If the basic idea behind the ELT-you crash, it tells the world where you are-was laudable, the performance of this technology has been anything but. Even the new-generation of 406 MHz ELTs havent proved much better and are hardly flying off the shelves. From this conundrum emerges a niche market for portable satellite vehicle tracking devices and personal messengers. This technology has been around for awhile in the transportation industry, but lately it has made inroads into the sporting and outdoor markets with a device called the Spot Satellite GPS Messenger, which recently introduced its second generation model. Another company, the New Zealand-based Spidertracks, has been marketing its own satellite tracker called the Spider S3. Although these devices use different satellite systems-the Spot uses the low-earth orbit Globalstar system, the Spider uses the 66-satellite Iridium communications network-the two gadgets work on the same principle. They rely on GPS to establish an accurate position, then communicate this through the commercial satellite networks to either rescue agencies or to public or private view Web tracking, or both, customizable by the user. The concept is fundamentally different than an ELT, which activates only after the crash, and then none too reliably, and then transmits a distress signal to a dedicated satellite network. Satellite trackers, on the other hand, lay down a path of electronic bread crumbs in near real time, providing searchers with accurate position datums from which to begin looking for a downed aircraft. Furthermore, unlike an ELT, whose signal is trackable only by government agencies, a satellite trackers data can be constantly monitored by people with a greater interest-family, friends and business associates. Think of it as do-it-yourself SAR. The purveyors of these gadgets are careful not to call them beacons, but satellite trackers or messengers. Nor do they necessarily claim theyll function as an ELT does, nominally activating during or after a crash and remaining on. What they do claim is that this inexpensive technology will reliably track vehicle or personal movements and relay that data to interested parties. 
The Spot messenger first appeared in aviation markets in 2008, when Spot International sponsored a promotional deal at EAA AirVenture. The original sold for $169.95, plus the cost of the satellite tracking service. Last fall, the company introduced a follow-on model, the Spot 2, which is smaller and equipped with a redesigned button set.