays” actually means

People searching airlines with worst delays want names. U.S. federal data answers with a moving list. The Bureau of Transportation Statistics (BTS) and the U.S. Department of Transportation (DOT) measure how often reported domestic flights arrive late against each carrier’s schedule. The airlines with the worst delays in any given month are the reporting carriers with the lowest on-time arrival rates for that period — not a permanent hall of shame.

Stale “top 10 worst airlines” posts freeze a single month and keep ranking for search clicks. Official tables are rebuilt on a schedule. If your booking decision depends on delay risk, open the newest BTS or DOT period before you treat any name as settled.

That framing matters. A very large airline can log more delayed flights in raw count simply because it flies more often, while a smaller carrier can give each passenger a higher chance of arriving late. Official consumer rankings emphasize on-time percentage so carriers of different sizes stay comparable.

How BTS decides a flight is delayed

Before you trust any chart, lock the definition. BTS TranStats states that a flight is considered on time when it arrives less than 15 minutes after its published arrival time. A late flight is one arriving or departing 15 minutes or more after the scheduled time. A four-minute gate hold does not count as a delay in these tables.

The same database covers U.S. certified air carriers that account for at least half of one percent of domestic scheduled passenger revenues (the threshold moved from one percent to half of one percent in 2018). TranStats’ on-time index also notes that airline on-time data are reported by the carriers meeting that 0.5 percent revenue test — described as 17 U.S. air carriers in the 2021 reporting note on the index page.

Official term	What BTS / FAA mean	Traveler takeaway
On-time arrival	Gate arrival less than 15 minutes after the published time	Slightly late can still count as “on time”
Late flight	Arrival or departure 15+ minutes after schedule	This is the delay counted in on-time rates
Marketing carrier network	Brand that sells the flight, including code-share partners where applicable	Best match for the airline name on your ticket
Reporting / operating carrier	Carrier that reports or physically operates the flight	Check “operated by” on regional segments

Where to find which airlines currently rank worst

Two official surfaces cover the question:

• DOT Air Travel Consumer Report — monthly consumer tables that rank reporting marketing carriers by on-time arrival percentage. The carrier at the bottom of that month’s list is the worst among majors for that month; year-to-date tables average longer windows.
• BTS TranStats Airline On-Time Statistics — the public database behind those summaries. Data run from January 1995 through June 2026. You can pull departures, arrivals, cancellations, and diversions by airline, origin, destination, or flight number.

Do not mix a marketing-carrier year-to-date rate with an operating-carrier single-month rate and call it a ranking. BTS publishes both views for a reason: marketing carriers sell flights for themselves and, in some cases, for regional code-share partners; reporting carriers submit data for flights they operate.

In practice that means the airline logo on your confirmation can look better — or worse — than the regional operator flying the metal. When two itineraries are close in price, read both the marketing-carrier network rate and the “operated by” line before you decide which brand is truly riskier for your trip.

How to check the worst performers yourself

1. Open BTS TranStats Airline On-Time Statistics.
2. Choose a lookup by airline (for a brand-wide view) or by flight number / airport pair (for your itinerary).
3. Pull several recent months — one storm week can distort a single-month snapshot.
4. Note whether you are looking at a marketing network or an operating carrier before you compare two brands.
5. Cross-check the latest DOT Air Travel Consumer Report table for the official monthly rank order among reporting majors.

If you only need the single lowest-ranked brand for the newest published month, see how DOT ranks which airline has the most delays and what airline has the most delays in the latest table. This page is for reading the list of poor performers correctly — not for freezing one name forever.

Why several airlines can look “worst” at once

Delay causes are not all equal. FAA ASPM records minutes of delay for five DOT-defined arrival-delay causes: carrier, weather, NAS (National Airspace System), security, and late arrival.

• Carrier delay — within the airline’s control (examples FAA lists include maintenance, late crew, fueling, baggage, and slow boarding).
• Late arrival delay — the same aircraft arrived late at a previous airport; the ripple is delay propagation.
• NAS delay — non-extreme weather, airport operations, heavy traffic volume, air traffic control, and related system limits.
• Weather delay — extreme or hazardous weather at departure, en route, or arrival.
• Security delay — terminal evacuation, re-boarding after a security breach, inoperative screening equipment, or screening lines longer than 29 minutes.

Separately, the FAA’s OPSNET weather FAQ states that weather is the largest cause of system-impacting air-traffic delay: 74.26 percent of those delays longer than 15 minutes from June 2017 through May 2023, with volume alone accounting for 14.92 percent. That OPSNET pie includes air carriers, air taxis, general aviation, and military traffic — it is not the same number as a passenger airline’s BTS on-time percentage. Use it to understand why many airlines can look bad on the same thunderstorm day, not as a personal probability for your boarding group.

Scale of the system you are ranking against

Even the best-ranked carrier can delay you when the National Airspace System is saturated. The FAA provides air traffic service to more than 45,000 flights and 2.9 million airline passengers daily across more than 29 million square miles of U.S. airspace. Its air-traffic page lists an average of 44,360 daily flights handled, with about 5,500 aircraft in the sky at peak times. Ground delay programs and airport capacity limits can hit multiple carriers at once.

When your specific flight slips, start with the operating airline and FAA airport-status pages. Traffic-management programs can hold many carriers at once; your carrier names the cause and rebooking options for your ticket. See why your flight is delayed for that split.

Using the ranking before you book

• Compare the same reporting window for every airline.
• Prefer marketing-carrier network rates when the brand name on the ticket is what you care about.
• Read the “operated by” line for regional segments.
• Favor nonstops when two fares are similar — a connection adds a second failure point.
• Leave buffer on same-day connections; delay propagation is a defined BTS/FAA category, not bad luck.
• Treat early-day departures as lower inheritance risk for late-arriving aircraft when schedules otherwise match.

None of that replaces live status on travel day. A historically punctual airline can still strand you behind a ground delay program. Save your boarding pass and connection plan offline before you lose reliable service.

For national how-often context, read how often flights get delayed. If you are already stuck, use cancellations and delays: what to do next.

DOT rankings, BTS tables, and FAA traffic programs change. Confirm the latest TranStats period and the current Air Travel Consumer Report before you rebook or abandon a trip based on an old “worst airlines” list.