Safety issue

Safety issue description

The Robinson Helicopter pilot’s operating handbook sections for operation in high winds or turbulence did not warn of the potential for turbulence-induced low‑G, and rapid right roll, particularly at high airspeed or provide guidance for appropriate control inputs in response to a turbulence-induced low‑G situation. This increased the risk of pilots encountering low‑G independent of control inputs, and an in‑flight break‑up. 

Response by Robinson Helicopter Company

Robinson Helicopter Company (RHC) advised that it was currently reviewing and revising the pilot’s operating handbook, including the applicable safety notices, to improve guidance on the low-G condition, flight in turbulent conditions, and pilot distraction.

ATSB comment

The ATSB welcomes the documentation review being undertaken by RHC and will continue to monitor the safety issue until the proposed safety action is complete.
Issue number AO-2023-051-SI-01
Issue owner Robinson Helicopter Company
Transport function Aviation: General aviation
Issue status Closed – Partially addressed
Date issue released 30/06/2025
Issue status justification

The Robinson Helicopter Company updated Safety Notice SN-11 and SN-32 to establish a link between turbulence and a possible low-G condition. However, it did not emphasise the possibility of turbulence induced low-G without pilot control inputs. For this reason, the safety issue is closed as partially addressed.
Issue finalisation date 23/03/2026

Safety action

Action type Proactive action
Action number AO-2023-051-PSA-02
Organisation Robinson Helicopter Company
Action description

Robinson Helicopter Company updated the wording in Safety Notices SN-11 to introduce the contribution of the asymmetric stabiliser and clarify the role airspeed plays with relation to the low-G right roll, as well as introduce the symmetric stabiliser and the expected aircraft reaction to low-G. The SN-11 update also acknowledges turbulence as a possible contributing factor to low-G.

The updates also introduce the low-G condition and response with respect to turbulence in Safety Notice SN-32, as well as clarifying the defined turbulence conditions where reduced airspeed is recommended.
ATSB response

The updates to Safety Notice SN-11 and SN-32 go some way to addressing the concerns raised in Safety Issue AO-2023-051-SI-01, in that they acknowledge that turbulence as a possible contributing factor to the low-G condition, clarify the role airspeed plays in the development of a low-G right roll, and describe the mechanism that produces the uncommanded right roll.

However, both Safety Notices effectively state that the low-G condition can only result as a result of pilot mishandling, and does not acknowledge the potential risk of a turbulence induced low-G condition without pilot control input.

The ATSB believe that informing pilots of the potential dangers of turbulence, specifically the risk of turbulence induced low-G, is critical for safety. By avoiding clear communication of this point, the opportunity to improve safety has not been fully taken advantage of.

For this reason, a standalone Safety Recommendation AO-2023-051-SR-01 has been raised specifically to this point,
Action status Closed

Safety action

Action type Safety recommendation
Action number AO-2023-051-SR-01
Organisation Robinson Helicopter Company
Action description

The Australian Transport Safety Bureau recommends that Robinson Helicopter Company warns pilots of the potential for turbulence to induce a low-G condition, without any requisite pilot control inputs.

Due to the potentially small window of time available for pilots to recognise and respond to the condition, the ATSB considers that the emphasis that was initially proposed by the Robinson Helicopter Company is necessary to sufficiently alert pilots to the hazard.
Action status Closed

Organisation response

Date received 21/03/2026
Organisation Robinson Helicopter Company (RHC)
Response text

On 21 March 2026, the Robinson Helicopter Company (RHC) advised the ATSB that it had accepted the recommendation of the ATSB to implement changes to the Pilot’s Operating Handbook to increase information available to pilots concerning conditions that may lead to moderate or greater turbulence, the potential for turbulence induced low-G, and proper procedures to follow in these conditions.

RHC also advised that it did not accept the ATSB recommendation that it is necessary to provide a sentence that loss of loading on rotor due to turbulence is dangerous because it incorrectly asserts that a turbulence induced low-G condition in and of itself is dangerous when, in fact, it is the pilot’s improper response to a low-G condition that can lead to a dangerous condition. What is most important to emphasize is the recognition of conditions that may lead to significant turbulence so the pilot may avoid these conditions and procedures to follow in the event turbulence is encountered.

RHC advised that numerous changes were made in response to report AO-2023-051 including revising Safety Notices 11, 32, and 41 and that these changes were sufficient to reduce risk to an acceptable level, are fully effective, and address AO-2023-051-SR-01 Safety Recommendation.

RHC also called attention to Safety Notice SN-41, Pilot Distractions, addressing the negative consequences of mental distraction and possible complacency resultant from the use of automation.

In summary, to ensure safe outcomes, RHC advised that the pilot must 

1) Be aware of their surroundings (not distracted) 
2) Avoid potentially hazardous conditions based on their knowledge and awareness, and 
3) Know to correctly respond if they do encounter potentially hazardous conditions. 
RHC advised that it believed the combination of Robinson Helicopter Safety Notices SN-11, SN-32, and SN-41 achieved this objective.
ATSB response

The ATSB recommended that the Robinson Helicopter Company warns pilots of the potential for turbulence to induce a low-G condition, without any requisite pilot control inputs. The published amendment to Safety Notice 11 that included 'A pilot's improper response to turbulence may also introduce a dangerous loss of loading on the rotor' was considered insufficient to alert pilots to the hazard of a turbulence-induced low G condition in the absence of pilot input. Therefore, the safety issue was closed as partially addressed.
ATSB response date 23/03/2026