How to avoid bad weather delays

In this article Doug Johnson describes how aviation users can utilise improved meteorological information to move beyond minimum safety requirements and towards increased business benefits. Airlines and pilots rely on weather information on a daily basis in order to make safety-critical decisions. Commercial airlines are duty-bound to follow the strict regulations laid down by ICAO Annex 3 and other regulatory bodies on the use of weather information for operational safety. However, despite huge strides forward in terms of forecasting capability, these requirements have remained essentially unchanged since 1984. Aviation has also traditionally used weather in a limited way for improving business performance, e.g. the use of wind and temperature information in calculating optimum flight routes. However, with the significant developments in weather forecasting during the last 20 years, we believe that airlines, airports and air traffic controllers can be helped to use these enhanced capabilities more intelligently and, ultimately, make better business and operational decisions through the reduction of avoidable weather-related delays.

Weather affects every part of the aviation industry, yet the Met Office believes that attempts at mitigating the effects of poor weather remain limited. As air traffic increases, airports will be forced to unlock latent capacity. Congestion and capacity restrictions initially manifested themselves in the en-route arena. Now with projects such as reduced vertical separation criteria increasing the number of airways available, the focus has turned to enhancing airport safety, efficiency and capacity. Poor weather costs the industry a huge amount; figures for Europe suggest that flight delays cost USD 750 million in January 2005 alone.

Managing weather

ATC is also faced with capacity challenges for the coming years. In 2001 alone, one flight in four was delayed due to air traffic problems. Air traffic management has a key role to play, maximising airspace capacity, minimising emissions, reducing delays and maximising runway utilisation, all against a need to maintain the highest safety levels. The Met Office believes that making better use of weather information can help achieve this. As a result, the organisation has embarked on a drive to offer higher value weather services to the aviation industry, which goes beyond simple weather forecasts to provide value-added information for business decision making. New services are coming online that utilise the current weather forecast capabilities and provide business benefits to airports, airlines and ATC. These services include Open Runway (an airport runway icing prediction and warning service), an aircraft de-icing forecast service, an advanced weather consultancy service and new web-based weather briefing tools for airports, airlines and ATC users.

Meteorological advances

At the heart of the new developments is the Met Office’s supercomputing capacity. The NEC SX-8 supercomputer has enabled a substantial increase in forecasting accuracy. Independent data which compares the output from the world’s five leading national weather services shows that the accuracy of Met Office forecasts for the northern hemisphere has improved by around 11 per cent since the introduction of the supercomputer. This compares with a historic improvement across all modelling centres of around 3 per cent per year. The first, most important step in getting accurate weather forecasts to customers is being able to use all available observational data from a wide range of sources. The NEC supercomputer enables this data to be processed very quickly. The forecaster then adds to or modifies the computer output as necessary, to produce the most accurate, reliable and timely forecast possible. The SX-8 also enables new computer models to be brought into operational use, which will provide a more complex simulation of the atmosphere. It is predicted that this will for the first time enable the accurate forecasting of small-scale weather features such as thunderstorms at airports — events that have a high impact on airlines, air traffic controllers and airport operators.

The de-icing forecast service

Based on the Met Office Site-Specific Forecast Model (SSFM), the de-icing forecast service uses local geographic details to provide the most accurate automated forecast of weather conditions likely to cause icing at airports. The de-icing forecast service is available for airports worldwide and provides a unique tool for airlines, airports and ground handling agents to plan de-icing operations more effectively. The concept for the de-icing forecast service was born from a series of workshops hosted by the Met Office with airline staff. During these sessions, the logistical planning of de-icing operations was identified as a major issue which was often poorly planned and executed, contributing significantly to winter departure delays and associated costs. Airlines expressed the view that the current sources of information (TAF and airport warnings) were not sufficiently timely or detailed to enable them to plan effectively. They outlined a number of problems associated with the current poor planning of de-icing operations:

• Inefficient staff, de-icing fluid and equipment utilisation.
• Flight departure delays, cancellations and associated costs.
• Longer fleet turnaround times and lost utilisation.
• The environmental impact of fluid over-use.
• Passenger dissatisfaction and damage to brand.

As a result, the Met Office worked with bmi, Ryanair and Virgin Atlantic to develop a prototype aircraft de-icing prediction service. After a successful trial, a fully operational version of the service was launched in Winter 2004. Following this a formal value assessment of the service was conducted in association with bmi and 12 major UK airports, to prove the service’s worth. The assessment showed that the Met Office correctly forecast days on which icing conditions would occur on 89 per cent of occasions, two days in advance. Detailed icing conditions in the critical morning departure period were correctly forecast on 86 per cent of occasions, six hours in advance. Overall, bmi found that the service significantly improved its proactive de-icing decisions, leading to reduced delays. As a result of the study, bmi has now signed up to the service for many of its UK and overseas bases. As well as access to the web-based de-icing forecast service, in winter 2005 Met Office forecasters will also be issuing direct instructions to bmi ground staff and de-icing contractors on when they should pro-actively anti-ice their aircraft. This move is part of a package of measures aimed at reducing avoidable de-icing related delays by up to 80 per cent.

How it works

The service is delivered through the web and offers forecasts of weather conditions likely to require the de-icing of aircraft on the ground. It is available for airports worldwide, is updated twice a day and includes the following key features:

• 24-hour temperature chart showing dew point and screen temperature.
• 24-hour advance warnings of likely icing conditions including confidence levels for the occurrence of relevant weather types (e.g. snow).
• Traffic-light risk of aircraft icing conditions for the next 24 hours.
• Guide to holdover times for customer specified fluid types.
• Advance warning of likely icing conditions over the next five days.
• Icing alerts to ground and operations staff via email, SMS or fax.
• Direct access to experienced Met Office forecasters for further clarification, if required.

The service is available direct from the Met Office’s model, with or without human forecaster input. Forecaster intervention offers enhanced confidence at major airports, whilst the automated service offers a cost–effective option for other bases. Computer models provide a guide to how the atmosphere is behaving and developing, but a forecaster will improve on that by consulting the latest observations and satellite and radar pictures. Furthermore by combining weather forecasts with the characteristics of de-icing fluids, the service warns airlines and airport service providers worldwide when de-icing is likely to be required and allows them to be proactive in planning to mitigate its effects. The forecast provides more detail than a standard Terminal Aerodrome Forecast (TAF), which lacks any temperature information. A key benefit of the service according to its users is that they have been able to use the five-day outlook to effectively plan the availability of staff, equipment and fluid. They have also been utilising the detailed icing and holdover forecasts to effectively plan when to proactively anti-ice/de-ice, significantly reducing morning departure delays, their impacts on later schedules and the associated significant costs. To trial the services and for feedback on your meteorological needs, please email [email protected]. or call +44 (0)1392 885680. The UK Met Office also offers consultancy, training and climate information across the aviation industry.

Doug Johnson

Doug Johnson is the Aviation Programme Manager at the Met Office and is responsible for the maintenance of all services to the aviation community, both nationally and internationally. This portfolio includes services to airlines, airports, ATC and General Aviators. He has more than 20 years experience of Aviation Meteorology including time as an observer and then forecaster before joining the Aviation Programme.