Status:	Final
Date:	19 MAY 1980
Time:	12:05 EDT
Type:	Learjet 25D
Operator:	Northeast Jet
Registration:	N125NE
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)
Nature:	Ferry/positioning
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

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 encouter 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 aircreft 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."

Events:

Sources: