Narrative:

While en route at our cruise altitude of FL340; I noticed that the L4 eyebrow window had numerous cracks in it. We were about 2 hours into the flight. We referenced the QRH and followed the procedures for a cracked window. Using the QRH procedure we determined it was either an inner or middle pane of the L4 window. With this situation; the procedure directed us to land at the nearest suitable airport. We concluded that the best course of action was to divert to ZZZ. We were both familiar with the airport; the WX was clear; and it was an online station. We knew that we needed customs and were not sure of the availability of customs at ZZZ. We notified the flight attendant of our situation; our plan to proceed to ZZZ and our ETA. We told her not to notify the passenger at this time and we would make a PA after we coordination the divert. We declared an emergency with ARTCC on HF and requested clearance direct to ZZZ and a descent to 14000 ft; as directed in the procedure. We also told them the reason for the divert and to relay to our company our situation. We received a clearance direct to ZZZ and a clearance to descend. As we headed toward ZZZ we sent an ACARS message to the dispatcher telling them of our situation. The ACARS communication coverage was intermittent; but the message was able to go out. The dispatcher replied asking us if we would consider diverting to ZZZ2. We sent another message saying that ZZZ2 was too far to go. I made a PA telling the passenger what was happening in reassuring terms and our ETA to ZZZ. At lower altitude the controling agency became unusable. We coordination a phone patch with them to the dispatcher. We notified the dispatcher of our intentions. We received a reply from the dispatcher to call me on the ground in ZZZ. During this time we also attempted communication on the commercial radio frequency; but with no success. We did the descent and approach checks at the appropriate times. As we proceeded towards ZZZ the dispatcher sent us a message saying an aircraft will be landing about 45 mins after we land and that our passenger will be flown to destination on that aircraft. I notified the passenger of this possibility. I also told them about our customs situation and that they should remain seated until we get more information on how we will work that out. As we got closer to ZZZ we continued to keep the passenger updated. I made a PA notifying them to expect to feel a little more pressure change on their ears during the approach; because we would be depressurized sooner than normal; and that this is part of the procedure. I also notified them of the fire trucks that they will see after we land and not to be concerned and that this is normal procedure for the situation. The first officer made a normal approach and landing. On our way to the gate the first officer made a PA to remind everyone to remain on the aircraft and that we will get them more information once we talk to the ground personnel. I called the dispatcher to let him know we were on the ground and to confirm the outbound flight for the passenger. We then made an announcement telling the passenger the plan. One area that caused us difficulty was communicating with the oxygen masks on. With the loud breathing and having to talk pilot-to-pilot through the interphone system it was hard to hear each other. Another area that caused difficulty was communicating with our company in a timely manner. Our ACARS system was not in a communication mode initially and we were out of VHF range. The HF radio was also very busy to attempt a phone patch. We started getting good communication with the ACARS; but then it would drop out again. With it being intermittent we focused on trying to use that instead of using the HF radio.

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Original NASA ASRS Text

Title: B737 REPORTS CRACKED EYEBROW WINDOW WHILE OVER THE ATLANTIC WITH A DESCENT AND DIVERSION TO THE NEAREST SUITABLE AIRPORT; FOLLOWING QRH PROCEDURES.

Narrative: WHILE ENRTE AT OUR CRUISE ALT OF FL340; I NOTICED THAT THE L4 EYEBROW WINDOW HAD NUMEROUS CRACKS IN IT. WE WERE ABOUT 2 HRS INTO THE FLT. WE REFED THE QRH AND FOLLOWED THE PROCS FOR A CRACKED WINDOW. USING THE QRH PROC WE DETERMINED IT WAS EITHER AN INNER OR MIDDLE PANE OF THE L4 WINDOW. WITH THIS SITUATION; THE PROC DIRECTED US TO LAND AT THE NEAREST SUITABLE ARPT. WE CONCLUDED THAT THE BEST COURSE OF ACTION WAS TO DIVERT TO ZZZ. WE WERE BOTH FAMILIAR WITH THE ARPT; THE WX WAS CLR; AND IT WAS AN ONLINE STATION. WE KNEW THAT WE NEEDED CUSTOMS AND WERE NOT SURE OF THE AVAILABILITY OF CUSTOMS AT ZZZ. WE NOTIFIED THE FLT ATTENDANT OF OUR SITUATION; OUR PLAN TO PROCEED TO ZZZ AND OUR ETA. WE TOLD HER NOT TO NOTIFY THE PAX AT THIS TIME AND WE WOULD MAKE A PA AFTER WE COORD THE DIVERT. WE DECLARED AN EMER WITH ARTCC ON HF AND REQUESTED CLRNC DIRECT TO ZZZ AND A DSCNT TO 14000 FT; AS DIRECTED IN THE PROC. WE ALSO TOLD THEM THE REASON FOR THE DIVERT AND TO RELAY TO OUR COMPANY OUR SITUATION. WE RECEIVED A CLRNC DIRECT TO ZZZ AND A CLRNC TO DSND. AS WE HEADED TOWARD ZZZ WE SENT AN ACARS MESSAGE TO THE DISPATCHER TELLING THEM OF OUR SITUATION. THE ACARS COM COVERAGE WAS INTERMITTENT; BUT THE MESSAGE WAS ABLE TO GO OUT. THE DISPATCHER REPLIED ASKING US IF WE WOULD CONSIDER DIVERTING TO ZZZ2. WE SENT ANOTHER MESSAGE SAYING THAT ZZZ2 WAS TOO FAR TO GO. I MADE A PA TELLING THE PAX WHAT WAS HAPPENING IN REASSURING TERMS AND OUR ETA TO ZZZ. AT LOWER ALT THE CTLING AGENCY BECAME UNUSABLE. WE COORD A PHONE PATCH WITH THEM TO THE DISPATCHER. WE NOTIFIED THE DISPATCHER OF OUR INTENTIONS. WE RECEIVED A REPLY FROM THE DISPATCHER TO CALL ME ON THE GND IN ZZZ. DURING THIS TIME WE ALSO ATTEMPTED COM ON THE COMMERCIAL RADIO FREQ; BUT WITH NO SUCCESS. WE DID THE DSCNT AND APCH CHKS AT THE APPROPRIATE TIMES. AS WE PROCEEDED TOWARDS ZZZ THE DISPATCHER SENT US A MESSAGE SAYING AN ACFT WILL BE LNDG ABOUT 45 MINS AFTER WE LAND AND THAT OUR PAX WILL BE FLOWN TO DEST ON THAT ACFT. I NOTIFIED THE PAX OF THIS POSSIBILITY. I ALSO TOLD THEM ABOUT OUR CUSTOMS SITUATION AND THAT THEY SHOULD REMAIN SEATED UNTIL WE GET MORE INFO ON HOW WE WILL WORK THAT OUT. AS WE GOT CLOSER TO ZZZ WE CONTINUED TO KEEP THE PAX UPDATED. I MADE A PA NOTIFYING THEM TO EXPECT TO FEEL A LITTLE MORE PRESSURE CHANGE ON THEIR EARS DURING THE APCH; BECAUSE WE WOULD BE DEPRESSURIZED SOONER THAN NORMAL; AND THAT THIS IS PART OF THE PROC. I ALSO NOTIFIED THEM OF THE FIRE TRUCKS THAT THEY WILL SEE AFTER WE LAND AND NOT TO BE CONCERNED AND THAT THIS IS NORMAL PROC FOR THE SITUATION. THE FO MADE A NORMAL APCH AND LNDG. ON OUR WAY TO THE GATE THE FO MADE A PA TO REMIND EVERYONE TO REMAIN ON THE ACFT AND THAT WE WILL GET THEM MORE INFO ONCE WE TALK TO THE GND PERSONNEL. I CALLED THE DISPATCHER TO LET HIM KNOW WE WERE ON THE GND AND TO CONFIRM THE OUTBOUND FLT FOR THE PAX. WE THEN MADE AN ANNOUNCEMENT TELLING THE PAX THE PLAN. ONE AREA THAT CAUSED US DIFFICULTY WAS COMMUNICATING WITH THE OXYGEN MASKS ON. WITH THE LOUD BREATHING AND HAVING TO TALK PLT-TO-PLT THROUGH THE INTERPHONE SYS IT WAS HARD TO HEAR EACH OTHER. ANOTHER AREA THAT CAUSED DIFFICULTY WAS COMMUNICATING WITH OUR COMPANY IN A TIMELY MANNER. OUR ACARS SYS WAS NOT IN A COM MODE INITIALLY AND WE WERE OUT OF VHF RANGE. THE HF RADIO WAS ALSO VERY BUSY TO ATTEMPT A PHONE PATCH. WE STARTED GETTING GOOD COM WITH THE ACARS; BUT THEN IT WOULD DROP OUT AGAIN. WITH IT BEING INTERMITTENT WE FOCUSED ON TRYING TO USE THAT INSTEAD OF USING THE HF RADIO.

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.