there is a good time line and a list of deaths on Mt Hood from 1981 on at www.oregonlive.com. One question I have not had answered whether the tracking devices would have worked for the hikers, or are they just for skiers?
The GPS radios can track almost anywhere...hiking, climbing, jeeping, skiing...
Many believe that it is a good idea to carry one in your car, too.
The above have a range of 2 to 5 miles...?
Seperately, there are satelitte radios and beacons that can be heard by aircraft, etc.
I am not an expert on the current technology, but I have carried rescue beacons on the ocean well beyond the sight of land. Never needed it, but it could have been activated manually or by the salt water.
There are other options, too.