European airspace: a bad summer, while the 'Single Sky' remains elusive

ATFM delays per flight, Jun-Aug 2024: +41% vs 2023 and +48% vs 2019

If the number of aircraft due at an airport, or passing through an air traffic control sector, is more than the declared capacity, Eurocontrol will sequence the traffic by issuing a departure slot.

This will delay some flights on the ground, and this is known as an Air Traffic Flow Management (ATFM) delay.

ATFM delays per flight averaged 5.4 minutes per flight in the peak summer months of 2024, which was an increase of 41% (from 3.8 minutes) a year earlier, and of 48% versus the 3.7 minute average of the same period of 2019.

In the three peak northern summer months of 2024, daily ATFM delays only rarely fell as low as the average levels of 2023 and 2019.

They were frequently above 5 minutes, peaking at 9.43 minutes per flight on 25-Jul-2024.

En route delays per flight were the highest in 25 years

En route delays, which account for the bulk of delay time, averaged 4.6 minutes per flight for the three-month period.

This was the highest number in 25 years, exceeded only by the figure of 5.9 minutes in 1999. That was the year in which a capacity crisis triggered the creation of the 'Single European Sky'.

The impact of weather in summer 2024: +41% vs 2023, +99% vs 2019

The impact of weather grew by 41% year-on-year this summer, to 2.2 minutes per flight, which was an increase of 99% on 2019.

Weather was the single biggest cause, accounting for 41% of delay time.

Weather must not be used as an excuse for other, controllable, factors

While weather is not controllable by air navigation service providers (ANSPs), Eurocontrol says that capacity constraints attributed to weather are often aggravated by other factors.

It has called on providers to increase transparency in order to demonstrate that weather is not being blamed for other issues - for example staffing or air space capacity - that are controllable.

Moreover, weather variability is increasing, and providers need to be able to mitigate its impact.

In other words, even if weather really is the cause of a delay and not just an excuse, the system has to learn to cope with it better.

Capacity and staffing delays also increased year-on-year

Capacity delays increased by 82% year-on-year, to 1.9 minutes per flight, up by 29% versus 2019.

Staffing delays increased by 15%, to 0.6 minutes, although this was down by 18% from 2019.

Arrival punctuality fell to 65.0%, down by 1.0ppts year-on-year and by 7.9ppts versus 2019.

European* air traffic flow management delays, Jun-Aug 2024

1 June - 31 August	2019	2023	2024	Change from 2023 to 2024	Change from 2019 to 2024
Traffic (flights)	3,214,547	2,989,583	3,131,864	+4.8%	-2.6%
Air Traffic Flow Management delay (minutes)	11.8 million	11.4 million	16.9 million	+48%	+44%
ATFM total delay/flight (minutes)	3.7	3.8	5.4	+41%	+48%
ATFM weather delay/flight (minutes)	1.1	1.6	2.2	+41%	+99%
ATFM capacity delay/flight (minutes)	1.5	1.0	1.9	+82%	+29%
AFTM staffing delay/flight (minutes)	0.7	0.5	0.6	+15%	-18%
Punctuality (arrival)	72.9%	66.0%	65.0%	-1.0 ppts	-7.9 ppts

*In the Eurocontrol area.
Source: Eurocontrol.

Traffic is down from summer peaks, but delays remain high for the time of year

The average number of daily flights from 1-Jun-2024 to 31-Aug-2024 was 34,042 - at around this level of daily traffic, delays typically increase very rapidly.

Since the end of Aug-2024, daily flight numbers and delays have fallen in line with seasonal schedule variations.

However, in the seven days to 22-Oct-2024, average daily flight numbers were at 31,276 - still a high level of traffic - and delays remained high, compared with the same week in 2023 and 2019.

Daily flight numbers in the Eurocontrol area, from 2019

Source: Eurocontrol.

Flight numbers were up by 6% year-on-year (and down by 2% versus the same week of 2019), whereas average daily AFTM delays were up by 31% year-on-year (and up by 40% from 2019).

As at 22-Oct-2024, average daily flights for the year to date were up by 5% year-on-year, and down by 4% versus 2019, whereas AFTM delays were up by 18% year-on-year, and up by 24% versus 2019.

Delays in the Eurocontrol area: total minutes (left hand axis) and delays per flight (right hand axis), 2023 and 2024

Source: Eurocontrol.

Airlines for Europe (A4E): 'Europe's airspace is failing'

Airlines for Europe (A4E) reacted strongly to the worsening figures for summer 2024.

The trade body's managing director, Ourania Georgoutsakou, said: "Europe's airspace is failing… for millions of passengers this summer, the agony was all too real".

"We know what the problems are and the capacity we have to work with, clearly we are not doing enough with what we have to prevent delays," she added in a press release on 2-Oct-2024.

The Single European Sky could triple capacity and halve ATM costs…

The Single European Sky (SES) is an initiative launched by the European Commission in 1999 to reduce the fragmentation of European air traffic management (ATM) and improve navigational efficiency.

The benefits are potentially very significant: compared to 2004, it could triple airspace capacity, halve the costs of air traffic management, improve safety tenfold, and reduce aviation's environmental impact by 10%.

…but suffers from 'a lack of political will'

However, progress towards the SES remains painfully slow.

"SES continues to suffer from a lack of political will," says Rafael Schvartzman, IATA's VP for Europe, "…politicians have left these significant gains on the table for over two decades".

Even SES' environmental benefits have not yet accelerated its progress

The expected environmental benefits of the SES might have been expected to motivate politicians to give the project a higher priority.

In addition to minimising delays for passengers, the more efficient use of airspace would cut CO2 and noise emissions.

The airline industry's four sustainability pillars include infrastructure, which refers to more efficient navigation and use of airspace, as well as optimising airport capacity.

However, progress has remained slow, even as environmental sustainability has risen to the top of the agenda for aviation.

In an interview published in IATA's Airlines magazine, Austrian Airlines CEO Annette Mann expressed the views of many in the airline industry when she said that it was "very hard to understand what is happening with the Single European Sky (SES)".

Further, "…decades after we started the discussion, we are still taking baby steps. Why aren't we grabbing this 10% that is apparently available?"

Eurocontrol coordinates, but nations retain sovereignty over airspace

Eurocontrol is a coordinating body for air traffic control across Europe, with 41 member states. It works with national governments, ANSPs, airlines and airports to coordinate traffic flows.

A more unified system, such as in place over the United States, for example, would allow flights to follow straighter pathways.

However, nations have sovereignty over their own airspace, and European governments have so far been very reluctant to compromise this.

Eurocontrol points to poor planning and staffing issues

In addition to the bigger picture patchwork approach to European ATM and the lack of progress with SES, Eurocontrol says that airspace inefficiency has been exacerbated by other problems.

The agency is critical of the lack of alignment between ANSP plans with capacity targets over the past decade. Moreover, it says that capacity actually delivered has often not met the plan.

Eurocontrol also identifies staffing issues arising from COVID-19, which have added to the challenges. The COVID-19 pandemic led to the departure of senior air traffic controllers, and to lower spending on training new staff.

According to Eurocontrol, the cost of reducing these staffing issues to provide additional capacity would be "a fraction of the cost of delays in 2024".

Geopolitical and labour factors are also challenges

Airspace capacity in Europe has also been squeezed by the Russian invasion of Ukraine, which has effectively removed the skies above both nations from what is available to airlines.

The conflict has also heightened political sensitivity over the issue of national sovereignty over airspace.

Integration is also challenged by labour issues, with industrial relations and pay levels varying across Europe. Moreover, some controllers worry that a more efficient system may threaten their jobs.

SES remains elusive and illusive

As long ago as Jun-2013, the then European Commission Transport VP, Siim Kallas, likened the SES to a mirage in the dessert - "each time you get close, it seems to move further away".

In Mar-2019 the man then at the helm of EUROCONTROL, Eamonn Brennan, said that air traffic capacity in Europe had had a long history of being saved by crises, which relieved pressure by lowering demand each time capacity appeared no longer able to cope.

The COVID-19 crisis certainly lowered demand - more dramatically than ever before.

However, even though traffic across Europe remains slightly below pre-pandemic flight numbers, delays are significantly above 2019 levels.

This most recent crisis has not saved air traffic capacity in Europe, and the mirage of SES remains elusive and, quite possibly, illusive.