NTSB Identification: SEA88FA069.
The docket is stored on NTSB microfiche number 37149.
Nonscheduled 14 CFR
Accident occurred Friday, April 08, 1988 in SODA SPRINGS, ID
Probable Cause Approval Date: 07/03/1989
Aircraft: AERO COMMANDER 680FL, registration: N291NC
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

WHILE EN ROUTE ON A NIGHT IFR CARGO FLT, THE PLT REQD & WAS CLRD FOR A DSCNT FROM AN IFR CRUISE ALT OF 16,000 FT TO PROCEED VFR-ON-TOP. THE LAST TRANSMISSION FROM THE ACFT WAS AT 2106 WHEN THE PLT ACKNOWLEDGED THAT HE WAS FAMILIAR WITH THE TERRAIN ALONG THE ROUTE. AT 2121:51 MDT, RADAR CONTACT WAS LOST AFTER THE ACFT MADE AN APRX 360 DEGREE LEFT TURN & DESCENDED THRU 13,800'. SHORTLY AFTER THAT, THE CONTROLLER TRIED TO CALL THE PLT TO INFORM HIM THAT RADAR CONTACT WAS LOST, BUT WAS UNABLE TO MAKE RADIO CONTACT. LATER, WRECKAGE OF THE ACFT WAS FOUND WHERE IT HAD CRASHED ABOUT 2 MI SW OF WERE RADAR CONTACT WAS LOST. THE WRECKAGE WAS SCATTERED OVER AN AREA OF MORE THAN ONE MILE. AN INVESTIGATION REVEALED THE LEFT WING & RGT HORIZONTAL STABILIZER HAD SEPD UPWARD FROM OVERLOAD. NO PRE-ACDNT FATIGUE OR PART FAILURE/MALFUNCTION WAS FND. WX RPRTS & PIREPS INDCD MODERATE TURBC & TOWERING CUMULUS CLOUDS IN THE AREA. APRX 60 MI WEST AT POCATELLO, ID, SNOW SHOWERS WERE RPRTD; 2 TO 3 INCHES OF SNOW FELL ON THE WRECKAGE OVERNIGHT.

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

DESIGN STRESS LIMITS OF AIRCRAFT..EXCEEDED..PILOT IN COMMAND


Contributing Factors

LIGHT CONDITION..DARK NIGHT


Contributing Factors

WEATHER CONDITION..SNOW


Contributing Factors

WEATHER CONDITION..THUNDERSTORM


Contributing Factors

WEATHER CONDITION..TURBULENCE




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