A B757-200 IN CRUISE AT FL350 DECLARED AN EMER AND DIVERTED DUE TO CAPT'S FORWARD WINDSHIELD ARCING AND OUTER PANE SPIDER CRACKING.

Narrative

AFTER A NORMAL STEP CLB AND LEVEL OFF AT FL350; APPROX 5-10 MINS AT CRUISE; I NOTICED 3 SMALL AREAS (2 LOWER L AND 1 LOWER R PORTION OF CAPT FORWARD WINDSHIELD) OF WHAT APPEARED TO BE ELECTRICAL ARCING (FLARING/SPARKLING). THE FO THEN NOTICED A GLOWING AREA UNDER THE FAR L UNDERSIDE OF THE GLARE SHIELD. AT ABOUT THIS SAME TIME; THE FORWARD WINDSHIELD 'SPIDER CRACKED' IN ITS ENTIRETY. WE THEN DECLARED THE EMER; DONNED THE OXYGEN MASKS; SLOWED THE ACFT; STARTED THE DSCNT; RAN THE CHKLIST; DISCUSSED AND AGREED ON DIVERSION (DUE TO CONTINUED AND EXPANDING ARCING AND QUESTIONABLE WINDSHIELD INTEGRITY). WE THEN NOTIFIED THE COMPANY AND FLT ATTENDANTS OF THE SIT AND MADE A PA TO THE PAX. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE FORWARD CAPT'S WINDSHIELD STARTED TO ARC AT THE LOWER L AND R CORNERS. THE RPTR SAID IT SPARKLED AND GLOWED THEN THE OUTER PANE CRACKED IN A SPIDER WEB PATTERN. THE RPTR STATED AN EMER WAS DECLARED AND A DSCNT AND DIVERSION BEGAN AS THE WINDSHIELD INTEGRITY WAS QUESTIONABLE.