CRACKED WINDSHIELD INFLT.

Narrative

LEVEL FL330; FO OBSERVED A RAPIDLY GROWING CRACK IN HIS FRONT OUTER WINDSCREEN. WE REQUESTED DSCNT AND WERE CLRED TO FL250. DURING DSCNT FO'S OUTER PANE SHATTERED. DUE TO THE ABRUPT NATURE AND SEVERITY OF THE SHATTER; AND OUR UNCERTAINTY OF ITS EFFECT UPON THE INNER PANE; WE REQUESTED DSCNT TO 10000 FT. ATC ADVISED WE WOULD NEED TO SQUAWK 7700 FOR IMMEDIATE DSCNT. WE DID SO. DURING DSCNT WE OBSERVED NO TFC CONFLICTS AND WERE KEPT WELL INFORMED AND CLR OF TFC BY ATC. ATC REQUESTED; IF POSSIBLE; WE LEVEL AT 13000 FT. WE COMPLIED AND AT 13000 FT CANCELED EMER STATUS; THEN DIVERTED TO CLEVELAND. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CRACKING WINDSHIELD SOUNDED LIKE A SHOTGUN BEING FIRED; WHEN IT HAPPENED. WINDSHIELD CRACKED INTO HUNDREDS OF PIECES. BECAUSE RADIO FREQ WAS CONGESTED THE FO WAS WAITING TO GET IN TO REQUEST LOWER ALT. CTLR STATED LOWER WAS NOT AVAILABLE SO THE CAPT THEN DECLARED AN EMER AND STARTED DSCNT. MAX AIRSPD WITH A CRACKED WINDSHIELD IS 305 KTS IAS BUT CAPT KEPT AIRSPD MUCH LOWER THAN THAT LIMIT. CAPT JUST WASN'T CERTAIN OF THE STRENGTH OF THE WINDSHIELD BECAUSE THE SHATTERING WAS SO DRAMATIC. SO HE KEPT EMER STATUS IN EFFECT UNTIL HE WAS AT A LOWER ALT; 13000 FT; AND AIRSPD LOW; THEN HE CANCELED THE EMER. AFTER LDNG AND THE PAX WERE DEPLANING; MANY OF THE PAX NOTICED THE SHATTERED WINDSHIELD BECAUSE IT WAS SO NOTICEABLE. THE WINDSHIELD WAS REPLACED IN ABOUT 5 HRS AND THE SAME FLC FLEW THE ACFT THE NEXT DAY. THE CAPT WAS NOT AWARE OF THIS PROB HAPPENING ON ANY OF THEIR ACFT BEFORE OR SINCE THIS INCIDENT.