Pilot Debrief

Beech 58 near Sioux Falls, SD — 2018-12-25

Final reportCEN19LA049
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Date
2018-12-25
Location
Sioux Falls, SD, USA
Airport
KFSD
Aircraft
Beech 58
Registration
N6745V
Category
Airplane
Highest injury
Fatal
Fatalities
2
Phase of flight
Approach

Probable cause

The pilot's failure to maintain adequate airspeed during the instrument approach which led to an aerodynamic stall.

NTSB narrative

The pilot and passenger were on a cross-country flight and an instrument flight rules approach in instrument meteorological conditions. According to air traffic control transcripts, an air traffic controller at the destination airport cleared the flight for the RNAV approach for runway 33. According to ADS-B flight track data, the airplane then turned toward the final approach path just inside the initial approach fix at 3,100 ft mean sea level (msl) and 156 knots calibrated airspeed (KCAS). Subsequently, the airplane proceeded west of the final approach centerline, turned back through the centerline to the east, and then back to the west, resembling s-turns through the extended centerline. During the s-turns across the extended centerline, the controller cleared the airplane to land. Two minutes later, the airplane was about 3,000 ft msl and 78 KCAS, and then began to rapidly descend. According to a witness and video footage of the accident, the airplane descended in a steep, nose down attitude. The witness added that it appeared that he then “saw airplane try to pull out of a dive” just before it impacted the ground. The airplane impacted trees and a building and then came to rest in a residential neighborhood about 200 ft south of the last radar location. The airplane was massively fragmented and a postimpact fire ensued. Impact and fire damage precluded a thorough examination and functional testing of the related airplane systems. Examination of both engines and propeller assemblies revealed signatures consistent with symmetric power development at the time of the accident. According to a family member of the pilot, 3 months before the accident, the pilot was en route at altitude when the airplane suddenly nosed over. According to a work order, 3 weeks before the accident, the autopilot was removed and repaired. The repair station owner reported that, after a flight 3 days before the accident, the pilot told him that he had no issues with the airplane and that the flight was uneventful. A review of the airplane’s flight track showed the pilot making S-turns across the approach course, which is consistent with the pilot hand-flying the approach, not a coupled autopilot approach. Therefore, it is unlikely that the pilot was flying the instrument approach using the autopilot system. Further, although the autopilot system could not be functionally tested due to impact and fire damage, it is unlikely that the autopilot system played a role in the accident if it was not in use. Therefore, based on the radar data, it is likely that the pilot failed to maintain adequate airspeed during the final approach, which resulted in the exceedance of the airplane’s critical angle of attack and a subsequent aerodynamic stall. Given the witness account and surveillance video, it is likely the pilot was attempting to recover from the stall but did not have adequate altitude to do so.

Analysis

Primary failure mode
Controlled flight into terrain
First missed decision gate
Pilot could have diverted to an alternate airport with instrument approach capability.

NTSB coding

Evidence available

  • ATC audio
  • Video
  • ADS-B / radar
  • Photos
  • 22 docket documents
View NTSB final reportView NTSB docket

Docket documents22

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