Not possible, as Vertibirds have very limited range (the reason Navarro was constructed and Enclave has outposts scattered all across Eastern Seaboard).
Isn't it a bit unclear what exactly Vertibird range is however? Its never fully stated (if I recall) that Vertibirds only have a range of X, Navarro was a refuel station yes, but there could be other reasons why a mainland supply depot was needed.
Then in Fallout 3 the Vertibirds explode with a mushroom cloud, which suggests that at some point a switch was made over to nuclear power. True, I don't believe Vertibirds would be able to reach the East-Coast without refueling, but I believe its possible they were able to make it to Chicago and then refuel there (perhaps giving a reason why the outposts there were established).
The Vertibird in the Mojave is almost certainly from the Enclave (and the robots guarding it are labeled as "Enclave Robots" in the GECK), which suggests that they can at least make the distance there.