Calling Vertibirds

After completing the Brotherhood of Steel quest Show No Mercy, you'll receive Vertibird Signal Grenades. You can get more of these grenades from Proctor Teagan aboard the Prydwen. Vertibirds are a good way of traveling in case you're encumbered and you'll also be able to use the door gun throughout the flight. You can order the pilot to land you anywhere along the designated flight path in case there's a change of plans.

To call in your personal aerial taxi, throw a vertibird signal grenade and wait for the confirmation on the upper left corner of the screen stating that a vertibird has been sent to your location. Wait for the vehicle to land then climb aboard. Open your map then select your location like you're fast-traveling. Vertibirds require a large open space where it can land. Avoid throwing it near hills or slopes since if the craft lands there, the game will prevent you from hopping aboard or flying to another location.