Subfixer may have been asking about your "how" for getting the deck and flightdeck grey painted on without disturbing the grey of the vertical surfaces.
This is a perennial ship modeler's question--whether to shoot the darker grey on first, and mask that; or to go with the lighter grey..
Having discovered that I had stashed a Trumpy Burke back when i was flush, this will be an interesting exercise when I get a workbench going again. One, I suspect, that will require both brush and airbrush.