B737 flight crew reported observing a slowing expanding crack in an interior window panel during cruise. Flight diverted and performed an overweight landing.
Synopsis
B737 flight crew reported observing a slowing expanding crack in an interior window panel during cruise. Flight diverted and performed an overweight landing.
Narrative
Flying at cruise; FL350; the FO was the PF and the CA was the PM. The CA identified a visible crack of the L1 interior window panel; which had feathering and perceptible depth. Maintenance Control and dispatch were contacted. Due to the slow expansion of the crack and considering the long international routing ahead; the decision was made to immediately divert while still in domestic airspace due to safety of flight. Priority handling was requested and the 'Window Damage' Non-Normal Checklist was executed. Routing to ZZZ and a descent to 14;000' was requested and issued by ATC. Airspeed was reduced to 250 KIAS and the landing gear was extended to maximize fuel burn and reduce landing weight. Once at 14;000'; further descents were made at a minimal rate of descent to reduce the effects of pressurization change. Prior to beginning the arrival; the CA assumed duties as PF and the FO assumed duties as PM. A visual approach backed up by the ILS XXL was executed. An overweight landing to RXXL was executed; with touchdown occurring approximately 7;500 pounds over max landing weight. Several actions were taken on landing to reduce the possibility of overheating the brakes: flaps 40 were used to reduce final approach speed; autobrakes 1 was used; full thrust reversers were immediately deployed after touchdown; and most of the available runway length was used to bring the aircraft to a gradual stop. Two ELB (Electronic Logbook) entries were made: one documenting the cracked windshield and one documenting the overweight landing. The event was handled in accordance with SOP and CRM/TEM (Threat and Error Management) was leveraged to ensure safety of flight.
Second reporter narrative
At cruise; FL350; during level-off; the Captain identified the formation of a visible crack in the L1 door interior panel. The crack terminated in 'feathering;' with perceptible depth confirmed by tactile inspection. Due to the nature and progression of the defect; and considering the long overwater/international routing ahead (X+XX planned flight time); the decision was made to return while still in CONUS airspace.Priority handing was requested following direct coordination with dispatch and Maintenance Control. Based on the provided crack description; Maintenance Control advised an immediate return due to safety-of-flight implications.Initiated descent to 14;000' and extended landing gear early to maximize fuel burn and reduce weight.Descended using a 600 fpm rate to promote crew and passenger acclimatization to cabin pressure changes and mitigate aeromedical risks.Captain assumed control of the landing due to its non-normal nature; First Officer had been PF up to that point and had performed admirably.Overweight landing executed on Runway XXL at ZZZ; approximately 7;500 lbs over max landing weight.Flaps 40 used for final approach; landing was managed with primary use of thrust reversers and minimal braking to preserve brake energy.All QRC/QRH items were completed promptly and correctly. Two ELB (Electronic Logbook) entries were made: one documenting the crack; the other the overweight landing. Dispatch and Maintenance Control provided consistent; actionable input throughout the return.Threats included a structural anomaly in flight; overweight landing dynamics; and potential passenger aeromedical concerns due to cabin pressure management.Effective crew resource management: Captain maintained decision authority while leveraging FO's performance and input. Flight path and workload management were continuous priorities.First Officer provided solid support in both PF role and post-transfer tasks. Coordination between flight crew; cabin crew; and maintenance was seamless.Discovery of the crack early in the route was fortunate; enabling a safe CONUS return rather than a high-risk international divert.Handling and descent strategy were calibrated to reduce physiological strain on passengers and minimize further structural stress.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.