All speculation ahead, so make of it what you will.
We know that the Brotherhood of Steel is capable of making airships. The Brotherhood members who would make up the midwest chapter who left the west coast after the fall of the Master by constructing airships to head east. Despite their best intentions however, they were unable to make the journey completely east as the main ship separated from the rest due to a horrible storm which could've likely destroyed or disabled the entire fleet...
Or so we think.
The Prydwen could very well be a remnant airship from that expedition. We know that more than one airship was constructed, so perhaps after the loss of the main airship, the storm likely scattered and destroyed the other airships. One such airship and its crew, the Prydwen, likely arrived at Boston at some point in time after the separation and since has been flying around the Boston area searching for technology or helping keep the peace, or perhaps evolving its ideology like the Midwestern brotherhood before it. This could beg a couple of questions.
-Does the Prydwen have the ability to travel to the Capitol Wasteland? If so, has the Brotherhood there and the Brotherhood in Boston have some sort of communication established?
- The Prydwen crew must be ancestors of the original crew if we are to believe that the crews left after the fall of the Master and before the arrival of the Enclave.
-The Prydwen crew could very well be some Brotherhood members who came east with Lyons and seperated, and upon discovering the Boston area, found the means to build an airship, which wouldn't be out of their reach as an organization.
Thoughts/Comments?