Narrative:
Lost control after encountering clear air turbulence at FL430. The Learjet had exceeded its Mach limits when the pilots responded to the encounter. The Mach overspeed warning horn had been disconnected with an unauthorized cut-off switch.
PROBABLE CAUSE: "An unexpected encounter with moderate to severe clear air turbulence, the flightcrew's improper response to the encounter, and the aircraft's marginal controllability characteristics when flown at and beyond the boundary of its high altitude speed envelope, all of which resulted in the aircraft exceeding its Mach limits and a progressive loss of control from which recovery was not possible. Contributing to the accident was the disconnection of the Mach overspeed warning horn with an unauthorized cut-out switch which resulted in the absence of an overspeed warning that probably delayed the crew's response to the turbulence encounter, and the insonsistencies in aircraft flight manuals and flightcrew training programs regarding the use of spoilers to regain control."
| Status: | Accident investigation report completed and information captured |
| Date: | Monday 19 May 1980 |
| Time: | 12:05 EDT |
| Type: |  Learjet 25D |
| Operator: | Northeast Jet |
| Registration: | N125NE |
| MSN: | 25-271 |
| First flight: | 1979 |
| Total airframe hrs: | 1200 |
| Engines: | 2 General Electric CJ610-8A |
| Crew: | Fatalities: 2 / Occupants: 2 |
| Passengers: | Fatalities: 0 / Occupants: 0 |
| Total: | Fatalities: 2 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Aircraft fate: | Written off (damaged beyond repair) |
| Location: | 167 km (104.4 mls) W off Sarasota, FL, USA [Gulf of Mexico] ( Atlantic Ocean)
|
| Phase: | En route (ENR) |
| Nature: | Ferry/positioning |
| Departure airport: | West Palm Beach International Airport, FL (PBI/KPBI), United States of America |
| New Orleans International Airport, LA (MSY/KMSY), United States of America |
Lost control after encountering clear air turbulence at FL430. The Learjet had exceeded its Mach limits when the pilots responded to the encounter. The Mach overspeed warning horn had been disconnected with an unauthorized cut-off switch.
Probable Cause:
PROBABLE CAUSE: "An unexpected encounter with moderate to severe clear air turbulence, the flightcrew's improper response to the encounter, and the aircraft's marginal controllability characteristics when flown at and beyond the boundary of its high altitude speed envelope, all of which resulted in the aircraft exceeding its Mach limits and a progressive loss of control from which recovery was not possible. Contributing to the accident was the disconnection of the Mach overspeed warning horn with an unauthorized cut-out switch which resulted in the absence of an overspeed warning that probably delayed the crew's response to the turbulence encounter, and the insonsistencies in aircraft flight manuals and flightcrew training programs regarding the use of spoilers to regain control."
Accident investigation:
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Classification:
Loss of control
Follow-up / safety actions
NTSB issued 1 Safety Recommendation
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Photos
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from West Palm Beach International Airport, FL to New Orleans International Airport, LA as the crow flies is 1053 km (658 miles).
Accident location: Exact; as reported in the official accident report.
Distance from West Palm Beach International Airport, FL to New Orleans International Airport, LA as the crow flies is 1053 km (658 miles).
Accident location: Exact; as reported in the official accident report.
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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