Boeing Flight Deck Door – Decompression Sensing Module (DSM):

In 2001 the commercial aircraft OEMs needed a solution to rapidly unlock the cockpit door in the event of a decompression event. NAT Engineering developed an electrical solution that responded to a decompression event in the millisecond range. In a matter of months it was taken from concept, through engineering design, computer modeling, prototyping, R&D testing, formal qualification testing, and into production for delivery to the OEMs. The NAT electrical device included integration of control for the keypad, thus providing for a secure keyless entry solution.

NAT provides its Patented Decompression Sensing Module (DSM) for all new and retrofit cockpit doors on B747, B767 and B777 aircraft models.