What was found
DURING DESCENT TO 370, CAPT NOTICED SMALL CRACK ON CAPT'S FRONT WINDSCREEN. FLT CREW REQUESTED LOWER ALTITUDE & ATC COULD NOT COMPLY & TOLD FLT TO MAINTAIN 370. CRACK STARTED TO WIDEN & SPREAD RAPIDLY, FLT CREW REQUESTED AN EMERGENCY DESCENT. FLT CREW SEAT HARNESSES WERE ON & O2 MASKS DONNED. OUTER LAYERS OF WINDSCREEN DAMAGED, NO LOSS OF PRESSURIZATION. AIRCRAFT DIVERTED INTO TPA. F/O TOOK OVER PF DUTIES, LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED CAPT'S FRONT WINDSCREEN PER AMM 56-11-11-PB400 AND OPS CK'D OK. AIRCRAFT WAS RETURNED TO SERVICE. MAINTENANCE REPLACED THE NR 1 WINDSHIELD HEAT COMPUTER PER AMM 30-42-34-401, FOR PRECAUTIONARY REASONS AND OPS CK'D OK ON 11/4/04.