Watcher Flying Discs are the equivalent of the Survivor Airplane, except in the fact that they look radically different than the Survivor Airplane. They look more like a UFO, whereas Survivor Airplanes look like slightly futuristic airplanes from WWII (which was probably a design choice instead of a coincidence, in keeping with the sci-fi conspiracy nature of Dark Void's plot).
Watcher Flying Discs come equipped with dual plasma machine-guns and 20 magnetic rockets (though they do not home in on anything that is metal). They are also equipped with a defense plasma machine-gun on the cockpit that will lock onto and attempt to shoot anyone trying to hijack the Disc; however, once the gun is locked onto someone, moving quickly to the side will cause it to fire at nothing, which is an obvious design flaw on the part of the Watchers.
By going through a QTE (quick-time event), Will Grey is able to pull a panel off of a Flying Disc, which causes the cockpit of the vehicle to malfunction, allowing you to kill its pilot and hijack the vessel. This is very useful for when you are overwhelmed by many Discs at once, and need more firepower in order to take them out.
Some Flying Discs come equipped with a shield generator, which makes them appear much more shiny blue and white in color. Putting this kind of Disc under enough firepower will result in the shields being destroyed, so make sure you aim straight.
Flying Discs will emit a warning sound when they have taken critical damage; when you hear this sound, you should promptly eject yourself from the vehicle before it explodes.
The Survivors sometimes steal Watcher vehicles (such as Flying Discs) and repaint them to make them more identifiable; however, in-game the only example of such a vehicle is Ava's Flying Disc, which is painted red and only appears at the end of the part where you escape with The Ark from the Watcher Base.