I can finally replicate what you are seeing.There's a "black hole" that you can see or fall into if you slowly slew your aircraft down the side of the hill at N55° 21.119066' W131° 42.250450' alt 82' at 317 degrees. It's in a really narrow window and seen at an angle when viewed below your aircraft. There's also a "porthole" that you can enter into the black hole that I've stumbled upon a couple of times at N55° 21.156091' W131° 42.304641' alt 6' heading 219. There may be other port holes too. It's an ORBX thing, due to the way they created the sloping runway, roads and patways.
Try moving your aircraft to the main runway, or just slew up out of the black hole and all looks OK. That works for me.
Steve