What I know about fs'02, you can't get them visible in game. But, if you buy a new upgrade fron your cp-game-shop, ther eshould be a accessory part to fs'02, wher eyou get better graphics to UK airports. Then you can see airport vehicles. Ofcourse I may be wrong, but i have never seen any airport vehicles on fs'02, still I've played it quite alot. I also haven't seen any buttons to adjust them in options.

             Hope this helps? 

i downloaded from simv a package with ground vehicles - from the misc section i think - there aren't loads of vehicles but there's certianly a noticeable improvement