Article „Outsmart the heavy weather“

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Source: ATO №195
December 2018: Airports and ground equipment
Details about the author:
Svetlana Margolit, representative of Airport Research Center GmbH in Russia

Outsmart the heavy weather

Optimization of winter operations at airports by simulation

A gloomy weather forecast can turn out a serious challenge for airport operators and airlines in the winter. Heavy snowfall or ice rain can cause significant damage to the airport’s day-to-day operations and spoil the mood of passengers caught in a snow trap, for example, on the eve of public holidays or during vacation periods.

IMPORTANT ISSUES. The severe winter storm that hit the North-East of the United States in January 2018 demonstrated the destructive force of heavy snowfalls, which caused John F. Kennedy International Airport in New York to be completely paralyzed and took several days to restore the flight schedule. Likewise, the massive snowfalls in Moscow in February this year led to massive delays of hundreds of flights from the capital’s airports, and again it took more than one day to restore normal operations, because with such airport malfunctions the problems tend to increase like a snowball.

However, heavy snowfalls in winter are a routine in northern latitudes, and the problem is not limited to sporadic “rush jobs”. Maintenance of the airfield infrastructure and aircraft in the winter has its specific features. In winter, runways and taxiways need to be periodically cleaned of snow and de-iced, as a result they are temporarily blocked, which in turn causes drop in infrastructure capacity and a reduced number of take-off and landing operations. Departing aircraft undergo de-icing treatment, so they occupy aircraft stands longer and cannot make room for arriving aircrafts. The organization and allocation of resources (including aircraft stands) becomes much more complex and requires a flexible approach.

Before the winter season, airport operators deal with the following questions:

  • What is the number of movements which can be executed during wintertime?
  • What factors specifically affect capacity limitations?
  • How will the aerodrome departure capacity change with due consideration of de-icing procedures?
  • How many de-icing pads will be required?
  • What capacity limitations will arise as a result of snow clearance and, thus, blocking of a part of the ground infrastructure?
  • What is the optimal allocation concept for aircraft stands during snowfalls?
  • What is the best snow clearance concept?
  • How to optimize the utilization of the available infrastructure?


These and many other questions determine the daily work of the various units at the airport and reasonable answers to these questions are crucial in terms of cost optimization. However, the difficulty of answering these questions is explained by the fact that the airport is a complex living organism, all components and processes in which are closely interrelated and interdependent. To minimize the negative impact of weather conditions and prevent the growth of expenses (for example, on the purchase of additional machinery), comprehensive planning is necessary taking into account the interaction of the infrastructure and various operating concepts. In order for the airport to quickly adapt to changes in demand and to the current situation, it is important to take into account not only strategic, but also short-term tactical aspects and to coordinate them in an integrated fashion.

MODELS FOR HELP. The software complex for airport simulation CAST (Comprehensive Airport Simulation Technology) developed by the specialists of Airport Research Center GmbH successfully deals with these tasks. A computer model of the airport created with the help of CAST and available at any time provides a great test environment that allows receiving answers to any arising questions.

To create a computer model of the airport in CAST, three main components are required: loading the airport infrastructure layout, drawing scenario schedules and formulating operational rules and concepts in the model, including separation rules, taxiing schemes, use principles of runways and high-speed exits, towing, de-icing, snow removal procedures. The CAST tools enable generating not only aircraft traffic, but also traffic of vehicles and special equipment on the apron, as well as simulating the ground handling processes. An important element of the scenarios is the allocation of aircraft stands, since different allocation strategies are used for different scenarios, including the “winter” ones. CAST is able to set the most complex rules and priorities, both hard and soft (related to allocation priorities) ones.

The computer model of the airport allows fast and efficient analyzing various KPIs (such as the capacity of individual elements and the entire system, taxiing time, delays), identifying bottlenecks and testing recommendations for eliminating them. Running multiple scenarios makes it possible to compare a wide variety of operational concepts and select the optimal ones with no additional costs. And the 3D-visualization contributes to a better understanding of the situation and tracking of cause-effect relationships. Visual three-dimensional reflection of all processes not only helps to make well-grounded high-quality decisions, but also enables employees to better understand and accept the management decisions.

NORWEGIAN EXPERIENCE. Those airports that regularly undergo blows of the snow storms in the winter cope with the winter problems more successfully. This applies, in particular, to the airports of Scandinavia, where the winter season lasts long, and cleaning the runways and aprons from snow, as well as the prolonged de-icing treatment of aircraft are quite routine operations.

In winter, the number of movements at the airport is significantly reduced due to snowfalls, de-icing and other operational restrictions. Therefore, prompt and high-quality clearance of the airport infrastructure from snow is of great importance for the smooth operation of the airport and maintaining the desired level of service. The airport management approached the specialists of Airport Research Center GmbH with a request to analyze the interdependencies and assess the actually possible throughput and the capacity of the airfield infrastructure during the winter period.

First, a base model of the airport was built using CAST, which was approved by airport experts, and then various future scenarios were simulated and analyzed with a consistent increase of peak hour’s demands. The powerful and flexible traffic management and control functionalities of CAST made it possible to simulate in detail and adequately the processes in the controlled area of ​​the airport. In particular, the snow clearance procedures on runways and taxiways were modeled thoroughly, including dynamic rerouting of aircraft to avoid taxi delays due to blocking of individual infrastructure elements, as well as the re-assignments of aircraft stands. In addition, the de-icing procedures were simulated taking into account the wing-span dependent use of certain de-icing pads and the stochastic de-icing durations as well as the de-icing queue-based taxi clearances.

In several scenarios, KPIs such as runway capacity, delays during aircraft landing and take-off, in-block and off-block delays, taxi-in and taxi-out delays, the aircraft stands demand, the length of the de-icing and departure queue were analyzed.

Comprehensive modeling of processes made it possible to thoroughly analyze the interdependencies between the snow clearance and de-icing procedures and the throughput of runways, taxiways and aircraft stands. The results and conclusions from the project will be used as an important basis for future decision making and will enable the airport to better prepare for the winter season.

Thus, along with expensive solutions, such as the purchase of additional special equipment, the organization of new aircraft stands and de-icing pads and the attraction of additional labor resources, the CAST simulation software package contributes significantly to ensuring the smooth airport operation during the winter season at an adequate level of quality and to cost savings in terms of operational and infrastructure costs.