Narrative:

We were descending through 16000 ft on profile to cross the intersection at 10000 ft; speed was about 290 KTS. Suddenly we noticed very bright arcing on top of the first officer's windshield. I immediately turned off the windshield heat to that window. I called for the QRH. Before we could read the QRH the window made a loud noise and cracked. The crack traveled all over the windshield; right to left and top to bottom. The cracks were so extensive that I expected the windshield to fail completely. I told my first officer to lower his seat all the way down and duck down. My 2 concerns were to slow down as soon as possible and then to descend below 10000 ft; so I could depressurize the aircraft. I leveled off to slow and this made meeting the restr intersection impossible. At this point ATC requested that we increase our rate of descent. I told him of our situation and requested descent to 10000 ft and airspeed of 210 KTS. He asked me if I was declaring an emergency. I stated that if I needed to; I was. He then vectored another aircraft to avoid us. After slowing and descending to 10000 ft I briefed the flight attendants and instructed the first officer to slowly depressurize the aircraft. We consulted the QRH for any additional guidance. We continued to destination (also closest airport) and landed without further problems. I don't know what we could have done differently. I feel we handled this potentially very serious event properly; but we did fail to make a crossing restr. We declared an emergency because of required ATC deviations.

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Original NASA ASRS Text

Title: B737 CREW HAS WINDSHIELD CRACK DURING DSCNT AND DECLARES AN EMER.

Narrative: WE WERE DSNDING THROUGH 16000 FT ON PROFILE TO CROSS THE INTXN AT 10000 FT; SPD WAS ABOUT 290 KTS. SUDDENLY WE NOTICED VERY BRIGHT ARCING ON TOP OF THE FO'S WINDSHIELD. I IMMEDIATELY TURNED OFF THE WINDSHIELD HEAT TO THAT WINDOW. I CALLED FOR THE QRH. BEFORE WE COULD READ THE QRH THE WINDOW MADE A LOUD NOISE AND CRACKED. THE CRACK TRAVELED ALL OVER THE WINDSHIELD; R TO L AND TOP TO BOTTOM. THE CRACKS WERE SO EXTENSIVE THAT I EXPECTED THE WINDSHIELD TO FAIL COMPLETELY. I TOLD MY FO TO LOWER HIS SEAT ALL THE WAY DOWN AND DUCK DOWN. MY 2 CONCERNS WERE TO SLOW DOWN ASAP AND THEN TO DSND BELOW 10000 FT; SO I COULD DEPRESSURIZE THE ACFT. I LEVELED OFF TO SLOW AND THIS MADE MEETING THE RESTR INTXN IMPOSSIBLE. AT THIS POINT ATC REQUESTED THAT WE INCREASE OUR RATE OF DSCNT. I TOLD HIM OF OUR SIT AND REQUESTED DSCNT TO 10000 FT AND AIRSPD OF 210 KTS. HE ASKED ME IF I WAS DECLARING AN EMER. I STATED THAT IF I NEEDED TO; I WAS. HE THEN VECTORED ANOTHER ACFT TO AVOID US. AFTER SLOWING AND DSNDING TO 10000 FT I BRIEFED THE FLT ATTENDANTS AND INSTRUCTED THE FO TO SLOWLY DEPRESSURIZE THE ACFT. WE CONSULTED THE QRH FOR ANY ADDITIONAL GUIDANCE. WE CONTINUED TO DEST (ALSO CLOSEST ARPT) AND LANDED WITHOUT FURTHER PROBS. I DON'T KNOW WHAT WE COULD HAVE DONE DIFFERENTLY. I FEEL WE HANDLED THIS POTENTIALLY VERY SERIOUS EVENT PROPERLY; BUT WE DID FAIL TO MAKE A XING RESTR. WE DECLARED AN EMER BECAUSE OF REQUIRED ATC DEVS.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.