Is it possible to settle the Boston Airport?

Solution 1:

No you cannot, at least not easily. You can build stuff in it but you are limited as to what. Some of things that cannot be built are water purifiers, crops, guard posts, stores, scavenging stations, or artillery. As you said, you cannot build a settlement recruitment beacon either.

You can as noted in the comments, send settlers here from other settlements, but it would be difficult to keep them happy without being able to build the necessities.

Additional Information about this location and its restrictions:

If you side with the Brotherhood, you build the teleporter to teleport into the Institute in this location as part of the Molecular Level quest. It is also used to construct parts for the Liberty Reprimed quest.

Source: Experience and the Fallout Wiki.

Solution 2:

as of 2017 it is definitely possible to build water pumps on the rubble at the far end of the BA. Also you CAN build a radio tower. But nobody will come. Since it is BOS territory.

Solution 3:

You can build purifiers or pumps in the rubble or dirt at the NW corners, the purifier that produces10 water can be strategically placed in some of the rubble, i've done this with three so far. Then you have to send settlers there from other settlements and make sure you have caravan going to a settlement that produces enough food.

Solution 4:

To figure this out, you will need to break your ties with the Brotherhood of Steel by becoming an enemy to the faction by murdering a named BoS soldier. You will then need to eliminate the BoS by taking down the Prydwen through the Railroad quest Rockets' Red Glare, or by going through the Institute quest Airship Down. The Minutemen can take down the Prydwen in the post-game by going through the optional Minutemen quest With Our Powers Combined after becoming an enemy to the Brotherhood of Steel. You will then need to go into the Boston Airport Ruins and kill the Feral Ghouls that reside in there. After that, the Boston Airport has been cleared and the workshop becomes available again. You no longer have limited building options and it has become an ordinary settlement!

Note: With Nuka-World installed, it can be set up as a raider outpost after doing all of this.

Solution 5:

You can successfully establish settlers here while siding with the BOS by going to other settlements and moving settlers to Boston Airport or use Rogue Settler Quests from the Mechanist to populate it as well.