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Downwash and Outwash

4/15/2025

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Helicopter downwash and outwash is a known problem that has caused fatal accidents and damage around landing sites. Some attempts have been made to inform users of downwash issues, such as this video produced by BP, with my assistance, in 2016 - 
https://www.youtube.com/watch?v=09bvuYRKwwc

A Coroner’s Report into the death of Mrs Jean Langan at Derriford Hospital, identified that she died after a landing helicopter’s downwash caused her to fall backwards and strike her head on the ground. 

The Coroner issued a REGULATION 28 REPORT TO PREVENT FUTURE DEATHS that identified concerns over the lack of a real time data base of Hospital Helicopter Landing sites to ensure the safe landing of helicopters. As the Department for Transport (DfT) identified in their response to the Regulation 28 Report, hospital landing sites are unlicensed and so they do not have to comply with the Guidance in CAP 1264. Ultimately, it is the helicopter operators using these sites that have to ensure they are safe to use. However, the hospitals (NHS), DfT and the CAA must all play a part, but I see some buck passing occurring. In the meantime larger SAR helicopters are unable to use many hospital sites, resulting in delays to treating casualties as they have to be landed at alternative sites and then moved by ground to the critical care they often require.

In April 2025 the CAA published CAP 3075-  
Protecting the Future: Trials and Simulation of Downwash and Outwash for Helicopters and Powered Lift Aircraft https://www.caa.co.uk/publication/download/24645

This follows on from CAP 2576 - 
Understanding the downwash/outwash characteristics of eVTOL aircraft https://www.caa.co.uk/publication/download/20721  

​Both of these CAPs are based on research support from Sophrodyne Aerospace - https://sophrodyne-aerospace.com/
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RTCA DO-405 Onshore HTAWS MOPS Published

8/2/2024

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Rotor Downwash

5/23/2024

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An incident at Derriford Hospital resulted in a passing member of the public suffering fatal injuries caused by the downwash from a landing helicopter.

Aircraft Accident Report AAR 2/2023 - Sikorsky S-92A, G-MCGY - GOV.UK (www.gov.uk)


Rotor downwash and outwash are a known problem and need to be considered at all landing sites. The CAA has recently published CAP 2576 that assesses downwash from eVTOL air vehicles. Their downwash is likely to be more intense than classic helicopters due to a combination of higher disc loading and interactions between their individual rotor downwash.

The author of CAP 2576A, Dr Richard Brown, gave a fascinating  RAeS 2023 Cierva Lecture on this topic.
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CAP 2576 - 20721 (caa.co.uk)

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HeliOffshore Safety Award

5/23/2024

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Joint RAeS/VFS-UK Conference Concluded Successfully!

6/6/2023

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Turbulence presents a hazard to all rotorcraft operations. Smaller UAVs and urban mobility vehicles are likely to be affected more than larger helicopters.

A conference on the 24th May brought together brilliant presenters from the UK and abroad. The audience was treated with 12 extraordinary presentations over a tight day, sparking insightful discussions. See more details here - 
here to edit.  uk.vtol.org/vfs-uk-raes-conference-technical-program-released 
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Lighthouses

11/17/2022

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In conjunction with Aerossurance, I audit helicopter operations on behalf of the General Lighthouse Authorities, Trinity House, Northern Lighthouse Board and Irish Lights.

The history of lighthouses in the UK and Ireland is very interesting. The Museum of Scottish Lighthouses in Fraserburgh is worth a visit. Amongst other things, it highlights the pioneering work of the Stevenson (of R.L. Stevenson fame) family.
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 In May 2022 Maria and I visited Iceland, where we saw typical Icelandic lighthouses, which are usually orange in colour.

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In September I was auditing the Trinity House Vessel Galatea off the Farne islands.
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In October we visited Cape Horn, as we sailed to the Antarctic. The Cape Horn lighthouse was occupied by a Chilean Marine and his family. They welcomed us as they did not get many visitors. The Chilean Navy dropped off supplies every 2 months but this was sometimes disrupted by weather.
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1992 at EPNER

10/17/2021

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On 16th September 1992 the helicopter flight test course at  EPNER (École du personnel navigant d'essais et de réception) commenced. This is a photograph of staff and students, with me third from the right.  I think the guy third from left, Guillaume Faury, wins the prize for having the most successful career!
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HTAWS Update

5/13/2021

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The Offshore HTAWS Minimum Operational Performance Standards (MOPS) were published  in April 2021.

The EUROCAE Working Group 110/RTCA Special Committee 237 has now moved onto defining MOPS for onshore HTAWS.

​Full details can be seen on the RTCA website - https://www.rtca.org/sc-237/
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Helicopter Terrain Awareness Warning Systems (HTAWS)- Update

8/13/2020

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​EUROCAE Working Group 110 and RTCA Special Committee 237 are close to finalising Minimum Operating Standards (MOPS)  for offshore HTAWS: I am acting as Secretary to these groups. The alerting envelopes will largely be based around those published by the UK CAA in CAP 1519.
 
Once the groups have met next month (virtually) to conduct an internal review of the MOPS, they will be issued for public consultation, with the aim of publishing the MOPS in March 2021.
 
Leonardo has announced that it has implemented some of the CAP 1519 offshore modes in its latest avionics software update to the AW139.  Although it seems that the low energy warning provided by Mode 7 is not yet incorporated. https://www.leonardocompany.com/en/press-release-detail/-/detail/17-07-2020-leonardo-aw139-s-capabilities-further-enhanced-with-new-avionics-software-release-and-kit-certification 
 
This table  has been presented a number of times by the UK CAA. It shows the additional warning times provided by Modes 7 and 3B, which warn of a low energy state on approach (Mode 7)  and loss of airspeed on take-off (Mode 3B).


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Onshore Helicopter Operations and Safety

12/3/2019

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The CAA has recently published CAP 1864, which is the Onshore Helicopter Review Report. This conducts a similar review into onshore operations which CAP 1145 did to offshore operations, following a number of offshore accidents including the Sumburgh AS332L2 in 2013.
 
As onshore operations are more diverse, it covers  training, CAT, HEMS, Police, SAR and GA operations -http://publicapps.caa.co.uk/modalapplication.aspx?catid=1&pagetype=65&appid=11&mode=detail&id=9304 . Due to the diverse nature of onshore operations, it might be more difficult to focus on specific industry issues as there will be major differences between the various types of operation. However, one interesting element of the study is the proposed adoption of the principles in the EUROCONTROL White Paper entitled “From Safety I to Safety II”. This basically focuses on the large number of occasions when things go right and not on the very small number of occasions when things go wrong. In some ways, this is similar to the approach we took when defining the HTAWS envelopes in CAP 1519, where we attempted to define “normality” and then warned the crew when things were abnormal.
 
One of the accidents referenced in CAP 1864 is to G-SPAO, an EC 135 which suffered a double engine flameout and impacted the Clutha Vaults in Glasgow on the 29th November 2013, resulting in 10 deaths. I was an expert witness for the Crown and Procurator Fiscal’s Office for this case. The Sheriff Principal’s report is available online https://www.scotcourts.gov.uk/docs/default-source/cos-general-docs/pdf-docs-for-opinions/2019fai46.pdf?sfvrsn=0. Two of the four safety recommendations made by the AAIB include recommendations on the installation of flight recorders to police helicopters, something the Regulations do not currently require. Flight and cockpit voice recorder data would have been helpful in this accident, as it would be with many other Part 27 helicopter accidents. A recent article by EASA seems to support the fitment of recorders to small helicopters, although stop short of mandating them https://www.easa.europa.eu/flight-recorders-light-helicopters. A few years ago, I was involved in an investigation into a fatal accident involving a Bell 407 which crashed in poor weather in Louisiana. The Appareo recording system fitted, although not connected to any aircraft instrumentation, provided invaluable data which allowed us to determine the cause of the accident. 

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