Severe weather

A survey of severe weather risk management in Europe reveals flight efficiency and safety performance gains to be achieved by better alignment of risk management strategies by ANSPs, Aircraft Operators and the Network Manager.

The Facts

Effective management of severe weather impact on the ATM system and flight operations is of great significance for improving the safety and cost-efficiency of aircraft operations and ATC service provision in Europe, in particular in congested airspaces. Severe weather phenomena disrupt air traffic flows and generate significant delays. If not managed properly, hazards to aviation associated to severe weather can lead to unsafe, high level of workload of pilots and controllers, and ultimately to losses of separation and aircraft accidents.

The Survey

In 2012, on stakeholder request, a dedicated severe weather risk management survey was carried out. The survey scope covered the entire chain of severe weather impact and risk management starting with weather forecasting by meteorological offices, addressing pre-tactical management by FMPs and the Network Manager and concluding with the deployment of tactical measures by ATC and pilots.

The information collected and analysed in the course of the survey revealed a number of potential areas for improvement of the meteorological products used in severe weather impact assessment and enabled the identification of important issues which need to be addressed in order to improve the management of severe weather impact on flight operations and ATM in Europe, notably:

  • With a few exceptions operational staff, responsible for severe weather risk management at ATC units, use standard weather forecasts and reports, weather radar data and some other meteorological products. Use of dedicated tools and models for assessment of severe weather impact on ATC and flight operations is rather an exception. ATM decision support systems making use of enhanced weather forecast products and ATC impact assessment algorithms are not yet in operational use. 
  • Meteorological products (forecasts and current weather reports) conform to standards (ICAO Annex 3). However, there are very few enhanced products providing better granularity and improved accuracy of weather forecasts, appropriate to support efficient pre-tactical severe weather impact assessment and decision making.
  • Optimisation of ATM system performance at network level as opposed to optimisation at ‘local” level (optimal operation of network components does not mean optimal operation of the network) would require review of the current set of performance indicators and implementation of incentives for ANSPs.

Main conclusions

Sufficiently managed Hazard Encounter Risk and Knock-on Flight Safety Risk

The in-flight Hazard Encounter Risk and Knock-on Flight Safety Risk are consistently managed in accordance with ICAO PANS-ATM and PANS-OPS provisions, aircraft operating procedures and other applicable national regulatory provisions. However, it can be argued within the context of this project that the risk of controllers’ excessive workload (associated with the Knock-on Flight Safety Risk) is not sufficiently managed.

Inconsistent pre-tactical and tactical strategies

The severe weather hazard encounter prevention strategies and measures are applied inconsistently at pre-tactical and tactical level. The European ANSPs have developed and deployed different capabilities. In the majority of cases severe weather risk management is not applied at pre-tactical level. Some ANSPs have built the needed capability and competence but the lack of incentives and of an established process to capitalise on the available capabilities prevents the implementation of an enhanced and more effective severe weather risk management. This leads to sub-optimal ATM efficiency and increased air traffic controllers’ workload, in particular in the critical time period before the tactical ATC measures take effect.

Non-interoperable pre-tactical and tactical strategies

In the rare cases of application, the risk prevention and mitigation strategies are based on locally developed capabilities, definitions and processes that are specific (not following common definitions, criteria, format, etc) and do not support an efficient communication and collaboration at Network level. 

Sub-optimal performance of the European ATM Network

With respect to severe weather risk management the operation of the European ATM Network is suboptimal when applying the following criteria: (1) missed opportunities and (2) use of the available best practices.  A risk management approach with adaptive incremental decision making presents a major opportunity for reducing weather related delays.

The reasons for the sub-optimal performance can be found in the following groups of impediments:

  • Lack of technical capabilities - tools to enable improved functioning of the risk management chain;
  • Insufficient competence (e.g. lack of appropriate training) of involved actors;
  • Lack of procedures - with few exceptions, operational supervisors are required to exercise their best judgment regarding the need to manage the anticipated impact of severe weather on the ATC operations;
  • Lack of or inefficient incentives due to institutional and organisational reasons, such as: insufficient incentives for the ANSPs to introduce risk-based severe weather impact management and strategies that are optimised for the efficient operation of the Network; insufficient incentives for the meteorological service providers to go beyond the provisions of ICAO Annex 3 and provide information better supporting risk-based impact assessment and decision making; insufficient incentives for the FMPs to apply strategies at the pre-tactical level.