As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) CREW NOTED STAB TRIM RUNAWAY IN THE NOSE DOWN DIRECTION DURING CLIMB FROM ATL WHILE ACCELERATING TO 250 KTS. CREW DECLARED EMERGENCY AND RETURNED. MAINTENANCE CONTROL NOTIFIED. MAINTENANCE FOUND INDICATION OF PILOT'S TRIM SWITCH JAMMED IN THE MDC. REMOVED AND REPLACED THE PILOT'S STAB TRIM SWITCH. OPS CHECK GOOD.