Q400
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Diverted
Aircraft
Reaching top of climb; we got a master warning FUSELAGE DOOR and; upon consulting the doors page on the MFD; the galley service door showed open. There was a pressure 'bump' when the warning occurred but within 15 seconds the pressurization system returned to normal. Per the checklist we consulted with the aft Flight Attendant and she visually confirmed that the galley service door handle was no longer locked. We advised her that; per the checklist; she should not touch the door and could reposition herself to a passenger seat if she felt that was a safer option. She chose to move to row 18. The checklist advised to LAND IMMEDIATELY AT THE NEAREST SUITABLE AIRPORT. We consulted with Dispatch and decided to divert to ZZZ; which was our closest airport in terms of time. Advised ATC; FA and passengers and continued to a normal landing. The passengers were bused to their destination and we went to the hotel for a much needed rest.
A Q-400 flight crew diverted to the nearest suitable airport when the aft galley door came unlocked during flight.