Cambridge to St Helens

Landing areas, aerodromes and airports

The weather was as shown in the Graphical Area Forecast for the day: low broken stratus in the northern midlands (shown on our left) and successive layers of cumulus, stratocumulus and higher cloud above our cruise altitude of 5500' on the east coast. Spectacular virga was falling ahead of us (and eventually on us). This conveniently provided confirmation of the expected wind direction at our destination of St Helens. The slope of the rain falling indicates wind direction with the cloud being pushed along by the stronger wind at altitude and the rain droplets being 'left behind'. Once at St Helens, the key exercise for the day was to navigate with a scenario that cloud base had descended to 1500' and we needed to find our way home from St Helens. The Fingal Valley was chosen for our route with waypoints at St Marys, Fingal and Avoca. My error was under-estimating the effect of wind on time intervals to waypoints. These errors accumulate quickly so our actual time of arrival at Avoca was out by several minutes. Once we had arrived over the Northern Midlands at Conara, our next exercise was instrument flying under the hood. As it turned out, low cloud had persisted so there were few features for visual flying in any event. My flying cap, pulled low, also helped to provide supplementary loss of any visual reference to land features.

The winter light and the variety of weather makes Tasmania an interesting location for the weather observer. As pilots, we become more than just observers. The safe completion of any flight requires a partnership with weather. We acknowledge the partnership when we look at the grid point wind and temperature for the day and start the process of compensating for the drift and calculating the airspeed that we will experience in flight. I sometimes spend too long lingering over grid point charts wondering about how best to interpolate three variables: location, timing and altitude. Just when you think you may have it mastered, the wind speed and direction may be significantly different during a climb as to potentially place you off track. Key cross-checking requirements for this situation are the selection of near to departure features and the effective and complementary use of available technology. 

Stephen

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