What Causes Flight Delays

A delayed flight has happened to all of us. Sometimes, it’s just a minor inconvenience. Other times it means missing a connection, and your tour group or cruise ship leaves without you.

In 2025, US travelers lost 1.5 million hours because of flight delays – which equals 171 years.

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What are the major causes of flight delays – weather, airline staffing issues including slow baggage on-loading or off-loading, and disruptions in the federal air traffic control system – and the ripple effects?

Here are the details –

SkyRefund, an air passenger claims company, analyzed data from Bureau of Transportation Statistics (BTS) to identify the main reasons which cause flight disruptions, including passenger waiting times.

The study discovered 93 million minutes of airport delays throughout the United States in2025, which helped explain that flight delays are not just a minor inconvenience but a significant and recurring issue that impacts millions of travelers each year.

Top Causes of Flight Delays in the USA

According to SkyRefund’s findings, the number one reason for delays in 2025 was “late arriving aircraft,” which accounted for 39.7% of the time spent delayed, or 600,000 hours.

Late arrivals cause a domino effect, where the aircraft falls behind schedule for cleaning, refueling, and maintenance, leading to a series of subsequent delays. This recurring cycle of hold-ups continues to disrupt the flow of air travel across the US.

The second most common cause of delays, contributing to 31.83% of the total delay time or 497,000 hours, was “air carrier delays.”

This category includes any delay caused by factors under the airline’s control, such as technical failures, staffing issues, slow baggage loading, or other operational delays.

Notably, air carrier delays also play a significant role in causing late arrivals, with over 50% of late aircraft arriving due to issues within the airline’s control.

This has a ripple effect on subsequent flights, contributing to even more delays.

The third leading cause of delays in 2025 was the “National Aviation System,” which includes disruptions caused by airports, air traffic control, or avoidable weather conditions.

These factors accounted for 21.4% of delays or 334,000 hours. While not directly caused by airlines, these disruptions are still critical to understanding the larger picture of air travel delays.

Furthermore, these delays were responsible for 35.5% of subsequent delays, including replacing flight crews which surpassed daily work time limits, highlighting how issues within the broader aviation system can have far-reaching effects.

“Extreme weather” accounted for 6.94% of delays, equating to 108,423 hours in 2025. These severe disruptions are caused by storms, unpredictable winds, and other extreme conditions that keep planes grounded.

While weather-related delays are often unavoidable, they remain one of the most frustrating causes of travel disruptions for passengers.

Security delays, though rare, are another factor that contributed to flight disruptions. These delays occur when terminals must be evacuated or planes are de-boarded for security reasons.

In 2025, security delays accounted for a mere 0.13% of the total time delayed, or 1,958 hours. While these delays are less frequent, they can be especially stressful for passengers and contribute to the overall disruption of travel plans.

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Improving Air Travel: A Path Forward

SkyRefund’s analysis of flight delays underscores the importance of ongoing improvements in air travel. While most delays are caused by air carrier issues or the National Aviation System, there have been significant investments in air traffic control and other areas to reduce these disruptions in the future.

Ivaylo Danailov, CEO of SkyRefund, encourages optimism among American air passengers, noting that improvements are already being seen year over year.

With continued investment and innovation, a large portion of this lost time could be eliminated, enhancing the flying experience for passengers across the US. The analysis highlights areas for improvement and calls for greater attention to be paid to the causes of delays that can be mitigated.

The Future of Air Travel Delays

In 2025, flight delays in the US led to a combined loss of 1.5 million hours for travelers, a statistic that reflects the ongoing challenges faced by the aviation industry.

The leading causes, late arrivals, air carrier delays, and National Aviation System disruptions, continue to affect millions of passengers each year. While extreme weather and security delays remain less frequent, they still contribute to the overall disruption of air travel.

SkyRefund’s study shows which elements cause flight delays and shows how necessary it is for airports to keep working on their airport operational efficiency.

The aviation industry develops new technologies while its companies spend money on research and development, which creates hope that future passenger travel will become less disrupted.

ecoXplorer Evelyn Kanter is an award-winning journalist with 25+ years of experience as a newspaper and magazine writer, radio & TV news producer & reporter, and author of guidebooks and smartphone apps – all focusing on travel, automotive, the environment and your rights as a consumer.