After fifty years, working together to deliver a better-quality forecast

13 March 2017

For nearly five decades, the EUROCONTROL Statistics and Forecast Service (STATFOR) has been serving European air traffic management with impartial air traffic forecasts. The scope but also the quality of its forecasts has significantly improved with time. One big step to improve quality was taken at the end of 2013 with the introduction of a new forecasting process, which involves the wider collaboration of EUROCONTROL Member States.

This process involves a preparation and review of the seven-year forecast spread over four months. It starts every year in November with gathering data, assumptions and inputs from the STATFOR User Group (SUG) and the Internal Forecasting Review Group (IFRG), an internal group of domain experts in EUROCONTROL. The SUG is the descendant of the meeting of experts on Eurocontrol long-term air traffic forecasts which first met in June 1967.

In December, a first draft forecast is produced and circulated to the SUG, which includes stakeholders from EUROCONTROL’s Member States, for comments. Then, a final draft is ready by February the following year, submitted to a broader range of users including the EUROCONTROL’s Provisional Council (PC), the Network Management Board (NMB) and the Enlarged Committee for Route Charges (ERC) and reviewed one last time by the Internal Forecasting Review Group and the SUG at its annual meeting.

“Each State reviews the figures in the STATFOR forecast for their country and compares them against their own internal forecast, and then they issue comments. Having this stepped process is really effective in making sure that the forecast is as good as we can get it for each State,” explains Vicki Chase from the National Air Traffic Services (NATS), UK.

She adds: “I think that having this collaborative environment and the workshops throughout the year helps all States understand STATFOR and work out how we can make the forecasts even better.”

According to Lorna Herda, from Skyguide, the provider of civil and military air navigation services in Switzerland, the added value of the SUG meetings is in obtaining an insight into what is happening in Switzerland’s neighbouring countries. “There are certain details that you don’t see in the published version of the STATFOR forecast. In these meetings, we have the opportunity of learning additional information from other countries that will have an impact on us,” she explains.

Anton Glössl, from the Austrian air navigation services provider Austro Control, believes that local know-how contributes to improved forecasting. “For instance, Austria is a small country and some behaviour patterns are difficult for STATFOR to model and see all the small effects. Bringing our knowledge and perspective to this process, especially information which is only locally available, like capacity plans for home carriers and airports, or what airlines at our home airports are planning, is important.”

Maria João Velez, from air navigation service provider NAV Portugal, believes that these meetings offer an ideal setting for exchanging information and discussing the reasons behind the numbers provided by Member States and STATFOR, in particular when there are discrepancies. “To date, STATFOR has always been open to discussing differences in data, how flights are counted and to adjust the figures on both sides,” she points out.

Assessing the quality of the forecasts

Recognising the particular sensitivity of its forecasts, since 2007, STATFOR has been publishing annual forecast performance reports to evaluate the quality of the forecasts. For 2015, the flight forecasts were, in terms of relative performance (RP), 80% more accurate than the benchmark, well exceeding the RP target of a minimum of 50%. The 2016 preliminary figures (78%) are in line with the previous year. 

But the high quality of the forecasts is not only made apparent through the numbers, but also through the opinions of the STATFOR User Group members.

Stuart Holloway from Deutsche Flugsicherung GmbH (DFS), the company in charge of air traffic control for Germany, observes: “STATFOR went through a process of completely overhauling their forecasting process and I think in the past years there has been a tremendous improvement in the quality delivered now - to the extent that we use its forecast frequently with only slight adjustments based on our knowledge and our internal needs. These days, it’s just fine-tuning.”

For Vicki Chase: “The fact that Member States are now feeding in their data has improved the quality of the forecast. Obviously, the more stakeholders contribute each year, the better it gets. From the UK point of view, STATFOR forecasts and our internal forecasts have been getting closer and closer for the past three years.”

“There used to be a big gap between our numbers and STATFOR’s,” says Maria João Velez. “Today, STATFOR and NAV Portugal’s numbers are practically identical; we are well tuned and the forecast is highly reliable – that’s why we use it,” she adds.

The 7-year forecast February 2017 release

The 7-year forecast, resulting from the collaborative process above mentioned, combines flight statistics with economic growth and models of other important drivers in the aviation industry such as costs, airport capacity, passengers, load factors, aircraft size, etc. The goal is to give a comprehensive picture of current and future trends in air traffic development in Europe for the next seven years. The main forecast update is published every year at the end of February/beginning of March and refreshed in September.

European flights (in the European Civil Aviation Conference area) increased by 2.8% in 2016, compared with 2015; the traffic figures were in line with the forecast updated in September 2016. There was a total of 10.2 million flights in 2016, just about the 2008 traffic levels. Removing the leap day effect, this represents a 2.5% growth in average daily terms in 2016 (compared with 2015). This relatively high growth rate was mainly driven by the low-cost airlines – which had 7.5% growth – and was also attributable to low oil prices throughout the year, along with a stable, if low, economic growth.

The flight growth prediction for 2017 has been revised upwards to 2.9%, consistent with the high growth scenario of the September 2016 forecast. At the time of the last forecast published in September 2016, the 2017 forecast for Europe was revised downwards due to the expected Brexit-induced shock to the UK and in general to the Euro area’s economy. The predictions were indeed expecting an immediate and significant impact on the economy and the consumer confidence. So far, these predictions have not come to pass and if a negative impact on the economy is still expected, it will be in a more medium to longer term.

For 2018, a growth of 1.9% is foreseen. From 2019 onwards, European flight growth is expected to remain stable at around 1.7% per year over the 2019-2023 period.

Find out more about the current and future trends in air traffic in Europe by downloading the 7-year forecast February 2017.


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