Mark Huber is an aviation industry veteran who has worked in the flight training, aircraft sales, aircraft component, and airport development businesses. He has flight time in more than 50 different and diverse aircraft, including helicopters, aerobatic aircraft, vintage warbirds, jet fighters, business jets and turboprops, and transport-category aircraft. He has jumped out of several of these—on purpose—with a parachute. His defense and aviation journalism has been published in a variety of national and international periodicals.

Contributor

Mark Huber

The crew of a search-and-rescue Leonardo AW189 narrowly avoided an accident due to an incomplete understanding of the helicopter’s automatic flight control system (AFCS) modes. So concluded the UK’s Air Accidents Investigation Branch (AAIB) in a recently released report.
The incident occurred on July 26, 2021, at Ballintoy Harbour in Northern Ireland. The helicopter was on its third approach to collect a casualty from a site adjacent to high ground in poor visibility. A mismatch between the previously selected AFCS heading reference and the heading flown by the pilot flying (PF) triggered uncommanded yaw oscillations. According to the AAIB, the pilot selected AFCS hover mode, which resulted in yaw toward the high ground. The PF then selected AFCS go-around and the helicopter accelerated toward the terrain. The crew made a climbing turn to its planned escape heading, recovered to a safe height, and returned to base.
The AAIB concluded that "the unexpected yaw occurred as a result of flying out-of-detent, thereby overriding the engaged HDG [heading] mode. Consequently, the reference heading used by the AFCS did not capture the helicopter’s current heading, but instead remained at the heading selected when HDG was last engaged. When the PF stopped flying out-of-detent, the AFCS yawed the helicopter towards the previously captured reference heading, which resulted in the helicopter tracking towards high ground.”
The AAIB also noted that, in this incident, standard operating procedures were not always followed, and lack of communication between the pilots meant that it might not have been obvious to the pilot monitoring that the PF was flying out-of-detent. The AAIB counseled, “In mixed mode flying it is important that both pilots have a clear understanding as to which axis the AFCS and pilot are controlling, and the effect this might have on parameters such as heading reference.”

News and information on safety procedures and concerns.

AAIB: AW189 Incident Crew Did Not Understand Its Automatic Flight Control System

An AFCS mismatch triggered an uncommanded yaw

A mismatch between the previously selected AFCS heading reference and the heading flown by the pilot flying triggered uncommanded yaw oscillations.

AAIB: AW189 Incident Crew Did Not Understand Its AFCS

2024 Corporate Aviation Leadership Summit

Amy Wilder

News and issues relating to business, corporate and private aviation, primarily regarding turbine-engine-powered airplanes and helicopters. Subjects include aircraft, engines, maintenance, operations, personnel, acquisitions, accidents, safety, security, and training.

Altitude and course deviation, traffic proximity remain top categories

ACSF Data Shows Stable Bizav Risk Amid 2026 Pressures

Kerry Lynch

News and issues relating to international air transport and cargo carriers, national airlines and regional airlines, including aircraft, engines, personnel, acquisitions, accidents, safety, security and training.

Essential news and analysis on the defense aerospace business. Your trusted source for new and ongoing programs and requirements in military aircraft (manned and unmanned), engines, avionics, weapons and associated systems, including ground-based air defense.

Aircraft remained within separation guidance but neared each other after the presidential helicopter was unable to alert ATC

Faulty Comms Preceded Marine One/Envoy Close Call

Graham leaving agency within months of confirmation to another term

NTSB Vice Chair Michael Graham To Retire October 2

Stuart “Kipp” Lau

News about bills, laws, regulations and other governmental decisions affecting aviation and aerospace. Topics include FAA re-authorizations, taxes on fuel and aviation activities, environmental legislation, ICAO decisions, governmental mediation of labor conflicts and World Trade Organization disputes and decisions.

UK CAA concerned over rise in unstable approaches continuing to land

AINsight: Go-arounds Are a Normal and Expected Outcome

News about significant aircraft accidents and information from accident reports.

News and issues regarding all manner of civil and military rotorcraft and their powerplants, including helicopters, tilt rotors and unmanned air vehicles.

Helicopters more than twice as vulnerable to loss of visual reference accidents than airplanes

TSB: Rotorcraft More Prone To Loss-of-visual-reference Accidents

Charlotte Bailey

News about environmental issues relating to aircraft operations, including noise issues, emissisions, and regulations. See Fuel for biofuel.

News and issues relating to the aerospace industry that are related to the science, engineering and business of flight in space involving civil, industrial and military applications, and similar topics related to flight in the atmosphere of the Earth that are not covered more directly by other AINonline subject channels. In other words, both astronautical and aeronautical subjects, except for those aeronautical topics that are specifically covered elsewhere on this website.

In this article

Leonardo AW189

Leonardo

More In Safety

ACSF Data Shows Stable Bizav Risk Amid 2026 Pressures

Altitude and course deviation, traffic proximity remain top categories

Faulty Comms Preceded Marine One/Envoy Close Call

Aircraft remained within separation guidance but neared each other after the presidential helicopter was unable to alert ATC

NTSB Vice Chair Michael Graham To Retire October 2

Graham leaving agency within months of confirmation to another term

AINsight: Go-arounds Are a Normal and Expected Outcome

UK CAA concerned over rise in unstable approaches continuing to land

TSB: Rotorcraft More Prone To Loss-of-visual-reference Accidents

Helicopters more than twice as vulnerable to loss of visual reference accidents than airplanes

EASA: Atmospheric Icing Insufficiently Understood

European air safety agency calls for more comprehensive studies into phenomenon

Embry-Riddle Introduces ‘Safer Skies’ Video Podcasts

First episode features three-time space shuttle veteranJanet Kavandi

Li-ion Thermal Runaways on the Rise in Aircraft Cabins

Numbers are rising and the risk of a serious incident is increasing

AIN Products

SUBSCRIPTIONS

RESOURCES

ABOUT AIN