Tilt Gold Skull Location | Halo 3
Location: In the large area with the purple platforms beyond the Pelican crash site. When you reach this area, get onto the circular platform in the middle of the room. Move towards the purple object to the right of the weapon rack and jump up onto the very tip of it. From there, jump on to the rock platform in front of you. Next, turn left and jump over to the rock platform there. From here, turn around and look up to spot the next platform. This next jump is a bit more difficult; run to the far end of the platform and jump over to the next one. Walk along the rock bridge and look over to your left to spot skull sitting in a puddle of guts.
This video is from our unofficial game guide. You can view the full guide here