As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ANCHORAGE - APPROX .25 MILE OUT FROM ANC PILOT NOTED THE DOOR OPEN WARNING LIGHT CAME ON. THE PILOT TURNED BACK TO ANC. WHILE RETURNING, THE UPPER CARGO DOOR OPENED IN FLIGHT. THE AIRCRAFT LANDED SAFELY AT ANC. MAINTENANCE ADJUSTED THE CARGO DOOR HANDLE DETENT. MAINTENANCE INSPECTED DOOR AND NO DAMAGE NOTED. AIRCRAFT WAS RETURNED TO SERVICE. (M)