It all looks seamless when one's on a bus headed to drop you off at a remote bay or a stand that doesn't have an aerobridge. The heavies are constantly either pushing back, or taxing in, firing up their engines getting ready to head out. In the middle of all this, other equipment like baggage carts, fuel trucks, and ground transportation all run in sync. It all runs smooth, as long as one simple rule is being followed: the aircraft comes first and all else follows after.