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Nobody likes a delayed flight; it’s inconvenient, throws plans into disarray, and puts additional costs on both passengers and the airline. There could be several reasons for such events — from technical issues and weather changes to personnel strikes and busy airspaces — and in many cases, the airline has no direct control over them. Nevertheless, some airlines have a better grip on their operations than their competitors, allowing them to keep delays at a minimum.

So, if you’re booking a flight and want to reduce your chances of getting hit with a late departure (or even a canceled flight), we’re looking at five American carriers that had the greatest number of delays by percentage. We based our numbers on the U.S. DOT’s Bureau of Transportation Statistics reports on arrival performance by marketing carrier, with data from March to October 2025. Unfortunately, we’re unsure if we’ll get more recent data, as the biggest U.S. airlines have asked the DOT to stop publishing performance statistics and are lobbying to make flying much worse for everyone.

Furthermore, we looked at the ratio of delayed flights versus the total number of flights. After all, it would be unfair to compare Delta, which had 207,770 delays out of more than 1.1 million flights and one of the best on-time performance rates in the United States, with Frontier, which operated fewer than 134,000 flights, of which more than 37,000 arrived late.

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The worst performer by far is Frontier Airlines, with 37,329 delays out of a total of 133,328 flights in the counted period. This meant that 28%, or more than one in four flights, were delayed. It also had the second-highest number of cancellations, with 2,111 flights, or 1.58% of its schedule, getting called off. This is probably one of the reasons why this airline is at the bottom of reliability and customer satisfaction rankings, with its cheap fares being the only thing going right for its passengers.

While airlines cannot do anything about airport traffic congestion and weather-based delays and cancellations, other issues, like crew scheduling limitations, can often be mitigated through advanced crew scheduling systems. Even delays caused by unforeseen technical problems at hub airports can be fixed with the ready availability of backup aircraft or by reducing the number of flights each airframe is assigned per day. However, these measures can be costly for airlines, especially for low-cost carriers that rely on razor-thin margins.

What’s worse is that Frontier says that it does not offer reimbursements, hotel accommodations, or monetary compensation to passengers who are impacted by flight delays or cancellations. The best that you can get is a seat on the next available Frontier flight and meal vouchers if your delay or rebooking is more than three hours and is considered a “controllable situation” like delayed baggage, aircraft damage, or a mechanical issue. If the delay is defined as an “uncontrollable situation,” like those caused by weather, Air Traffic Control, or an incident like a bird strike, then all you can get is a flight rebooking. Alternatively, you can seek a full refund under 14 CFR Part 260 if the delay is over three hours for domestic flights and six hours for international flights.

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JetBlue is the second-worst airline when it comes to delays, with 38,117, or 24.52% of flights, arriving 15 minutes late (or longer) out of a total of 155,432 scheduled flights. While this isn’t as bad as Frontier, it is still close to one in four flights getting delayed. It also ranked third when it comes to cancellations, with 1,885, or 1.21% of flights, affected. This number is likely influenced by the emergency software update on Airbus A320 family aircraft in late 2025 that resulted in numerous cancellations and delays. The update was prompted after a JetBlue A320 made an uncommanded rapid descent in flight due to solar radiation. This is especially notable given that JetBlue’s fleet is composed entirely of Airbus aircraft.

JetBlue outlines its policy regarding reimbursements and options in case of delays or cancellations. According to the airline’s website, flights affected by weather disruptions, domestic delays of more than three hours, international delays of more than six hours, or a change from nonstop to a connecting or stopover flight are eligible for a fee waiver. This allows you to change your flight at no extra cost or receive a full refund to the original form of payment.

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This is the first and only mainline carrier that lands on our list of airlines with the worst on-time performance. According to the U.S. DOT, out of American’s 1,363,530 flights (which, incidentally, is the highest number of scheduled flights within our time frame), 333,396 flights, or 24.45%, were delayed. That number is so high that it’s greater than the total number of flights operated by Frontier and JetBlue combined. American Airlines is also the worst airline when it comes to cancellations, with the carrier scrapping 28,204, or 2.07%, of its schedules.

Nevertheless, it seems that American is trying to do something about this, at least for affected passengers. The airline is said to be testing an AI tool that keeps track of passengers who could potentially miss their connecting flights because of a delay on a prior flight. It will then adjust the connecting flight without affecting the rest of the day’s schedule, ensuring that passengers can still reach their destination on time. This system will also benefit the airline, as it wouldn’t have to deal with rebooking the affected passengers (although it could likely infuriate other customers who might have to wait up to an hour for the incoming flight).

If you’re flying with American and you experience a significant delay or cancellation caused by the airline, it says that it will give you a voucher for an approved hotel plus round-trip transportation to the airport if the delay is overnight. Furthermore, it will provide meal vouchers for delays that are three or more hours after the scheduled departure. Unfortunately, if you’re affected by unforeseen delays and cancellations caused by weather, you’re not entitled to anything except a rebooking on the next flight with available seats at no extra charge.

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Despite having one of the fewest numbers of flights (second only to Hawaiian before it merged with Alaska Airlines), Allegiant still managed to have one of the worst on-time performances. This airline had 22,210 delays, which is 24.40% of its total of 91,015 flights. But despite offering some of the cheapest airfares available, it still manages to have the best cancellation record in our time frame, reporting only 238 canceled flights, or just 0.26% of its entire schedule.

Just like Frontier, which is also a low-cost carrier, Allegiant says it does not offer delayed passengers any meals, alternate transportation, or reimbursement for incurred overnight expenses. If your flight is rescheduled due to a delay or cancellation and you choose not to take it, your only available options are to either change to a different flight on the same route or cancel the remaining flights and receive a refund for the unused portions of your ticket.

This might be a deal breaker for some people, but those who are looking for the best possible deals on airfare might be willing to take the risk. The airline mentions on its page the possibility of getting reimbursed by Allianz Travel Insurance for cancellations. So, it might be a worthwhile investment to spend a little extra on this type of insurance, which is one of the services that AAA offers and is likely far more affordable than a ticket on a legacy airline.

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After the big three (American, Delta, and United), Southwest Airlines has the greatest number of flights, at 954,366 scheduled flights. However, it also has a significant number of delays, at 211,262 flights, or 22.14% of its schedule. Nevertheless, it does have a good track record when it comes to cancellations, with only 5,602 canceled flights, or just 0.59% of its total number of flights.

Southwest Airlines pioneered the low-cost carrier (LCC) model, so just like the other LCCs listed above, don’t expect to get any benefits from it in case of a delay, except the bare minimum required by law. Nevertheless, it is one of the U.S. airlines that offers onboard Wi-Fi, costing just $8 per device throughout the entire flight. While you may not appreciate this service for short hops around the country, you might find it an indispensable yet affordable offering on the airline’s longest routes, like the more than seven-hour flight from Phoenix to Honolulu.