R44 “Unanticipated Yaw” Accident During Tailwind Take Off Caught on Video Say NTSB

R44 “Unanticipated Yaw” Accident During Tailwind Take Off Caught on Video Say NTSB(N3264U)

On 20 December 2020 Robinson R44 N3264U crashed at Morris Municipal Airport/Washburn Field, Illinois  The pilot received minor injuries.

Wreckage of Robinson R44 N3264U (Credit: NTSB)

Wreckage of Robinson R44 N3264U (Credit: NTSB)

In their safety investigation report the US National Transportation Safety Board (NTSB) explain that the pilot has 1650 hours of flying experience, 280 on type.

There were three weather observations recorded from around the accident time and the wind was from 240° to 250° at 6 to 7 knots, with no reported gusts.

The pilot was practicing “pickups and set downs in the same spot on the ramp and the wind was from the west as he completed these maneuvers.  During the final maneuver, the wind shifted, and he lost control of the helicopter”.

An airport surveillance video showed that during accident sequence, the helicopter was facing east when it briefly touched down and wobbled, then lifted up as the tail boom swung around in a clockwise direction. The tail rotor impacted the ramp then climbed and continued to rotate.

N3264u r44 video headline https://twitter.com/Aerossurance/status/1473345712113041408

The helicopter completed about 1.5 rotations as it descended and impacted the ground and rolled onto its right side.

N3264u r44 video

The tail rotor struck the ground early in the sequence.

Damaged Tail Rotor of Robinson R44 N3264U (Credit: NTSB)

Damaged Tail Rotor of Robinson R44 N3264U (Credit: NTSB)

NTSB note that Robinson issued a safety notice on unanticipated yaw in May 2013:

A pilot’s failure to apply proper pedal inputs in response to strong or gusty winds during hover or low-speed flight may result in an unanticipated yaw…

To avoid unanticipated yaw, pilots should be aware of conditions (a left crosswind, for example) that may require large or rapid pedal inputs.  Practising slow, steady state hovering pedal turn will help maintain proficiency ibn controlling yaw.  Hover training with a qualified instructor in varying wind conditions may also be helpful.

robinson sn42

NTSB Probable Cause

The pilot’s inadequate pedal application during liftoff with a tailwind, which resulted in a loss of yaw control and a subsequent impact with terrain.

Or was this simply mishandling? Watch the video and make your own decision!

Safety Resources

The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn.  You may also find these Aerossurance articles of interest:

Airbus have discussed unanticipated yaw phenomena and the ‘myth of LTE’ here:

unaticipate yaw

Aerossurance has extensive air safety, operations, SAR, airworthiness, human factors, aviation regulation and safety analysis experience.  For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com