Abstract: An aircraft system for an aircraft is disclosed having a controller that is configured to receive at least one signal during a landing procedure of the aircraft and to determine that the aircraft is at a predetermined stage in the landing procedure, on the basis of the at least one signal. The predetermined stage in the landing procedure is before a command to extend at least one landing gear of the aircraft is issued during the landing procedure. The controller is configured to cause initiation of at least a part of a procedure to interrogate an aircraft braking system, on the basis of the determination.