Skydiving plane pilot reported after reaching what appeared to be the correct location for the skydivers to disembark; the aircraft experienced a GPS map shift. The pilot stated he visually found the correct location. The pilot reported there was military maneuvers in the area.

Narrative

While conducting skydive operations over Dillingham airfield (HDH) using GPS (OBS mode) to navigate to a user waypoint identifying the drop zone; I had a GPS malfunction where my moving map froze while climbing through 6000-8000 ft. MSL the issue corrected itself and GPS seemed to be working normally again. I notified HCF (Honolulu Control Facility) of the issue and that I was unsure if it was my equipment or if the military was affecting the GPS signal since they were in the middle of a military exercise in the area. At some point while turning to intercept the 080 course inbound to the drop zone my GPS was showing me on course and the GPS time; distance and course off set seemed to be indicating normally and outside sight picture looked good as well so I shifted most of my attention inside to ensure I configured the airplane at the right time. Right after I gave the skydivers the green light to jump and a couple jumped; out my moving map suddenly shifted to show me about 1.5 miles south of the drop zone in the restricted airspace R-3110B. I immediately stopped the rest of skydivers from jumping; made a left turn to exit the airspace; and notified HCF of the issue. I positioned the aircraft back over the drop zone using outside reference only; released the rest of the skydivers; descended and landed normally.