If PLB's give elevation it would be from a GPS at best, and from what I've read that is a pretty poor measure of elevation since it is relative to the datum (I think), which (I think) can be thought of as the mathematical model of the Earth's surface (I'm weak on the whole datum idea)

I don't think its phsically possible for the doppler method (using the 406 MHz signal) can determine elevation. It just identifies the point in space - or actually a line - that is at a right angle from the source.

If there was a GPS involved my guess is that since it was on the side of a cliff the GPS didn't see enough satellites to get a good position.

Ken