VFR into IMC · NTSB CEN11FA401
CIRRUS DESIGN CORP SR22 — Columbus, OH
| Date | June 19, 2011 |
| Location | Columbus, OH |
| Aircraft | CIRRUS DESIGN CORP SR22 |
| Purpose of flight | Personal |
| Conditions | Day · Instrument Meteorological Cond |
| Phase / occurrence | Uncontrolled descent Collision with terr/obj (non-CFIT) |
| Pilot age | 54 |
| Pilot total time | 509 hrs · Building experience |
| Time in type | 236 hrs |
| Fatalities | 2 |
Probable cause
NTSB findings
- Personnel issues-Psychological-Perception/orientation/illusion-Spatial disorientation-Pilot - C
- Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C
- Environmental issues-Conditions/weather/phenomena-Ceiling/visibility/precip-Low ceiling-Effect on personnel - C
What happened
After takeoff in instrument meteorological conditions, the airplane was cleared for a left turn. Shortly thereafter, the airplane entered a left climbing turn, and the pilot engaged the autopilot. The flight director subsequently commanded a right roll and a decrease in pitch attitude. (The GPS steering command was set to navigate to a waypoint, and the shortest way to get there was a turn to the right.) The airspeed decreased to 105 knots and the bank angle was over 45 degrees left-wing low, so the aural underspeed alert activated because of the risk of stall. The nose-up pitch attitude decreased through level flight and entered a nose-down attitude; the left bank angle continued to increase. The underspeed alert ceased when the airplane reached an airspeed of 141 knots; the airplane was at a maximum left bank angle of 72 degrees and a maximum nose-down attitude of 24 degrees. Recorded data showed the engine was producing power throughout the flight and the autopilot was operating normally. An examination of the engine and airplane revealed no evidence of mechanical malfunctions or failures that would have precluded normal operations. Given that the autopilot was set such that it would command a right turn when engaged, yet the pilot was instructed by the air traffic controller to turn left, it is likely that the pilot was overpowering the autopilot system to comply with the instructions. According to the airplane manufacturer, it would only take 17 pounds of force to override the autopilot in pitch and 3 to 5 pounds to override the roll. Further, given the instrument conditions that were present at the time, it is likely that the pilot experience spatial disorientation and did not recognize the effects of his inputs.
oxicological results indicated the pilot had taken a sedating medication at some point before the accident; however, the levels were such that a determination of the level of impairment was not possible.