Gordon asked:
> If there is going to be a reduction in GPS service, is > it wise to spend the money for newer GPS's. If a satellite dies and isn't replaced in time, there would be a gap in the whirling array of 24 low orbit satellites. On the other hand, my GPS usually has six to 12 satellites "in sight" at any time and that's inside my car, propped against the windshield. I often see accuracy listings of 8-12 feet. (This astounds me and is, by Clarke's Law, certified magic [even though I know just how it works].) In the air, a reduction of available satellites might degrade accuracy of position and altitude information. However, the number of satellites "in sight" of a decent antenna mount is so high (usually 8-12), most of us would never have any measurable degradation from one or even two or three satellites being missing from the fast-whirling grid. (When that degradation from a satellite gap is overhead, try to avoid using your GPS for a zero-zero landing in fog, OK?) In cities, forests and mountainous areas, where much of the sky is obscured, there may be times where position lock is lost as the number of satellites "in sight" drops below three. (Position and altitude requires at least four satellites.) Exact accuracy could degrade even earlier and you may only have accuracy in the hundreds of feet or hundreds of yards. As the airlines change over to GPS navigation, I do want them to have maximum accuracy at all times. And, when we drop a bomb on some bad guy's head, I'd much rather it hit the bad guys rather than the innocents in the next building. Me, I am going to write to my congress-critters and strongly urge that they put the GPS fixes and upgrades at the top of the priority list. Ed
