What happened
On April 15, 2005, an Airbus A320-231, registration I-LINH, was operating a commercial passenger flight from Catania Fontanarossa to Forlì at a cruising altitude of FL300. While passing near the Sorrento VOR, the flight crew experienced a loud impact in the cockpit, followed by an extensive crack appearing in the right-hand windshield.
Following standard emergency procedures, the crew immediately donned full-face oxygen masks and initiated a rapid descent. After approximately two minutes, the crew verified that cabin pressurization levels remained normal, subsequently reducing the rate of descent and requesting a diversion to Naples Capodichino. During the descent, the crew noted a brief "ANTI-ICE R WINDSHIELD" indication on the ECAM. The aircraft landed at Naples without further incident, carrying 67 passengers and 6 crew members.
The investigation
The ANSV investigation initially considered a birdstrike as a potential cause, but ground inspections and chemical-biological analysis of the area near the damage ruled out any biological remains or evidence of an avian impact.
Technical examinations of the damaged component were conducted in coordination with the manufacturer. The investigation revealed that the failure was confined strictly to the non-structural outer glass layer; the two internal structural layers, responsible for aerodynamic and pressurization loads, remained intact.
Detailed analysis identified a "burn-out" defect within the electro-conductive heating layer located between the outer glass and the PVB resin interlayer. This defect caused localized overheating, which ultimately fractured the outer glass. The investigation traced the origin of this overheating to moisture infiltration, which had entered the assembly due to the erosion of the windshield seal—a result of standard service wear. The component had accumulated approximately 21,600 flight hours since its installation in 1998.
Findings
- The primary cause of the outer windshield crack was localized overheating of the heating element.
- This overheating was triggered by moisture ingress into the heating layer.
- The moisture infiltration was caused by the erosion of the windshield seal due to normal operational wear.
- The crew's adherence to emergency procedures prevented any loss of cabin pressure or further structural compromise.