Vision does own 737s, (although I do believe that they are in the process of or have already replaced they with 767s). That said they are operated in part 91/125 operations and separately from the airline side of things.

These aircraft aren't the same ones as the 737s that Janet operates out of LAS to "Area 51", however they do operate under similar pretenses. Think long flights, to foreign destinations in hot/arid conditions, with a bunch of people who don't want you to know their names.

The aircraft are based in IAD (look on the south ramp just north of the new control tower, or on the cargo ramp just south of Landmark Aviation and you'll probably see at least one of them...)