First, there are circumstances where you may want to load a location into the beacon before you set out or before you enter a particular area, just as back-up or because you are going someplace you know does not allow for reliable, or perhaps any, GPS reception.

Also, the GPS "engine" and antenna in these units is generally not as effective as those of better quality stand-alone GPS units in my experience. Thus, you may not be able to gain a GPS location using the PLB alone in some circumstances where the high-end handheld you are using for navigation may be able to lock on.

In this PLB, the integral GPS is primary and will override any external GPS derived location if it acquires one.

Note that the 406 MHz distress signal's ability to reach the COSPAS-SARSAT satellites is totally unrelated to the ability of the integral GPS to acquire a location. One is transmitting at approximately 5 watts, the other is receiving a very weak and easily blocked signal from space.

Hope this helps.