Flagship Airlines Flight 5634
Aerospatiale ATR-42-300 · Incident: airframe, component or system failure en route
From Tampa International Airport (TPA) to Miami International Airport (MIA)
Event
- NTSB case
- MIA98IA100
- 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
- 0
- 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
Aerospatiale ATR-42-300
- Aircraft type
- Aerospatiale ATR-42
- 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
- N275BC
- Operator
- Flagship Airlines
- Onboard fatalities
- Unknown
- Route
- From Tampa International Airport (TPA), Tampa, FLTo Miami International Airport (MIA), Miami, FL
- 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
- First occurrenceThe 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
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Company maintenance personnel › Maintenance, installation, improper
- Electrical system, electric switch › Shorted
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The No. 1 generator failed while in cruise flight. When the flighcrew attempted to reset the No. 1 generator, the No. 2 generator also failed. Attempts to reset either of the generators were unsuccessful and after about 1 minute the main battery failed. The flightcrew switched to the emergency battery and made a precautionary landing. Postlanding examination showed the No. 1 generator had failed due to failure of the field excitation wire lug which was caused by improper installation of the wire. The aircraft was on the second flight since the No. 1 generator was changed. The No. 2 generator operated normally in postlanding tests. The main battery was found to be discharged. The battery was returned to service after charging. After the incident the aircraft continued to discharge the main battery and the engine start switch was found defective causing the main battery to discharge.
Probable cause
The failure of the No. 1 generator field excitation return wire terminal lug due to improper installation of the field excitation return wire by maintenance personnel; the subsequent failure of the No. 2 generator due to overvoltage, caused by the momentary closure of the No. 1 generator contactor, as a result of the flight crew's attempt to reset the No. 1 generator, while an overvoltage condition existed at its POR, due to the shorted failure of the No. 1 GCU diode CR17; and the rapid failure of the aircraft's main battery, accelerated by its existing depleted condition, following an extended period of inadequate charging, due to a damaged electrical system.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record MIA98IA100
- Event ID
- 20001211X09735
- Case number
- MIA98IA100
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: investigation status, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: f9a42506837790813d86209afe66fe040c5e61a54db688078e9951dd97ee99cd; retrieved 2026-09-18T17:12:03.959Z.