Fallout 4

Pre-Requisite: Advance far enough into the Brotherhood of Steel questline until you get the Vertibird signal grenades.

Note: You can get this achievement naturally via play, however getting 50 misc quests is quite difficult and would require you to explore every inch of the game. If you plan on doing that then I suggest doing this achievement naturally. If not then read on.

At some point during the Brotherhood questline you will unlock Vertibird signal grenades which allow you call a Vertbird to your location and take you wherever you wish. Everytime you call a bird you will get a misc quest for riding it. Do the following for optimal grinding:

1 Go to Boston Airport workshop (near the Prydrwen).
2. Clear out the area using the workshop to create an area big enough for the Vertbird to land.
3. Place down a chair.
4. Throw the grenade and call the vertbird.
5. As it lands you get the misc quest - get on the vertbird and when you complete the misc quest get out again.
6. Sit on the bench and wait one hour - the Vertbird will leave.
7. Repeat 4-6.

If you run out of Vertbird grenades you can buy them from the trader on the Prydwen. If he has none in stock then wait 48hrs for his inventory to restock.