Category: Safety

Upfront

Years of looking at the reliability of aircraft components and structure have given engineers a good understanding of the natural decay of mechanical workings. To that extent even electronic components are mechanical. Materials oxidise (rust), random shocks and vibration take their toll, temperatures cycles from cold to hot and back again a whole range of impacts are relentless. You can say – nothing lasts forever.

Occasionally a discovery adds to the knowledge of how materials behave under high stress. Sadly, that’s what hit the early years of civil jet aviation. The de Havilland DH106 “Comet” was the world’s first passenger carrying jet airliner. It first took to the air in 1949, which I find remarkable.

Catastrophic metal fatigue failure of the aircraft fuselage put paid to this British aviation project but only after several tragic fatal accidents. In 1954, the Comet aircraft were all grounded during an extensive accident investigation. The jets were redesigned and re-entered commercial service in 1958. However, by then the aircraft had a damaged reputation and others were doing far better. Now, those Comet aircraft that remain are museum exhibits[1].

Last week, I walked through the fuselage of a Comet 1A built in 1953 at Hatfield for Air France. It’s fascinating to see what advanced aviation technology was 70-years ago. What was surprising to me was the read across from that first version of a jet aircraft and what we have in-service now.

Automation has removed the place of the navigator and the flight engineer, but the stations of the pilot and co-pilot are familiar. The fuselage is cramped but the seating is generous and spacious. This aircraft must have been a dramatic revolution in flying at the time.

As we look to advance aviation in the coming years, with new ways of flying and new ways of powering flight so the warning of the Comet project should be heeded. We are at a time of extraordinary changes in the aviation industry. Advanced technology can deliver great benefits to society. It’s up to us to make sure we cover all the possible disbenefits as far upfront as we can. If we don’t, they will come back to bite us.

[1] https://www.dehavillandmuseum.co.uk/aircraft/de-havilland-dh106-comet-1a/

Society & Innovation

Yesterday, I drove up the main A303[1] in the stifling last summer heat. It was a windless sticky 30C. I drove past the road sign that says Micheldever Station[2]. By the way, “up” meaning heading towards London. Going “up” to London isn’t an unusual West County way of expressing that trip.

On that busy highway there are few, if any noticeable road signs that point towards a railway station. I’ve often wondered why that one was deemed so necessary. It’s not a tourist attraction, like the Watercress line[3] is in that part of the world. It’s an ordinary everyday railway station.

The small English hamlet known as Micheldever Station is a bit of an oddity. It’s the sort of place that could have been the location for The Avengers or The Saint, the popular British TV series of the 1960s. It’s in the green and pleasant countryside of Hampshire and about 10 miles north of Winchester city. An area that’s as conservative as can be.

Micheldever Station has a curious technological history. In 1895, it was the starting point for the first automobile journey in Britain. At that time a British Act of Parliament required that all self-propelled vehicles on public roads must travel at no more than 4 miles per hour and to be preceded by a man waving a red flag. In 1805, highly sensible. There’s no way that those infernal new machines should be allowed to scare the horses.

Not everyone thinks such thoughts while thundering along the A303 at 70 miles per hour. However, to me, ever since I got my first driving license at the age of 16, it’s been my most familiar of arterial roads. So, much traffic passes that way there’s never a time when it can’t be heard.

Well, we have come a long way in 138 years. Now, we are getting nervous about the safety of driverless cars, and no one even questions having a self-propelled vehicle on public owned roads. If they do, the likelihood of transforming that formula into something else is astronomically small. I can’t think of a bad time to write on the subject of: “Innovation and Its Enemies[4].” In fact, what may have graced a Victorian bookshelf can have some resonance today.

Next year, we will see commercial flights taken in electrically powered air-taxies. Without a shadow of a doubt these flights will arouse some vocal public resistance. We can take that from the history of technology. The airborne version of the man waving a red flag could raise its ugly head. I don’t say throw caution to the wind, but we need to be mindful of the natural propensity to object.

Striking a societal balance will not be easy. It would be a fool who says it will be. Slowly but surely, we will need to become accustomed to advanced new forms of mobility. Sticking a fair balance between the utility of these new machines and any burden they may place upon us will be a mighty tricky job.

I wake-up to the noise of the residential road outside. People commuting to work. The local trains send a rumble through the air. I don’t want to wake-up to the sound of an air-taxi hovering outside my window. Given the research[5] and technology under development, none of us should have to tolerate an increase in noise. Mobility and quality of life shouldn’t always be in conflict.

[1] https://youtu.be/C0sL3_NKPao

[2] https://www.southwesternrailway.com/travelling-with-us/at-the-station/micheldever

[3] https://watercressline.co.uk/

[4] https://global.oup.com/academic/product/innovation-and-its-enemies-9780190467036?cc=us&lang=en&

[5] https://ntrs.nasa.gov/citations/20210014173

Horizon

There’s been a couple of false dawns. Now, the morning’s News is that the UK will rejoin the European Horizon programme. The EU’s Horizon Europe Framework Programme (HORIZON) provides grant funding for research priority topics for the years 2021-2027.

The recognition that there’s a common interest in research across Europe is welcome. There are important areas of investigation that go well beyond the resources available to any one country. Benefiting from collaboration is a win-win.

Access to Horizon Europe will be a great opportunity for UK aerospace[1]. It has been in the past and surly will be in the future. Of the billions available there’s a good chunk for funding opportunities for aerospace research and technology. This funding is particularly focused on greening aviation.

Such subjects as the competitiveness and digital transformation in aviation are addressed too. Advancing the regions capabilities in a digital approach to aerospace design, development and manufacturing will be invaluable to UK industry. Artificial Intelligence (AI) used for Machine Learning (ML) and complex modelling are the tools that will be deployed throughout the global industrial environment.

Europe can pioneer the first hydrogen-powered commercial aircraft. The major role the UK can play in advancing this aim is self-evident. Ambition, capabilities, and expertise reside here. The magnification of this to tackle what are enormous challenges can only be a good move.

Projects like ENABLEH2[2] provide a pathway to the introduction of liquid H2 for civil aviation. These projects are not easy, but they do provide a long-term environmental and sustainability advantages. Access to these projects can minimise duplication and the dangers of spending valuable resources on pursuing blind alleys.

Research is not just a matter of hard technology. Without the new skills that are required to meet the targets for a green transition it will fail. Investments in upskilling and reskilling opportunities are equally important to enabling change.

The principles of propulsion of hydrogen and electric systems need to be taught at every level. It’s not academics in lab coats that will keep civil aviation flying on a day-by-day basis. Training programmes for a new generation of manufacturing and maintenance engineers will need to be put in place. Research will underpin that work. 

[1] https://www.ati.org.uk/news/access-to-horizon-europe/

[2] https://www.enableh2.eu/

RAAC

Reinforced autoclaved aerated concrete (RAAC) is making the News in the UK. An unknown number of buildings are deemed dangerous because of the aging of this material[1]. RAAC has a limited lifespan. It’s inferior to standard concrete but lightweight and low-cost at the start of its life. It was typically used in precast panels in walls, roofs and sometimes floors.

The UK Government says it has been aware of RAAC in public sector buildings, including schools, since 1994. Warnings from the Health and Safety Executive (HSE) says that RAAC could – collapse with little or no notice. This “bubbly” form of concrete can creep and deflect over time, and this can be aggravated by water penetration. So, regular inspection and maintenance are vital to keep this material safe. Especially in a country known for its inclement weather.

It’s reasonable to say there lies a problem. The public estate has been through a period of austerity. One of the first tasks to get cut back, when funds are short is regular maintenance. Now, I am making some assumptions in this respect, but they are reasonable. Public sector spending has been under significant pressure for a long time.

The other dogmatic notion that has hindered a solution to this building problem is centralisation. There was a time when local authorities managed schools. They still do but in smaller numbers. Centralised funding has decreased the power of local people to address problems with the school estate.

Aging buildings have something in common with aging structures in aviation. There’s always a demand to keep going for as long as possible. There’s always the difficulty of determining the safety margin that is acceptable. There’s always a pressure on maintenance costs.

Believe it or not aircraft structures do fail[2]. There’s a tendency to forget this source of incidents and accidents but they never go away[3]. What happens in industries where safety is a priority is investigation, feedback and learning from incidents and accidents. The aim being to ensure that there’s no repeat of known failures. Rules and regulations change to address known problems.

The vulnerability to moisture and the limited lifespan of RAAC should have been a loud wake-up call. No doubt it was for some well-managed, well-resourced enlightened organisations. Central Government has bulked at the cost of fixing this known building safety problem. A culture of delaying the fixing of difficult problems has won.

In civil aviation there’s a powerful tool called an Airworthiness Directive (AD). It’s not something that an aircraft operator can ignore or put on the back burner. The AD can mandate inspections and changes to an aircraft when an unsafe condition exists.

In the schools cases in the News, the impression is given that Government Ministers have dragged their heels and only acted at the last possible moment. Maybe the construction industry and public estate needs a strong regulator that can issue mandatory directives. Known unsafe conditions should not be left unaddressed or significantly delayed.

[1] https://www.local.gov.uk/topics/housing-and-planning/information-reinforced-autoclaved-aerated-concrete-raac

[2] https://www.faa.gov/lessons_learned/transport_airplane/accidents/N73711

[3] https://www.faa.gov/lessons_learned/transport_airplane/accidents/TC-JAV

Learn by testing

Back in the mid-1980s, aircraft system integration was part of my stock-in-trade. Project managing the integration of a safety critical system into a large new helicopter. It was a challenging but rewarding job. Rewarding in that there was a successful new aircraft at the end of the day.

For big and expensive development projects there are a great number of risks. The technical ones focus on functionality, performance, and safety. The commercial ones focus on getting the job done on-time and at a reasonable price. Project managers are in the middle of that sandwich.

Naturally, the expectations of corporate managers in the companies that take on these big challenges is that systems and equipment integration can be done to the book. Quickly and without unexpected outcomes. The practical reality is that people must be well prepared and extremely lucky not to encounter setbacks and resets. It’s not just test failures and anomalies that must be investigated and addressed. Systems integrators are working on shifting sand. The more that is known about overall aircraft flight test performance and customers preferences so technical specifications change.

With cockpit display systems, in the early days, that was often feedback from customer pilots who called for changes to the colour, size or shape of the symbology that was displayed on their screens. What can seem a simple post-flight debriefing remark could then turn into a huge change programme.

That was particularly true of safety critical software-based systems. Equipment suppliers may have advanced their design to a state where much of the expensive design validation and verification was complete. Then a system integrator comes up with a whole set of change that need to be done without additional costs and delivered super-fast. Once a flight test programme gets going it can’t be stopped without serious implications. It’s a highly dynamic situation[1].

I’m writing this blog in reaction to the news coming from Vertical Aerospace. Their VX4 prototype aircraft was involved in an flight test incident that did a lot of damage[2]. There’s no doubt this incident can provide data to feedback into the design, performance, and safety of future versions of their aircraft[3]. Integrating complex hardware and software is hard but the rewards are great.

“Excellence is never an accident. It is always the result of high intention, sincere effort, and intelligent execution.” – Aristotle

[1] https://youtu.be/Gb_eta4mZkc

[2] https://evtolinsights.com/2023/08/vertical-aerospace-identifies-propeller-as-root-cause-of-august-9-vx4-incident/

[3] https://investor.vertical-aerospace.com/news/news-details/2023/Vertical-Aerospaces-VX4-Programme-Moves-to-the-Next-Phase/default.aspx

NATS

A “technical issue” has caused UK National Air Traffic Services, NATS to impose air traffic flow restrictions[1]. They did not close UK airspace. This was not a repeat of the volcanic ash events of early 2010. Going from a fully automated system to a fully manual system had the dramatic impact that might be expected. The consequences, on one of the busiest weekends in the holiday calendar were extremely significant. Huge numbers of people have had their travel disrupted. Restricting the air traffic system ensured that aviation safety was maintained. The costs came to the UK’s air traffic handling capacity and that meant delays and cancelled flights.

Although the failures that caused the air traffic restriction were quickly resolved the time to recover from this incident meant it had a long tail. Lots of spoilt holidays and messed up travel plans.

It is normal for an Air Traffic Service (ATS) provider to undertake a common cause failure analysis. This is to identify multiple failures that may result from one event. So, the early public explanations coming from NATS of the causes of this major incident are surprising. Across the globe, contingency planning is a requirement for ATS. The requirement for the development, promulgation and application of contingency plans is called up in international standards, namely ICAO Annex 11.

So, the story that a single piece of flight data brought down the traffic handling capacity of a safety related system, to such a low level, is difficult to accept. It’s evident that there is redundancy in the systems of NATS, but it seems to be woefully inadequate when faced with reality. ATS comprise of people, procedures, and systems. Each has a role to play. Safety of operations comes first in priority and then air traffic handling capacity. What we know about even highly trained people and data entry is that human error is an everyday issue. System design and implementation needs to be robust enough to accommodate this fact. So, again attributing such a highly disruptive event to one set of incorrect data inputs does not chime with good practice or basic aviation safety management. It is concerning that one action can bring down a major network in this way.

EUROCONTROL would have had been sent a “rogue” flight plan in the same way as UK NATS. Brussels does not seem to have had the problems of the UK.

It is early days in respect of any detailed technical investigation. Drawing conclusions, whatever is said in public by senior officials may not be the best thing to do.

Calls for compensation have a good basis for proceeding. The holiday flight chaos across Europe comes down to one single failure, if initial reports are correct. That can not be acceptable. The incident left thousands stranded abroad with high costs to pay to get home.

Before privatisation, there was a time when the UK Civil Aviation Authority (CAA), ran the nation’s air traffic services[2]. It had a poor reputation at the time. I remember a popular newspaper cartoon saying – and now for some clowns from the CAA. They were entertaining delayed passengers.

UK NATS has done much good work to manage a safe expansion in air traffic and address many changes in technology, it would be a shame if this sad incident marks a decline in overall network performance.

NOTE 1: And this topical cartoon from the Daily Mail in April 2002: https://www.pinterest.es/pin/497577458805993023/

NOTE 2: A report on the incident is to be sent to the regulator, UK CAA on Monday, 6th September. Transport secretary to see Nats’ ATC meltdown report next week | Travel Weekly

NOTE 3: The likelihood of one in 15 million sounds like a low number but it’s not “incredibly rare” by any definition. Certainty when there are around 6000 flights a day in the UK. A duplicate error occurring is a basic error that could be anticipated.

[1] https://www.bbc.co.uk/news/live/uk-66644343

[2] https://commonslibrary.parliament.uk/research-briefings/sn01309/

New Walk

It’s a step to the left and then a step to the right. It’s not quite the “Time Warp” that featured in the 1970s rock musical: The Rocky Horror Show.

It’s a little mini dance that people do every day in the streets of Britain. I found myself doing it over the weekend. It’s that moment when you realise that you have lost a sense of what’s around you. A tiny drift away from where you intended to go. Then a step to correct, and look-up and set-off again towards your destination. A wiggle on the pavement.

Maybe this walk didn’t exist before 2006. Well, that is all but in the most exceptional situations. Hand-held devices are not entirely new. What’s much more frequent now is the compulsion to look at the small screen.

The colours, the constant demand for attention, the tickling of our curiosity, the mobile phone has it all. In fact, its dam silly to continue to call our devices “phones.” The primary purpose of these handy devices has long since passed from being able to make telephone calls from any location.

We call them a “mobile”, but the Germans call them a “handy”. An American will call them a cell phone. Given the way we use these ubiquitous hand-held devices, I think the Germans have got it right. The whole essence of the thing is its utility.

Now, if we are fixated with heads down there’s a lot that can go wrong. This has been the source of numerous aviation accidents. Looking up and checking visual references remains a fundamental part of flying. The basics of “see and avoid” are drummed into every new flyer.

On the pavement us poor humans are evolving in a world of every more connected technology. In our heads we have a perception of the world around us as we walk the urban streets. That’s made up of sights, sounds, and even smells. Our brains gather information and then do some spatial and temporal filtering before making sense of where we are and what we need to do to get where we want to go. The eyes, and image processing in the brain are on the top of the list of our normal priorities.

Heads-down attention is drawn to the small screen and away from our surroundings. Staring at the small screen draws us into the content of an e-mail, or a text message, or a cuddly cat picture running around social media. Luckily our other senses are keeping track of the world around us.

The textbook case is where we start to drift in our three-dimensional environment. Not much. It’s a step to the left and not a step to the right. Suddenly there’s a need to correct. Our ever-active brains pick up on the misstep. That’s where our tiny dance comes in and nobody but us may notice.

I’m talking about something that’s almost trivial. Hardly noticeable. However, there are far too many cases where fatalities have resulted from missteps[1]. There’s some evidence that bumping into people and objects is most likely. Slips and falls follow those incidents.

I’ll bet not much is known about the vast number of micro-events like my tiny mobile phone dance. Now, there’s a topic of study for a student of visual perception. 

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6034962/

Even more H2

There’s a couple of Hydrogen related topics that are worth a moment. One is super conductors and the other is fire.

Heavy complex equipment like the magnets for particle accelerators use superconductors[1]. When there’s space and a need for powerful magnetics, materials with special physical properties, at extreme cold temperatures find a good use.

Talk of room-temperature superconductors is far from what it seems. Such a wonderful innovation is a million miles from any practical applications, if it exists at all. There’s no theory of high-temperature superconductivity, but there’s quite a few physicists who would like to find one[2].

Aviation researchers search for high temperature superconductors for electrical propulsion with extraordinary performance is on. The likelihood of success is low, and the timeframes are very long.

When an aircraft is flying at high altitude, the cabin altitude is maintained for the safety and comfort of passengers and crew. Air compressors, valves, sensors, and controllers make sure that cabin pressure remains at equivalent to an altitude of about 8,000 feet, and lower in some cases. So, any kind of simply flammable gasses or materials inside an aircraft cabin are a definite no no. It’s a big hazard.

In flight, the positive pressure should keep leaking gas out of the cabin. That is as long as the sources of fresh air for the cabin are keep well away from potential leaks.

That’s where Hydrogen gas can present trouble. Leaks can be common in dynamic Hydrogen systems. Storage tanks must be very strong to resist pressures and insulated to keep cold, at around –250°C. Escaping H2 gas is tiny. If that’s vented overboard then the risk of explosion or fire is significantly lowered. Knowing the exact flows of liquid or gas is a must.

However, if the gas finds its way into a pressurise cabin that basic option is limited. Not only that but detecting low concentrations of the gas in the first place is mighty difficult. Its odourless but at least Hydrogen isn’t poisonous.

The big safety issue is that the gas has a very wide flammability range (4 – 70% H2 in air mixture)[3]. Yes, H2 needs a spark to ignite. A typical aircraft cabin environment will easily provide that event. Dry air and static electricity will do it even if other sources will not.

To compound difficulties, if H2 does ignite, and not explode, then its flame may not be visible to the human eye. The flame is almost colourless. Certainly, not what most people think of as a gas flame. Gas and flame detectors could be installed in aircraft cabins and baggage compartments. Audible and visual alarms could be generated but what would be the associated crew actions?

All the above requires detailed consideration in aircraft safety assessments. The move away from prescriptive regulatory requirements means each specific aircraft configuration must be addressed. There are no generic lessons to learn from past aviation accidents and incidents.

Although, I think these puzzles can be solved it’s a huge leap from here to there.

POST: Yes, Hydrogen is not for every application. Small scale aviation is better served by electrification Five Hydrogen Myths – Busted. – RMI

[1] https://home.cern/science/engineering/superconductivity

[2] https://www.science.org/doi/epdf/10.1126/science.adk2105

[3] https://h2tools.org/bestpractices/hydrogen-flames

Electric Flight

Hype has its place. Being positive while buffeted by the inevitable ups and downs of life is purposeful and necessary. What’s not true, and might be the impression, is that electric aviation is easy. When forging ahead to build a future, that is not yet realised, there’s a need to maintain confidence. However, being blinded by the light doesn’t help when it comes to tackling difficult problems. Proof-of-concept is just that.

The big positives of electric aviation are the environmental benefits. Electric aviation is spawning many new types of aircraft and the possibilities of new types of operation. So, there’s no doubt that this is an exciting time to be an aviation enthusiast. What a great time to be in aerospace design and manufacturing. Here we are at the start of a new era[1].

My point is that high power electrics, and their control are not “simple” or intrinsically safe in ways other types of aircraft are not. I know that’s a double negative. Better I say that high power electrics, operated in a harsh airborne environment have their own complexities, especially in control and failure management. Fostering an illusion that the time between having an idea and getting it into service can be done in the blink of an eye is dangerous.

The design, development and production of advanced aircraft power distribution, control and avionics systems is not for the faint hearted. Handling large amounts of electrical power doesn’t have the outward evidence of large spinning mechanical systems but never underestimate the real power involved. Power is power.

The eVTOL aircraft in development deploy innovative design strategies. There’s a lot that’s new. Especially all together in one flying vehicle. Everyone wants fully electric and hybrid-electric aircraft with usable range and payload capacity. So, the race is one. Companies are productising the designs for electric motors of powers of greater than 10kW/kg[2] with high efficiency and impressive reliable. These systems will demand suitable care and attention when they get out into the operating world.

A 500kW motor will go up with one hell of a bang and fire when it fails. The avionics may shut it down, but everything will have to work smoothy as designed every day, not just in-flight but on the ground too. Suppressing an electrical fire isn’t the same as a conventional fuel fire either. To fix these machines the care needed will be great. 1000 Volt connections capable of supplying high power can kill.

Not wishing to be focussed on the problems but here I go. Another major problem is the number of qualified engineers, with knowledge and experience who can work in this area. The companies who know how to do this demanding work are desperately searching for new people to join their ranks.

Educators are starting to consider these demands as they plan for the future. Sadly, there’s not so many of them across the globe who are so foward looking.

The global aviation industry needs to step-up and train people like crazy. The demand for Subject Matter Experts (SMEs) is self-evident. That’s true in design, production, and maintenance. Post COVID budgets maybe stretched but without the big-time investments in people as well as machinery success will be nothing but an illusion.

POST1 : Or 150 kW motors when you have many of them going at once. Rolls-Royce Electrical Testing eVTOL Lift Motor | Aviation Week Network

POST 2: Getting ready Preparing Your Airport for Electric Aircraft and Hydrogen Technologies | The National Academies Press

[1] https://smg-consulting.com/advanced-air-mobility

[2] https://www.electricmotorengineering.com/h3x-new-investments-for-the-sustainable-aviation/

H2 is difficult

I mentioned Hydrogen as an option for aviation. The use of Hydrogen to either power jet engines or to power fuel cells to provide electricity is a real technical option. Although the person I was talking to was engaged in environmental work, they shrugged their shoulders when I mentioned Hydrogen. They were certainly not impressed by these possibilities despite our agreement on the urgent need for de-carbonisation.

I can understand why there’s a level of cynicisms. On my part, it’s like the X-Files[1]. Fox Mulder was the believer and Dana Scully the sceptic. Broadly, I want to believe.

Today’s, liquid fuels can be explosive in certain conditions. However, it takes a considerable effort to create the conditions whereby a devastating explosion can occur. The Boeing 747-100 that was Trans World Airlines Flight 800 (TWA 800)[2] exploded, broke up in the air and fell into the Atlantic Ocean in 1996. This was an example of a worst-case scenario. 230 people were lost in that fatal accident. Now, the ignition of a flammable fuel/air mixture in aircraft tanks is better prevented by design and operational procedures.

If Hydrogen is to be viable in civil aviation such hazardous conditions will be harder to prevent. A flammable hydrogen/air mixture can be ignited much more easily than conventional liquid fuels. Such dangerous situations can be prevented but the measure to do so will require robust design and stringent operational procedures.

Several development programmes are underway, making practical Hydrogen powered aircraft viable. A range of aircraft configurations are possible. From hybrid generator and electric motor set-ups to combustion-based propulsion. This work is moving from academic research into commercial possibilities.

There little read across between the behaviour of conventional hydrocarbon liquid fuels and liquid Hydrogen. This would be evident in any serious incident or accident scenario. Let us imagine the case of British Airways Flight 38, in 2006, a Boeing 777-236 that came down at the end of a runway at London Heathrow[3]. A significant amount of fuel leaked from the aircraft after it came to rest, but there was no fire. There were no fatalities.

The breakup of liquid Hydrogen tanks or plumbing in such a scenario would almost certainly result in a significant fire. The mitigating impact of that fire is the lightness of the gas. Instead of liquid fuel pooling on the ground, Hydrogen would burn upward. However, any explosion could be devastating.

So, for large aircraft design the provisions to protect liquid Hydrogen tanks and plumbing must be extensive and extremely robust. This would have to be maintained, as such throughout the whole operational life of the aircraft. These requirements would be onerous.

Keeping crew and passengers well away from Hydrogen infrastructure will be a must.

POST 1: Crashworthiness doesn’t get much of a look-in. Without it there’s going to be a problem over the horizon. https://www.ati.org.uk/flyzero-reports/

POST 2: At least for eVTOL aircraft some work is being done. https://ieeexplore.ieee.org/document/10011735

[1] https://www.imdb.com/title/tt0106179/

[2] https://www.history.com/news/twa-flight-800-crash-investigation

[3] https://assets.publishing.service.gov.uk/media/5422ec32e5274a13170000ed/S1-2008_G-YMMM.pdf