Category: Safety

Technology and Probability

Everyday numbers don’t scare me. The day, the date, the time are important and simply communicated. I can throw a couple of round numbers at anyone, and they should know what’s happening. Yes, convention does matter. Standards matter. I don’t know how, but I know some people struggle with the 24-hour clock notation.

When we get to small scales and tiny numbers, less familiarity means that it’s not so easy to communicate. To make those numbers meaningful media people like to use analogies. A common one is saying that a thing is: less than the width of a human hair. If you still have it, and I do, hair is an everyday item.

Let’s say a human hair is typically 100,000 nanometres wide. Sounds big in nanometres. That’s a tenth of a millimetre. Now, I can get a plastic ruler and visualise that size. My perception of scale depends on where I put the decimal point. Remember in SI Units a “nano” is 1 x 10-9[1]. Something to think about when seeing newspaper headlines about nanotechnology.

Visual depictions do help. Even if they can be slightly misleading when comparing dissimilar objects. Our planet, Earth is about 12,756 kilometres in diameter. So, for a bit of fun I could say the Earth is about 128 x 109 times wider than a hair on my head. Nice but not so useful. Tiny probability numbers like the range from 1 x 10-6 to 1 x 10-9 require some imagination.

It’s not such a big leap. Let’s say that I make mistakes. That said, I’m well trained at a specific simple task. Flicking a switch at the right time. My measured error rate is about 1 in 100. However hard I try, I make mistakes, not necessarily the same one, but with a reasonably quantifiable average frequency when nothing changes.

A well-designed machine, doing the same mechanical task, can do better than me. It’s measured error (or failure) rate is about 1 in 10,000. That might be considered good if it’s merely to switch on a toaster at precisely 6 am. It might not be so good if the result of a single mistake is instant death. In other words, I’ve become highly dependent on this mythical machine.

To do better, I could devise a means of checking the results of this machine. If I did this checking perfectly, entirely independently and without distraction, then experiencing a negative result might get up to a rate of one in a million. With this arrangement, I’m still not happy enough to place my life, or the lives of my colleagues in the hands of such a system.

Instead, I’ll construct two entirely independent well-designed machines, each doing the same simple task and each constantly checking the other one. Now, I’m cooking on gas, as the expression goes. Will this result in a negative outcome rate of around 1 in 1 x 108? One in a ten million. At least it’s an analysis worth doing. However, calculations may not give the result as one in a ten million. That result can hinge on the notion of what is entirely “independent”.

To make my general point here I have grossly oversimplified a problem. What I hope I have conveyed is that tiny probability numbers can be grasped without entertaining rocket science or nuclear physics. In the world of computational systems, we can make machines that are exceptionally good at performing consistently, persistently and error free. Not perfect. Not at all. Not prefect in so much as making life and death decisions.

[1] https://www.nano.gov/about-nanotechnology/just-how-small-is-nano

Probabilistic Predictions

Uncertainty is the only certainty. Not a radical statement. As long as I live, dealing with uncertainty is inevitable. Unavoidable everywhere. I wouldn’t have it any other way, even if it can be uncomfortable.

Prominent Ancient Greeks may have travelled to Delphi for advice as to what the future may hold. There’re those three enigmatic witches who warn Macbeth of his fate. History and fiction are littered with references.

For me, I can pick-up a newspaper and look for a daily astrological prediction. One I like. I can flick around social media and see more prophecies than ever. Mostly gibberish. There are those convinced of their foresight.

Despite a cynical disposition towards the above, science can be applied to the world of uncertainty. Generally, the proposition is that an element of the past and present will be reproduced in the future. This is not absolute. However, human engineered systems tend to behave with a degree of predictability.

Empirical methods, where society collects data from the past and present, can be useful in trying to forecast what may happen next. The more deterministic the systems under study, the more useful acquired data can be. For these, forecasting challenges mount for the new, novel, or radically altered.

I’m writing this given the interest there is in probabilistic safety. There are figures that hit the headlines that are almost incompressible. If the rationale behind the numbers is not clear then incorrect assumptions result. Tiny numbers from 1 x 10-6 to 1 x 10-9 are quoted in the News (SI Units). What do they mean? Let’s start with simple probability.

If an occurrence is certain then a numerical value of “1” can be given to it.

Absolute certainty is a rare thing. I can say that the Sun will rise tomorrow, and most people will take that as a statement of certainty. Intriguingly there’s the most incredibly improbable case where the solar system is thrown into instability and the Sunrise isn’t as expected.

If an occurrence never happens then a numerical value of “0” can be given to it.

Absolute impossibility is only possible with absolute knowledge. So, again it’s rare. I can say that human time-travel, to and from the distant past, is only fiction to next discover that a way has been found.

Let’s say we live in a world where the probability of occurrences ranges from the 0.99999, with ever more “9s”, to a number as small as 1 x 10-30[1]. A quecto.

These extreme numbers are nice for physicists and astronomers to play with, but they are outside normal engineering practices. As yet, we do not have the means to operate at the level of these limits. Time will tell. Or I maybe wrong.

By the way, I used the word “occurrence” above to denote anything that can happen in an instant. When talking about undesirable happenings, that can mean an incident, accident, mishap, slip, failure, or error. Each of these has a definition. Often more than one.

Next. I’ll go back to the tiny numbers more commonly quoted.

POST: For extraordinary numbers we need look no further than the nimble electron. So far, the best measurement for the life of an electron suggests that one now will still be around in 66,000 yottayears (6.6 × 1028 yrs). That’s about 5-quintillion times the current age of our universe. 

[1] https://www.nist.gov/pml/owm/metric-si-prefixes

Avoiding Contrails and Enhancing Operations

Here I’m expanding on my earlier words on aircraft Contrails.

Airspace is a busy place. It’s most busy over Europe and the US. Over the oceans there’s more room, although on certain routes, like the North Atlantic, there’s plenty of daily air traffic.

Those who manage the airspace are primarily concerned with ensuring that aircraft collisions do not occur. The impact of mid-air collisions is devastating. There’re few people in aviation who can forget the events of an evening in July 2002. Over Überlingen, Germany[1], 71 people lost their lives at a time when the sky was not busy at all.

Managing the use of airspace is more than collision avoidance. Flying is perpetually concerned with the weather. What’s it doing, how is it changing and is it a hazard? It’s not just the safety of flying that demands up-to-date meteorological information. Knowing about the winds can enable more efficient operations, and that’s less fuel use for a given route.

Large thunderstorms need to be avoided. Regions of the world (example: intertropical convergence zone) make this a dynamic challenge. Manoeuvres may be planned but flight crews must be ready to act based on the information they have, like weather radar.

Turbulence is another phenomenon to be avoided, if possible. This can occur in clear air. It can be difficult to detect. Which explains the unpleasant examples that hit the News now and then[2].

Back in 2010, aviation had a reminder that avoidance encompassed any hazardous airspace. That was when an unpronounceable volcano in Iceland was spewing out ash at high altitudes. Plumes of volcanic ash, if ingested into aircraft engines, can cause major difficulties.

I’ve written these words to emphasise that the avoidance of contrail formation cannot be done as a stand-along consideration. It becomes one factor in a whole mix of factors.

Avoidance of contrail formation is about considering the mechanism that cause them to form. Clearly, the warmer the air is the harder it is for a contrail to form. The more humidity there is in the air, the easier it is for a contrail to form. Outside Air Temperature (OAT) and atmospheric humidity vary at each altitude. That relationship interacts with the aircraft inflight, and the outcome may be different for each aircraft type.

At least one academic study[3] says that adjustments of aircraft altitude of around 2000 ft could have a useful effect on contrail formation. That’s good to know but let’s not forget that Reduced Vertical Separation Minima (RVSM) [4] means a vertical spacing of 1000 ft in busy airspace.

My take on this fascinating subject is that there both a tactical and operational approach that can be practically taken by aviation.

At the tactical level, airlines can factor contrail avoidance into flight planning. Creating an algorithm that will weigh all the relevant flight factors. Improved sources of accurate and timely meteorological data and predictions will be needed.

At the operational level, it’s down to the flight crews to take advantage of environmental conditions as the opportunity arises. Much as dealing with turbulence, that is when safety and operational rules permit. To change altitude when its beneficial, computational help is likely to be needed. Over the ocean, air-ground communications systems may need to be further improved. An altitude change that avoids contrail formation but increases fuel consumption would not be a sustainable solution.

These computational tasks may well be well suited to machine learning. A useful application of artificial intelligence. I can imagine a cockpit weather radar display with a new set of symbology that indicates a low probability contrail formation zone ahead.

[Back in the 1990s, I worked on RVSM when the ARINC organisation was creating international standards. Safely increasing traffic in the North Atlantic region. Additionally, I participated in the certification of Future Air Navigation System (FANS) 1/A for use over the ocean. FANS led to more efficient aircraft operation due to shorter flying times and decreased fuel burn.]

POST: Looks like data crunching is underway Flight plans, but greener: The ICCT and Google’s mission to refine the Travel Impact Model – International Council on Clean Transportation

[1] https://www.bfu-web.de/EN/Publications/FinalReports/2002/Report_02_AX001-1-2_Ueberlingen_Report.pdf?__blob=publicationFile&v=1

[2] https://www.flightglobal.com/safety/turkish-777-rapidly-descended-during-crews-aggressive-response-to-turbulence-encounter/162937.article

[3] https://www.imperial.ac.uk/news/195294/small-altitude-changes-could-contrail-impact/

[4] https://skybrary.aero/articles/reduced-vertical-separation-minima-rvsm

Sustainable Aviation: Innovations and Challenges

Gas guzzling continues to be one of aviation’s problems. Combustion remains that the heart of most aircraft power plants. Taking large amounts of fossil fuel. Squeezing energy out of every drop of gasoline. Gobbling up more day after day. Pushing out emissions.

As I look out across the garden, I see gliding effortlessly as the warm air rises, a Red Kite[1] gracefully circling. Wings outstretched they hardly move them as they climb. They’re a distinctive small bird of prey, easily spotted because of their forked tail. Now, that’s what I call efficient flying. Using all that nature provides and wasting little energy.

Human attempts at flying are a million miles behind these magnificent birds. There’s still so much to learn about aerial navigation. It’s a matter of control. The sensing of ambient conditions and the precision movements needed to ascend and dive at will.

The search is on for effective change. There’s no pretence that the way commercial aviation operates is unsustainable. It’s true that the gas guzzlers of the air guzzle less gas now than they ever have but the physical facts remain.

None of this is new. I’m about to send a book called “Towards Sustainable Aviation” to a charity shop. It’s not that there’s anything wrong with it. The book is full of pertinent analysis and observations. Trouble is that it’s dated 2003.

I’m led to ask – what’s changed in over 20-years? In answering my own question – quite a lot but not enough. Discourse has moved on from academic quarters to the political sphere. Aircraft have become more fuel efficient. Driven by economic imperatives as much as any concern for the climate. Research initiatives are generously funded to come up with answers. Solutions like hydrogen, electric propulsion, and SAF (sustainable aviation fuel) are slowly moving from theory to practice. A few prototypes are flying. Limited supplies of SAF are flowing.

Unmistakable that’s where the problem lies. For all the hype, policy and government funding the pathway to genuinely sustainable aviation disappears way off into the horizon. There are setbacks too. Gas guzzling is back in fashion. Certainly, in Trump’s America.

We could make a much more of the technology that’s currently available. Yes, there are costs involved. Change is not a free ride. That said, sticking with the status-quo isn’t free either. Legacy costs mount up. One reason why older jets disappeared from fleets so quickly.

The next generation of commercial aircraft must make major steps forward. Since the life of a typical aircraft type can easily extend to 30-years, then change must happen in design now.

Typically, commercial aviation moves with graduated change. There’s an inherent conservatism in the system, as might be expected when safety and security are paramount. Facing this global challenge, there’s a need for a degree more radicalism.

Since high impact disruption is also in fashion, it’s time for airlines and manufacturers to adopt a pioneering spirt. It’s been done before. In the 1960s, that pioneering spirt gave us the Boeing 747, the Jumbo jet. That opened flying to a whole generation.

[1] https://www.rspb.org.uk/birds-and-wildlife/red-kite

Europe Day Highlights the Need for Unity

Keeping the peace is never easy. There’s an irrational propensity to conflict in human nature. Keeping the peace is not a passive task. First, it requires communication and engagement. When those two go, trouble is not far behind. It’s by expressing concerns that each side knows where the other stands. Escalation can come when ignorance and propaganda take over.

After the second world war, institutions were established to ensure that communication and engagement became a non-stop affair. With only a small number of exceptions, the countries of the regions of the world engaged in these institutions. Those measure have contributed to making a more prosperous world.

“Never again” are two words that refer to the atrocities of war. The moto is to remind everyone that the worst can and does happen, and that perpetual effort is needed to ensure that history does not repeat itself. The concept of “lessons learned” is essential for safety and security. This is as much true for micro day to day activities as it is for the macro events that shape the path global ahead. Taking teaching not from narcissistic demigods and snake oil salesman but from the pages of history. Appeasing tyranny is not an option.

This week has been a reminder of the lessons learned from the world wars. For most people it’s been a continuing commitment to ensure such events never happen again in Europe. Sadly, let’s not be coy. Despite an overwhelming desire for peace, conflict in still Europe is a reality. But the lesson is there in black and white, appeasing tyranny never works.

Today, Friday 9th May is Europe Day. That’s because a speech by Robert Schuman[1] changed the course of European history on this day. Five years after the war in Europe had come to an end, he put forward a proposal that would make a future similar conflict impossible. The idea was to create an interdependence that would secure peace, unity and solidarity.

It worked. His proposal led to the creation of a European Coal and Steel Community. That measure lay solid foundation for what would later become the European Union (EU). Behind this is move is the echo of “Never again”. Europe has seen centuries of war. This was a moment in time to bring that to an end.

For now, 75-years on, this has been a success. It’s not a regional project with a defined end, even if it has a defined beginning. Where the EU chooses to go next is in the hands of its Member States and its citizens. Changing the course of European history doesn’t stop because the EU exists. Without the cooperation and dialogue, it provides there’s always a chance that ancient rivalries will be reignited. In fact, unscrupulous right-wing politicians[2] are trying to do that just now.

Sadly, in the UK, we stand on the sidelines, looking across the water at continental Europe. Brexit has done a great deal of damage. But as I have said, nothing is static, the world is entering an ever-uncertain phase. The opportunity for the UK to restore EU relations is open. I see the wisdom in the words of the Governor of the Bank of England. He has said the UK now needs to “rebuild” Britain’s relationship with the EU. Amen to that.

[1] www.europa.eu/!9JbCd9

[2] https://www.politico.eu/article/germany-spy-agency-walk-back-extremist-label-afd/

Finding Balance

Regulation can be a contentious issue. That’s an understatement. A spectrum of views extends from the complete libertarian to the past soviet model. Citizens shouldn’t be encumbered by any restrictions to the State has the right to dictate every aspect of life. Clearly, there are immense downsides to either of these extremes. Luckily, although not everyone will agree, the set of political choices available in the UK covers the wide range from the far-right to the far-left. These labels are deficient when it comes to the detail. Often these two camps are similar in their authoritarian ways and means.

Rejecting the extremes, being a liberal, means finding a balance. That means a minimal number of rules and regulations to achieve the prosperity, safety and security goals that most people happily support.

A pendulum swings in the British political cycle. Never quite sure what the cycle time is on this one. What’s for sure is that our society’s tendency is to go from urges to tighten-up rules and regulations to impulses to eliminate or relax them with gusto. Often, the aim is to tweak or protect economic stability or tweak or promote economic growth. After the banking crisis of 2008 it was the first of these, now it’s the second.

Brexit is a strange oddity. Although, great claims were made for the loosening of the ties that bind us, the reality has been much onshoring of past rules and regulation. The forces of continuity have some good arguments.

It’s reported that Prime Minister Starmer is considering dynamically aligning UK regulations with EU regulations, as if that’s not happening pragmatically and piecemeal already. OK, this is not consistent across every sector of the economy. It’s a mixed bag. Politicians banging the drum but not doing much.

Let’s say the financial services market goes a different way from the technology sector. One has a history as long as your arm the other is being made-up as we speak. Clearly, there are risks in both deregulation and overregulation. Thus, I get back to that notion of finding a balance.

To hardened Brexiters EU and UK rules constrain. To their supporters they enable, facilitate and transform.

Now, what’s difficult to discern is where do Starmer and Reeves stand?

A direction of travel, to encourage investment in the UK, has been touted. That implies alignment rules. Investors rightly seek the largest market on offer. Like it or not, the UK is not the US, or even the EU when it comes to the size of its economy. Maybe, it’s taken Brexit to realise that we align as a matter of common interest. Mutual benefit.

Most of our safety and security goals are not subjects of intense competition. If you fly internationally, why would it make sense to compete on safety or security? The general expectation is that common high levels of safety and security are desirable.

As the weather improves so we are heading towards a year of the Labour Party in power. There’s disappointment and concern about the timidity of their actions. The word “reset” is banded about. A ridiculous word. Press the reset button to restore a past condition. No, choices need to be made. Closer alignment and partnership with the EU are the rational choices.

Travel’s Societal Impact

Privilege is all around us. It’s, by definition, not equality. It’s a privilege to live in a country not torn by war or where the environment has not been decimated. It’s a privilege to be able to protest and strongly disagree with the powers that be. Indeed, in this country it’s a right too.

Debates about the moral or ethical grounds of inequality will never cease. That’s a hope of mine. For the minute we become timid and cowed by an authority that would rather supress such debates, then that’s the end of our democracy. We’d be free no more.

A large part of my career has been in the aviation industry, in one way or another. Putting aside the military uses of aviation, that’s another debate, civil aviation and the travel industry are two peas in a pod. Flying facilitates travel. Largely international travel. Apologies to the cargo industry, leisure flying and so many others.

One phenomenon that is not new, is that of raising the issue of responsibility. For example, the consequences of tourism to natural environments are often negative. Not always so. Huge effort is made by some countries and organisations to make tourism a positive. However, generally there are significant challenges to be grappled with in making travel affordable for all.

Wealthy young Europeans have been roving across boarders as part of a rite of passage since the 1600s. A “Grand Tour” was a form of discovery, education and cultural enrichment. Today, a student might call that a gap-year. Time taken out of formal studies to travel abroad. The aim, as well as having fun, is to return a more rounded person ready for whatever life might throw up.

Where do we sit as a society in terms of the balance between personal freedom and our collective responsibilities? Are activists right to attempt to slam or shame travellers for the negative impacts that they can trigger? These are uncomfortable questions. Ironically, these difficult questions are often raised by the people who have enjoyed the privilege of travel.

In my mind, a debate on this subject of balance reflects greater societal issues. When we look at a basic hierarchy of human needs then international leisure travel may not be top priority. However, life would be less rich and colourful without it. Embarking on an epic journey, that takes a traveller outside their comfort zone, can be a life changing event.

To defend the freedom to travel, I cannot avoid looking at the other side of the equation. There is an overwhelming responsibility to do something restorative. Ignoring the impact of travel, particularly civil aviation, is not an option anymore.

I know there are some politicians who scream for the abandonment of Net Zero policies and all they entail, but they are extremely foolish. Shifting the burden onto future generations is reckless. Appealing to those who want to escape the debate, or force a return to mythical age, is nothing more than doomed short-termism.

This is one reason I’m an advocate for electrification and the exportation of radical solutions, like hydrogen powered civil aviation. Technological solutions are part of the path to take. That, in of itself, may not be enough but at least engineering change is permanent.

Solutions by design are far more powerful than ephemeral political posturing. Legislation can be overturned in a weekend. A whole new way of operating aviation can be sustained for decades.

Communication Prevents Disasters

It’s often forgotten that there’s a need to repeat messages. We are not creatures that retain everything we see and hear. There are exceptional people, it’s true, those who cram away facts and have an amazing level of recall. Often that’s my reaction to watching students leading teams on University Challenge[1]. How on earth do they know those obscure facts?

Most of us do not respond well to those who say, “Well, I told them once. I’m not going to tell them again.” That line is probably one of the most misguided utterances a teacher can make. Like it or not, this approach is part of our heritage. Past ages, when deference was expected, listening was mandatory, and misremembering was entirely the listener’s fault.

We’ve had a cultural shift. Our complex technological society doesn’t work in a command-and-control way. Too many disasters can be traced to miscommunications and misunderstanding. Now, the obligation exists on those delivering a message to go some way to ensure that it’s received with a degree of comprehension. That’s when repetition has a role to play.

One of the pillars of Safety Management Systems (SMS) is Safety Promotion. It’s the Cinderella of the aviation safety world.

Why do I say that? Experience for one. It’s much easier to get policy made and funding for the “hard” sciences like data acquisition, analysis and decision-making systems. These are often perceived as providing tangible results. Actionable recommendations that satisfy the need to be recognised as doing something. Even if that something is questionable.

Communication is key to averting disasters. It’s no good having pertinent information and failing to do anything with it, other than file it. The need to know is not a narrow one. Confined to a specialist few.

Let’s go back to 2003 and the Space Shuttle Columbia accident[2]. This craft was destroyed in a disaster that claimed the lives of its crew. The resulting investigation report is extremely compressive, if slightly overwhelming, but it has some key points to make.

To quote, “That silence was not merely a failure of safety, but a failure of the entire organization.” [Page 192]. In other words, the hidden concerns and internal machinations of an organisation can smother safety messages and led to failure. Since 2003, it’s sad to say that there are multiple occasions when what has been learned has been ignored. The impact has been devastating.

So, to shape the future let’s remember the Cinderella of the aviation safety. Discovering problems is not enough. It’s vital that practical solutions and good practice gets promoted. That needs to be done forcefully and repetitiously.

NOTE: This is, in part, a reaction to watching this video presentation. https://acsf.aero/an-unforgettable-closing-to-the-2025-acsf-safety-symposium-with-tim-and-sheri-lilley/

[1] https://www.bbc.co.uk/programmes/b006t6l0

[2] https://ntrs.nasa.gov/api/citations/20030066167/downloads/20030066167.pdf

Revolution: Hype vs Reality

Talk is of a revolution[1]. That sounds sensational. It sounds like marketing talk aimed at creating an insatiable desire for something new. So, that kind of talk immediately switches on the cynical side of my brain. Is this hype or is it real?

We’ve had plenty of both in my lifetime. Colourful boys adventure books with novelties like nuclear powered aircraft and moonbase vacations. It’s not that “flying a kite” is entirely bad. Those imaginings of the future had pictures of prototype flying cars. Now, we maybe on the verge of that prediction becoming real.

AI is not new. It’s been a research subject for decades. What we have most recently is the coming together of concepts and the practical machines on which to run those concepts. Amazing has been the speed of progress. That’s a modest word considering the sudden adoption of new tools that go way beyond simple INTERNET search engines.

Bill Hunter’s line: “You can’t stop progress”. At least that’s the line I remember of the 1994 film Muriel’s Wedding[2]. It was said on a rocky path to “progress” induced disaster.

My curiosity centres around avoiding the hype and finding out what’s real. That’s in the vain hope that I might not be left behind in this rapid surge of “progress”. So, to keep up with the latest technical developments I clicked on a TED App. The boss of TED, Chris Anderson has recently interviewed Sam Altman, the CEO of OpenAI[3]. He’s the guy behind ChatGPT. AI has elevated new people into the spotlight. It’s given established technology companies a headache. Their desire to be in the pack, or leading the pack is mighty strong.

My takeaways form this interview are that AI will outpace human intelligence, in time. No one knows how much time, but the path is set. The direction of travel isn’t in the control of traditional institutions or government departments. Society must get its head around a time when we live with machines that out pace us.

Second, it would be nice to have an enlightened global regulator to ensure that the massive amount of development going on produces outcomes that are for the public good. Chances of that happening are about zero, although not zero. There’s even a possibility that the industry at work on this technology realises the need for a set of enforceable rules.

Questions of safety are paramount. Even though society debated the impact that the INTERNET would have on us, steps to provide protections and boundaries only came about after the event. Lost in a storage box, I once had a book called “The Sleeping Sentinels”. Basically, the thought was that political parties and the legal profession are always more than ten steps behind the technologists. We are highly reactive.

One interesting aspect of the interview was the pauses. What was evident is that it’s hard to find the right language to describe what’s happening. Walking a tight rope between sounding like Chicken Little[4] and a wise respected elderly professor. Revolution is the right word.

POST: It’s not just IT Why AI Demands a New Breed of Leaders

[1] https://youtu.be/Xv8FBjo1Y8I

[2] https://www.youtube.com/watch?v=PLDcevp5w5o

[3] https://www.ted.com/talks/sam_altman_openai_s_sam_altman_talks_chatgpt_ai_agents_and_superintelligence_live_at_ted2025

[4] https://www.rottentomatoes.com/m/chicken_little

Tragic Helicopter Crash

The record of sightseeing helicopters is not a good one. In the most recent case 6 people perished as helicopter crashed into the Hudson River in New York City. It’s with a heavy heart that I offer my condolences to the family and friends of those involved. These are devastating events for all concerned.

It’s certainly far to early to say why this helicopter fell from the sky. Eyewitness reports suggest a catastrophic occurrence. Also, that the helicopter tumbled and hit the water inverted. Again, suggesting an occurrence where the pilot had no opportunity to avoid the outcome.

Initially, the indications are that the local weather was not a significant factor in the accident. Also, reports are that no other aircraft was involved. In this fatal accident the US National Transportation Safety Board (NTSB) will be on the scene as they manage the technical investigation. They have already published initial information.

Given the size and nature of operations there will be no Flight Data Recorder (FDR) installed on this helicopter. There is a strong argument for requiring light weight flight recorders on small helicopters. It will be interesting to read of what electronics are recovered from the accident site. Images from a mobile phone may be most useful to the investigators.

The helicopter’s maintenance records will be reviewed for indications of mechanical problems. However, it is highly unusual for a complete rotor system to fall apart in flight. Mechanical failures often have some precursors that give an indication that all is not well.

The list of Bell 206 type helicopter accidents and incidents is long[1]. That’s not an indicator of their relative safety. This is a popular single engine small helicopter with a long history. Both civil and in other variants, military. First flight dates to 1966. It’s going back a while, but I clearly remember a sightseeing flight I took on such a helicopter back in the 1980s.

This type of small helicopter is often operated in difficult conditions. They have the advantage of being highly maneuverable. However, there are maneuvers that can case serious problems. The term “mast bumping” was used by the US Army[2]. In the worst cases this results in catastrophic occurrences.

One of the factors in such accidents and incidents is a significant change in the helicopter’s center of gravity and an inappropriate response to that condition.

POST 2: Pictures of the recovery of the rotor system from the river suggest structural failure. It’s as if the rotating mechanical parts ripped themselves from the body of the helicopter. Bell 206 L-4 helicopter crash, Jersey City, New Jersey (April 10, 2025) | Flickr

POST 1: Social media is littered with theories, as per usual. One seems highly unlikely. Namely, fuel exhaustion. Another, concerning a strike of a flock of birds over the river is worth investigation. In that possible case evidence will surely be easily uncovered.

[1] https://asn.flightsafety.org/wikibase/495847

[2] https://youtu.be/_QkOpH2e6tM?si=AtMfqztc_cjrUOSm