Aircraft Accident Report AAR 2/2023 - Sikorsky S-92A, G-MCGY

Air Accidents Investigation Branch

November 2
10:00 2023


The Air Accidents Investigation Branch (AAIB) were notified of this accident on 4March2022, the day that it occurred. In exercise of his powers, the Chief Inspector of Air Accidents ordered an investigation to be carried out in accordance with the provisions of retained Regulation (EU) 996/2010 (as amended) and the UK Civil Aviation (Investigation of Air Accidents and Incidents) Regulations 2018.

The sole objective of the investigation of an accident or serious incident under these regulations is the prevention of accidents and serious incidents. It shall not be the purpose of such an investigation to apportion blame or liability.

In accordance with established international arrangements, the National Transportation Safety Board (NTSB) in the USA, representing the State of Design and Manufacture of the helicopter, appointed an Accredited Representative to the investigation. The helicopter operator, the hospital Helicopter Landing Site (HLS) Site Keeper, and the UK Civil Aviation Authority (CAA) also assisted with the investigation.


The helicopter, G-MCGY, was engaged on a Search and Rescue mission to extract a casualty near Tintagel, Cornwall and fly them to hospital for emergency treatment. The helicopter flew to Derriford Hospital (DH), Plymouth which has a Helicopter Landing Site (HLS) located in a secured area within one of its public car parks. During the approach and landing, several members of the public in the car park were subjected to high levels of downwash from the landing helicopter. One person suffered fatal injuries, and another was seriously injured.

The investigation identified the following causal factors:

  1. The persons that suffered fatal and serious injuries were blown over by high levels of downwash from a landing helicopter when in publicly accessible locations near the DH HLS.

  2. Whilst helicopters were landing or taking off, uninvolved persons were not prevented from being present in the area around the DH HLS that was subject to high levels of downwash.

The investigation identified the following contributory factors:

  1. The HLS at DH was designed and built to comply with the guidance available at that time, but that guidance did not adequately address the issue of helicopter downwash.

  2. The hazard of helicopter downwash in the car parks adjacent to the HLS was not identified, and the risk of possible injury to uninvolved persons was not properly assessed.

  3. A number of helicopter downwash complaints and incidents at DH were recorded and investigated. Action was taken in each case to address the causes identified, but the investigations did not identify the need to manage the downwash hazard in Car ParkB, so the actions taken were not effective in preventing future occurrences.

  4. Prior to this accident, nobody at DH that the AAIB spoke to was aware of the existence of Civil Aviation Publication (CAP)1264, which includes additional guidance on downwash and was published after the HLS at DH was constructed. The document was not retrospectively applicable to existing HLS.

  5. The operator of G-MCGY was not fully aware of the DH HLS Response Team staffs roles, responsibilities, and standard operating procedures.

  6. The commander of G-MCGY believed that the car park surrounding the DH HLS would be secured by the hospitals HLS Response Team staff, but the co?pilot believed these staff were only responsible for securing the HLS.

  7. The DH staff responsible for the management of the HLS only considered the risk of downwash causing harm to members of the public within the boundary of the HLS and all the mitigations focused on limiting access to this space.

  8. The DH staff responsible for the management of the HLS had insufficient knowledge about helicopter operations to safely manage the downwash risk around the site.

  9. The HLS safety management processes at DH did not result in effective interventions to address the downwash hazard to people immediately outside the HLS.

  10. HLS safety management processes at DH did not identify that the mitigations for the downwash hazard were not working well enough to provide adequate control of the risk from downwash.

  11. Communication between helicopter operators and DH was ineffective in ensuring that all the risks at the DH HLS were identified and appropriately managed.

  12. Safety at hospital HLS throughout the UK requires effective information sharing and collaboration between HLS Site Keepers and helicopter operators but, at the time of the accident, there was no convenient mechanism for information sharing between them.

Following this accident, Safety Action was taken by the helicopter operator, Derriford Hospital and NHS England Estates to control and mitigate the risk. The specific action taken is detailed in paragraph 4.2.1 of this report. Additional action by Derriford Hospital and NHS England Estates to improve safety, as described in paragraph 4.2.2 of this report, is either planned or in progress.

Helicopters used for Search and Rescue and Helicopter Emergency Medical Services (HEMS) perform a vital role in the UK and, although the operators of these are regulated by the UK Civil Aviation Authority, the many helicopter landing sites provided by hospitals are not. It is essential that the risks associated with helicopter operations into areas accessible by members of the public are fully understood by the HLS Site Keepers, and that effective communication between all the stakeholders involved is established and maintained. Therefore, nine Safety Recommendations have been made to address these issues, and these are listed in paragraph 4.1 of this report.

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AAR 2/2023: Sikorsky S-92A, G-MCGY

Published 2 November 2023

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