| ||For the alien crash site in Fallout 3, see Alien crash site.|
The start of the event is a random encounter, and, as such, it triggers upon reaching level 20, right after fast traveling outside or traveling long enough. It may even happen at a long distance away from the crash site. When traveling around, the Sole Survivor may hear the sound of a crashing plane. A ship will then pass quickly by overhead before crashing in the distance. Actually seeing the ship might be difficult because of how quickly it is moving, but it does leave a short-lived yet distinct trail of smoke. The explosion is usually too distant to see, but is very loud nonetheless. The ship always crashes in the same location.
Alternatively, if the Sole Survivor activates relay tower 1DL-109, a radio signal titled "garbled radio beacon" will be discovered. If the Sole Survivor tunes their radio to the frequency, they can travel east and the signal will resolve to a higher quality until they discover what appears to be a crashed alien vessel.
The site features a half-buried UFO in a hillside with a skid area of destruction including broken trees, flattened ground and scattered flames. The surrounding trees will be permanently on fire, making the location easier to spot from afar. There isn't anything particularly valuable about the crash site itself (no way to enter the UFO, nor anything to scavenge at the crash). Next to the still burning UFO is a trail of green blood. The Sole Survivor can follow the trail slightly north, down into a ravine and then into a nearby unmarked cave.
Inside the cave is an alien with an alien blaster pistol and 181–441 alien blaster rounds. If the alien is targeted in V.A.T.S., it will show that its right leg is crippled, presumably a result of its crash landing. On sight, the alien will immediately attack the Sole Survivor. Next to the alien is a human skeleton and a ham radio which is the source of the nearby garbled radio beacon. Turning the ham radio off will disable the beacon.
- The alien language appears to be similar to the language used by the aliens in Mothership Zeta.
- Upon approaching the alien ship, go to the rear and look north. There will be a set of trees that mark the direction of the cave. Alternatively, there is a trail of green blood on the ground that leads from the spaceship to the cave.
- The UFO crash can be witnessed as far away as the Museum of Witchcraft.
- Although the trail of destruction at the crash site clearly indicates the ship hit the ground while traveling northwest, the sky flash/smoke trail can appear in whatever direction is needed to hint toward the crash site.
- If the player character is traveling with a companion, they will say something as the ship flies overhead.
- The player character cannot pacify the alien with the Wasteland Whisperer perk.
- Prior to the crash, the trees in the area already appear burned. A skeleton on a sleeping bag, crushed by a fallen tree, can be found at the location. Alongside the skeleton is a burned book, eyeglasses and a metal box containing assorted loot.
- If the Sole Survivor arrives early at a lower level, the ship may not have crashed yet. If this is the case, the Sole Survivor will only encounter some mole rats instead of the alien.
- The green blood trail on the floor may disappear once the alien is encountered in the cave and killed.
The UFO crash site appears only in Fallout 4.