If you fire your ultimate first your rockets hits at a timing where the Airship cannot possibly dodge/kite the ultimate completely. Lane or not makes no difference for this mechanic.
Edit: The only difference for lane is that your movement before casting your ultimate might be a giveaway. But you can fix that by faking the same movement over and over again.
Edit: The only difference for lane is that your movement before casting your ultimate might be a giveaway. But you can fix that by faking the same movement over and over again.