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.
|Date:||Monday 19 May 1980|
|C/n / 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 |
|Airplane damage:|| Destroyed|
|Airplane 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)|
|Departure airport:||West Palm Beach International Airport, FL (PBI/KPBI), United States of America|
|Destination airport:||New Orleans International Airport, LA (MSY/KMSY), United States of America|
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."
Follow-up / safety actions
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).