Final Departure is a main quest at Morgantown airport. You can find Morgantown east of Vault 76.
Here's the steps of the quest:
1 Head to the Morgantown Airport.
2 Enter the Morgantown Airport Terminal.
3 Loot the Overseer's Cache to find out what happened to the responders.
The Overseer's Cache can be found on the 2nd floor of the Terminal.
4 Leave the Terminal.
5 Find and interact with the Responder's Laboratory Terminal in Morgantown.
The Terminal is locationed on the 2nd floor of the third hangar at the base behind a wall.