Investigation Summary
The aircraft was being positioned empty from Terre Haute to West Lafayette under IFR conditions conducive to airframe icing. Although the crew utilized engine, pitot, and windshield anti-ice systems, the wing and empennage deice systems remained off. During the flight, approximately 1/2 to 3/4 inch of rime ice accumulated on the leading edge of the horizontal stabilizer. As the aircraft reached short final at approximately 400 feet AGL, the crew selected 35 degrees of landing flaps. This configuration change, combined with a forward center of gravity (22.1% MAC) and the disrupted airflow over the iced tailplane, induced a tailplane stall. The aircraft pitched down into a steep descent; while the crew attempted a partial recovery, the aircraft struck a rising embankment and was destroyed by impact and a post-ground fire.
Final Conclusions
The National Transportation Safety Board determined the probable cause to be a loss of control resulting from improper in-flight decisions by the crew and the undetected accumulation of ice on the horizontal stabilizer. The condition was exacerbated by the aircraft's forward center of gravity and the extension of full landing flaps, which triggered a tailplane stall.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Age 36. Held an Airline Transport certificate with 6,294 hours as PIC. Held a Class 1 medical certificate issued December 20, 1988, with no waivers or limitations.
Systems & Failure Modes
Horizontal Stabilizer Deice
The system intended to clear ice from the tailplane was found to be in the 'off' position despite icing conditions.
Landing Flaps
The extension of flaps to 35 degrees increased the downwash over the tail, which, when combined with ice accumulation, led to a tailplane stall.
Interesting Facts
- 01Post-accident examination found 1/2 to 3/4 inch of rime ice on the leading edge of the horizontal stabilizer.
- 02No ice was found on any other portion of the airframe.
- 03Cockpit evidence indicated that wing and empennage deice systems were not activated.
- 04The aircraft was operating with a forward center of gravity at 22.1% MAC.
- 05Weather at the time of the accident included winds from 280 degrees at 16 knots gusting to 23 knots, visibility of 8 miles, and an overcast ceiling at 2,200 feet AGL.
- 06The temperature was 0 degrees Celsius with a dew point of -4 degrees Celsius.
Safety Actions & Advisories
FAA Airworthiness Directive 92-02-03
Following this and other tailplane stall incidents, the FAA issued AD 92-02-03 for all Nihon YS-11 series airplanes, requiring revisions to the Airplane Flight Manual to include procedures for operating in icing conditions and specific warnings regarding tailplane stall symptoms and recovery.
Location
NO VERIFIED COORDINATES · Coordinates are the estimate published in the ntsb final report. No map is shown, because a marker here would imply a precision the record does not have.
Reported location: West Lafayette, Indiana, United States