As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CRUISE FLIGHT CREW ERROR CONTRIBUTED TO A LOSS OF PRESSURIZATION. PASSENGER OXYGEN MASKS DROPPED AUTOMATICALLY. SEAT ROW 7 RT SIDE THE OXY MASK VALVE PULL PINS WERE MISSING PREVENTING THE FLOW OF OXYGEN, AND AT ROW 22 RT SIDE THE MASKS DID NOT DEPLOY. BOTH CHAIRS WERE BLOCKED FROM USE PER MEL. ON LAYOVER THE MASK PINS WERE REPLACED, AND AT ROW 22 MASKS WERE ADJUSTED PER MAINT MANUAL. CHECK-C 10-14-99 STL.