Abstract: An altitude switch limit assembly has two independent limit switches to monitor cabin pressure and back up performance of the auto and monitor channels on the aircraft. The auto channel closes a first switch upon sensing that a cabin pressure falls below a set value, the monitor channel closes a second switch upon sensing that the cabin pressure falls below the set value. A first independent limit switch may be wired to the auto channel and a second independent limit switch may be wired to the monitor channel. Logic circuitry may determine that the assembly closes an outflow valve regulating cabin pressure when either both independent limit switches sense the condition, or when one of the independent limit switch senses the condition and either the auto channel or monitor channel to which that independent limit switch may be wired senses the same condition.

Abstract: An altitude switch limit assembly has two independent limit switches to monitor cabin pressure and back up performance of the auto and monitor channels on the aircraft. The auto channel closes a first switch upon sensing that a cabin pressure falls below a set value, the monitor channel closes a second switch upon sensing that the cabin pressure falls below the set value. A first independent limit switch may be wired to the auto channel and a second independent limit switch may be wired to the monitor channel. Logic circuitry may determine that the assembly closes an outflow valve regulating cabin pressure when either both independent limit switches sense the condition, or when one of the independent limit switch senses the condition and either the auto channel or monitor channel to which that independent limit switch may be wired senses the same condition.