As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIT - FL 1211 - THE A/C RETURNED TO FIELD (PIT) DUE TO THE AFT CARGO DOOR WARNING LIGHT ILLUMINATED. A/C LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE CLEANED AND LUBED AFT CARGO DOOR WARNING SWITCH (390FW04A10). OPERATIONAL CHECK GOOD. (M)