My hat is off to your father for staying active, but I understand why your mother worries a little.
Really, theres no great solutions to this. Wireless phones lose the signal, of course, because theyre line-of-sight devices that must be able to see" a repeater or other type of antenna. Otherwise the rock walls of the canyons block the radio waves. The two-way radios that are popular suffer from the same problem. The odds that you can get a signal to travel more than a half mile or so are extremely low.
So what to do? Satellite phones solve much of the problem because they pull a signal down from the sky. So youre much more apt to be able to make a call. But a satellite phone such as the Iridium 9505A (www.iridium.com) sells for $1,000 or so, and then you have to subscribe to a calling plan, and those are $60 a month or more for plans that give you less than an hour of calling time (of course, it takes only a few seconds to shout, Help!").
The other choice, as I discussed a while back, is a personal locator beacon. These sit in your pack or pocket until needed, then, when activated in an emergency, broadcast your position on a special frequency, via satellite, to emergency services providers. A unit such as the ACR TerraFix 406 (www.acrelectronics.com) also broadcasts your location down to 100 yards or so. But theyre fairly expensive, too, $700 or so. And, to put a fine point on it, you have to be in a position to activate it (or dial out on the satellite phone, for that matter). If your father is somehow incapacitated, then what?
My own feeling is that your father needs to be a little more responsible. None of this tramping around." He needs to have a route and a schedule in mind, and leave information about that behind, along with an expected time when hell be back in wireless coverage. Thats what anybody should do, really. Accidents can happen in the blink of an eye, and if nobody knows where to look for you, it makes things that much harder.
Get more advice from the Gear Guy as he picks this seasons top gifts in Away.coms Holiday Gift Guide. Youll probably find a few things to put on your own wish list, too.