American Airlines Commercial Flight Operations Flight 1738
Boeing B757-200 · Incident: system/component malfunction/failure (non-power) en route
From Luis Munoz Marin International Airport (SJU) to Philadelphia International Airport (PHL)
Event
- NTSB case
- ENG08IA011
- 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
Boeing B757-200
- Aircraft type
- Boeing 757
- 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
- N624AA
- Onboard fatalities
- Unknown
- Route
- From Luis Munoz Marin International Airport (SJU), San Juan, PRTo Philadelphia International Airport (PHL), Philadelphia, PA
- Aircraft age
- Not recorded
- 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
- Aircraft › Aircraft systems
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
During cruise flight the crew experienced smoke in the cockpit, none of it coming from an obvious place, followed by the fracture of the inner pane of the first officer's windshield. They declared an emergency and diverted the airplane to a local airport where an uneventful landing was made. Examination of the widow revealed evidence of arcing at the upper, aft (J1) and upper, forward (J4) windshield heat terminal locations and inner pane fracture initiation beneath the upper, forward (J4) terminal block. The initiation point for the arcing at both terminal locations could not be identified due to the damage sustained.
Probable cause
the arcing of the windshield heat system at the upper, aft (J1) and upper, forward (J4) terminal locations on the first officer's windshield, which caused the inner pane of glass to fracture.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ENG08IA011
- Event ID
- 20080212X00178
- Case number
- ENG08IA011
- 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, coordinates. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2008-01-31.
- API snapshot SHA-256: 649c3fa536dc158848a272d3142c848ba710624ee3ea7971555e8667c7f8824b; retrieved 2026-09-15T09:21:53.780Z.