European carriers make most of their money during summer months, and schedules are getting increasingly tight and prone to disruption. One flight getting delayed even by a few minutes can trigger downstream delays affecting flights scheduled for the same aircraft later in the day. The situation came to a head in July 2024, when air traffic management-related delays shot up 64% compared to 2023. Abdelmagid Bouzougarh, CEO of international aviation recruitment firm Aerviva, shares his thoughts on the causes and effects of this situation.

“EUROCONTROL reported an average of 6.5 minutes of delay per flight this past July,” Bouzougarh said. “While one-off events like the CrowdStrike outage skewed the numbers somewhat, there is no denying the impact of changing weather patterns on the big picture.”

According to EUROCONTROL, there was a 41% increase in weather-related delays in July 2024 compared to July 2023, with a further 84% increase since 2019. Summer thunderstorms, now more frequent across Europe, are behind many of these delays. When a storm hits, ground crews cannot operate safely, alternate flight paths get congested, and takeoffs become too risky.

Delayed flights can add airline costs in the form of refunds, complimentary meals and lodging for passengers, and other unforeseen expenses stemming from efficiency disruptions. In the United States, the Air Transportation Association found that delays cost the airline industry $30 billion in losses annually. Due to the diversity of costs associated with delays, it is difficult for airlines to report individual tolls on their financial reporting, however, on-time performance can sometimes be correlated with performance and customer satisfaction, leading to material changes in investment for the airline. Beyond the effect on individual airlines, airports, and regional economies also experience a change from the total economic impact of flight, with studies done by the National Center for APEC estimating flight delays in the Asia-Pacific region cost the region’s economy $13 billion in productivity and increased travel expenses.

Unfortunately for European carriers, thunderstorms and heavy rain events in Europe are becoming increasingly frequent. A joint study conducted by the American Meteorological Society and Newcastle University shows approximately a 14% increase in the number and intensity of thunderstorms and heavy rain in Central Europe. EUROCONTROL’s report and previous publications have emphasized that changing weather patterns are impacting aviation operations more frequently.

“The increasing heat from our climate creates a snowball effect on aviation operations, as pilots are likely to encounter longer duty days that include more challenging flight operations,” Bouzougarh said. “When weather events occur, they impact entire networks and systems, increasing the amount of congestion and delay at airports.”

Bouzougarh added that, according to EUROCONTROL, a narrowbody jet in scheduled service will typically be involved in an average of six flights per day. If the day starts behind schedule, it might prove to be difficult to pick up the pace later on in the day. Those initial 10 minutes of delay eat into critical ground time, leaving crews with a compressed window to ready the aircraft for its next flight. As the aircraft continues its schedule in the day, the 10 minutes can slowly add up to waiting for additional time for the arrival slot at the airport, or in airspace, or a myriad of other delays that could turn into hours. Hours of lost time result in the need to replace aircrews at the end of their duty day or the need to reschedule aircraft. These effects are increased on high-traffic routes such as between major European capitals.

“Airline schedules are tight, and while they might allow some flexibility, delays will often be passed down to subsequent flights,” Bouzougarh said. “By the end of the day, if an aircraft’s departure was late in the morning, a tightly scheduled crew could reach the limit of their duty day, or the time they are legally permitted to fly, before completing the day’s tasks for the airline, causing the airline to need another set of crew members.”

EUROCONTROL’s recent report on delays was not limited to weather but also included issues related to staffing and available capacity. When routes get overcrowded, air traffic controllers need to space flights further apart for safety. These capacity-related delays surged 117% compared to July 2023, putting extra pressure on flight crews who can only work a set number of hours per day. For scheduled passenger service, when the crew has been working multiple flights, they can approach the end of their “duty” day. This means that aircraft involved in delays could exceed the hours available for a crew member, thus creating the need for an additional crew. For an industry already dealing with significant difficulty in recruiting and retaining talent, this poses another major complication.

Reports by EUROCONTROL also shed light on other potential causes for flight delays. For example, during September 2024, an average delay of 21 minutes compared to 18.1 minutes the same time last year was noted. Of these delays, airport capacity accounted for a delay of 12 minutes, available airspace accounted for 3 minutes, and weather delays only averaged .4 minutes of delays. For September 2024, airline delays, or delays from the airline’s own operation only accounted for 4.7 with a further 10 minutes of delay caused by the reaction to a late inbound aircraft.

“What is clearly evident from EUROCONTROL’s summertime data is the difference that a skilled flight crew has,” Bouzougarh said. “Despite a 41% increase in delays, the on-time record of arriving aircraft decreased by a mere 2%. In 2024, aircrews are working even more diligently than in 2019 to ensure on-time performance when facing departure delays.”

Delays will likely continue to increase as climate change affects the probability of severe weather incidents. As airlines operate in worsening weather climates, delays will also be impacted by continued limits on capacity for the airspace system and routes, as well as staffing shortages for aircrew, air traffic controllers, and ground handling personnel.

Including more innovative solutions (increased digitization, Machine Learning, and so on) into the practice of how air traffic is managed might look like the only way forward. According to the latest report by Worldmetrics, AI-driven air traffic management systems can reduce delays by up to 40%. The track record of the global ATC when it comes to adopting cutting-edge technologies is a solid one, with the U.S. NextGen and European SESAR programs representing impressive changes that have already come to life. However, as climate becomes an increasingly important “actor”, AI solutions need to be implemented and deployed in an even quicker and more decisive manner. Airlines around the world are already using advanced, AI-based weather intelligence tools, reportedly saving them hundreds of thousands of dollars per hub. As similar solutions are adopted wider across the board, the whole industry will be more prepared to weather any storm.