ADDS - C&V Help Page (3 of 5)
Back to C&V Page or C&V help page 2 or C&V help page 4.
CVA presents simplified area maps of ceiling, visibility and flight category as outlined below:
As explained further in help page 4 , CVA's ceiling and visibility fields are derived through nearest-neighbor interpolation of METAR data. This interpolation process, in effect, ‘stretches’ limited-area METAR observations across the broader domain between stations and accounts for terrain effects on ceiling height. The resulting fields help to visualize the ‘likely’ conditions at range from METARs. However, the reliability of these fields degrades as distance from a METAR site increases. Thus, users should apply cautious practical judgment in considering the representativeness of the product as distance from a METAR site increases.
METAR Station Plots
Each regional display includes station plots showing the current ceiling and visibility observations reported at selected METAR stations. To avoid overcrowding, the display shows only a subset of the total number of stations available. Station plot content is shown in the figure below.
Refer to the following links for a complete list of METAR stations and associated station plots:
Viewing CVA Through the HEMS Tool
CVA can also be viewed using the HEMS (Helicopter Emergency Medical Service) Tool available on Experimental ADDS (see HEMS tool). The HEMS tool viewer is approved for use by EMS (Emergency Medical Services) personnel by OpSpec (Operational Specification) A021.