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When traveling around, the Sole Survivor may hear the sound of a crashing plane. The start of the event is a random encounter, and, as such, it comes exactly when you reach level 20, right after fast traveling outside or traveling long enough. It may even happen at a long distance away from the crash site. 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, but 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 the Sole Survivor discovers 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 trees all around 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 of green blood, 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 300-500 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 apparent 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 cause the beacon to turn off.
- 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 lead from the spaceship to the cave.
- The UFO crash can be witnessed as far away as Recon bunker Theta, Tenpines Bluff, Red Rocket, Starlight Drive In and Sanctuary Hills. It has also been seen from the Castle, Museum of Witchcraft, Old North Church, Weatherby Investment Trust, Hyde Park, Boston Common and even Wildwood Cemetery.
- It is possible to witness this event via Pip-boy only, as a yellow UFO icon blinking on the map.
- 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.
- If the player character has the Wasteland Whisperer perk, the player can pacify the injured alien.
- 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 zetan ship may not have crashed yet. If this is the case, the Sole Survivor will only encounter some mole rats instead of the zetan.
The UFO crash site appears only in Fallout 4.