Winter optimisation

Controlling ice and snow in major hub operations is an increasingly challenging task. In this article, Munich Airport reveals what it takes to remain open through the winter months.

A single runway closure of 30 minutes can easily build up to average delays of 2-3 hours with a traffic density on the scale of 70-90 movements per hour. Subsequently, if ATC doesn´t imposing pre-tactical flow control measures, the holding stock capacity of major airports can easily be exceeded when snow clearance requires a sudden runway closure during peak hours.

After completion of the runway clearance, delays can be further exacerbated by bottlenecks in remote aircraft de-icing areas. Crew duty hour limitations on long-haul services might also result in cancellations, even if the initial weather-induced delay was only minor.

Another consideration is that an initial departure delay is exacerbated if the aircraft cannot keep its slot. This situation may even worsen if the destination airport is also subject to weather-related closures and delays. Night flight restrictions, which are a very present concern here in Germany, also limit the capability to absorb delays, causing backlogs in scheduling the following day.

These challenges become evident at Munich Airport during the winter months. Currently number eight in Europe in terms of passenger throughput, Munich Airport has doubled its passenger and tripled its cargo capacity since opening in May 1992. With 89/ 90 (the latter number going into effect in Spring 2006) scheduled commercial aircraft movements allowed per hour , Munich ranks top among European airports in terms of runway capacity.

Challenging conditions

Situated only 70 km north of the Alps and with a field elevation of 448m /msl, Munich is more frequently exposed to snow and ice conditions than any other of Europe’s ten busiest airports. Munich experiences an average of 30 days of snowfall each winter, with the average amount of snowfall averaging between 4 and 20 cm per day. In total, Munich Airport registers more than 50 days of snow removal or de-icing activities per year.

Indeed, this constitutes a competitive disadvantage vis a vis Europe´s other major hubs such as Madrid, Paris or Heathrow, which are affected by snow and ice conditions more rarely, if ever, in comparison with Munich. Thus, continuous efforts in improving the reliability of flight operations, even in adverse conditions, are of strategic importance for further hub development.

Whereas airports in northern Europe are more exposed to permanent frost conditions, temperatures at Munich fluctuate around the freezing point during winter. Munich airport faces the difficulty of fighting frequent slush conditions and ice formation caused by the sudden freezing of surface water.

The evening inbound rush starts at ca. 5 p.m. during the winter months, which coincides with the sunset and therefore with the drop in temperatures below the freezing point. The formation of black ice and the onset of snowfall often kicks in during one of Munich´s four busiest peak periods.

Carriers

Munich is not only Lufthansa’s parallel hub next to Frankfurt, but also serves as an important charter hub during the winter season. Germany’s major charter carriers, Condor, Hapag-Lloyd and LTU, have chosen Germany’s southernmost airport for their hub operations, involving up to 26 aircraft per hub event.

As Lufthansa’s European gateway, the traffic nature of Munich is predominantly short haul traffic operated by B737’s, the A320 series and regional jets. With scheduled turnaround times of only 25-30 minutes, this type of traffic is highly susceptible to delays. Weather- induced delays also cause severe stand constraints and apron congestion by overlapping hub waves.

Equipping and preparedness

Munich exerts the utmost effort in fighting the elements with the latest technology, and is continuously reviewing and updating its snow removal and de-icing concepts. (or, Winter preparedness and operations cost an average of ?8 million per year. In total, Munich operates a fleet of 133 specialised vehicles. The de-icing concept foresees six distinct alerting phases catering to a range of situations from frost de-icing only to fighting heavy snowfalls.

In the season of winter preparedness, from the 1st of November to 15th April, the airport duty officer can activate up to 170 staff within only one hour on a 24-hour basis. Throughout the entire winter season more than 400 staff are rostered on winter services standby shifts.

Depending on the density of snowfall, the closure of one of Munich´s two parallel, 4,000-meter runways can be de-iced and cleared of snow in less than 20 minutes. Snow removal and chemical de-icing of a 4000 x 60 meter runway, two parallel taxiways and three high-speed turn-offs per landing direction is accomplished during this very short amount of time.

This kind of speed is made possible by a dedicated runway team consisting of 24 towed air-blast sweepers, two airport sprayers, two multi-de-icers and two solo ploughs concentrate on the two runways and ancillary taxiways only, whereas the clearing and de-icing of aprons will be initiated simultaneously by a separate apron team.

But today´s challenges in a high-density winter operation cannot be controlled by improvements in clearing and de-icing technology alone. Due to the necessity of pretactical flow control measures, at high volume airports the delays will be created before the snowfall sets in. Thus, the advance anticipation of both the expected weather development and the effectiveness of mitigation measures is becoming more decisive than the actual weather development.

The effective minimisation of delays requires a seamless interaction between snow clearing, aircraft de-icing, air traffic control and airline flight operations activities. Winter operations at high-volume airports must be increasingly viewed as a holistic exercise with the entire airport system in mind.

Collaborative Decision Making (CDM) is playing an increasingly important role in exploring further potential for improving hub operation under adverse weather conditions. At Munich Airport the CDM tool has successfully been implemented on both the strategic and the tactical level.

The primary CDM platforms in Munich are as follows.

Snow Committee

The Snow Committee is the primary decision-making body on the strategic level and convenes frequently before the start of the season and for a debriefing session at the end of the season.

During the season, the committee is called in when required, for example if adaptations of procedures are deemed necessary or after demanding weather situations have been faced. Irregular meetings are convened whenever weaknesses or potential for improvement have been identified. The snow committee is chaired by Airport Operations and comprises senior representatives of all the key players:

The Snow Committee is the primary platform for the alignment of snow clearing and de-icing strategies, clearing priorities and communication procedures among the various stakeholders involved in winter operation. Beyond operational aspects, it deals with mitigating the environmental impacts of de-icing activities, particularly the impact on aquatic life—which, as Munich Airport lies directly adjacent to a river and protected natural areas, is a large consideration.

Within the framework of the committee, the application rates for chemical de-icing agents are subject to constant review. GPS recordings of any snow removal or de-icing activity support the continuous improvement of winter performance. Munich Airport has integrated the GPS technology for online performance monitoring purposes as well as a debriefing tool.

GPS allows the real time tracing of all vehicles involved in snow and ice control operations, including the three Saab friction testers operated by the operations division. In order to complement the picture, the GPS data are fused with the data recorded by the ice warning system.

Situational Shift Briefing

On a tactical level, an operational shift briefing is conducted in case of prevailing or forecasted winter weather situations.

The situational shift briefing is held as a telephone conference involving the following parties:

• Airport Duty Officer.
• ATC Supervisor ACC.
• ATC Supervisor TWR.
• DWD (German Meteorological Services).
• Lufthansa Hub Control Centre – Supervisor.

Based on the meteorological briefing by the German Meteorological Services (DWD), the airport duty officer estimates the expected runway closure time, accounting for factors such as residual surface chemicals, temperature, wind drifts and the water saturation of snow. The airport duty officer may indicate the probability of overlapping runway closures, which is important for assessing the need for flow control measures.

Early anticipation of delays allows the airport to coordinate with the ministry of transport at an early stage as to whether and to what extent exemptions from the night curfew will be granted. This allows the airlines to respond accordingly.

The ‘Snow Desk’

During winter operations, a tactical coordination cell is activated on the ATC Control Tower. The `snow desk´ is manned by the Airport Duty Officer, the ATC-Tower Supervisor and the Supervisor of the aircraft de-icing company.

The integrated Winter Management Centre serves to find the most suitable and least disruptive time windows to conduct snow removal activities. Capacity impairments are minimised by a timely notification of all involved parties regarding the initiation and termination of any snow removal activity. Thus the provider of aircraft de-icing can effectively utilise the timeframe of suspended flight operations for vehicle replenishment.

Meeting meteorological needs

Considerable potential for enhancing winter operations has been identified in improving the quality of the weather forecasts available to airports. In recent years self-briefing tools have increasingly replaced the face-to-face weather briefing with the meteorological advisor.

Jointly with the German Meteorological Services (DWD), the meteorological needs of Munich airport have been substantially reviewed. In the Winter 2004 season, a meteorologist was based on site at the airport on a trial basis whenever winter weather conditions were anticipated. The meteorologist was directly located in the airport operations division, where valuable insight into the microclimatic conditions of the airport as well as the specific information needs of the operational staff was gained. In future DWD will permanently locate a meteorologist at Munich airport.

It has been identified that airports do not only require those meteorological products that are designed for the aviation community but also those products that are tailored to other target groups, such as road authorities or fire fighting services. These forecasts are now also being made accessible to Munich airport.

The improvement of weather forecasts resulted in considerable reductions of more than 21 percent in winter crew waiting times and a minimisation of flow control-induced delays.

Henning Pfisterer

Henning Pfisterer, Airport Safety Manager and Duty Officer for Munich International Airport, has in 12 years gained extensive experience in various functions of airport operations. As airport safety manger he deals with a range of issues such as emergency planning, SMS, incident reporting and certification.