EHEST Leaflet HE 13 Weather Threat For VMC Flights

This leaflet aims to reinforce to pilots the need to understand aviation weather, including the appropriate threat assessments and strategies to adopt in relation to pre-flight, in-flight and post-flight operations for a helicopter flight to be conducted under Visual Meteorology Conditions (VMC).

Aviation forecasts are important for pilots to identify weather threats and put in place a strategy to mitigate those threats during pre-flight planning. However, a forecast only describes what is most likely to happen, and pilots must consider other possible outcomes associated with particular weather patterns.

Besides, it is not unusual for in-flight weather to differ from the forecast weather. When this occurs pilots have to recognise the unanticipated threat of deteriorating weather and put into place a timely strategy to mitigate the threat of an undesired aircraft state.