Page 15 - Volumne 18 Number 5

ain”Controlcan continue to be used for weather avoidance should WX mode fail.) In general, colors will be off about a half color level in MAP compared to WX. That is, in MAP, the echoes are displayed as being a little less hazardous than fact.Now that you have all that figured out, using the CAL control is as simple as anything can possibly be. Surprisingly, the most positive thing you can do with the CAL control is turn it in the negative direction, usually counterclockwise. Normally, you fly with it at the “CAL” position, wherever that is on your radar. Then, when a weather echo is detected and displayed, simply position the CAL control halfwaybetween the calibrated position and MIN. Because of various laws of physics and radar engineering, that will cause echoes to be displayed one color level less reflective, less hazardous, than fact. That is, a red echo will then be yellow, and a yellow echo shows as green. If your radar also displays magenta, it will drop back to only red.If, when in CAL, echoes are being detected and displayed in all colors, but those colors don’t shift down one level with the CAL control reduced, it’s time to sit up and pay close attention; you’re approaching an exceedingly hazardous weather situation. I repeat, if the colors don’t shift back one level between normalCAL and 1/2 CAL, the weather detected is extremely hazardous.Why? Because, if you still see any red with CAL halfway to MIN, the storm is a level 5 hazard. It will most likely contain severe to extreme turbulence, intense rain and possibly large hail. You’d be wise to avoid it by at least 10 nm on the upwind side relative to high-level winds. If your radar displays magenta, and any magenta is still seen with the CAL control turned down halfway to MIN, the storm certainly contains extreme turbulence, large hail, a rain rate greater than seven inches per hour, possible microbursts, and tornadoes. Avoid it by 20 nm on the upwind side. (In tropical areas, it will be extreme rain, but probably no hail.)MAY 2014TWIN & TURBINE • 13G