Saturday, November 28, 2020

Hard Landing: Hughes OH-6A, N911EP; accident occurred August 06, 2020 at Spirit of St. Louis Airport (KSUS), Chesterfield, Missouri

Aviation Accident Final Report - National Transportation Safety Board

Additional Participating Entity: 
Federal Aviation Administration / Flight Standards District Office; St. Louis, Missouri

Investigation Docket - National Transportation Safety Board:

St. Louis County Police Department

Location: St Louis, MO
Accident Number: CEN20CA326
Date & Time: 08/06/2020, 1515 CDT
Aircraft: Hughes 369A
Aircraft Damage: Substantial
Defining Event: Hard landing
Injuries: 2 None
Flight Conducted Under: Public Aircraft 


The instructor reported that during the instructional flight, he was manipulating the controls and accepted the option to land on the taxiway; he decreased the throttle for a full touchdown auto rotation. About 50 ft above the ground (agl), he flared the helicopter and leveled off about 5 to 10 ft agl. The instructor reported that everything seemed "normal" at this point. He then raised the collective, but the descent was not arrested, so he raised the collective full up. The helicopter landed hard and shook violently. The instructor closed the throttle to which stopped the fuel supply. The tailboom was substantially damaged.

The flight instructor reported that there were no mechanical anomalies with the helicopter that would have precluded normal operation.

The instructor added that he felt a slight tailwind after exiting the helicopter and that the tail wind caused a "vortex ring state" which stalled the main rotor blades.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The flight instructor's failure to maintain helicopter control which resulted in a hard landing while preforming a practice autorotation.


Personnel issues Aircraft control - Instructor/check pilot
Aircraft Descent rate - Capability exceeded
Environmental issues Tailwind - Effect on operation

Factual Information

History of Flight

Landing Other weather encounter
Landing Attempted remediation/recovery

Pilot Information

Certificate: Flight Instructor; Commercial
Age: 51
Airplane Rating(s): None
Seat Occupied: Left
Other Aircraft Rating(s): Helicopter
Restraint Used:
Instrument Rating(s): Helicopter
Second Pilot Present: Yes
Instructor Rating(s): Helicopter
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 06/22/2020
Occupational Pilot: No
Last Flight Review or Equivalent: 
Flight Time: 6814 hours (Total, all aircraft), 6814 hours (Total, this make and model), 6338 hours (Pilot In Command, all aircraft)

Pilot Information

Certificate: Commercial
Age: 39
Airplane Rating(s): None
Seat Occupied: Right
Other Aircraft Rating(s): Helicopter
Restraint Used: 
Instrument Rating(s): None
Second Pilot Present: Yes
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 06/29/2020
Occupational Pilot: No
Last Flight Review or Equivalent: 06/18/2020
Flight Time: 635 hours (Total, all aircraft), 91 hours (Total, this make and model), 585 hours (Pilot In Command, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: Hughes
Registration: N911EP
Model/Series: 369A No Series
Aircraft Category: Helicopter
Year of Manufacture:
Amateur Built:No 
Airworthiness Certificate:
Serial Number: 591176
Landing Gear Type: Skid
Date/Type of Last Inspection: 08/04/2020, 100 Hour
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines: Turbo Shaft
Airframe Total Time: 1229.4 Hours at time of accident
Engine Manufacturer: Rolls Royce
ELT: C91 installed, activated, did not aid in locating accident
Engine Model/Series: 250-c20C
Registered Owner: St Louis County Police Department
Rated Power:
Operator: St Louis County Police Department
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation:
Distance from Accident Site:
Observation Time: 1454 CDT
Direction from Accident Site:
Lowest Cloud Condition: Scattered / 25000 ft agl
Visibility: 10 Miles
Lowest Ceiling:
Visibility (RVR):
Wind Speed/Gusts: 3 knots /
Turbulence Type Forecast/Actual:
Wind Direction: Variable
Turbulence Severity Forecast/Actual:
Altimeter Setting: 30.09 inches Hg
Temperature/Dew Point: 27°C / 13°C
Precipitation and Obscuration: No Precipitation
Departure Point: St Louis, MO (KSUS)
Type of Flight Plan Filed:
Destination: St Louis, MO (KSUS)
Type of Clearance: VFR
Departure Time: CDT 
Type of Airspace: Class D

Airport Information

Airport: Spirit of St Louis Airport (KSUS)
Runway Surface Type: Unknown
Airport Elevation: 463 ft
Runway Surface Condition: Dry
Runway Used: N/A
IFR Approach: None
Runway Length/Width:
VFR Approach/Landing: Simulated Forced Landing

Wreckage and Impact Information

Crew Injuries: 2 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 2 None
Latitude, Longitude: 38.663611, -90.644722 (est)


  1. Looks like the controller dropped the ball on this mast bump.

  2. Helicopter land all in all sort of locations without benefit of controller or wind socks. How do the pilots judge wind speed and direction in those situations?

    1. "... hovering 360, the helicopter wants to weathervane into the wind. It is made that way to facilitate more comfortable flying (straight and level) for obvious reasons. When you fight that, you really have to do the “pedal dance” to get the helicopter to do what you want it to." @

  3. Over 50 years ago in SE Asia, Helicopter Scouts "Saw Combat Up Close in  'Loaches,' a Army OH-6A ... Although most combat aircraft in Vietnam aimed for altitudes and speeds that helped them avoid anti-aircraft weapons, U.S. Army crews flying Hughes OH-6A Cayuse helicopters flew low and drew fire—to set up the shots for the Bell AH-1G Cobras circling above. These hunter-killer missions, among the most hazardous of the Vietnam War, tested the resolve of the OH-6 pilots and the aerial observers sitting beside them. Although many were still teenagers, their survival depended on well-honed instincts and razor-sharp reflexes, along with plenty of luck." @ military-aviation/snakes-loaches


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