Panasonic 3.0 User Manual

EchoMap v3.0 

39 

7.1 

Data Link Weather vs. Onboard Radar 

Data Link Weather is different from onboard weather radar in 

several important ways.  

Onboard Radar 
Has the advantage of providing instantaneous information on 

echo returns in front of the aircraft, making it ideal for tactical 

decision making while in close vicinity of thunderstorms.  
Has the disadvantage of not being able to detect storms at a 

distance.  Additionally, it has problems seeing through a cell 

to let you know what is beyond that echo due to attenuation. 
 
Data Link Weather 
Has the advantage of providing the big picture of NexRAD 

Doppler radar activity for several hundred nautical miles 

ahead, making it ideal for strategic flying.  
Has a slight time delay due the fact the NWS provides 

updates once every 5 minutes.  Any data link information is 

near real-time (typically no more than 5-10 minutes old on 
average) but not instantaneous and should never be used for 
tactical weather avoidance.  It should be used for strategic 

weather avoidance only.       
The addition of Metar weather provides the pilot with a much 

greater awareness of various weather conditions at the 

airports with types of information not available via onboard 

radar. 

7.2  NexRAD Weather Radar 

NexRAD weather is collected from the National Weather Service 

and compiled into a composite image.  This image contains 

colored cells that represent precipitation (snow, rain or hail) falling 

in a particular area.  The color of the cell represents the highest 

level of precipitation registered at the time of the image. 
There are approximately 120 NexRAD stations in the US that are 

combined to create the NexRad composite.  The map below shows 

the approximate coverage of the Nexrad data.  The map is subject 

to change as NexRAD stations are added or change.  Areas 

without NexRAD coverage are shown as White.