S92, Plymouth UK, 2022

S92, Plymouth UK, 2022


On 4 March 2022, a Sikorsky S92A touching down on the designated landing site at a Plymouth hospital to deliver a recovered casualty subjected several people in an adjacent car park to significant downwash. Two were blown over sustaining serious injuries with one dying later the same day. Hospital management was found to have failed to effectively assess the risks of landing site operation and its communications with the operator to ensure safe site use. The landing site was not being operated in accordance with guidance applicable to more recently opened sites nor was it required to be.

Event Details
Event Type
Flight Conditions
Flight Details
Type of Flight
Public Transport (Non Revenue)
Flight Origin
Take-off Commenced
Flight Airborne
Flight Completed
Phase of Flight
Derriford Hospital, Plymouth
Helicopter Involved, Inadequate Airport Procedures
Flight Crew / Ground Crew Co-operation
Aircraft / Person conflict
Damage or injury
Aircraft damage
Non-aircraft damage
Non-occupant Casualties
Number of Non-occupant Fatalities
Occupant Injuries
Occupant Fatalities
Off Airport Landing
Causal Factor Group(s)
Aircraft Operation
Airport Operation
Safety Recommendation(s)
Airport Management
Investigation Type


On 4 March 2022, a Sikorsky S92A (G-MCGY) being operated by Bristow Helicopters and dedicated to providing airborne SAR capability for the UK Maritime and Coastguard Agency had taken off from its base at Newquay to recover a casualty by winch from a river near Tintagel. It had then transported them to the designated helicopter landing site at Derriford Hospital in Plymouth. As it was about to touch down in day VMC after approximately 50 minutes airborne, two people in an adjacent car park not within the landing site were blown over and seriously injured with one subsequently dying as a result of their injuries later the same day. 


An Accident Investigation was carried out by the UK Aircraft Accident Investigation Branch. The aircraft was fitted with a solid‑state Multi Purpose Flight Recorder (MFPR) from which all relevant data were successfully downloaded. CCTV recordings were available and a wide range of interviews were conducted and multiple statements obtained.

The Flight Crew

The 55 year-old Training Captain in command had a total of 7,239 hours flying experience which included 2,797 hours on type in the SAR role since joining the operator in 2008. Prior to joining the operator, he had been a naval pilot and instructor on the Sikorsky S61. The 53 year-old Co-pilot was also a qualified SAR commander on type and had a total of 5,217 hours flying experience which included 1,801 hours on type in the SAR role since joining the operator in 2013. Prior to joining the operator, he had also been a naval instructor and pilot on the Sikorsky S61 as well as the commanding officer of a Royal Navy SAR squadron. In addition to the flight crew, two rear crew as carried on all SAR missions were also on board acting respectively as a winch operator and as a winchman.

What Happened

With the Co-pilot acting as PF for the transit to and from the incident site and the Training Captain in command acting as PF for the casualty recovery task, the helicopter arrived at the site after a 10 minute flight from the operator’s base at Newquay Airport. Having successfully winched the casualty into the helicopter, it became clear that given their condition as advised by the paramedic-qualified rear crew members, the most appropriate action was to transfer them to the nearest hospital with a Helicopter Landing Site (HLS). This was Derriford Hospital in Plymouth which was about 10-12 minutes flying time away and which both pilots were familiar with having operated into it several times before.

During the short transit, it was decided not to make a vertical approach to the HLS but to make a dynamic approach on a westerly track - see the illustration below where the approach track is shown as a yellow arrow. It was noted that with the prevailing light northwest breeze, the downwash would be blown towards the car parking area that bordered the south and east side of the HLS. Given that positioning for this approach would mean that only the co-pilot would be visual with this area, it was deemed appropriate for them to continue as PF for the approach and landing.


The HLS showing the direction of the helicopter’s approach and the locations of the two people seriously injured after their stability was compromised by the downwash. [Reproduced from the Official Report]


As the helicopter approached 1,000 feet agl, the commander was recorded remarking that “our downwash will be going over the car park to the left” and added that “if anything or anyone was seen that would be affected by the downwash, they would go around and consider their options” as he believed that the casualty was not critical. However, the winchman countered by advising the casualty was in need of some “fairly urgent” medical attention, which was acknowledged.

Although the crew saw a few people in the vicinity of but outside the fenced-off HLS, they were not perceived to be at risk from the downwash and the landing was completed without crew awareness of any injuries. However, approximately 20 seconds prior to touchdown, two people who had stopped to watch the helicopter land and were in position 2 on the illustration above were blown over (one sustaining a serious head injury) as was another person in position 1 on the illustration who had just got out of a car and also sustained a serious injury. It was subsequently concluded that it was unlikely that the flight crew had seen the people who were blown over.  

The person with the head injury was taken to the hospital emergency department by paramedics “about 14 minutes after the helicopter landed” and the other seriously injured person arrived at the same emergency department about half an hour after that. The person with the head injury died as a result of their injury later the same day. They had been attending an outpatient appointment accompanied by a relative and both had been walking unaided back to their car which was parked just round the corner at the end of the footpath alongside what was the southern boundary fence of the HLS. The relative reported having been unaware of the existence of the HLS and on initially seeing the helicopter had assumed it would turn away and fly somewhere else. She had seen her outpatient relative “being lifted off the ground by the downwash”, before landing on the ground hitting the back of her head on the surface and losing consciousness. The relative reported that she had been blown over onto her back but that her feet had not left the ground although she had sustained some minor injuries to her hand and ankle and had subsequently suffered from some back pain. The other seriously injured person was also female and was also accompanying a friend who had an outpatient’s appointment. While this friend went to get a parking ticket, she had got out of the car and waited for her to return. As the helicopter flew “very low” over her head, the downwash had “lifted her off her feet" and she landed on the ground between the two cars and was unable to get up. When her friend returned, she was not visible but attracted her by shouting for help. These women were also unaware of the existence of a HLS at the hospital.

It was noted that the purpose-built HLS at the hospital on its partially raised and fully fenced off site had opened in 2015. Since that time, records indicated that there had been over 2,500 landings including at least 140 by SAR-type heavy helicopters (the remainder being by much smaller HEMS helicopter types).

Why It Happened 

Helicopter Landing Sites routinely used by both Helicopter Emergency Medical Services (HEMS) and Search and Rescue (SAR) helicopters in the UK are not licensed unless they are part of an otherwise licensed aerodrome. The operational context for the accident flight was noted as being that “a UK SAR crew can theoretically be tasked to land at any hospital HLS in the UK”. Had they been tasked to fly to an unfamiliar HLS, the crew would have checked the operator’s Flying Staff Instruction ‘Compatibility of UK Hospital Sites with UK SAR Aircraft Types’ which specified which helicopter types are authorised to land at a specific HLS. If so approved, crews would then check the relevant entry in the operator’s ‘HLS Directory’. These were the only two site-specific documents carried on board the helicopter. The operator’s OM Part ‘C’ was found to contain the following general remarks in respect of the use of hospital HLS:

”There is currently no comprehensive National Database of Hospital Helicopter Landing Sites. While it is anticipated that this will be forthcoming, to date, crews are to make use of the RAF Aeronautical Information Documents Unit (AIDU) Hospital Landing Sites Directory and the equivalent Helicopter Landing Sites documents for planning purposes. These documents are available on SAR Crew iPads. Each site will have its unique characteristics and will have been surveyed to a varying degree. It is anticipated that all major Hospital Helicopter Landing Sites (HHLS) within the UK will be certified to demonstrate compliance with National guidelines for such facilities. This certification will be based on a ‘Design Helicopter’ and include an Aviation Protocol Document that establishes due diligence in the control and supervision of the HHLS. By their nature, HHLSs are located in areas that attract a lot of third party activity in obstacle rich environments. To minimise the risk of third party injury or damage following an emergency or due to rotor downwash etc., it is important that SAR crews conduct a dynamic risk assessment prior to landing to confirm performance and establish whether anything has changed since the last inspection of the HLS.”

The entry in the AIDU Directory for Derriford Hospital at the time of the accident is reproduced in the first illustration below. The Hospital stated to the Investigation that they had been unaware that there was an entry for their HLS in this Directory until shown it by the Investigation team and added that “they had no records of any correspondence with the No 1 AIDU”.

The aircraft commander stated that all the operators’ S92 pilots were aware that downwash from the type was “massive” and that this fact was always on their minds and the second illustration below illustrates the (still air) downwash from the two helicopter types operated for SAR purposes by Bristow. The OM text accompanying this illustration was found to state that “the maximum downwash velocity for the S92 is about 51 knots and occurs at approximately 100 feet (which is twice the S92 rotor diameter) below the helicopter”. The available flight data showed that the helicopter had descended through 100 feet agl about 25 seconds before touchdown and at that time the twin-torque power applied had been about 68%.


The AIDU Directory Entry for the Accident HLS. [Reproduced from the Official Report]


The Bristow Operations Manual illustration of the area of maximum downwash. [Reproduced from the Official Report]

The crew had discussed downwash about five minutes prior to the landing and noted that the light prevailing surface wind direction relative to the intended approach track was likely to result in the helicopter’s downwash being taken towards the car park. The aircraft commander commented that he had no knowledge of third party risk mitigations for use of the site and “was not aware of what risk assessments the hospital authorities may have carried out”. He added that since personnel from the hospital’s HLS Response Team staff attended when helicopters landed, he had “assumed they were responsible for ensuring that the HLS and the surrounding area were prepared and that third party people were informed of the helicopter’s arrival and controlled as necessary”. He added that he had flown go‑arounds at other HLS before due to crew observations of people in potentially unsafe locations near the site, one of which was due to a pedestrian walking alongside a wire fence enclosing the HLS.

It was found that the Derriford Hospital HLS had been created in 2012. The Hospital’s Head of Estate Site Management at the time of the Accident, who had been employed in various capacities there for 23 years, had been the manager of the HLS until 2020. He had not received any formal training or had any previous experience in managing an HLS. His responsibilities included oversight of the corporate safety and compliance aspects of the HLS and the work of the Hospital’s HLS Risk Assessor. This HLS Risk Assessor had signed off the most recent risk assessment for the HLS and had worked for the hospital for 16 years. She had initially been “employed in secretarial and personal assistant roles and was then trained as a security specialist in 2015”. It was found that her role as a security specialist included securing the HLS operation from the public. However, in 2020, she had also become responsible for “overseeing all aspects of the HLS, including risk assessment and maintenance”. It was found that “she had no knowledge of helicopter operations prior to this and did not complete any specific training for it”. It was also found that whilst she had received no formal risk assessment training, she “did have experience of undertaking other risk assessments at the hospital”

It was found that in 2016, shortly after the new Derriford HLS had opened, the First Edition of UK CAA CAP 1264 ‘Standards for helicopter landing areas at hospitals’ had been published to replace the previous less formal and less comprehensive guidance available. However this was explicitly applicable - although not mandatory - only for new Hospital HLSs and not existing ones. Although its content would have been useful from a risk management perspective, particularly in its recognition that the area of third party downwash risk was likely to extend beyond the designated HLS, the Derriford Hospital management had not been aware of it or the amended reissue of it in 2019.

The effective consequences of this staffing, both direct and indirect, were the apparent absence of any recognition that an effective process of safety risk management in respect of the area outside the designated HLS was not being delivered. One specific example of this was the response of the hospital to previous less serious downwash-related incidents - in 2016 when a person was blown over by S92 downwash in the same car park area as in the accident under investigation and in 2019 when another such fall was caused by downwash from a much smaller HEMS aircraft. 


The location of the persons blown over by downwash. [Reproduced from the Official Report]

As can be seen from the illustration above, all those affected were outside the designated HLS but within 50 metres of the HLS midpoint, with 50 metres being the minimum of the 50-65 metre downwash risk zone given in CAP1264 for large helicopters such as the S92 which it was observed was compatible with the content of ICAO Annex 14 ‘Aerodromes’ and the associated ICAO Heliport Manual (Doc 9261). Unfortunately, the hospital’s investigations into the two earlier events were signed off in isolation with no lessons learned on downwash risks even though the subject was also raised by Bristow Helicopters during a 2019 meeting. It was further noted that the following year, the hospital’s risk assessor had specifically requested a briefing from Bristow which “in addition to again highlighting areas around the HLS where the control of third party individuals was a potential issue (also) covered regulation and helicopter performance” but “the risk assessor did not understand the material presented”.

The overall Message from the Investigation was, in abbreviated summary, as follows:

Helicopters used for Search and Rescue (SAR) and Helicopter Emergency Medical Services (HEMS) perform a vital role in the UK and although the operators of these aircraft are regulated by the UK Civil Aviation Authority, many of the Helicopter Landing Sites (HLS) which they use at hospitals are not. It is essential that the risks associated with helicopter operations into areas accessible by members of the public within hospital grounds are fully understood by those responsible for safe operations and that effective communication between all the stakeholders involved is established and maintained. This was found not to be the case.

Two Causal Factors identified by the Investigation were formally recorded as follows:

  • 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 Derriford Hospital Helicopter Landing Site (DH HLS).
  • 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.

A total of 12 Contributory Factors were also formally documented:

  1. The DH HLS 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 Park B, 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 DH HLS was constructed. The document was not retrospectively applicable to existing HLS.
  5. The operator of the helicopter involved was not fully aware of the DH HLS Response Team staff’s roles, responsibilities and Standard Operating Procedures
  6. The commander of the helicopter involved believed that the car park surrounding the DH HLS would be secured by the hospital’s 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. The 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.

Safety Action taken prior to the completion of the Investigation was noted to have included the following:

  • Bristow Helicopters removed the approval for its S92 and AW189 helicopters to operate into the HLS at DH from its Flying Staff Instruction until further notice and initiated more frequent reviews of this document and the addition of more information as whether a site has facilities for it to be secured and if so by whom i.e. a coastguard rescue team, police and/or hospital staff.
  • The DH HLS Site Keeper
    • prohibited its use by helicopters with a MTOW greater than 5,000 kg until further notice and a NOTAM to that effect was issued.
    • closed car park B to all vehicles other than ambulances until further notice. 
    • arranged for all pedestrian movements in Car Park B to be controlled during all helicopter landings and takeoffs. 
    • Sought to ensure that pedestrian movements on the pavement of the public highway of Derriford Road would be controlled as far as reasonably practicable during helicopter operations but noted DH has no legal authority to prevent pedestrian movements on the public highway.
    • The risk assessment for Car Park B was amended to include an assessment of the risk to pedestrians from helicopter downwash.
    • Additional visual and audible signs around the landing pad on the main pedestrians’ routes around the location have been installed.
    • Yellow hatched floor markings have been installed outside each of the gated entrances to the pad, warning pedestrians not to stand in that location to view helicopters landing or taking off.
    • Audible message points around the external walls of the landing pad, activated by the security team once they reach the pad, have been installed. The audible message will warn pedestrians of helicopter movements, the risks of downwash and asking them to move to a different location quickly.
  • NHS England Estates hosted online events for stakeholders at NHS hospitals to draw attention to the guidance in CAP 1264 on the safe and compliant design and management of HLS sites amongst the industry and local planning authorities. 
  • The UK Heath and Safety Executive (the UK-wide Agency responsible for the oversight of workplace health and safety) wrote to all NHS Trust and Board Chief Executives to remind them of their legal duty to ensure workplace safety and how this responsibility should be discharged to effectively manage risk associated with hospital helipad use.

Nine Safety Recommendations based on the Findings of the Investigation were made at its conclusion as follows:

  • that the UK Civil Aviation Authority includes the appropriate downwash guidance relevant to hospital helicopter landing sites in one published document. [2023-028]
  • that the UK Civil Aviation Authority, in conjunction with the Onshore Safety Leadership Group and the relevant NHS organisations in the UK, develop and promulgate enhanced risk management guidance for hospital helicopter landing sites, and provide information on the range and use of potential mitigations for the protection of uninvolved persons from helicopter downwash. [2023-029]
  • that NHS England Estates, in conjunction with the Onshore Safety Leadership Group and the UK Civil Aviation Authority, develop competency requirements and introduce training for all hospital helicopter landing site managers that includes, as a minimum, a basic introduction to helicopter operations and safety management practices appropriate for such facilities. NHS England Estates should seek participation from the healthcare organisations in Scotland, Wales, and Northern Ireland to develop these competency requirements. [2023-030]
  • that NHS England Estates review all existing hospital helicopter landing sites for which it has responsibility against the latest guidance and instigate appropriate actions to minimise the risk of injury from downwash to uninvolved persons. [2023-031] 
  • that NHS Wales Health Boards and Trusts review all existing hospital helicopter landing sites for which they have responsibility against the latest guidance and instigate appropriate actions to minimise the risk of injury from downwash to uninvolved persons. [2023-032] 
  • that NHS Scotland Assure review all existing hospital helicopter landing sites for which it has responsibility against the latest guidance and instigate appropriate actions to minimise the risk of injury from downwash to uninvolved persons. [2023-033]
  • that the Northern Ireland Health and Social Care Trusts review all existing hospital helicopter landing sites for which they have responsibility against the latest guidance and instigate appropriate actions to minimise the risk of injury from downwash to uninvolved persons. [2023-034]
  • that the Onshore Safety Leadership Group (OnSLG), in conjunction with the UK Department for Transport, facilitate and support the development and introduction of a dedicated national hospital helicopter landing sites (HLS) database that can be updated in an operational environment by helicopter operators and hospital HLS Site Keepers. In addition to helicopter operators and other stakeholders, the OnSLG should seek participation from the healthcare organisations in England, Scotland, Wales, and Northern Ireland. [2023-035]
  • that the UK Department for Transport, in conjunction with the Onshore Safety Leadership Group, establish and lead a national initiative to improve the protection of uninvolved persons from helicopter operations at hospital helicopter landing sites (HLS). This initiative should have sufficient authority, representation, resources, and expertise to ensure that coordination between the various risk owners and stakeholders is effective. The various stakeholder roles and responsibilities (in particular those of HLS Site Keepers and helicopter operators) should be clear to all those involved, and the planning, design, and ongoing risk management of hospital HLS should be considered appropriately. [2023-036]

The 132 page Final Report of the Investigation was published on 2 November 2023. 

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