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Summary

Over a 10-year period, the Accident Investigation Board Norway (AIBN) has received 30 reports of accidents and incidents related to operations on contaminated and slippery runways. Nine of these reports concerned accidents and serious incidents. In the same period AIBN has published 12 investigation reports and issued 36 safety recommendations.

ECA’s concerns concur with the AIBN report “Winter operations, Friction Measurements and conditions for friction predictions”, issued in May 2011.

  • “The AIBN believes that incidents relating to slippery runways occur because the involved parties do not realise that existing rules and regulations are based on a simplification of the actual physical conditions. The measured/estimated friction values are used as scientific truths and not compared to other meteorological conditions (‘safety indicators’).”
  • “The safety margins are reduced by operational procedures which to a limited degree take into account the uncertainties connected to input parameters used for landing distance calculations. The AIBN’s findings are supported by research programs and studies.”
  • “The AIBN findings show that the national regulations governing operations on contaminated and slippery runways are less strict than those that govern operations in summer conditions. This is in spite of the ICAO and EASA guidelines and regulations which prescribe that if winter operations are to be performed on a regular basis, the authorities require the operators to take special measures in order to attain an ‘equivalent level of safety’ to summer conditions.”

 

ECA notes that
  • today’s reporting and measuring system is out of date and gives no reliable correlation between ground friction tests and airplane braking performance.
  • friction tests are not reliable, especially during tests on contaminated runways with small spread (< 3 K) between OAT and Dew Point.
  • pilots’ knowledge on the background of todays’ system is limited and mostly restricted to the use of tables and performance computers.
  • pilot reports are not standardised, mostly subjective and have only restricted operational value.
  • runway friction is handled differently at European airports and between European countries, although there is an international ICAO standard for runway condition reporting.

Way forward

Following last year ICAO State Letter (AN 4/1.1.55-15/30) a new set of Standards and Recommended Practices (SARPs) regarding operations on contaminated and slippery runways will be applicable as of late 2018. The implementation of the amended SARPs into EASA regulatory framework will take place by latest 2020.


We welcome the changes to set forth as leading to an increase of both, in the level of standardisation in Europe and elsewhere as well as in the level of flight safety overall. ECA’s goal is to ensure that procedures are correctly understood and applied by those responsible – the pilots. A number of key recommendations have also been developed to ensure a smooth and effective implementation of the revised SARPs in Europe.

    ECA recommendations
    1. Ensure pilots’ contribution and inputs in all on-going and upcoming EASA rulemaking activities related to SARPs implementation, in the extensive research programmes and in the Take-Off and Landing Performance Assessment (TALPA) trials that are under way or planned ahead.
    2. Standardise within Europe the use of the new Runway Condition Assessment Matrix, the global reporting format and the the even more important contribution of pilot reports.
    3. Secure the development of new procedures, tables and inflight software to enhance the pilots’ ability to assess a slippery or contaminated runway.
    4. Ensure proper training and education of line pilots before implementation.