Despite the preponderance of datalink weather sources today, lightning detection gear still plays a critical role in weather avoidance. In fact, lightning detection equipment is probably the single most important and affordable piece of weather-avoidance gear you can buy. This explains its growing popularity and why so many pilots insist on having it aboard and operational for flights in the warmer months of the year. There are three principal manufacturers of lightning detection equipment and many models to choose from. These vary in their displays, map views, and depictions of lightning strike information, but all share the same basic methodology. They "listen" for the type of electrical discharges associated with lightning strikes and then plot them on a display.
Depending on the unit and the display mode, screen plots can use dots, crosses, colors, and other symbology to represent lightning discharges. Users brand-new to lightning detection equipment are tempted to think that interpretation is stone simple: The dots or other symbols show the range and bearing of the lightning, so avoid the symbols and you avoid the thunderstorms that invariably include lightning.
While that's true enough, there are some caveats. All dots are not alike. Lightning detection equipment is becoming more accurate and reliable all the time, but it has its secrets and subtleties, and there are ways it can lie to you. Here are some helpful points to bear in mind:
- Notice what happens after you clear the screen. Hit the Clear button and the screen goes blank. Any dots or symbols that were depicted instantly go away. If dots immediately return at a fast rate and in great numbers, this indicates a strong and growing storm cell or cells.
- Be aware of false ranging. Each model behaves differently, but as a general rule, numerous lightning returns from strong thunderstorms appear at closer-than-actual display ranges. So if strong returns appear, say, at the 50-nm range, their actual locations can be up to 200 nm farther away. This can work in your favor by giving you plenty of advance warning to alter your course, turn around, or make some other avoidance maneuver.
- On the other hand, weak returns can appear farther away than they really are. This can work against you in cases where storms are weak but building in strength. One or two dots at 50 nm may not seem like trouble, but if activity increases, know that the storm cell or cells could be a lot closer — dangerously so — to your position.
- Watch for discharge points lined up off the airplane's nose. Consider this advance warning of a strong thunderstorm beyond the display's longest-range setting.
- Be aware of false returns. Electrical power plants and substations, cables buried beneath runways and taxiways, poorly grounded aircraft electrical components, distant electrical energy skipping off the atmosphere, and other sources of random electrical energy can show up on the display. Single discharge returns that continually reappear after clearing are the usual tip-offs in these cases.
As for storm evasion techniques, think of lightning detection as a gross avoidance tool. Stay well clear of any depicted lightning returns, and don't try to "shoot the gap" between dense clusters of dots. You may be able to weave your way through a line of cells if you're flying an airplane with a sophisticated, powerful weather radar (and are aware of radar's own limitations) but don't try it with lightning detection.
That goes double if you're flying in instrument conditions. We'll say it again: Maintaining visual separation from clouds is the only surefire way to avoid stumbling into a thunderstorm or an aggressive, growing precipitation cell. Having lightning detection is a whole lot better than nothing when you're flying on the gauges (in fact, many pilots trust lightning detection more than low-powered airborne weather radar), but it doesn't guarantee a trouble-free ride.
As with every other aspect of flying, there's no substitute for training and experience when it comes to understanding, interpreting, and operating with lightning detection equipment — and there's a lot to know. Some units plot your flight-planned route on the display, some have rate counters to help you keep track of storm intensity, some have checklists and timers, some show aircraft heading, some give you a choice of plotting individual strikes or groups of strike concentrations, and high-end models are set up to display strikes on EFIS (electronic flight information system) screens. With all this capability, it takes time to become comfortable.
E-mail the author at [email protected].
The Manufacturers
Currently there are three manufacturers of lightning detection equipment: L-3 Communications Avionics Systems, Insight Avionics, and Honeywell.
L-3 took over the Stormscope product line that was previously sold under the Goodrich name. It sells six different models, including the $4,995 WX-900; the $6,995 WX-500; the $7,995 WX-950; and five versions of its WX-1000 model, which range in price from $13,095 to $18,950.
Insight Avionics sells its Strike Finder (with a gas plasma screen) for $4,995 and its Ultrabrite Strike Finder (this has a light-emitting-diode screen) for $5,995.
Honeywell sells its model LSZ-860, which overlays strike information on an EFIS or weather radar display, for $22,870.
For more information, contact L-3 at 5353 52nd Street, Southeast, Grand Rapids, Michigan 49512-9704; telephone 616/949-6600; fax 616/285-4224; or visit the Web site ( www.as.l-3com.com).
Find Insight Avionics at Post Office Box 194, Buffalo, New York 14205; telephone 716/852-3217; fax 905/871-5460; or visit the Web site ( www.strikefinder.com).
Honeywell can be reached at Post Office Box 2111, Phoenix, Arizona 85036; telephone 602/436-4001; fax 602/436-8200; or visit the Web site ( www.honeywell.com). — TAH
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