Happened to us once at Moab, above Potash Rd. We were scoping out a route to climb and *BAM* a chute opens up about 500ft straight above us! I know there is a popular Jeep trail up there, my first thought was that it was a Jeep, rectangular shape of chute. Which way do we run! Scared the crap out of us! Luckily all four landed safely on the road.