Operational data from airlines on delays from all-causes illustrate a significant increase in delays in the third quarter of 2018. July and August saw particularly strong delays due to en-route air traffic flow management (ATFM) and convective weather.
Traffic growth also contributed to delays, European flights (ECAC) in average daily terms increased by 3.3% in Q3 2018 compared to Q3 2017. Indeed growth would have been higher had the delay situation not contributed to a jump in operational cancellations, these increasing to 2.0% (up from 1.6% in Q3 2017).
This was coupled with poorer punctuality, 72% of arrivals were punctual compared to 76% in Q3 2017.
Airlines reported that en-route ATFM delays increased significantly at 2.6 minutes per flight. Major reasons driving this were convective weather and ATC staffing issues, notably in Karlsruhe UAC. Overall in Q3 2018 ATC staffing delays more than doubled, accounting for 21% of total airline reported ATFM delay.
Delays due to airline operations remained the main cause of primary delay, contributing 4 minutes to the average delay per flight, a 0.3 minute per flight increase compared to Q3 2017.
Reactionary (knock-on) delay increased by 1.5 minutes per flight and contributed 8 minutes to the average delay per flight due to an increase in primary delays. However its proportion of the total hardly changed, resulting in a 46% share of delay minutes.
Put together, these factors resulted in an average all-causes departure delay of 17.8 minutes per flight, up by 3 minutes per flight on Q3 2017.