Flight delays happen to roughly one in four flights in the United States

About 20 to 25 percent of commercial flights experience some delay on any given day, though the exact number shifts by season, airport, and airline. Summer and winter holidays see higher delay rates because airports handle more traffic. Morning flights tend to run closer to schedule than afternoon ones, partly because delays compound throughout the day—a plane that lands late in the morning will depart late in the afternoon.

The Federal Aviation Administration (FAA) tracks on-time performance for all major carriers. A flight counts as delayed if it lands more than 15 minutes after its scheduled arrival time. Longer delays—those over an hour—affect roughly 5 to 8 percent of flights on a typical day, though this varies widely by season and weather patterns.

Key Takeaways

  • About one in five flights arrives more than 15 minutes late on an average day, with rates climbing during peak travel seasons.
  • Weather, air traffic congestion, and mechanical issues cause the majority of delays, though staffing shortages and ground operations also play a role.
  • Afternoon and evening flights are more likely to be delayed than morning flights because earlier delays ripple through the day's schedule.
  • Delays lasting over an hour are less common than minor delays but still affect millions of passengers annually.
  • You can check historical on-time performance for specific routes and airlines before booking to reduce your risk of delay.

Why weather causes the most delays

Weather is the single largest cause of flight delays in the United States. Thunderstorms, heavy snow, fog, and high winds all force airports to slow down operations or close runways temporarily. When visibility drops or wind speeds exceed safe landing limits, planes must circle, divert, or wait on the ground. A single severe weather system can delay hundreds of flights across multiple airports.

Winter months see more weather delays because ice, snow, and freezing rain are common. Summer brings thunderstorms, particularly in the afternoon and evening. Spring and fall generally have fewer weather delays, though they are not immune. The worst weather delays often happen in the Northeast and Midwest, where winter storms are frequent and severe.

Air traffic congestion and ground operations

Busy airports like Atlanta, Dallas, Los Angeles, and New York handle so many flights that congestion alone causes delays even on clear days. When an airport reaches capacity, the FAA issues ground stops or slot delays—planes must wait on the tarmac or at their origin airport before taking off. A single accident, medical emergency, or disabled aircraft on a runway can back up dozens of flights behind it.

Ground operations also matter. If a plane arrives late, the crew may need time to deplane passengers, clean the cabin, and board the next group. If ground staff are short-handed or baggage handling is slow, the departure time slips. Connecting passengers who miss their flight because of a late arrival create further delays as airlines rebook them and adjust crew schedules.

Mechanical issues and maintenance delays

Airlines discover mechanical problems during preflight checks or after a flight lands. A faulty hydraulic system, engine warning light, or malfunctioning door latch grounds a plane until a mechanic repairs it. These delays are usually shorter than weather delays—often 30 minutes to two hours—but they are unpredictable and happen year-round.

Older aircraft tend to have more mechanical delays than newer ones, though all planes require regular maintenance. Some airlines have better on-time records than others partly because they invest in newer fleets or more aggressive maintenance schedules. If you fly frequently, checking an airline's historical on-time performance can help you choose carriers with lower mechanical delay rates.

How delays compound throughout the day

A single delay early in the morning can trigger a cascade of delays for the rest of the day. If a plane is scheduled to fly from New York to Los Angeles and then back to New York, and it departs two hours late from New York, it will arrive in Los Angeles two hours late. The crew may then be behind schedule for their next flight, and passengers connecting through Los Angeles will miss their connections. By evening, that one aircraft may have caused delays on three or four separate flights.

This is why afternoon flights are statistically more likely to be delayed than morning flights. Early morning flights have fresh crews, planes that have been sitting overnight, and no backlog from earlier in the day. By 3 p.m. or later, the accumulated delays from the morning and early afternoon have spread through the system.

Seasonal patterns and peak travel times

Thanksgiving week, Christmas week, and the summer months (June through August) see the highest delay rates. During these periods, airports operate at or near capacity, and a single weather event or mechanical issue can overwhelm the system. Spring break and Easter also bring spikes in delays, though usually less severe than winter holidays.

The day after Thanksgiving and the day before Christmas are historically among the worst days to fly. If you have flexibility, flying on the holiday itself or a few days after the peak rush can reduce your delay risk. Midweek flights (Tuesday through Thursday) also tend to have lower delay rates than Friday through Sunday flights.

How to check on-time performance before you book

The Bureau of Transportation Statistics publishes monthly on-time performance data for every airline and major airport. You can view this information on the BTS website to see which airlines and routes have the best track records. Some flight search engines also display historical on-time data alongside ticket prices, letting you compare delay risk as you shop.

When checking performance data, look at the specific route you plan to fly, not just the airline. A carrier might have a strong overall record but struggle on a particular route due to airport congestion or weather patterns. Also check the time of day—if you are considering an evening flight, look at evening delay rates for that route, not the airline's average across all times of day.

Frequently Asked Questions

What counts as a flight delay?

The FAA counts a flight as delayed if it arrives more than 15 minutes after its scheduled arrival time. Airlines may use different definitions internally, but the 15-minute threshold is the standard for reporting and tracking on-time performance.

Are some airlines more reliable than others?

Yes. Major carriers have different on-time records, and these records are public. Hawaiian Airlines, Delta, and Alaska Airlines have historically ranked among the most reliable, while others have higher delay rates. However, performance varies by route and season, so check the specific flight you are considering.

Can I get compensation if my flight is delayed?

Compensation rules depend on the cause and length of delay. Weather delays are typically not compensable, but delays caused by airline operations (mechanical issues, crew problems, overselling) may may have access to you for compensation under Department of Transportation rules. Check your airline's policy or the DOT website for details on your specific situation.

Is flying early in the morning really safer from delays?

Morning flights are statistically less likely to be delayed because they have not been affected by earlier delays in the day. However, weather can still cause morning delays, and mechanical issues can happen anytime. Morning flights are a better bet statistically, but not a may provide.

Do budget airlines have more delays than full-service carriers?

Budget airlines have mixed records. Some have strong on-time performance because they operate simpler networks with fewer connections. Others have higher delay rates due to tighter scheduling or older aircraft. Check the specific airline's historical data rather than assuming budget means more delays.