EUROCONTROL Data Snapshot #44 delves into the causes of flight delays

In 2023, nearly 3 flights in 10 arrived more than 15 minutes late, more than in 2022 and much worse than in pre-pandemic 2019. What is causing this?

The ‘all-causes' or 'schedule’ delay measures the difference between the time an aircraft arrives at/departs from the parking position and the scheduled time; it reflects the passenger experience. In 2023, the average schedule departure delay per flight was 17.8 minutes, very similar to 2022, while the average arrival delay in 2023 rose 0.2 minutes to 16.2 minutes. This lower delay on arrival is an indication of an airline’s ability to absorb part of the departure delay during the flight phase.

EUROCONTROL collects delay reason data directly from airlines in order to better understand the delays in the Network. To identify schedule delay drivers, we need to focus on the departure phase where airlines record the reason(s) for the delay; a flight might have both a reactionary delay caused by the late arrival of the aircraft and also some baggage loading delay or an Air Traffic Flow Management (ATFM) delay.

In 2023, reactionary delays added 8.2 minutes per flight, with peaks occurring in the afternoon and evening. One objective of the Network is to keep delays as low as possible during the first rotation hours in order to reduce the risk of a snowball effect of reactionary delays throughout the rest of the operational day.

Airline delays (such as passenger and baggage handling, cargo processing and technical issues) contributed an average of 4.5 minutes per flight. ATFM en-route delays increased to an average of 1.9 minutes per flight, up slightly from 1.8 minutes in the previous year. Weather-related en-route ATFM delays in 2023 were particularly high due to increased convective weather in the summer. Additionally, local weather delays at airports (such as ground handling impaired by adverse weather conditions or de-icing) added 0.6 minutes per flight, bringing the total average weather-related departure delay to 1.2 minutes per flight in 2023.

Delays caused by airport restrictions, which include local ATC delays as well as ATFM arrival regulations due to ATC capacity, staffing, equipment, etc., contributed 1.8 minutes per flight on departure. Government procedures, including security and customs checks, added an average of 0.4 minutes per flight.

A great deal of work goes into reducing delays, which impact passengers, reduce predictability and have a major financial cost. This can only be achieved through effective cooperation between airlines, airports, air navigation service providers and the EUROCONTROL Network Manager.