The main reasons flights are delayed or cancelled

Flight delays and cancellations happen for three broad reasons: weather, mechanical problems with the aircraft, and operational issues at the airport or airline. Weather is the most common cause — thunderstorms, fog, snow, and high winds can ground planes or force them to circle while waiting for conditions to improve. Mechanical delays happen when maintenance crews find a problem during pre-flight checks or when a plane develops an issue mid-journey. Operational delays include crew scheduling problems, air traffic control delays, late arrivals from a previous flight, or a shortage of ground staff to load baggage or prepare the plane.

The Federal Aviation Administration (FAA) does not publish a single national breakdown of delay causes, but individual airlines report their reasons to the Department of Transportation. Weather accounts for roughly one-third to one-half of all delays, depending on the season and region. Mechanical issues and operational problems split the remainder. Cancellations are rarer than delays — most airlines cancel only when safety is at risk or when the disruption is so severe that operating the flight would cause a cascade of problems throughout the day.

Key Takeaways

  • Weather is the most frequent cause of delays, followed by mechanical problems and airport or airline operational issues.
  • Airlines must report the reason for each delay to the Department of Transportation, though the categories are broad and sometimes overlap.
  • A cancellation usually means the airline has decided the flight cannot operate safely or on time, rather than a random decision to cancel.
  • Your airline is required to rebook you on the next available flight at no extra cost if they cancel your flight or delay it significantly.
  • Checking weather forecasts and arriving early on days with storms or snow reduces the chance you will be caught off-guard by a delay.

Weather delays and how they work

Thunderstorms are the single most disruptive weather event for flights. A storm near an airport forces planes to hold in the air, divert to another airport, or wait on the ground until the storm passes. The FAA imposes ground stops — temporary halts to all departures — when lightning is within a certain distance of the runway. These stops can last anywhere from 15 minutes to several hours. Winter weather — snow, ice, and freezing rain — causes delays because runways must be cleared and de-iced, and planes themselves must be de-iced before takeoff.

Fog reduces visibility and forces planes to land more slowly or divert. High winds can close runways entirely if they exceed the maximum crosswind limit for the aircraft type. Tropical storms and hurricanes cause the longest delays because airlines often cancel entire days of flights rather than risk operating in dangerous conditions. The timing of weather matters: a storm that hits at 3 p.m. affects evening flights, but a storm that clears by 6 p.m. may allow later flights to depart on schedule.

Mechanical problems and maintenance delays

Before every flight, mechanics perform a pre-flight inspection that checks engines, hydraulics, electrical systems, and safety equipment. If they find a problem — a cracked windscreen, a faulty hydraulic line, a malfunctioning door latch — the plane cannot depart until it is fixed. Some repairs take 30 minutes; others take hours. The airline must decide whether to fix the problem, cancel the flight, or swap in a different aircraft if one is available.

Mechanical delays are less common than weather delays because modern aircraft are reliable and airlines maintain them aggressively. However, when a mechanical problem does occur, it often causes a long delay because the repair must be done correctly and signed off by a licensed mechanic. A plane that develops a problem mid-journey may have to land at an unscheduled airport for repairs, which then delays all subsequent flights that aircraft was scheduled to operate.

Operational delays caused by airlines and airports

Operational delays include crew scheduling problems — a pilot or flight attendant is late arriving from a previous flight, or a crew member calls in sick and a replacement must be found. They also include ground handling delays: baggage loaders are running behind, catering trucks are late, or the gate is occupied by another plane. Air traffic control delays happen when the airspace is congested and planes must wait for a takeoff slot, which is common at major hubs during peak hours.

A late arrival from a previous flight is one of the most common operational delays. If a plane lands 45 minutes late, the next flight scheduled to depart on that same aircraft will also be delayed unless the airline has a spare aircraft to use. This is called a cascading delay, and it can ripple through an airline's schedule all day. Staffing shortages — fewer ground crews or fewer available pilots — have become more common since 2021 and cause delays at some airports more than others.

How airlines decide to cancel instead of delay

An airline cancels a flight when it determines that operating the flight would be unsafe, or when the delay would be so long that cancelling and rebooking passengers is the better option. A cancellation is not a random decision — it is a deliberate choice based on the airline's assessment of the situation. If a thunderstorm is forecast to last eight hours, the airline may cancel rather than have passengers sit in the airport for most of the day.

Safety is the primary reason for cancellation. If weather is severe enough that landing safely is uncertain, or if a mechanical problem cannot be fixed in a reasonable time, the airline will cancel. The airline is also required to cancel if it cannot staff the flight — if all available pilots and flight attendants are already assigned to other flights. Cancellations are less common than delays because they are expensive for the airline: they must rebook passengers, provide meals and hotel rooms in some cases, and face potential compensation claims.

What happens to your flight information during a delay

When a delay occurs, the airline updates the departure time in its system, and that information flows to the airport's display boards, airline websites, and third-party flight tracking apps. You will see the new departure time on your airline's app or website, and you should receive a text or email notification if you signed up for alerts. The airline is not required to notify you by phone, but many do for delays over two hours.

For a cancellation, the airline must contact you and offer a rebooking on the next available flight at no extra cost, or a refund of your ticket price. The airline chooses the rebooking option in most cases. If the rebooking is on a flight more than one hour later than your original departure, you may be may have access to to compensation under Department of Transportation rules, though the amount varies by flight distance and reason for cancellation. Weather and mechanical problems are usually considered outside the airline's control, so compensation is not required in those cases.

How to prepare for delays and stay informed

Check the weather forecast for your departure and arrival cities the day before your flight. If thunderstorms or snow are predicted, expect possible delays. Arrive at the airport earlier than usual on days with bad weather — the airport will be crowded and security lines will be longer. read your airline's app and enable push notifications so you receive alerts about delays or cancellations as soon as the airline posts them.

Sign up for text or email alerts from your airline when you book your ticket. These alerts notify you of changes before you head to the airport. If you are flying during winter in a northern city, or during hurricane season in a coastal city, build extra time into your travel plans. If your flight is cancelled, contact your airline when ready to rebook on the next available flight, because rebooking slots fill up quickly. If you are stranded overnight, ask the airline about meal vouchers and hotel accommodations — they are required to provide these in some situations, depending on the reason for the cancellation.

Frequently Asked Questions

Can an airline cancel a flight just because it is not full?

No. An airline can cancel a flight for safety reasons, weather, mechanical problems, or crew scheduling issues, but not straightforward because ticket sales are low. However, airlines do consolidate flights — combining two partially full flights into one full flight — which results in cancellations of one of the flights. Passengers on the cancelled flight are reboked on the consolidated flight.

Do I get money back if my flight is delayed but not cancelled?

The Department of Transportation does not require airlines to compensate passengers for delays in the United States. However, some airlines offer travel vouchers or meal vouchers for long delays. If your delay causes you to miss a connection, the airline must rebook you on the next available flight at no extra cost. Check your airline's policy on its website.

What is the difference between a delay and a cancellation?

A delay means the flight will depart later than scheduled but will still operate. A cancellation means the flight will not operate at all that day. The airline will rebook you on another flight if your flight is cancelled. If your flight is delayed, you remain on the same flight unless you choose to rebook yourself.

Why do some airports have more delays than others?

Large, busy airports like Atlanta, Chicago, and New York have more delays because they handle more flights and have less flexibility when something goes wrong. Weather also varies by region — airports in Florida and the Southeast experience more thunderstorm delays in summer, while northern airports experience more winter weather delays. Some airports have older infrastructure that makes it harder to recover from disruptions.

How long can an airline keep a plane on the ground before it must let passengers off?

The Department of Transportation requires airlines to allow passengers to deplane after three hours on the tarmac for domestic flights, unless safety or security reasons prevent it. However, this rule applies only to planes that are sitting at the gate or on the runway — not to planes that are actively taxiing or waiting in a queue to take off. If you are stuck on a plane, ask a flight attendant about your rights.