LONDON—Accident investigators probing the crash of Germanwings Flight 9525 may face barriers in reconstructing conclusively what actions the co-pilot may have taken to keep others out of the cockpit as key information may not be available on one of the black boxes.
The locking and unlocking of the cockpit door is generally not one of the parameters stored on Airbus A320 jetliner flight data recorders, one of two black boxes used on...