Narrative:

While in cruise at FL370 my forward window shattered. Immediately the captain and I donned our oxygen masks and checked cabin pressurization. We found the cabin to be holding pressure for the time being. The captain went to the irregular procedure which stated to observe the window and turn the window heat off. Because we were dispatched with one of the window heat controllers inoperative, after a quick glance we both incorrectly assumed it was the same one and as a result never did get the window heat off to the shattered window. During this time cracks were continuing to develop so we decided a lower altitude and a diversion to the nearest suitable airport was in order. Phx was the nearest suitable airport, so we received a clearance direct to the airport. On the way there we contacted the company who advised us that phx was not an approved B777 emergency airport and asked if we could make alb or den. After considering their advice, we elected to declare an emergency and continue inbound to phx as we had no idea how much longer the window would last. We also had both landed at phx in other airplanes and knew the airport was perfectly fine for the B777. An uneventful safe landing was made 17000 pounds overweight in phx where the airplane was repaired. Callback conversation with first officer revealed the following information: the aircraft had departed lax for iad and was near winslow, az, when the window shattered. It wasn't known at the time, but there are 3 layers on the B777 window. In this case, the middle layer had shattered but that was not determined at the time by this crew. They believed it was a 2 layer window and they wanted to preserve the integrity of the 'remaining' panel and that is why they overrode the company request to proceed to denver where the aircraft could be more readily repaired. As the first officer said, 'dispatch and maintenance control was not riding in the cockpit that day.' the crew's concern was with the apparent pressing of the shattered pane against the outer pane. Their operating manual does not show that there are 3 panes, crews are unaware of this fact. The thickest pane is the inner which is structural. Airline maintenance personnel knew this but did not inform the crew. Reporter stated that he was informed by his airline later that this was the 8TH shattered window the carrier has experienced on the B777 fleet. The airline wants the aircraft manufacturer to change vendors that produce the B777 windows since there is a problem in the manufacturing process. They want to switch to the one that produces the B767/757 window but the aircraft manufacturer is not moving on that request, showing reluctance to change vendors. ASRS database does not show any prior B777 window problems.

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Original NASA ASRS Text

Title: A B777 EXPERIENCES A SHATTERED FO'S FORWARD WINDOW AT FL370. THE FLT DIVERTS TO PHX WHICH WAS DETERMINED TO BE A NON B777 DIVERSIONARY EMER ARPT. CAPT DECLARES AN EMER AND PROCEEDS TO PHX AS PLANNED.

Narrative: WHILE IN CRUISE AT FL370 MY FORWARD WINDOW SHATTERED. IMMEDIATELY THE CAPT AND I DONNED OUR OXYGEN MASKS AND CHKED CABIN PRESSURIZATION. WE FOUND THE CABIN TO BE HOLDING PRESSURE FOR THE TIME BEING. THE CAPT WENT TO THE IRREGULAR PROC WHICH STATED TO OBSERVE THE WINDOW AND TURN THE WINDOW HEAT OFF. BECAUSE WE WERE DISPATCHED WITH ONE OF THE WINDOW HEAT CTLRS INOP, AFTER A QUICK GLANCE WE BOTH INCORRECTLY ASSUMED IT WAS THE SAME ONE AND AS A RESULT NEVER DID GET THE WINDOW HEAT OFF TO THE SHATTERED WINDOW. DURING THIS TIME CRACKS WERE CONTINUING TO DEVELOP SO WE DECIDED A LOWER ALT AND A DIVERSION TO THE NEAREST SUITABLE ARPT WAS IN ORDER. PHX WAS THE NEAREST SUITABLE ARPT, SO WE RECEIVED A CLRNC DIRECT TO THE ARPT. ON THE WAY THERE WE CONTACTED THE COMPANY WHO ADVISED US THAT PHX WAS NOT AN APPROVED B777 EMER ARPT AND ASKED IF WE COULD MAKE ALB OR DEN. AFTER CONSIDERING THEIR ADVICE, WE ELECTED TO DECLARE AN EMER AND CONTINUE INBOUND TO PHX AS WE HAD NO IDEA HOW MUCH LONGER THE WINDOW WOULD LAST. WE ALSO HAD BOTH LANDED AT PHX IN OTHER AIRPLANES AND KNEW THE ARPT WAS PERFECTLY FINE FOR THE B777. AN UNEVENTFUL SAFE LNDG WAS MADE 17000 LBS OVERWT IN PHX WHERE THE AIRPLANE WAS REPAIRED. CALLBACK CONVERSATION WITH FO REVEALED THE FOLLOWING INFO: THE ACFT HAD DEPARTED LAX FOR IAD AND WAS NEAR WINSLOW, AZ, WHEN THE WINDOW SHATTERED. IT WASN'T KNOWN AT THE TIME, BUT THERE ARE 3 LAYERS ON THE B777 WINDOW. IN THIS CASE, THE MIDDLE LAYER HAD SHATTERED BUT THAT WAS NOT DETERMINED AT THE TIME BY THIS CREW. THEY BELIEVED IT WAS A 2 LAYER WINDOW AND THEY WANTED TO PRESERVE THE INTEGRITY OF THE 'REMAINING' PANEL AND THAT IS WHY THEY OVERRODE THE COMPANY REQUEST TO PROCEED TO DENVER WHERE THE ACFT COULD BE MORE READILY REPAIRED. AS THE FO SAID, 'DISPATCH AND MAINT CTL WAS NOT RIDING IN THE COCKPIT THAT DAY.' THE CREW'S CONCERN WAS WITH THE APPARENT PRESSING OF THE SHATTERED PANE AGAINST THE OUTER PANE. THEIR OPERATING MANUAL DOES NOT SHOW THAT THERE ARE 3 PANES, CREWS ARE UNAWARE OF THIS FACT. THE THICKEST PANE IS THE INNER WHICH IS STRUCTURAL. AIRLINE MAINT PERSONNEL KNEW THIS BUT DID NOT INFORM THE CREW. RPTR STATED THAT HE WAS INFORMED BY HIS AIRLINE LATER THAT THIS WAS THE 8TH SHATTERED WINDOW THE CARRIER HAS EXPERIENCED ON THE B777 FLEET. THE AIRLINE WANTS THE ACFT MANUFACTURER TO CHANGE VENDORS THAT PRODUCE THE B777 WINDOWS SINCE THERE IS A PROB IN THE MANUFACTURING PROCESS. THEY WANT TO SWITCH TO THE ONE THAT PRODUCES THE B767/757 WINDOW BUT THE ACFT MANUFACTURER IS NOT MOVING ON THAT REQUEST, SHOWING RELUCTANCE TO CHANGE VENDORS. ASRS DATABASE DOES NOT SHOW ANY PRIOR B777 WINDOW PROBS.

Data retrieved from NASA's ASRS site as of July 2007 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.