B777 flight crew reported the Captain's forward window shattered at FL370. The flight returned to the mainland.
Synopsis
B777 flight crew reported the Captain's forward window shattered at FL370. The flight returned to the mainland.
Narrative
On Day 3; I was the First Officer on Aircraft X from ZZZ to ZZZZ. The airplane used was Aircraft X; a B777-200. After climbing to our cruising altitude of FL370 and approximately one hour into the flight; while the Relief Pilot was on break; the Captain and I noticed the forward left windshield was arcing in the lower right corner. We watched for approximately 45 seconds as the arc moved from the lower right corner; up and diagonally to the middle of the windshield. Shortly after the arc ceased; we heard a loud pop and watched as the windshield began to shatter. We were not aware which layer/pane failed.At this time; EICAS messages began to appear on the upper EICAS screen and I stated 'My aircraft' and continued to fly the airplane while the Captain completed the checklists. The Window Heat L and the Window Damage FWD L messages appeared and he accomplished both checklists in accordance with Company standard operating procedures.Once the checklists were complete; we began a discussion on the need to divert and we requested the Relief Pilot return to the flight deck to help with coordination and workload management.At this point we utilized HF radio [requested priority handling] to ZZZ and CPDLC technology alerting them of our need to divert off of our assigned track. In accordance with oceanic procedures; we turned on all exterior lighting; transmitted our intentions on both and turned to begin our divert.There was a discussion about retuning to ZZZ or diverting to ZZZ1. We decided ZZZ1 would be the best option due to the forecast weather deteriorating in ZZZ. At this time; we also overheard reports of severe turbulence in the ZZZ area; so ZZZ1 made the most sense considering the situation.We were able to coordinate a descent to FL250 and requested speed at our discretion. That was approved and we descended and slowed to 280 kts. We had some time and referenced the QRH for any supplemental information that might be pertinent to our situation.We requested ZZZ1 weather and briefed an ILS XXL approach into ZZZ1. The winds were reported to be 230/23G38.Approximately 100 miles east of ZZZ1; we accomplished the descent checklist and descended to 11;000 feet and slowed to 250 kts in preparation for the arrival and landing. As a precaution; we also requested Airport Rescue and Firefighting (ARF) be available on landing.I flew the approach and landing and it was normal. We taxied off of Runway XXL under our own power and subsequently parked at gate 1.I appreciate working with the FO's. At all times; they were professional and efficient in their communication. They; along with the flight attendants; did a fantastic job that contributed to a successful diversion. It should be noted that the Captain's forward windshield had been written up a week prior on Day 0 for de-laminating all corners and the Maintenance Discrepancy was put on. There was also an info to maintenance item on Day 1 of the left window heat needing to be reset prior to departure and then again in flight. Additionally; there was a separate info item to maintenance on Day 2 4 for 'EICAS window heat R side.'A thorough review and potential streamlining of the deferral process especially in instances with multiple and common write ups. A requirement to shorten deferral times in order to fix issues.
Second reporter narrative
After leveling off at a cruising altitude of FL370 about one hour into the flight the Captain's forward windshield indicated electrical arcing in the lower right corner. This was immediately followed by a loud pop and subsequent shattering of one of the layers of the Captain's windshield. The Window Heat L and Window Damage FWD L checklist were completed and it was determined a divert was necessary. At this point via HF to ZZZ we [requested priority handling] to coordinate a divert to ZZZ1. ZZZ was considered; but a strong frontal boundary was already causing severe turbulence at 6000 ft in the ZZZ area (reported by a 737) which made ZZZ1 a better choice and a closer suitable airport. A descent off track was coordinated via HF and CPDLC to FL250 speed at our discretion with ZZZ Oceanic. Approximately 75 miles from ZZZ1 we descended to 11;000 250 kts. The First Officer (FO) landed uneventfully to Runway XXL ZZZ1 winds were 230@23 gust to 38. Airport Rescue and Firefighting (ARF) had been notified and were available upon landing. We taxied to gate 1 without incident.It should be noted the Captain's FWD windshield had a write-up on Day 0 for delamination and a Maintenance Discrepancy was issued. Also on Day 1 an info to maintenance report of the L window heat being reset just prior to departure and again in-flight.Differing the maintenance of the FWD L windshield delamination along with the FWD L windshield heat having a write-up with no action was the causal factor. The aircraft sat a ZZZ for 24 hours prior to this flight with adequate time to replace the FWD L windshield. If this was done it would have prevented the issue and diversion.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.