A proximity sensor 20, 21, 22 and method for detection of wear in a brake disc stack 55 on an aircraft including a wear pin 40, 43, 50 for moving in a first direction as the brake wears, and a switch 20, 21, 22 for measuring movement of the wear pin in the first direction. When the wear pin 40, 43, 50 moves in the first direction to a predetermined position, the switch 20, 21, 22 signals that the brake disc stack 55 has worn the predetermined amount.