Incident Details
On May 4, 2015, about 2105 central daylight time, a Frontier Airlines Airbus A319-112, registration N941FR, operating as Flight 1225, sustained minor damage when the copilot's window cracked during cruise at flight level 340 northeast of New Orleans, Louisiana. The flight crew reported smoke in the cockpit, declared an emergency, and diverted to Louis Armstrong New Orleans International Airport, landing about 2136 without further incident. There were no injuries among the 2 flight crew, 3 cabin crew, and 131 passengers. The flight originated from Orlando International Airport about 2002 and was destined for McCarran International Airport in Las Vegas. Night visual flight rules conditions prevailed, and the flight operated on an activated instrument flight rules flight plan.
Flight Crew Actions
The first officer, who was the non-flying pilot, pointed to his windshield. The flight crew observed arcing and sparks along the bottom of the windshield, moving from left to right and intensifying. The captain was about to reference the quick reference handbook (QRH) windshield/window arcing procedure when a popping sound was heard and the entire windshield cracked. The captain did not recall any tripped circuit breakers or electronic centralized aircraft monitor (ECAM) messages during the event. However, the fault 'ANTI ICE R WINDSHIELD' was recorded during the flight.
Windshield Examination
The incident window was removed and shipped to PPG Aerospace for detailed examination under NTSB oversight on August 11, 2015. The windshield, Airbus part number 6968962000 and PPG part number NP165311, was a laminated glass configuration with multiple layers. The specific windshield from N941FR was serial number 05052H1528, manufactured in 2005 and installed on the aircraft during production, accumulating 38,085 flight hours and 16,015 flight cycles.
Examination Findings
The NTSB aerospace engineer reported a moderate network of fractures on the outer glass pane, with evidence of moisture seal repairs along the upper and aft edges. The primary fracture origin was centered about 4.5 inches above the lower edge and 8.5 inches forward of the aft edge, with a secondary origin about 29 inches forward and 1 inch above the lower edge. Brown, bubbled interlayer material at the origins indicated the windshield was powered at the time of fracture. An arc path in the heating film was observed passing through both origins. Cloudiness and cracking of the interlayer material near the edges suggested moisture ingression, particularly along the forward edge and lower forward corner near the terminal block. The silicone gasket was in good condition, but the foam closure plate was removed from the inner pane along the lower edge. Resistance measurements between pins A and B of the terminal connector did not meet manufacturer specifications.
Maintenance History
The operator's maintenance program includes detailed visual inspections of cockpit windshields from the inside at every A-check (750 flight hours, 375 flight cycles, or 121 days) and from the outside every 20 months. The most recent inside inspection was on April 27, 2015, 93:52 flight hours and 43 flight cycles before the incident, with no findings. The most recent outside inspection was during a C-check on April 30, 2014, 3,874:22 flight hours and 1,750 flight cycles prior, where the moisture seal was noted as eroded and repaired.
Operational Procedures
QRH procedure 80.13A for windshield/window arcing instructs pulling the circuit breaker for the affected windshield if arcing, burning smell, or smoke is observed. Procedure 80.14A for a cracked windshield directs checking if the inner ply is cracked; if not, no limitations apply. The captain, four months later, could not recall if ECAM messages or circuit breakers were involved and noted the flight crew could not determine if the inner ply was cracked due to possible melting and smoke.
Windshield Manufacturer Information
PPG Aerospace indicated the current windshield design (NP165331-1/-2) entered service in April 2010 with improved seals and heating system, and no reported arcing events or age-related failures. The older design (NP165311) remains approved for installation. In the operator's fleet, mean time between replacements for the older design was about 31,863 hours. PPG reported an average life of about 21,050 flight hours (7 years) based on operator data. Approximately 800 to 1,000 of the older windshields were estimated to be in service at the time of the report.