Weather detection on a budget
Although the phrase low-cost weather-avoidance equipment sounds like an oxymoron to many aircraft owners, competition in the marketplace has indeed brought new value and options to pilots of light aircraft. For years, an aircraft owner's only choice in lightning detection was BFGoodrich's Stormscope, until Insight Avionics introduced its Strike Finder. At a price of about $5,000 installed, the Strike Finder is one of the lowest-cost entrants into thunderstorm detection boxes.
Introduced in May 1991, the Strike Finder was deemed a quick success by users and in press reviews. However, only 9 months after shipments of the unit started, BFGoodrich obtained an injunction against the upstart company, prohibiting further deliveries of the Strike Finder in the United States. BFG claimed Insight had infringed on the patent that protects Stormscope technology. Meanwhile, BFG, perhaps threatened by the Strike Finder's competition, introduced its own low-cost box, the WX-900, which utilizes a liquid-crystal dislay (see " Lightning on the Fly," June Pilot). BFG uses more expensive cathode ray tube displays in its WX-950 and -1000 Stormscopes. Insight appealed the injunction and started to ship the Strike Finder again in 1994 after the patents on the technology had expired. Today, the Strike Finder has made its way into more than 5,000 cockpits worldwide. But more important, Insight's entry into the lightning detection market has sparked a healthy competition that brings lower-cost weather detection equipment to owners of light GA aircraft.
Strike Finders and Stormscopes, often termed atmospheric devices, detect the electromagnetic signals spewed by lightning strokes. The Strike Finder pinpoints the worst part of a storm — where the lightning is — by displaying a dot or cluster of dots. Atmospheric devices are not capable of keeping you out of the rain — detecting water is the job of radar (see " Spark Detectors" and " Radar Realities," June Pilot). What makes them so attractive to owners of light aircraft is the cost compared to that of radar. Entry-level radar systems cost $25,000, not including installation, whereas a lightning detector can be had and installed for about $5,000.
Installation
Installation of a Strike Finder requires a standard 3.125-inch hole on the instrument panel and about 12 inches of depth behind the panel. Weight is not really a concern with the Strike Finder. The display/processor box weighs just more than a pound, and the sensor (externally mounted antenna) is less than a pound. By comparison, a radar system can easily eat up 25 pounds or more from an airplane's useful load. The Strike Finder can run off a DC current of 10 to 33 volts.
In-air familiarization with a Strike Finder or Stormscope is a must before launching into an area of convective activity. Ground tests and VFR flights a safe distance from thunderstorms should be made to determine whether the unit is giving accurate bearing and range information. A few years back, Ihad the opportunity to fly an airplane that just had a Strike Finder installed. Because of a bad sensor, the unit was depicting storms where there weren't any, and vice-versa.
Operation
The Strike Finder's gas-plasma display lacks the clarity of the cathode ray tube used in higher-end Stormscopes. The Strike Finder attempts to make up for that shortcoming in lighter weight, less complexity, and lower cost. When the sparks begin to fly, the detection range can be controlled by the two inner buttons on the unit's face. Sensitivity is a better term for the way lightning detectors determine range. In the 200-mile mode, the Strike Finder is at its maximum sensitivity, while the 25-mile mode is its lowest sensitivity. After the operator has zoomed the unit in or out, the selected range is displayed only momentarily. After the range depiction disappears, to determine the current selected range, you must rely on a few dots obscured somewhat by the numbers painted on the instrument face. In direct sunlight this can sometimes be a problem.
In the 25- and 50-mile range selections, the Strike Finder displays each strike with four dots, making the scale of a storm a little more realistic. The button at the far right clears the display and is useful to determine the rate of strikes and, therefore, the severity of the storms. If numerous dots begin showing up immediately after clearing the unit, you can bet that you're looking at a very active area of weather.
The far-left button, labeled Time Travel, is used to view an accelerated replay of the storms in the last 30 to 60 minutes. This feature allows the user to determine the movement of storms that may be too slow to be recognized in real time. This feature works best if the aircraft has been on a near-constant heading for some time.
Impressions
The Strike Finder takes the pucker factor out of many trips in airplanes that were previously defenseless against storms. In flights along the East Coast, where thunderstorms hide in summertime's haze and murk, the Strike Finder is a very useful tool. If you're planning a short trip, weather for the entire route can be viewed in 360 degrees while you are still safely parked in a tiedown spot. On longer trips, where it's possible to maintain a near-constant heading, the Strike Finder allows you to survey approaching weather long before it affects your flight. The Time Travel function comes in handy in such instances. This feature allows you to track the movement and lifespan of storms in only a few seconds.
As you get closer to the weather, zooming down to 100- and 50-mile ranges improves the accuracy and allows for easier avoidance planning. For stronger storms, it's best to keep the dots out of the 50-mile veil around your airplane. Weaker storms don't require that large a berth, but remember that the Strike Finder can see only the strongest portion of the storm — the center. The air within 15 to 20 miles of the center may still be very active with turbulence, rain, or even hail. This brings up another important point about Strike Finders and Stormscopes — neither can be relied upon to navigate you through a storm system. In many instances, though, they can give you enough guidance to get around storm systems — or, at least, tell you that you need to land.
The Strike Finder is not immune to interference, especially when the airplane is on the ground. The airport from which I fly is adjacent to an industrial park. Huge arc welders and other equipment in the area occasionally cause the Strike Finder in my airplane to depict what it thinks are lightning strikes. In flight, the Strike Finder has been fooled only once, when some sort of ground disturbance over western Kansas lit up what looked like a huge cell 150 miles away from the airplane. It slid along the right side of the airplane over the course of the next few minutes and disappeared as quickly as it had appeared. Another Strike Finder-equipped airplane 100 miles behind us reported the same problem.
Lightning detectors can also be affected by equipment on board your airplane, such as DME, strobe lights, or a transponder. In flight this would show up as a dot that would "follow" the airplane at the same relative bearing and distance. Insight claims that its newest sensors are immune to disturbances such as those from DME; to be sure, however, it's best to locate the sensor far away from DME antennas and the like.
Heading stabilization?
The Strike Finder currently does not come with heading stabilization. For the user, that means every time you turn the airplane more than a few degrees, you must clear the unit to get an accurate weather picture that corresponds to the new heading. If your airplane has a horizontal situation indicator (HSI), the Strike Finder can be bootstrapped to its heading synchro output and will alter the view accordingly every time the airplane is turned. Likewise, for those on tighter budgets, Sigma-Tek offers a plain directional gyro (DG) that provides heading information to the Strike Finder. Insight is working on approval for its long-awaited Relative Bearing Stabilizer (RBS) that will snap onto existing Strike Finders in the field. Both the Sigma-Tek DG and Insight RBS will cost about $1,500.
Insight's introduction (and reintroduction) of the Strike Finder spurred the necessary competition from BFGoodrich. BFG has since counter-attacked with its latest lightning detector in the Strike Finder price range, the WX-950. We can hope that Insight and BFG continue to battle each other in bringing more technology at a lower price to more and more GA pilots — we'll all benefit in the long run.
E-mail the author at [email protected]. For more information or to obtain the Strike Finder Pilot's Guide, contact Insight Avionics Inc., Post Office Box 194, Buffalo, New York 14205-0194; telephone 716/852-3217.
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