Beech B100 N4490M accident near Rapid City, South Dakota

Probable cause

The flight crewmembers’ failure to secure the patient using the available over-the-shoulder restraints and the encounter with clear-air turbulence during cruise descent.

NTSB analysis

The air-ambulance flight encountered clear-air turbulence during cruise descent. During the turbulence encounter, the patient’s unrestrained upper-torso fell off the aircraft mounted stretcher assembly. After the turbulence had subsided, the patient’s unrestrained head, neck, and upper-torso were laying off the stretcher in the center aisle. His restrained lower body remained attached to the stretcher which was elevated off the cabin floor. The cabin flight crewmembers stabilized the patient’s neck before repositioning him back onto the stretcher. The airplane then made an uneventful landing at its intended destination. The patient suffered a fracture of the C3 cervical vertebra during the turbulence encounter. The stretcher’s available over-the-shoulder restraints were not used because of an interference caused by a flexible lift system that was used to transfer the patient from the ambulance gurney to the aircraft’s stretcher. After the accident the aeromedical transport company discontinued the use of the flexible patient lift system model used during the accident flight and required flight crewmembers to only use lift systems that allowed the use of the aircraft stretcher’s available over-the-shoulder restraints.

Text from the NTSB. Open the NTSB docket for CEN09LA388 for the full record.