Which airlines delay most often

The airline with the most delays varies by month and by airport, but Spirit Airlines and Frontier Airlines consistently rank highest for on-time performance problems across the U.S. network. Spirit averaged around 23% of flights delayed in 2023, while Frontier ran close behind. Southwest Airlines also appears regularly in delay rankings, particularly after operational disruptions. The major carriers — American, Delta, United, and JetBlue — typically fall in the middle range, with delay rates between 15% and 20%.

Delay rates shift based on weather, airport congestion, and seasonal travel. A carrier that performs well in spring may struggle during summer peak season. The U.S. Department of Transportation publishes monthly on-time performance reports that break down delays by airline and airport, so the ranking changes throughout the year. If you are planning a specific route on a specific date, historical performance for that airline-airport pair matters more than the national average.

Key Takeaways

  • Spirit and Frontier have historically reported the highest delay rates among U.S. carriers, though rankings shift month to month.
  • Major carriers like Delta, United, and American typically fall in the middle for delays, not at the top or bottom.
  • The same airline performs differently depending on the airport — a carrier may be reliable from one hub but delayed frequently from another.
  • The U.S. Department of Transportation publishes free monthly reports showing which airlines and airports had the most delays that month.
  • Delays caused by the airline itself (maintenance, crew issues, mechanical problems) differ from delays caused by weather or air traffic control.

How the Department of Transportation measures delays

The U.S. Department of Transportation tracks every commercial flight and publishes a monthly report called the Airline On-Time Performance report. A flight counts as delayed if it arrives 15 minutes or more after the scheduled time. The report separates delays by cause: weather, air traffic control, airline-caused, security, and late arrival of the aircraft.

You can read these reports for free from the Bureau of Transportation Statistics website. The data is broken down by airline, airport, and month, so you can see which carriers struggled in a specific month or which airports had the worst congestion. This is the same data the airlines themselves use to track their own performance.

Airline-caused delays — the ones the carrier is responsible for — include mechanical problems, crew scheduling issues, maintenance, and ground handling. These are separate from weather delays or delays caused by the Federal Aviation Administration's air traffic control system. When you read that an airline has a high delay rate, check whether the delays are mostly airline-caused or mostly weather-related, because that changes what you can expect on your route.

Why budget carriers have higher delay rates

Budget airlines like Spirit and Frontier operate with thinner margins and fewer backup aircraft than major carriers. When a plane breaks down or a crew member calls in sick, a major airline can often swap in a spare aircraft or reassign crew from another flight. A budget carrier with a smaller fleet may not have that option, so one mechanical problem cascades into multiple delayed flights.

Budget carriers also tend to operate on tighter turnaround times — the time between when a plane lands and when it takes off again. A 25-minute turnaround leaves no buffer for cleaning, refueling, or boarding delays. If boarding runs 10 minutes late, the flight departs late, and that delay carries forward to the next flight the aircraft operates. Major carriers typically build in longer turnarounds, which absorbs small delays before they ripple through the schedule.

Staffing levels also matter. Budget carriers operate with smaller ground crews, so a single absence can slow down boarding or baggage handling. During peak travel times, this compounds quickly.

Delays by airport matter as much as delays by airline

Some airports are structurally more congested than others. Newark Liberty International, LaGuardia, and Atlanta Hartsfield-Jackson consistently report high delay rates because they handle enormous volumes of traffic in limited airspace. A flight from Newark to Boston may be delayed not because of the airline, but because Newark's runways are saturated and the Federal Aviation Administration is holding planes on the ground.

The same airline performs differently depending on which airport it operates from. Southwest, for example, may have a 18% delay rate overall but a 25% delay rate from LaGuardia specifically, because LaGuardia's congestion affects every carrier. If you are choosing between two airlines for a route that includes a congested airport, the airport's delay rate may matter more than the airline's national average.

You can check delay rates by airport in the same Department of Transportation reports. Look at the specific airport pair you are flying — for example, "New York LaGuardia to Los Angeles" — rather than relying on national numbers.

Seasonal and weather patterns affect delay rankings

Winter months bring weather delays that affect all carriers equally. Summer sees peak travel volume, which pushes congested airports to their limits. Spring and fall typically have lower delay rates across the board. An airline's ranking in January may not hold in July.

Thunderstorm season in the Southeast (May through August) creates widespread delays at hubs like Atlanta and Charlotte. Carriers operating primarily from those hubs will show higher delay rates during those months, even if their operations are efficient. Conversely, an airline that operates mostly from West Coast airports may avoid the worst of summer thunderstorm delays.

If you are planning travel months in advance, check the historical delay data for that month and airport combination, not just the airline's year-to-date average.

What counts as a delay and what does not

The Department of Transportation counts a flight as delayed only if it arrives 15 minutes or more late. A flight that arrives 14 minutes late does not appear in the delay statistics. This means an airline's reported delay rate does not capture flights that are slightly behind schedule.

Delays are also measured from gate to gate — from when the aircraft pushes back from the departure gate to when it arrives at the destination gate. If you are boarding and the plane sits on the tarmac for 20 minutes before takeoff, that time counts toward the delay. If the plane lands early but sits waiting for a gate, that also counts.

Cancelled flights are tracked separately from delayed flights. A carrier with a high cancellation rate may have a lower delay rate because cancelled flights do not appear in the delay statistics — they are removed from the schedule entirely. When comparing airlines, look at both delay rates and cancellation rates together.

How to find current delay data for your specific route

The Bureau of Transportation Statistics publishes monthly reports at bts.dot.gov. read the most recent month's Airline On-Time Performance report. The data includes every airline and airport, broken down by cause of delay.

You can also check real-time delay information on the Federal Aviation Administration's website or through flight-tracking apps like FlightAware, which show current delays at specific airports. These tools show what is happening today, not historical patterns, but they help you understand whether delays at your departure airport are widespread or specific to your flight.

If you are booking a flight weeks in advance, historical data from the same month in previous years is your best guide. If you are checking the day before travel, real-time data and current weather forecasts matter more than historical averages.

Frequently Asked Questions

Does flying early in the morning reduce delay risk?

Yes, generally. Early morning flights (before 8 a.m.) have lower delay rates than afternoon and evening flights because the schedule has not yet backed up. By mid-afternoon, any earlier delays have cascaded through the day's flights. Weather is also more predictable in the morning. However, weather delays and mechanical problems can still affect early flights, so this is a trend, not a may provide.

Are low-cost carriers always more delayed than full-service airlines?

Not always, but they trend higher. Spirit and Frontier have worse on-time records than Delta or United on average, but Southwest — also a low-cost carrier — performs closer to the middle. The difference comes down to fleet size, turnaround times, and staffing levels, not just the business model. A budget carrier with good operational discipline can outperform a major carrier with poor scheduling.

Can I see which specific flights are delayed most often?

The Department of Transportation data does not break down to individual flight numbers, only to airline and airport pairs. However, FlightAware and other flight-tracking sites show historical on-time performance for specific routes. You can search "Flight 123 history" and see how often that flight has been delayed over the past months. This is more useful than airline-wide averages if you are flying the same route repeatedly.

What should I do if I am booked on an airline with a high delay rate?

Check the delay data for your specific airport pair and the month you are traveling, not just the airline's national average. If delays are common on your route, book an earlier flight if possible so a delay does not cause you to miss a connection. Allow extra time between connecting flights. If the flight is cancelled, know your rights: the airline must rebook you on the next available flight or refund your ticket.

Do airlines improve their on-time performance, or do the same carriers stay delayed?

Rankings shift over time. An airline that performs poorly one year may invest in fleet upgrades or staffing and improve the next year. Southwest had significant operational problems in late 2022 but improved substantially in 2023. Conversely, carriers that perform well can decline if they expand too quickly or face unexpected challenges. Check current data rather than assuming last year's rankings hold.