The testing and verification of contrail forecasts using pilot observations from aircraft

Contrail forecasting techniques used within the UK Meteorological Office ha ve changed little since the early 1940s and there has been no formal verifi cation of the results. Recent research has shown that old forecasting techn iques may not be wholly applicable to modern aircraft that now use more eff icient engines. In order to compare the performance of both the old and new forecasting techniques a validation trial was carried out over a nine-mont h period in which RAF pilots reported when and where contrails did and did not occur. These observations were compared with the predicted contrail lev els from both the old and newer forecasting techniques. The results indicat e that both techniques give a similar performance and that neither signific antly out-perform a simple persistence prediction.