1969 — July 6, Air South Flight 168 System Failure and crash, near Monroe, GA — 14

–14 Aviation Safety Network. Accident Description. Air South Flight 168, 06 Jul 1969.
–14 Kimura. World Commercial Aircraft Accidents 3rd Ed., 1946-1993, V.1. 4-11-1994, p. 3-19.
–14 NTSB. AAR. Air South, Inc. Beechcraft… N844NS Near Monroe, GA July 6, 1969. 1970.

Narrative Information

Aviation Safety Network: Planned flight from Atlanta Airport, Georgia, for Greenville-Spartanburg Airport, South Carolina, with crew of 2 and 12 passengers.

“Air South Flight 168 departed Atlanta at 21:07. At 21:13 the flight reported level at its assigned cruising altitude of 7,000 feet. The Beech had been cruising for eleven minutes when it attained a gradual nose down attitude due to a change in the longitudinal trim. The pilots noticed the change after about six seconds and initiated a recovery action. The horizontal stabilizer continued to move to a full nose down position. Excessive pulling force on the control column was necessary to recover from the high speed dive. The necessary stick forces for such an out-of-trim condition can exceed the capability of one pilot, and in some cases two pilots, to control. The Beech continued to descend until both wings failed at high speed, just before the airplane crashed into the ground in a near vertical attitude.” (ASN. AD. Air South Flight 168, 06 Jul 1969; cites NTSB/AAR-70-18, Aug 26, 1970.)

National Transportation Safety Board Synopsis:

“An Air South, Inc., Beechcraft E99, N844NS, crashed near Monroe, Georgia, at approximately 2122 eastern daylight time, July 6, 1969. The aircraft, operating as Air South Flight 168, was en route from Atlanta, Georgia, to Greer, South Carolina. The 12 passengers and two crewmembers received fatal injuries in the accident and the aircraft was destroyed.

“An eyewitness to the accident stated that the aircraft descended in a near-vertical dive, with no change in attitude after it had nosed down. The weather in the accident area was reported to be clear and the wind was calm.

“The Board determines that the probable cause of this accident was an unwanted change in longitudinal trim which resulted in a nosedown high-speed flight condition that n was beyond the physical capability of the pilots to overcome. The initiating element in the accident sequence could not be specifically determined. However, the design of the air-craft flight control system was conducive to malfunctions which, if undetected by the crew, could lead t o a loss of control.

On August 1, 1969, the Board recommended that the Administrator, Federal Aviation Administration, establish emergency recovery procedures from unwanted or adverse longitudinal trim conditions and publish them in the FAA-approved Flight Manual. The Board also recommended that a horizontal stabilizer “In-Transit” warning system be installed in E99 aircraft and that the horizontal stabilizer trim range be restricted to prevent excessive aircraft nosedown trim while in flight.

“The Administrator replied on August 6, 1969, that he had taken action to carry out the Board’s recommendations.

“In addition, the Administrator took a number of other corrective actions relating to the longitudinal control system of the E-99.

“Finally, the Board recommends that direct FAA participation in the certification of new items be mandatory; that information gained from the investigation of large aircraft accidents be used by the FAA in the certification of mall aircraft; and that the FAA review the existing fault analysis system and require the completion of hazard analyses of the type required by par. 5.8.2, Military Standard 882, dated July 15, 1969.” (NTSB 1970, 1-2)

Sources

Aviation Safety Network. Accident Description. Air South Flight 168, 06 Jul 1969. Accessed 3-2-2009 at: http://aviation-safety.net/database/record.php?id=19690706-0

Kimura, Chris Y. World Commercial Aircraft Accidents 3rd Edition, 1946-1993, Volume 1: Jet and Turboprop Aircrafts. Livermore, CA: Lawrence Livermore National Laboratory, Risk Assessment and Nuclear Engineering Group. 4-11-1994.

National Transportation Safety Board. Aircraft Accident Report. Air South, Inc. Beechcraft B-99, N844NS Near Monroe, Georgia July 6, 1969 (NTSB-AAR-70-18). Washington DC: NTSB, adopted August 26, 1970, 57 pages. Accessed at:
http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR70-18.pdf