Airside transfer
A Neoplan airside transfer bus in Malta
In the cases where airports do not use a jet bridge, for long distance transfers or for reasons of safety, passengers will be transferred from the airport terminal arrival or departure gate to the aircraft using an airside transfer bus or apron bus.
Airside transfer buses can be of normal bus design, or due to not running on the public highway, can be extra long and wide, to hold the maximum number of passengers. Sometimes a trailer bus is employed. Transfer buses are usually fitted with minimal or no seating, with passengers standing for the journey. Transfer buses will usually be fitted with flashing beacons for operating airside near runways. They may also feature driving cabs at both ends.
Terminal transfer
The Wiki Wiki terminal transfer bus at Honolulu International Airport
In cases where the airport features multiple terminals which are far apart or not physically connected, and where there exists no people mover or other transfer alternative, a zero-fare transfer bus may be employed to transfer connecting passengers from one terminal to another.[3][4] Terminal transfer may also be incorporated into public transport bus networks.
Car park transfer
In cases where the airport owned or affiliated car parks are large or relatively far from the terminal building, the airport owner or contractor may provide free car park shuttle buses making circular or shuttle runs between terminals and car park bus stands.