Victor 933 was a United Nations Space Command Pelican dropship attached to the UNSC Pillar of Autumn in 2552. When the Autumn was shot down over Installation 04 that year, Victor 933 escaped intact, and was used by the Marines of Alpha Base.
It was sent out with Captain Keyes, Sergeant Johnson, and a few other Marines (including Private Wallace Jenkins and Private Manuel Mendoza) in hopes of finding a Covenant weapons cache. Twelve hours after the last transmission from the Pelican, the Master Chief dropped into the swamp aboard Echo 419 and found the wreckage of Victor 933. Apparently, the Pelican had been ambushed on takeoff and crashed into the swamp. One of the pilots managed to record a last message, in case anyone found the dropship:
"Dropship Victor 93-(static)-the Pillar of Autumn-(static)-eed assistance. We are under att-(static)-attack by some kind of hostile-(static)-it isn't Covenant. (Static) Captain Keyes has been captured by hostiles. (static)-dug in at a large structure in a swampy area. We need to pull out. Please-(static)-I will set this message to repeat at-(static)-given interval. Dropship Victor 933, clear."
The recording is loudest in the back of the passenger bay, by the cockpit.
The vessel was likely shot down by the Flood with repurposed heavy weapons, as implied by the recording saying: "attack by some kind of hostile-(static)-It isn't Covenant.