Frontier Airlines Flight 1225
Airbus A319 112 · Incident: system/component malfunction/failure (non-power) en route
From Orlando International Airport (MCO) to Harry Reid International Airport (LAS)
Event
- NTSB case
- CEN15IA225
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Airbus A319 112
- Aircraft type
- Airbus A319
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N941FR
- Operator
- Frontier Airlines
- Onboard fatalities
- Unknown
- Route
- From Orlando International Airport (MCO), Orlando, FLTo Harry Reid International Airport (LAS), Las Vegas, NV
- Aircraft age
- About 10 years (built 2005)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- System/component malfunction/failure (non-power)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Aircraft › Aircraft structures
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
About 1 hour into the air carrier flight, the flight crew observed arcing and sparks along the bottom of the windshield. The flight crew then heard a popping sound and observed the windshield cracking. The crew subsequently declared an emergency, diverted the flight to another airport, and landed the airplane without further incident. The captain did not remember if any breakers popped or if there was an electronic centralized aircraft monitor message during the event.
Postincident examination of the windshield revealed evidence of repairs to the moisture seal along the windshield's entire upper and aft edges, and the windshield exhibited typical signs of aging. The interlayer material adjacent to the edges of the windshield was cloudy and cracked. Evidence of moisture ingression into the laminate around the edges of the windshield was found. The moisture ingression at the lower, forward corner of the windshield had progressed inward to the bus bar. Brown, bubbled interlayer material was found adjacent to the windshield fracture origins, indicating that the windshield heat was powered at the time of fracture and that electrical arcing had occurred. The moisture likely disrupted the electrical path between the bus bar and the windshield's electrical heating film, which resulted in the electrical arcing and subsequent cracking of the windshield's outer glass pane.
The operator's maintenance program required periodic inspections of the incident part number windshields in its fleet, which were in accordance with the windshield manufacturer's recommended inspections. A review of the airplane's maintenance records revealed that the windshield was inspected about 11 months before the incident. During this inspection, the windshield's moisture seal was noted to be eroded and was subsequently repaired. The incident windshield was last inspected 8 days before the accident and included a detailed inspection of the moisture seal for cracks and erosion, and no findings were noted. The delamination, discoloration, interlayer microflakes, bubbling, and burn spots were within the specified limits of the airplane maintenance manual.
The incident windshield was installed on the airplane at manufacture, and it had accumulated 38,085 flight hours since its installation. The latest windshield design, which entered service 5 years before the incident, includes enhancements that reduce the potential for moisture ingress and electrical arcing. To date, there have been no reported electrical arcing events or age-related failures of the latest windshield design.
Probable cause
The ingression of moisture into the windshield’s laminate layer, which induced electrical arcing in the windshield heating system that subsequently cracked the outer glass pane of the windshield.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN15IA225
- Event ID
- 20150511X92031
- Case number
- CEN15IA225
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2015-05-05.
- API snapshot SHA-256: bc4e9559637c0fe1cbd4196582201875d12bbdd269f3f5685aab98ee953f21af; retrieved 2026-09-16T02:18:04.043Z.