Page 38 - Nov/Dec 18 MMOPA
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Look Up, Look Down ... Look Out!
A basic guide to the most valuable navigation device you probably rarely use.
Iby Joe Ratterman
f you are experienced using your airplane’s on-board radar, and you turn it on during most of your flights, then congratulations! You are a rare breed!
However, if you are like most pilots, you probably don’t use your radar often and feel much more
comfortable using NEXRAD when it comes to navigating through the springtime thunderstorm season each year. My goal in writing this article on basic radar usage is to get your attention, arm you with enough information
to start effectively using your radar, and encourage you to keep learning how to use your radar. It’s possibly one of the most valuable tools in your aviation arsenal, and my hope is that you come to trust and rely on it as much as I do.
NEXRAD versus Radar
The first question we need to ask is, why do we need on-board radar at all if we have a NEXRAD weather product available in the cockpit? Sure, NEXRAD is easy
  to read and packaged up nicely so anyone can interpret where the weather dangers are, right? Well yes, and mostly NO! Yes, it’s easy to read, but it doesn’t tell you where the storms are, it only tells you where they used to be. You need to understand that, based on the way these images are created on the ground beforehand, the data on your screen is actually older than what it says, by as much as 15 to 20 minutes!
Have a look at these two images I took this spring, one of my NEXRAD (on the left), and the other of my radar (on the right), both taken within a few seconds of each other as I was planning to land at KOJC.
Quite a different perspective, wouldn’t you say? If I had decided to fly a heading directly toward KOJC (my airport destination), the NEXRAD image indicated, “Come on over, the coast is clear.” But the radar image was screaming, “Steer clear, a thunderstorm just popped up in front of you!” Because I was using the radar, I flew around the

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