A method and apparatus for determining a discrete position of a first surface of an aircraft is disclosed. The first surface and a second surface movable relative to the first surface are provided. A sensor is disposed on one of the first surface and a second surface and a magnetic field source disposed on the other of the first surface and the second surface. The sensor detects a local magnetic field related to the magnetic field source and generates a voltage indicative of strength of the local magnetic field. The strength of the local magnetic field and therefore the generated voltage is related to a relative position between the sensor and the magnetic field source. The relative distance between the first surface and the second surface is determined from the generated voltage.