Category: Flying

Impact of Speculation

The sadness of the loss of live and the suffering of air crash victims’ families, must be respected. On 12th June, Air India’s London Gatwick bound flight AI171 crashed after take-off from Ahmedabad airport. Only one passenger walked away from this catastrophe. Additionally, there were fatalities on the ground as the Boeing 787 aircraft came down in a built-up area.

My heartfelt condolences to those connected with this tragic fatal accident.

The technical accident investigation is well underway. In time, a probable cause for this accident will be determined. This will be published and available to all. As per the international arrangements of ICAO Annex 13 a report will be published. Organisations, with appropriate expertise, will carefully sift through the evidence to establish a sequence of events. This is not a matter of establishing blame. It’s a process of determining what happened with the aim of preventing it from happening again.

Meanwhile, the widespread reporting of the accident can only offer speculation as to the details of who, what, where, when and how and why. There are facts. The time, place and the people involved. Media interviews, with whatever pictures and video recording there are dominate the public domain. However, this is far from the volume of information the accident investigators will handle. They will have access to every nut and bolt, every document, every recording.

After another aircraft accident, back in August last year I wrote: Speculation is a natural human response. When faced with a paucity of information we often put together what we know and then make a best guess as to what happened or what might happen. However, wise or unwise it’s not possible to stop speculation.

In the case of flight AI171 the global media speculation has been, and is, of a new order of magnitude. Normally, the authorities caution against giving too much weight to early conjecture. This is prudent in that the obvious is often not as obvious as it might first seem. Accident investigation can be like putting the pieces of a complex jigsaw together. Deliberately and with great care.

What has been surprising in this case is the intensity of the speculation related to this accident both through traditional and social media. The proliferation of experts offering opinions has reached a new high. Until conflict and war grabbed the headlines everyday a novel theory, or a variation of a theory has been offered. Each one chasing credibility and expanding on limited sources.

Let’s not be pious. I’m not immune from this need to fill a void. My own reasonably well-informed theories float around in my head, but I question my senses in sharing them with others. It’s not a fear of being wrong, as I might be, no, more a fear of cluttering up a confusing mass of information to an even greater extent. Piling theories on top of theories.

Can we have too much of “experts” offering their opinions? Some will be trustworthy and considered, and others will not. How far is it reasonable to stretch what little is known into detailed stories of possible cause and effect?

How is the average person going to tell the difference between sound reasoning and imaginative nonsense? This problem was brought home to me in a recent conversation. When a newspaper revelation is told to me as a “fact” when I know it isn’t, then I see the dangers in excessive speculation.

This may not matter so much to me. In so far as it affects me. However, to an air crash victims’ family this not considerate. To be led to thinking that the cause of an accident is generally known, when it isn’t, that’s disrespectful. It’s the downside of speculation. Not something that is ever going to stop, it’s true. What some keyboard warriors need to think about is the impact of their wild guesses or prejudices.

POST 1: Even reputable publishers latch on to theories that are at best well intentioned and at worse just flying a kite. Air India crash: Early speculation points to possible dual-engine failure | Engineering and Technology Magazine

POST 2: To be fair this YouTube commentator does a good job at making it clear what is fact and what is not https://youtu.be/dIgnR0zw3FU

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

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

My First US Adventure

Let’s wind the clock back. My first trip to the US. It was a big adventure. One that I’d recommend to anyone in their 20s. The trip was a Pam Am fly-drive affair. A travel package that took me and three friends from London Heathrow to Seattle and back. In 1981, I had no idea that I’d be returning to Seattle numerous times in the following decade.

I keep a personal flight logbook. It’s a simple way of keeping track of the dates, times and places. Memory can be unreliable. When 40 years or more has past recollections of individual trips get jumbled up. Although this one is difficult for me to mistake.

We took off in the afternoon and flew across the Atlantic on flight PA 123. Slightly being in awe of the mighty Boeing 747-100. It was the largest aircraft doing that route on a regular basis.

Sadly, the Lockerbie bombing occurred 7-years later to a similar transatlantic Pan Am flight. The airline that brought the Boeing 747 to life didn’t survive after that tragic event.

One of the advantages of being a sandwich student was the ability to earn. To put some money away. To have the funds to plan an exploration like this trip without depending on the bank of mum and dad. To keep the costs down the four of us shared a car, the driving and the motel rooms along the way. In fact, we had a detailed itinerary that didn’t leave much slack time at all. Our travel planning was meticulous. I’d even arranged to visit an offshoot of the Plessey company in the Los Angeles suburbs. It was a real eyeopener. A maker of precision metals for the aerospace industry.

We arrived in Washington State only a year after the deadliest volcanic eruption[1] in US history. Naturally, being the students we were, we drove as close to the devastated area as the open roads would let us. I took pictures of that too. Views of forests felled like matchsticks.

We packed an enormous amount into August 1981. Returning to our final year as soon as we got back. This trip always reminds me that if you plan well and are determined enough you can do a hell of a lot in a short time. We drove over 6000 miles and took in a lot of the West Coast.

[1] The Mount St. Helens major eruption of May 18, 1980.

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/