Recently, me bro & I discovered a bug in Burnley district's GCR radio station where you hack the terminal. Obviously after getting trapped inside there's a vent shaft above, but here's the buggy part...
After you use the Grapnel gun to get up, you CANNOT enter the air duct...LITERATELY!!
Which means if you cannot get into it, you cannot fully disable the jamming signal in Burnley for Fast Travel.
you can still disable that tower with a glitch that has been found. i suggest you to get the long range cryptographer upgrade first before trying to unlock this tower. get to the tower, use the reclaw to get out of the area. you will see a ledge, hack the device outside the window so you wont get locked in.
and most importantly. watch this youtube video to disable the tower. www.youtube.com/watch?v=HkDLaojdCCw
it has worked for me and many others. also suggest you to use the trainer for transport option, you will need a couple tries to perform this glitch.