NTSB Identification: FTW86MA058.
The docket is stored on NTSB microfiche number 30068.
Accident occurred Friday, April 04, 1986 in REDWATER, TX
Probable Cause Approval Date: 02/02/1988
Aircraft: Israel Aircraft Industries 1124A, registration: N50SK
Injuries: 7 Fatal.

NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft accident report.

AIRPLANE CRASHED DURING A UNCONTROLLED DESCENT, FOLLOWING A TURBULENCE UPSET AT FL370. THE UPSET OCCURRED AS A RESULT OF CLR AIR TURB ASSOCIATED WITH A VIP LVL 6 THUNDERSTORM LOCATED WITHIN 7 MILES OF THE LAST POS OF THE AIRPLANE. AFTER THE UPSET, THE AIRPLANE PENETRATED AND DESCENDED THRU THE CELL WHICH CONTAINED LIGHTNING, EXTREME TURB AND SEVERE ICING. DURING THE UPSET/DESCENT BOTH ENG'S FLAMED OUT AND THE CREW'S ATTEMPTS TO RECOVER THE AIRPLANE WERE UNSUCCESSFUL DUE TO CONDITIONS IN THE CELL. CREW RECV'D AN IMPROPER BRIEFING FROM FSS AND RPT'D THEIR RADAR WAS MALFUNCTIONING TO THE DEP CONTROLLER. SIGMET AND AWW INFO WAS NOT GIVEN DURING THE BRIEFING. AS THE AIRPLANE CAME OUT OF THE BOTTOM OF THE CELL AT 4,000', THE CREW OVERSTRESSED THE AIRPLANE CAUSING THE LFT MLG DOOR TO SEPARATE AND HIT THE LFT HORZ STAB WHICH SUBSEQUENTLY SEPARATED IN OVERLOAD. IMPACT WAS 82 DEGREES NOSE DOWN. NATURE OF THE AIRPLANE RADAR MALF COULD NOT BE DETERMINED.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

FLIGHT/NAV INSTRUMENTS,WEATHER RADAR SYSTEM..FAILURE,PARTIAL

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

WEATHER CONDITION..THUNDERSTORM

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

WEATHER CONDITION..TURBULENCE,CLEAR AIR

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

WEATHER CONDITION..GUSTS

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

WEATHER CONDITION..DOWNDRAFT

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

PREFLIGHT BRIEFING SERVICE..IMPROPER..ATC PERSONNEL(FSS)

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

HAZARDOUS WEATHER ADVISORY..NOT ISSUED..ATC PERSONNEL(FSS)

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

IN-FLIGHT WEATHER ADVISORIES..NOT ISSUED..ATC PERSONNEL(FSS)

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

INFORMATION UNCLEAR..ATC PERSONNEL(FSS)


Contributing Factors

OPERATION WITH KNOWN DEFICIENCIES IN EQUIPMENT..CONTINUED..PILOT IN COMMAND


Contributing Factors

LIGHT CONDITION..DARK NIGHT



Contributing Factors

EXCESSIVE WORKLOAD (TASK OVERLOAD)..PILOT IN COMMAND


Contributing Factors

EXCESSIVE WORKLOAD (TASK OVERLOAD)..COPILOT/SECOND PILOT

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