If you've ever lost an RC plane then you may be interested in just how you can use one of the telemetry-equipped RC systems (such as the FrSky) to track down a missing model.
Sorry about the bad lighting in parts of this video -- the low winter sun makes it difficult, however, I hope you can see just how directional the stock whip antenna can be and how you can use the "null point" to locate the direction in which your model may be located.
If you've ever wondered whether you might need telemetry, perhaps this video will convince you.
Providing there's enough interest, I'll show you how to wire up the FrSky telemetry dashboard to work as a stand-alone model-finder for any model which has a matching FrSky receiver onboard. And remember, this trick will work with 72MHz and 433MHz RC systems, so long as you've put a cheap FrSky Telemetry receiver onboard as well.
Even if your model goes down many miles from the launch point, using a higher-gain antenna (such as the FrSky patch or a $20 yagi) may allow you to find it even from a great distance.