Helicopter Safety and How it Might be Improved

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)

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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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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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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​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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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. 

The CAA has published CAP 1519 and 1538 which provide enhanced alerting envelopes for offshore HTAWS. These should go some way to alerting crews on the unsafe conditions which led to accidents at the Cormorant Alpha and  ETAP platforms, in Morecambe Bay and on approach to Sumburgh Airport.
 
Another part of the problem is ensuring that crew “hear” the alerts. Hear is shown in quotations as evidence points to the fact that under some conditions pilots are not aware of the warnings despite them being generated. One example is the near miss to G-WIWI https://assets.publishing.service.gov.uk/media/548aff04ed915d4c100002ce/Sikorsky_S-76C_G-WIWI_12-14_v2.pdf 
 
Recently the CAA has publish CAP 1747, which addresses the Human Factors side of HTAWS and looks at how best to gain the pilots attention when an HTAWS alert is generated.  
https://publicapps.caa.co.uk/docs/33/CAP1747_HTAWS_Warning_Annunciation.pdf


Unfortunately, the pace of implementing the new envelopes has been slow. In my view, this is largely a result of the poor state of the offshore helicopter industry and their suppliers, which resulted from the shock fall in the oil price in 2014 from $115 per barrel to under $35 per barrel in 2016. 

EUROCAE Working Group 110 has started developing Minimum Operation Performance Standards (MOPS) for offshore HTAWS.  https://www.eurocae.net/news/posts/2018/october/new-working-group-wg-110-helicopter-terrain-awareness-and-warning-systems-htaws/. The USA's RTCA is joining this effort in June 2019. The MOPS will help by defining internationally agreed standards for offshore HTAWS.