Page 29 - TNT Dec 2017

down. Of course, it wasn’t quite that simple, but almost.
Amid that development, Bendix was acquired by AlliedSignal as was the Bendix/King line of avionics. When the Bendix/King RDR 2000 was next added to the Allied radar lineup, that radar also had the VP feature. Later Allied/Bendix/ King was scooped up by Honeywell and the Bendix/King RDR 2000 then became a division of Honeywell, where it remains today.
Next, when Garmin decided to expand into airborne radar products with the GWX 68, Vertical Profile was one of several features copied from those earlier Bendix/King radars. That was followed by the GWX 70, also with VP. Today only those three have it: RDR 2000, GWX 68 and 70. (The top-to-bottom scan of certain other “high-tech” radars isn’t true VP, but a limited, mixed horizontal/ vertical scan.)
Why VP is Important to Flying
Why hasn’t it become a feature of other radars? Because radar engineers know so little about convective meteorology they don’t know what it’s good for. After inventing it, Bendix/King had no idea of what value it was except as another gadget for radar salesmen and ladies to brag on. Their early RDR 2000 POG reflects that lack of understanding.
Why VP is extremely useful for flight safety is not a deep mystery; it’s been known for 45 years. A study by Dr. Kenneth Wilk at the NOAA National Severe Storms Laboratory published an illustrated report about it that long ago. Fact is, his report revealed, typically thunderstorms do not grow from the ground up, they grow from precipitation that forms aloft and then propagates downward. Furthermore – and this is a critical fact – common air mass “popcorn” thunderstorms tend to begin at 15,000 to 25,000 feet then grow down to the surface. But severe, extremely dangerous supercells tend to begin much higher, way up around 25,000 to 35,000 feet and then rapidly descend to the surface.
Properly educated pilots have known that for 40 years. That’s the reason for the well-publicized “TUT” position of TILT, which is simply +10 degrees.
December 2017
Echoes most likely to grow into hazardous Supercells tend to begin as a weak echo at a much higher 25,000 to 40,000 feet and develop a red core at about 35,000 feet.
When +10 degrees TILT is selected the height of storms is instantly revealed; the ratio is 1,000 feet per nautical mile. So, in operations below 20,000 feet, select TUT for several sweeps and any echoes detected at 10 nm are at minimum 10,000 feet above your current altitude; at 20 nm 20,000 feet above; at 30 nm 30,000 feet.
Thus, if a pilot climbing through 10,000 feet with TUT selected sees an echo at 10 nm he or she knows instantly that it’s a thunderstorm at minimum
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