Passenger boarding bridge

A passenger boarding bridge comprising:

• a rotunda connected to an entrance of a terminal building and supported such that the rotunda is rotatable horizontally;
• a tunnel unit including a first end and a second end, the first end being connected to the rotunda, the tunnel unit being extendable and retractable;
• a cab provided at the second end of the tunnel unit, the cab being configured to be docked with an aircraft;
• a travel device that supports the tunnel unit and includes a pair of travel wheels, the travel device being configured to travel forward in a first direction by regular rotation of the pair of travel wheels and to travel backward in a second direction opposite to the first direction by reverse rotation of the pair of travel wheels, wherein the first direction is a direction along which movement of the travel device causes the tunnel unit to be extended, and the second direction is a direction along which movement of the travel device causes the tunnel unit to retract;
• an operating device that is manually operated to input an operation command to the travel device;
• and
• a controller including a processing unit and a storage unit that stores a control program, wherein when the processing unit executes the control program, the control program causes the controller to, during a period from when the cab starts being moved from a predetermined position through an operation of the operating device to cause the travel device to travel, until the cab is docked with the aircraft, while the travel device is traveling backward in the second direction in accordance with a manual control input of a backward travel operation command from the operating device, determine whether or not the cab comes closer to the aircraft as a result of the travel device traveling backward in the second direction,
• wherein the passenger boarding bridge is configured to perform a warning and/or stop the travel device from traveling backward in the second direction in a case where the controller determines that the cab comes closer to the aircraft as a result of the travel device traveling backward in the second direction, thereby avoiding the cab becoming docked with the aircraft by backward travel of the travel wheels.