Category: Systems

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

Understanding Contrails

Crisscrossing the sky, as I look up on a clear day, there are civil aircraft going about their business. People travelling across the Atlantic or coming back or on a day trip to Glasgow.

These shiny pinpoints of light in motion, set against a blue sky, are all the more visible because of the vapour trails they leave behind. Aircraft speed through the rarified atmosphere to leave a momentary trail as evidence of their presence.

Up with the aircraft in flight are natural clouds. Up at 30,000 feet there can be Cirrus clouds[1]. There might not be much air pressure at that altitude but there’s enough moisture to support cloud formation. The word “wispy” sums them up.

Aircraft create condensation trails that are known as contrails. How the English language likes to shorten. They are not mysterious or generate with evil intent in mind. It’s simple physics.

In my bathroom, with hot water gushing from the shower, moisture is the air. When that moist air meets a cold surface, like a window, condensation is sure to be seen. Airbourne it’s not so different. Hot emissions from powerful jet engines shooting out into a cold low-pressure environment and guess what?

Typically, contrails don’t last long. If there’s appreciable wind at high altitude, then they get dispersed quickly. Not only that but the icy temperatures up there soon return things to the status-quo. There are days, when the air is still, that the sky can become a crisscross of contrails where dispersion is more like a gentle merging.

The theory goes that the cumulative impact of lots of high-altitude flying is like the impact of additional cloud formation. It’s water vapour after all. It’s known, high altitude clouds can contribute to the greenhouse effect.

The point I’m getting to here is that lots of flying contributes to climate change. Primarily because of the burning of significant amounts of fossil fuel. As a secondary consideration there’s the issue of contrails across the globe.

This leads to the question – can their formation be avoided? Even, is there something useful to be gained in doing so. Trials and research are trying to establish the answer to these questions[2].

Initially, contrail avoidance sounds like it should be relatively easy to do. However, like so many good proposals it’s not so easy. Change needs to involve air traffic management, flight operations and international regulators.

First the atmospheric conditions need to be detected or predicted in a given location and then an avoidance needs to be planned and undertaken in coordination with everyone flying at high altitude at a given time. Lost of data to crunch.

It’s possible, in oceanic airspace, a dynamic aircraft system could perform this avoidance function. It would be an interesting design challenge for an avionics company to take up.

#Net Zero #SustainableAviation

[1] https://weather.metoffice.gov.uk/learn-about/weather/types-of-weather/clouds/high-clouds/cirrus

[2] https://news.aa.com/esg/climate-change/contrail-avoidance/

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

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

Transform of Future Careers

My education was an industrial one. I guess I was fortunate. No “A” levels for me.

Part of my apprentice programme was to move around the different departments of a major electronics company. That included a range from demanding technical areas, testing new designs, to the everyday pressure of a print room run by an ex-Army man who ran it as if he’d never left the Army. Yes, print rooms were once a staple part of an engineering company. Huge dyeline machines that constantly ponged of ammonia twinned with the noisiest dot-matrix printers ever made. I even got to learn some COBAL[1] with the business unit that put together our payslips. Amazingly enough I was introduced to mathematical concepts, like Fast Fourier Transforms (FFT), at a time when the digital logic needed to implement such algorithms consisted of large cabinet loads of discrete electronics. Now, my simple mobile phone can crunch numbers in this way.

Several weeks here, and several weeks there. One excursion meant spending hot summer days in the Mendip Hills at a quarry testing equipment in deep water. Another meant time working in a former brick-built railway shed that served as a small machine shop.

Of all the different experiences that I had in those formative years (16-18 years) the one that I’ll never forget was a secondment to a London based factory. The company’s training officer recognised that this small village country boy needed to go to the big city. Uppark Drive, Ilford no longer exists as a manufacturing plant. That’s no surprise. In the late 1970s that factory handled the company’s long-lived products. Technology that has gone forever.

Anyway, this is not so much about me. What I’m led to speculate about is what sort of modern-day engineering apprenticeship offers. Does it offer the variety of experiences that I had? Is industrial sponsorship as generous and altruistic as it once was? Do industry and government work hand in hand to ensure a future workforce has the skills that are needed?

Simply the answer is probably “no”. In fact, the structure and organisation of design and manufacturing organisations has changed dramatically. In aerospace there are some companies that have a major factory with every facility at their heart but most subcontract extensively. Colleges have been turned into educational shops, paid by student numbers.

Here’s a thought. It’s not so much what’s taught that’s key as much as the exposure to a variety of ways of thinking and working. A variety of exposure give a student a toolbox from which they can then draw. Finding interesting work will depend on adaptation and repurposing past skills. That’ll be the only way to assure the world doesn’t pass by at an ever-increasing pace.

I’m sure that advances in artificial intelligence (AI) will affect everyone[2]. The idea that all AI will do is displace people is wrong. It just means that, like my recollections above, the types of activities that needs to be done will be entirely different in 2065. Unless I’m highly unusual, I will be long gone. But if you are 25 years old this is worth a thought.

[1] https://archive.org/details/historyofprogram0000hist/page/n7/mode/2up

[2] https://nap.nationalacademies.org/download/27644#

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

Safety Analysis

In discussions about safety one model is often called up. Its simplicity has given it longevity. It also nicely relates to common human experience. The model is not one of those abstract ideas that take a while to understand. If you have been on a safety training course, a lecturer will give it couple of minutes and then use it to draw conclusions as to why we collect and value safety data.

On illustration, and it’s a good one for sticking in the memory, is a picture of a big iceberg. Most of an iceberg is underwater. One the surface we only see a fraction of what is there. This is the Heinrich pyramid. Or Heinrich’s Law[1] but it’s not really a law in the sense of a complete mathematical law.

The logic goes like this. In discissions about industrial major accidents, there are generally a lot more minor accidents that precede the major ones. Although this was drawn up in the 1930s the model has been used ever since. And we extend its useful applicability to transport operations as much as workplace accidents.

Intuitively the model seems to fit everyday events. Just imagine an electrical cable carelessly extended over the floor of a hanger. It’s a trip hazard. Most of the time the trips that occur will be minor, annoying events, but every so often someone will trip and incur a major injury.

What we can argue about is the number of precursor events that may occur and their severity. It wouldn’t be a simple universal ratio, either. Heinrich said there were generally about 30 accidents that cause minor injuries but 300 accidents with no injuries. A ten to one ratio.

Forget the numbers. The general idea is that of the iceberg illustration. Underlying that example of the pyramid is the notion that there are a lot more low severity events that occur before the big event happens. Also, that those low severity events may not be seen or counted.

It’s by attempting to see and count those lesser events that we may have the opportunity to learn. By learning it then becomes possible to put measures in place to avoid the occurrence of the most destructive events.

In British aviation I will reference the 1972 Staines air accident[2]. A Brussels-bound aircraft took off from London Heathrow. It crashed moments later killing those onboard. One of the findings from this fatal aircraft accident was that opportunities to learn from previous lesser events were not taken. Events not seen or counted.

Thus, Mandatory Occurrence Reporting[3] was born. Collecting data on lesser events became a way of, at least having a chance of, anticipating what could happen next. Looking at the parts of the iceberg sitting under the water.

How many fatal accidents have been prevented because of the safety analysis of data collected under MOR schemes? If only it was possible to say.

[1] https://skybrary.aero/articles/heinrich-pyramid

[2] https://www.bbc.co.uk/news/uk-england-surrey-61822837

[3] https://www.caa.co.uk/our-work/make-a-report-or-complaint/report-something/mor/occurrence-reporting/