If you are talking about jumpseats on the flight deck, then in BA, unless you are a current BA crew member with BA ID, sadly it is no longer allowed.
UK security regulations, imposed after 9/11 prohibit it, so I imagine the same must apply to VS.
A great shame, as in happier times, on a previous BA type, I carried several US pilots on the flight deck jump seat. They had all paid for a passenger ticket, but for some reason preferred to sit up front!
