High ALT

Normal commercial air traffic control doesn’t go beyond 60,000 ft in altitude. That makes sense since civil flying activities have been limited to lower altitudes. In fact, modern commercial airliners are not designed to fly above about 45,000 feet. This is a compromise based on what works commercially as much as what’s works best. Aircraft instruments are calibrated making standard assumption about the atmosphere.

For some of its flight, Concorde cruised at a height of 60,000 feet. More like a military jet, with its speed it had the capability to make use of higher altitudes.

It’s even possible to fly above 50,000 feet without an engine. The world record glider flight by AIRBUS shows it’s possible.

The Earth’s atmosphere is not uniform. It changes its characteristics with altitude. The atmosphere can be divided into five layers, as the temperature and density change. They are named: Troposphere, Stratosphere Mesosphere, Ionosphere and Exosphere. 

The Troposphere is a layer that goes from 8 kms (26,247 ft) on the poles to about 18 kms (59,055 ft) on the equator. This is the layer where weather is experienced.

On average, the Stratosphere goes up to about 40 kms (131,234 ft). The winds blows fast but they tend to be more consistent as they wrap around the globe. The lower portion of the Stratosphere is virtually isothermal (layer of constant temperature). 

A medieval English philosopher and Franciscan friar, Roger Bacon[1] figured out that the air might support a ship in the same way that water supports ships. In the 13th Century that was a nice academic conclusion but little more.

With all the current controversy surrounding high altitude balloons, that the road to flight started with balloons, could be said to be a bit ironic. It’s long been known about that balloons fly well at high altitudes but it’s a new frontier as far as commercial activity is concerned. For science, weather balloons may go up to 40 km to measure the high level winds.

Some experimental work has been done on trying to commercially use the airspace above normally civil flying. The Google Loon trials[2] are an example of an attempt to float a telecommunications platform high in the sky. These balloon trials were abandoned as difficulties proved greater than anticipated.

It’s not so easy to keep a high altitue balloon on-station.

Now, considering the news in North America, maybe high-altitude operations ought to be a matter of regulatory concern. This is not a subject that any one country can address alone.

There is some legal, regulatory and technical work[3] underway in Europe[4] but it needs to make progress. This is a subject for international collaboration. 

[1] https://en.wikipedia.org/wiki/Roger_Bacon

[2] https://blog.x.company/loons-final-flight-e9d699123a96

[3] https://www.eurocontrol.int/article/echo-making-space-new-high-altitude-entrants

[4] https://www.eurocontrol.int/events/european-higher-airspace-operations-symposium


It’s intriguing. Reports of unidentified flying objects being shot down over Alaska, Canada, and Michigan prompts a lot of questions.

The Earth’s atmosphere eventually becomes space at 100 km up. The Kármán line[1] is one way to define the boundary. All aeronautic activities are deemed to take place below that imaginary line. Theodore Karman[2] did his best to determine a height at which the Earth’s atmosphere is too thin to support flight. Now, there’s an international discussion about bringing that boundary down to 80 km. That is the hight above which a person in a space vehicle is said to become an astronaut.

I guess my point is that there’s a lot of the Earth’s atmosphere to continuously monitor, if the task is to know about everything that is flying everywhere. So, it’s perfectly reasonable that reports of unidentified flying objects will crop up, now and then.

It doesn’t mean that there are alien probes popping in to keep an eye on us earthlings. No, in so far as is commonly known there’s no evidence that stands up to scrutiny to definitively prove the existence of sustained airborne craft that are not of this Earth. However, extra-terrestrial objects fall to Earth all the time. Mostly ice and rocks. I wrote about objects falling from the sky in an earlier article.

It’s worth recalling the first article of the Chicago Convention on Sovereignty:  

The contracting States recognize that every State has complete and exclusive sovereignty over the airspace above its territory.

For those monitoring what’s in the air, the primary concern remains about flights over land and populated areas. This is the case where hazards can exist to those below.

All said and done, it’s no time to become alarmed. It may well be the case that these unidentified flying objects were previously ignored. Only now has the militaries in North America been galvanised into action and being more vigilant. The more people look, the more people see.

What do I know? Spy balloon, craft and drones may be much more common than has been generally reported.

Claims and counter claims that everyone is doing it shouldn’t be dismissed out of hand. The technology involved in flying above normal air traffic has a multitude of potential applications. A framework for higher altitude operations is now being written[1].

POST: Diplomatic tensions between the US and China continue to escalate as the US explains its shooting down of high altitude flying objects over North America. Much is still to be uncovered.

[1] https://www.eurocontrol.int/article/echo-making-space-new-high-altitude-entrants

[1] https://www.fai.org/news/statement-about-karman-line

[2] A Hungarian American physicist and engineer who was born 11 May 1881.

Fatal accident in Nepal 3

The air transport year started badly. A Yeti Airlines twin-engine ATR 72-500[1] aircraft plunged into a gorge as it was approaching Pokhara International Airport (PKR) in Nepal.

Singapore’s Ministry of Transport (MOT) is supporting Nepalese authorities.

The latest news is that the aircraft’s Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) have been replayed. It is reported that the analysis of the FDR and CVR data shows that the propellers of both engines were feathered during approach.

It is not known if this was due to the actions of the crew or a technical fault.

The investigation continues.

The propellers on this aircraft type have pitch control of their blades. The pitch of the blades can be changed to the “feather” position (approximately 90 degrees). Feathered blades reduces the drag that would occur in the event of an engine shutdown.

This event occurring while the aircraft is slowing on approach will have an impact on the aircraft’s air speed. Monitoring air speed on approach is vital.

The suspicion that the aircraft may have stalled remains one theory.

The normal actions required on an approach are called up on a checklist. 

Example: Here is a video of an ATR 72-500 landing.

Notice the pilots’ hands at 4:57 minutes in.

An incident involving an aircraft of the ATR 72 type on the way from Stockholm to Visby[2] is interesting but may not be relevant in the Yeti Airlines case.

[1] https://skybrary.aero/aircraft/at75

[2] https://www.havkom.se/en/investigations/civil-luftfart/tillbud-med-ett-luftfartyg-av-typen-atr-72-pa-vaeg-fran-bromma-till-visby


What do you think are the reasons behind the overall decline in engineering apprenticeship starts in recent years? We are particularly interested in understanding more about supply and demand.

What do you think are the reasons behind the overall decline in engineering apprenticeship starts in recent years? We are particularly interested in understanding more about supply and demand.

Image. It persists even now. In fact, the paper[1] that asks these questions has images of spanner turning. It’s so easy to pick royalty free pictures that pop-up from search engines searches. These images show mechanics in blue overalls. Don’t get me wrong, this is not the least bit disrespectful of spanner turning.

A deep cultural memory persists. It has multiple elements. You could say, in part, industrialisation, still conjures up images of dark satanic mills contrasted with grand country homes of a class of business owners. Basically, dirty, and clean as two key words.

The Victorians did a great deal to both elevate engineering personalities, like Brunel[2], but to hold them as different or apart from the upper middle-class society that the fortunate aspired to join. Those who forged the prosperity of the age had to work hard to be accepted in “society”.

Today, it makes no difference that’s it’s American, popular comedies like “The Big Bang Theory[3]” entertain us immensely but pocket the “nerd” as eccentric, peculiar and unfathomable. I admit this is attractive to a proportion of young people but maybe such shows create exclusivity rather than opening people’s eyes to possibilities.

Having Government Ministers standing=up can calling for Britan to become a version of Silicon Valley doesn’t help. Immediately, that signal is heard from those in authority, young people switch “off”. To boot, the image conquered up is a whole generation out of date. We have the Windows 95 generation telling the iPhone generation what’s the best direction to get to the 2030s.

Here’s a proposition – you must see yourself as an “engineer” to become an engineer. That can be said of a whole myriad of different professions. Each with a common stereotype. Look at it the other way. If you cant’t see yourself as a person who can shape the future, it isn’t likely you will choose engineering.

My observation is that we need to get away from too many images of activities. In other words, this is an engineer at work. This is what they do. This is what they look like. What we need to address is the touchy-feely stuff. Let’s consider how young people feel about the world they have inherited from my generation.

A high level of motivation comes from the wish to make changes and the feeling that it’s possible to make changes. That the skills picked-up as an apprentice will help you shape the future. Engineering is part of making a better world.

[My history is that of an Engineering Industry Training Board (EITB) apprentice who started work in 1976.]

[1] https://www.engineeringuk.com/media/318763/fit_for_the_future_knight_and_willetts_apprenticeship_inquiry_euk_call_for_evidence.pdf

[2] https://en.wikipedia.org/wiki/Isambard_Kingdom_Brunel

[3] https://www.imdb.com/title/tt0898266/


There’s not just one form of Artificial Intelligence (AI). This group term hides a great panoply of different configurations, shapes, and forms of applications.

One of the most impactful applications is that of machine learning or expert systems. It’s where we go beyond a conventional computer’s ability to store and manipulate information against set rules. It’s where the machine has the capability to learn new ways of interpreting information and thus becomes different every day of operation from the day it was switched on. That’s a bit vague but it captures the essence of moving from deterministic to non-deterministic systems.

In all this we do presuppose that such complex systems are in the hands of able and highly illiterate users who understand what they are doing in training that learning machine. There’s debate about how bias in algorithms can produce unintended consequences. In addition, a reliable and trustworthy machine can be trained in a way that embeds errors and biases too[1].

Just as a child picks up the bad habits of a parent, so “intelligent” machines can learn from pilots, controllers and engineers who may have less than optimal ways of undertaking tasks. This Human-AI interplay is likely to become a major area of study. As the topic of Human Factors is itself a large body of material.

Already with the debate on social media it is all too obvious that the aviation community has a wide range of views on the use of AI. All the way from utter rejection, or scepticism deeming such systems as “unsafe” to advocates who profess only the benefits and merits of such systems.

Clearly, both extreme ends of the spectrum of professional views don’t help much. I don’t think that the promoters of AI want to see blind overreliance on it. Equally, surly even ardent sceptics can see virtue in making the best use of the accumulated knowledge that is available.

I can foresee a system of systems approach. With my parent and child analogy, from time to time a child will ask a question that is blunt and to the point. A question that demands a straightforward answer. This can be uncomfortable but hits out at biases and bad habits.

In aircraft systems there are boundaries that must be respected. The physics of flight dictate that going beyond those boundaries is generally not good for life and limb. So, a system programmed to question an expert system, one AI questioning another AI, or even question its trainer, is not beyond the realms of possibility. It might even be a good idea.

[1] https://www.nature.com/articles/s41746-022-00737-z

Poor law making

If you thought the Truss era was an aberration, and that the UK’s Conservative Party had learned a lesson, then please think again. Wheels set in motion by the ideologue Jacob Rees-Mogg MP are still spinning.

The Retained European Union Law (Revocation and Reform) Bill is trundling its way through the UK Parliament. The Government Bill will next be prepared for its 3rd reading in the House of Commons[1]. The Conservative Government has brought forward this Bill to revoke, reform or revise all the remaining law in the UK that was formerly derived from the UK’s membership of the EU. This turns on its head the normal approach to changing UK legislation. Revocation is automatic unless there’s an intervention by a Minister.

UK civil aviation depends on several thousand pages of legislation derived from EU law[2]. Much of this law was created with considerable contributions from the UK. There’s hardly any if any advocates for automatic revocation of current aviation legislation. Even the thought of this action sends a shiver down the spin of aviation professionals. Generations of them have worked to harmonise rules and regulations to ensure that this most international of industries works efficiently.

Unless amended, the Government’s EU Retained Law (Revocation and Reform) Bill[3] could turn out to be an absolute disaster. Even those who have an irrational wish to eliminate any and every past, present, or future link to Europe must come up with a practical alternative and do this in an incredibly short time. Without a consistent, stable, and effective framework civil aviation in the UK will grind to a halt. Again, even those who have an unsound need to change for change’s sake will be hitting a vital industry hard, as it is only just getting back on its feet after the COVID pandemic and now setting out to meet tough environmental standards.

It’s going to be interesting to see what happens when this poor Bill reaches the House of Lords. Once again, the country will be relying on the upper house to add some common sense to this draft law.  

POST 1: The 3rd reading debate makes it clear that the Government is unsure which laws are covered by the Bill. If the Ministers responsible for this legislation do not themselves know its extent, how can anyone expect civil servants working on this legislation to know the full extent of change? A most strange state of affairs Retained EU Law (Revocation and Reform) Bill (Third si – Hansard – UK Parliament

POST 2: Retained EU law lays down rules for the airworthiness and environmental certification of aircraft and related products, parts and appliances, as well as for the certification of design and production organisations in the UK Commission Regulation (EU) No 748/2012 of 3 August 2012 laying down implementing rules for the airworthiness and environmental certification of aircraft and related products, parts and appliances, as well as for the certification of design and production organisations (recast) (Text with EEA relevance) (legislation.gov.uk)

POST 3: Retained EU Law Bill is being debated in the House of Lords on Monday, 6 February.

[1] https://bills.parliament.uk/bills/3340

[2] https://www.eiag.org.uk/paper/future-retained-eu-law/

[3] https://www.gov.uk/government/news/the-retained-eu-law-revocation-and-reform-bill-2022


Now, there’s an activity with two humans in the loop. Given the physics involved the goalkeeper should be beaten every time. Well, I’m saying that assuming a high level of expected performance on the part of the footballer taking the penalty. I guess that’s why we are often critical when they miss. In the last few weeks there have been more than a few examples to watch.

What we know is that football penalties are much more than mechanical actions and reactions. However, there’s a degree of mythology about the inevitability of human factors taking control of the outcome: goal or no goal. I’d like to think that there’s an ever-shifting blend of what physics does to the ball and what the human does. Is it always possible to predict the slipperiness of a spinning ball traveling at speed that is then touched by the fingertip of a goalkeeper?

What if the footballer taking the penalty, was an “intelligent” machine. That is a machine with a sensor array and computational capability that far exceeded normal human performance. Such advance automation could calculate the most probable reaction of a goalkeeper based on history and the immediate movements they make right up to the last millisecond before the ball is struck.

Assuming the machine was limited in term of the force it can apply to the ball, it could still adjust its actions as soon as any new information was available. I’m not saying the outcome will always be better for the machine football striker. However, it could reduce the scope for error and randomness to dictate what finally happens.

So, with that argument, in aviation, I’m saying it’s not right to say that Single Pilot Operation will always be worse than two crew operations. Don’t get me wrong, those people aggressively advancing the idea that the intelligent machine will always be better than a human are missing something too.

One thing that highly capable automation could have to bring to the party is not only early detection and diagnosis of problems but a massive library of stored experience. How we embed and constantly update that flight experience is an almighty challenge.

Afterall, the dread in aviation is knowledge with hindsight. It takes the form: “You should have known. Why did you let this incident happen?”

I’m now tempted to think of a Star Trek analogy. Every second an aircraft of a type is flying, experience of its operation is being accumulated. If there are hundreds of a type flying at any moment across the globe, that’s a lot of data to collect and absorb and think about before acting. 

The fictional and scarry Borg are cybernetic creatures linked by a hive mind and they know a thing or two about assimilation. Granted that’s farfetched as analogies go but my point is that I believe we are generations away from that kind of capability. Not only that, just as humans fail so any such “intelligence” designed by humans will fail to.


An instant reaction to Single Pilot Operations (SPO) is like the instant reaction to completely autonomous flight. “I’m not getting on an aircraft without a pilot!” Then to justify that reaction fatal accidents of the past are cited. Typically, this is to remind everyone of the tragic Germanwings accident[1]. It was 24 March 2015, that an Airbus A320 was crashed deliberately killing all onboard.  

However, it’s wise to remember that the likelihood of incapacitation[2] is much greater than that of the malicious behaviour of the pilot in command. Cases of malicious behaviour leading to a catastrophic outcome are truly shocking but extremely rare.

One fatal accident, that is still disputed is EgyptAir Flight 990[3] that killed 217 people in 1999. The possibility of inflight pilot suicide is unnerving, since on the face of it there is little any of the aircraft’s cabin crew or passengers can do to stop it.

This could be a future opportunity to use automation to prevent these scenarios occurring. Afterall the aircraft knows where it is and that a sustained high-speed dive towards the ground is not normally intended. A safety system exists to do this[4], but its outputs are not connected to the aircraft’s flight controls.

Humans being adaptable, extremely creative and capable of highly irrational actions, it’s unlikely that malicious behaviour resulting in aviation accidents will ever be reduced to zero. This is said regardless of the procedures or technology involved. The fate of flight MH 370 remains a mystery.

Thus, the prominent safety issue in respect of SPO is pilot incapacitation. Where the pilot in command is no longer able to perform as expected. That is, if the aircraft flown is not capable of safely landing itself. The objective always being safe continued flight and landing.

I’ve had the “1% Rule” rule explained to me by a notable aviation doctor, but I must admit I didn’t fully take it in. So far, the rule has stood the test of time. When the pilot in command of a Czech Airlines aircraft collapsed and died on route from Warsaw to Prague in 2012, the co-pilot took over and everyone got home safely.

Any automated co-pilot must be at least as capable as a human co-pilot in all aspects of operation of an aircraft. The key word here being “all”. It’s not enough to have the functions necessary to undertake safe continued flight and landing. Task such as communicating with the cabin crew and passengers must also be considered. Including preparation for an emergency landing.

[1] https://www.bbc.co.uk/news/world-europe-32072218

[2] http://www.avmed.in/2012/02/pilot-incapacitation-debate-on-assessment-1-rule-etc/

[3] https://www.theguardian.com/world/2002/mar/16/duncancampbell

[4] https://skybrary.aero/articles/terrain-avoidance-and-warning-system-taws

Single Pilot Operations

Single Pilot Operations is not new. What’s new is considering this way of working for everyday public transport operations of large aircraft

Research is of fundamental importance. It seems obvious to say so given the benefits it has given us. When proposals come forward to exploit new technologies there needs to be that moment when everyone steps back and takes a long hard look at the implications of its use.

In basic technical research it’s not the most important consideration is to focus on the drivers for change. They can be multifarious: economic, environmental, social, safety, security, political, and maybe just a matter of preference. Policy directions are taken by the industry and governments not constrained by what is happening now as much as what might happen tomorrow.

Research has delivered incredible safety improvements in aviation. This is not only in the basic design and construction of aircraft but all aspects of their operation. So, to see that the European Union Aviation Safety Agency (EASA) sponsoring research to study the implications of aircraft Single Pilot Operations[1] is a wholly good measure.

My history goes back to the early days of fly-by-wire aircraft systems. This is where the mechanical and physical connection between an aircraft pilot’s actions and the control surfaces that determine flight are replaced by digital computers. Back in the 1980s, a great deal of research and experimental flying proved the technology to make fly-by-wire work. It first found favour with the military. One reason being that an aircraft’s capability could be extended well beyond what was formerly reached. This change was introduced with caution, analysis, testing and much detailed risk assessment.

At the time, there was a significant body of professional pessimists who predicted a diminishment of aviation safety. Today, four decades on, studies show that even as air traffic has increased so civil aviation safety has improved. A momentous achievement. An achievement that has, in part, been because of the well-regulated adoption of advanced technologies. 

It is important to look at potential changes with an open mind. It’s easy to come to an instant opinion and dismiss proposals before a detailed study has been conducted. The detailed technical research can then be part of the challenge and response that is necessary to before approval of any major change. First difficult questions need to be tabled and thoroughly investigated.

[1] https://www.easa.europa.eu/en/research-projects/emco-sipo-extended-minimum-crew-operations-single-pilot-operations-safety-risk

Air Safety List

A long time ago in a far away place. Well, that’s how it seems, and it was more than 17 years ago.

A flight ban was placed on Turkish airline Onur Air back in 2005. At that time, I was in my first full year in Cologne, Germany building up the European Aviation Safety Agency (EASA). We were well on the road managing the handover of responsibilities from activities of the Joint Aviation Authorities (JAA) to EASA. However, the European legislation that empowered EASA was in a first and most basic version. This was planned to be so because taking on aircraft certification work was a big enough task to start the new Agency.

The JAA had coordinated an aircraft ramp inspection programme and maintained a centralised database for its members. This was where a member state would inspect an aircraft arriving from a third country to ensure that international rules were fully met. The SAFA programme was launched by the European Civil Aviation Conference (ECAC) in 1996. SAFA standing for Safety Assessment of Foreign Aircraft.

Onur Air failed such inspections, and the Dutch government imposed a flight ban[1]. Similar bans were imposed by Germany, Switzerland, and France. However, if my reflections are correct the airline moved operations to Beligum where there was no ban. As you might imagine this caused concern amongst EU Member States. Where everyone had agreed to cooperate on aviation safety matters there seemed to be a degree of incoherence.

Long before the first EASA Basic Regulation, which by the way, didn’t address this subject, there was Regulation 3922/91[2]. I remember a hastily convened committee composed of representatives of the Member States and chaired by the European Commission (EC). The “3922[3]” committee hadn’t sat for years but then it sprung into action in response to the lack of a consistent approach to airline safety bans across Europe. I was there representing EASA.

So, the EU Air Safety List was born and the associated legislation[4] to support it. Even though the UK has left the EU, and left EASA this safety list remains the basis of the UK’s own Air Safety List[5]. Adding and removing air carriers and States that fail to meet internationally agreed safety standards is work that no one State should do alone.

[For safety’s sake, this should not be one of the parts of adopted EU legislation the UK Parliament wants to sweep away with its planned new Brexit law].

POST: Current list The EU Air Safety List (europa.eu)

[1] https://www.expatica.com/nl/general/dutch-lift-ban-on-onur-air-38258/

[2] Council Regulation (EEC) No 3922/91 of 16 December 1991 on the harmonization of technical requirements and administrative procedures in the field of civil aviation.

[3] https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ%3AL%3A1991%3A373%3A0004%3A0008%3AEN%3APDF

[4] https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32005R2111&rid=6

[5] https://www.caa.co.uk/commercial-industry/airlines/licensing/requirements-and-guidance/third-country-operator-certificates/