As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 1214 - DURING CLIMB, CABIN RATE OF CLIMB EXCEEDED 700 FEET PER MINUTE. CABIN CONTINUED TO CLIMB WITH CONTROL FULL CLOCKWISE. RETURNED AND LANDED ORD WITHOUT FURTHER INCIDENT. REPLACED LEFT PACK AIR PRESSURE TRANSMITTER. SYSTEM GROUND CHECKED, NORMAL OPERATION. (X)