Warning device

A warning device 1 alerts operators of towable aircraft ground support equipment (GSE) 7 when a procedural error is made, such as the equipment still being attached to an aircraft. The ground support equipment has a connector 11 for connecting to the aircraft, which is stowed when not in use, and a first coupler 6 which cooperates with a second coupler 8 on a towing device 9. The warning device has an actuator with a piston 3 which extends forwards, occluding at least one coupler when the connector is not in the stowed position. A body 2 of the actuator is biased in the forwards direction relative to a backplate 5 and is mounted such that obstructions encountered during piston extension move the body backwards, triggering an alert mechanism. The GSE may be a ground power unit and the alert switches it off, or has warning lights, alarms or cuts actuator power. The actuator may move a limited distance backwards before the alert mechanism is triggered, with motion controlled by a slot in a backplate mounting boss (fig.7,16) in which a mounting pin (fig.7,17) of the body may slide up to 2cm. An override may be provided, which retracts the piston.