Comms

The long history of data communications between air and ground has had numerous stops and starts. It’s not new to use digital communications while flying around the globe. That said, it has not been cheap, and traditional systems have evolved only slowly. If we think Controller Pilot Data Link Communications (CPDLC)[1] is quite whizzy. It’s not. It belongs to a Windows 95 generation. Clunky messages and limited applications.

The sluggishness of adoption of digital communications in commercial aviation has been for several reasons. For one, standardised, certified, and maintainable systems and equipment have been expensive. It’s not just the purchase and installation but the connection charges that mount-up.

Unsurprisingly, aircraft operators have moved cautiously unless they can identify an income stream to be developed from airborne communication. That’s one reason why the passengers accessing the internet from their seats can have better connections than the two-crew in the cockpit.

Larger nations’ military flyers don’t have a problem spending money on airborne networking. For them it’s an integral part of being able to operate effectively. In the civil world, each part of the aviation system must make an economic contribution or be essential to safety to make the cut.

The regulatory material applicable to Airborne Communications, Navigation and Surveillance (CS-ACNS)[2] can be found in publications coming from the aviation authorities. This material has the purpose of ensuring a high level of safety and aircraft interoperability. Much of this generally applicable material has evolved slowly over the last 30-years.

Now, it’s good to ask – is this collection of legacy aviation system going to be changed by the new technologies that are rapidly coming on-stream this year? Or are the current mandatory equipage requirements likely to stay the same but be greatly enhanced by cheaper, faster, and lower latency digital connections?

This year, Starlink[3] is offering high-speed, in-flight internet connections with global connectivity. This company is not the only one developing Low Earth Orbit (LEO)[4] satellite communications. There are technical questions to be asked in respect of safety, performance, and interoperability but it’s a good bet that these new services will very capable and what’s more, not so expensive[5].

It’s time for airborne communications to step into the internet age.

NOTE: The author was a part of the EUROCAE/RTCA Special Committee 169 that created Minimum Operational Performance Standards for ATC Two-Way Data Link Communications back in the 1990s.

POST 1: Elon Musk’s Starlink Internet Service Coming to US Airlines; Free WiFi (businessinsider.com)

POST 2: With the mandate of VDLM2 we evolve at the pace of a snail. Internet Protocol (IP) Data Link may not be suitable for all uses but there’s a lot more that can be done.


[1] https://skybrary.aero/articles/controller-pilot-data-link-communications-cpdlc

[2] https://www.easa.europa.eu/en/document-library/easy-access-rules/easy-access-rules-airborne-communications-navigation-and

[3] https://www.starlink.com/

[4] https://www.esa.int/ESA_Multimedia/Images/2020/03/Low_Earth_orbit

[5] https://arstechnica.com/information-technology/2022/10/starlink-unveils-airplane-service-musk-says-its-like-using-internet-at-home/

To provoke

Social media provocateurs are on the rise. Say something that’s a bit on the edge and wait for the avalanche of responses. It’s a way of getting traffic to a site. The scientific and technical sphere has these digital provocateurs less than the glossy magazine brigade, but the phenomena is growing.

Take a method or technique that is commonly used, challenge people to say why it’s good while branding it rubbish. It’s not a bad way to get clicks. This approach to the on-line world stimulates several typical responses.

One: Jump on-board. I agree the method is rubbish. Two: I’m a believer. You’re wrong and here’s why. Three: So, what? I’m going to argue for the sake of arguing. Four: Classical fence sitting. On the one hand you maybe right on the other hand you may be wrong.

Here’s one I saw recently about safety management[1]. You know those five-by-five risk matrices we use – they’re rubbish. They are subjective and unscientific. They give consultants the opportunity to escalate risks to make new work or they give managers the opportunity to deescalate risk to avoid doing more work. Now, that’s not a bad provocation. 

If the author starts by alleging all consultants and managers of being manipulative bad actors that sure is going to provoke a response. In safety management there are four pillars and one of them is safety culture. So, if there are manipulative bad actors applying the process there’s surely a poor safety culture which makes everything else moot.

This plays into the discomfort some people have with the inevitable subjectivity of risk classification. It’s true that safety risk classification uses quantitative and qualitative methods. However, most typically quantitative methods are used to support qualitative decisions.

There’s an in-built complication with any risk classification scheme. It’s one reason why three-by-three risk matrices are often inadequate. When boundaries are set there’s always the cases to decide for items that are marginally one side or other side of a prescribed line.

An assessment of safety risk is just that – an assessment. When we use the word “analysis” it’s the supporting work that is being referenced. Even an analysis contains estimations of the risk. This is particularly the case in calculations involving any kind of human action.

To say that this approach is not “scientific” is again a provocation. Science is far more than measuring phenomena. Far more than crunching numbers. It includes the judgement of experts. Yes, that judgement must be open to question. Testing and challenging is a good way of giving increased the credibility of conclusions drawn from risk assessment.


[1] https://publicapps.caa.co.uk/docs/33/CAP795_SMS_guidance_to_organisations.pdf

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

Fatal accident in Nepal 2

We are now one week from the fatal accident that occurred on Sunday, 15 January in Nepal. Yeti Airlines Flight 691, an ATR 72-500 aircraft, crashed while on approach at Pokhara International Airport in Nepal

We are now one week from the fatal accident that occurred on Sunday, 15 January in Nepal. Yeti Airlines Flight 691, an ATR 72-500 aircraft, crashed while on approach at Pokhara International Airport in Nepal[1]. Sadly, this accident resulted in 72 fatalities. No one survived. Only one body remains to be discovered[2].

This has been Nepal’s deadliest aviation accident in over 30 years.

After years of pandemic-caused travel disruption this land locked nation was hopeful that their new airport would bring the tourists back. The nation’s second-largest city sits in the shadows of a towering mountain range. It’s a picture postcode setting for this tragedy.

Nepal’s government has set-up a five-member committee to investigate the accident.

As stated in the International Civil Aviation Organisation (ICAO) Annex 13, Aircraft Accident, and Incident Investigation[3], it’s the responsibility of the State of Occurrence to lead an investigation. The objective of that investigation should be prevention of future accidents and incidents. It’s not the purpose of a technical activity to apportion blame or liability.

Nepal is the State of Registry and the State of the Operator, but they must notify the State of Design, the State of Manufacture (France) of the aircraft and ICAO in Montreal.

There are numerous speculations concerning the cause of this accident. The scant evidence available on social media does suggest that this aircraft accident fits into the category of Loss of Control in Flight. However, that suggestion is purely informed conjecture at this time.

I agree with David Learmount[4] in that it’s likely that this will be found to be a preventable accident. That said, once the accident flight recorders have been replayed there should be a substantially better indication of what really happened on that fateful day.

Whereas it was previously reported the accident recoders were going to France it’s now reported that they are going to Singapotre for replay Black boxes from Nepal plane crash to be sent to Singapore – ABC News (go.com)

Based on the experience of the analysis of numerous accidents it’s unlikely to be a simple single cause. Such fatal aircraft accidents are often combinations of factors that come together. Approach to a new airport plus an unexpected event or error plus aspects of organisational culture can be enough to tip the balance.

Aviation, in itself, is not inherently dangerous. But to an even greater degree than the sea, it is terribly unforgiving of any carelessness, incapacity or neglect.

A quote of Captain A. G. Lamplugh, British Aviation Insurance Group, London. c. early 1930’s. This famous phrase has been reproduced on posters many times.

POST: Here’s some examples of what can happen again and again. Lessons learned from business aviation accidents maybe equally applicable to this case. Lessons Learned from Business Aviation Accidents | NBAA – National Business Aviation Association


[1] https://aviation-safety.net/database/record.php?id=20230115-0

[2] https://www.thehindu.com/news/international/nepal-plane-crash-search-continues-for-lone-missing-person/article66415303.ece

[3] https://store.icao.int/en/annexes/annex-13

[4] https://davidlearmount.com/2023/01/21/regional-airline-safety-really-doesnt-have-to-be-this-bad/

SPO 2

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 2

It may seem obvious that there should be an Air Safety List that bans airlines that do not sufficiently met international standards. It’s a right that exists within the Chicago Convention[1]. The first words of the convention concern sovereignty. Every State has complete and exclusive sovereignty over their airspace. From the first days of flight the potential use of aircraft to wage war was recognised. Thus, it could be said that the first article of the Chicago Convention existed even before it was written down and agreed.

However, it’s similarly recognised that the future development of international civil aviation has always depended upon agreements between States. Without over-flight and permission to land in another country there is no international civil aviation.

I do remember some agonising over having an explicit list of banned countries and airlines. In a liberal democracy choice is greatly valued. Here the choice concerns passengers being permitted to board aircraft from another country where there is knowledge of safety deficiencies related to the operation of the aircraft of that country. Should the law make that choice for the air traveller, or should the air traveller be free to make an informed choice?

There lies the crux of the matter. How do ordinary citizens, without aviation safety expertise make judgements concerning complex technical information? Understanding the implications of failing to meet the International Civil Aviation Organization’s Standards and Recommended Practices (SARPs)[2] is not so easy even for aviation experts.

Additionally, there is the issue of third-party risks. It would not be wise to permit foreign aircraft, whose safety is not sufficiently assured, to fly over a nation’s towns and cities.

Regulatory legislation was framed not only to put airlines on the Air Safety List but to take them off the list too. In fact, sometimes this is harder law to frame. In this case the decisions must be made in a fair, transparent, and technically rigorous manner otherwise the politics of such choices could overwhelm the whole process.

There’s been much success in this endeavour. It’s clear that this is a valuable aviation safety measure. It may have driven some contracting States to improve the performance of their airlines.


[1] https://www.icao.int/publications/Pages/doc7300.aspx

[2] https://www.icao.int/safety/CMAForum/Pages/default.aspx

Walk the line

Aeronautical products must be certified before entering transport services. Is certification too complex? Is it too expensive and thus a barrier to innovation? Hasn’t deregulation delivered successes since the 1970s? More choice and more aviation services across the globe.

These are perfectly reasonable questions. They are asked frequently. Especially during economically tough times and when new products are pushing to get operational. In answering, it’s all too often a butting of heads that results. Industry puts its point. Authorities put theirs. Commercial reality and public interests settle at some point which leaves the debate on the table for next time.

Walking that line between satisfying the demand of the new and protecting the good safety performance of the aviation system is a perpetual challenge. It goes without saying that we all know what happens when the line is crossed. Textbooks will continue to chew over stories like that of the Boeing 737 MAX development. In fact, the stories of safety lapses are an important part of the learning process that led to aviation’s admirable safety record.

The counter argument is that we are in a new situation and that technology has significantly changed. This argument of the “new” is not new. Every major new step encountered significant hurdles to overcome. Pick-up the story of the development of the Boeing 747[1][2] and it’s a real dramatic page turner. However, the problem remains the same but as much innovative thinking needs to go into certification as the products that are certified. There’s a reason that’s difficult and its called legacy.

On the public’s behalf, how big is the risk appetite of the certification authorities? At the same time how far do the innovators want to push the envelope knowing that liability rest on their shoulders?

What I find inadequate is that when reading reports like “Funding Growth in Aerospace[3]” I find little, or no consideration is given to funding regulatory improvement. Arguments are for product development and little else. It’s as if certification activities are to be blamed for holding up innovations introduction to service but forget any thought of increasing the resources for certification activities.

It’s short-sighted. Believe it or not there is money to be made in testing and validation. There’s money to be made in education and training. These go hand in hand with efforts to exploit innovative products.


[1] https://www.bbc.co.uk/news/business-37231980

[2] https://www.theguardian.com/science/2016/sep/07/joe-sutter-obituary

[3] https://www.ati.org.uk/publications/

Air Taxi 3

Urban mobility by air, had a flurry of success in the 1970s. However, it did not end well.

Canadian Joni Mitchell is one of the most celebrated singer-songwriters and my favourite. She has tapped into the social and environmental issues that have concerned a lot of us for decades. Of her large catalogue, I can’t tell you how much I love this song[1]. The shear beauty of the lyric.

Anyway, it’s another track on the album called “Hejira” that I want to refer. When I looked it up, I found out, I was wrong. The song I want to refer to is on the 1975 album “The Hissing of Summer Lawns”. The song “Harry’s House[2]” contains the line “a helicopter lands on the Pan Am roof like a dragon fly on a tomb.” Without going into what it’s all about, the lyrical image is that flying from a city skyscraper roof was seen as glamorous and the pinnacle of success.

In 1970, prominent aviation authorities were talking about the regulatory criteria needed for the city-centre VTOL[3] aircraft of the future. Then on the afternoon of 16 May 1977, New York Airways Flight 971, a Sikorsky S-61 helicopter, crashed[4] on Pan Am’s building rooftop heliport[5]. That ghastly fatal accident reset thinking about city centre operations air transport operations.

So, what’s different 50-year on? Proposals for city centre eVTOL operations are much in the News. City planners are imagining how they integrate an airborne dimension into public transport operations. Cars, busses, trains and eVTOL aircraft may all be connected in new multimodal terminals. That’s the city transport planners’ vision for less than a decade ahead.

For one, the vehicles are radically different. Yes, the physics of flight will not change but getting airborne is quite different between a conventional large helicopter and the plethora of different eVTOL developments that are underway across the world.

Another point, and that’s why I’m writing this piece, is the shear amount of safety data that can be made available to aircraft operators. Whereas in the 1970s, a 5-parameter flight recorder was thought to be neat, now the number of digital parameters that could be collected weighs in over thousands. In the 1970s, large helicopters didn’t even have the basic recording of minimal flight data as a consideration. The complexity in the future of eVTOL will be, not how or where to get data but what to do with all the data that is streamed off the new aircraft.

Interestingly, this changes the shape of the Heinrich and Bird “safety pyramid” model[6]. Even knowing about such a safety model is a bit nerdy. That said, it’s cited by specialist in countless aviation safety presentations.

Top level events, that’s the peak of the pyramid, remain the same, but the base of the pyramid becomes much larger. The amount of safety data that could be available on operational occurrences grows dramatically. Or at least it should.

POST: Growing consideration is being given to the eVTOL ecosystem. This will mean a growing need to share data Advanced Air Mobility Portal (nasa.gov)


[1] https://youtu.be/nyj5Be5ovas

[2] A nice cover https://youtu.be/bjvYgpm–tY

[3] VTOL = Vertical Take Off and Landing.

[4] https://www.nytimes.com/1977/05/17/archives/5-killed-as-copter-on-pan-am-building-throws-rotor-blade-one-victim.html

[5] https://www.thisdayinaviation.com/16-may-1977/

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

Air Taxi

My daily routine once comprised of walking across a bridge over the Rhine to an office in Ottoplatz in Köln-Deutz[1]. That’s in Cologne, Germany on the eastern side of the river.

In the square outside the railway station is a small monument to a man called Otto. A small monument marking a massive transformation that took place in the way transport has been powered for well over than a century. This monument honours Nicolaus August Otto who created the world’s first viable four-stroke engine in 1876.

Today, the internal combustion engine hasn’t been banished. At least, not yet and Otto could never have known the contribution his invention would make to our current climate crisis. But now, rapid change is underway in all aspect of transport. It’s just as radical as the impact of Otto’s engine.

As the electrification of road transport gathers apace so does the electrification of flying. That transformation opens new opportunities. Ideas that have been much explored in SiFi movies now become practically achievable[2]. This is not the 23rd Century. This is the 21st Century. Fascinating as it is that in The Fifth Element the flying taxi that is a key part of the story, has a driver. So, will all flying cars of the future have drivers?

I think we know the answer to that already. No, they will not. Well, initially most of the electric vehicles that are under design and development propose that a pilot (driver) will be present. Some have been adventurous enough to suggest skipping that part of the transition into operational service. Certainly, the computing capability exists to make fully autonomous vehicles.

The bigger question is: will the travelling public accept to fly on a pilotless vehicle? Two concerns come up in recent studies[3][4]. Neither should be a surprise. One concerns passengers and the other concerns the communities that will see flying taxies every day of the week.

Public and passenger safety is the number one concern. I know that’s easy to say and seems so obvious, but studies have show that people tend to take safety for granted. As if this will happen de-facto because people assume the authorities will not let air taxies fly if they are unsafe.

The other major factor is noise. This historically has prevented commercial public transport helicopter businesses taking-off. Strong objections come from neighbourhoods effected by aircraft constantly flying overhead. Occasional noise maybe acceptable but everyday operations, unless below strict thresholds, can provoke strong objections.

So, would you step into an air taxi with no pilot? People I have asked this question often react quickly with a firm – No. Then, after a conversation the answer softens to a – Maybe.


[1] https://www.ksta.de/koeln/innenstadt/ottoplatz-in-koeln-deutz-eroeffnet–das-muss-nicht-gruen-sein–2253900?cb=1665388649599&

[2] https://www.imdb.com/title/tt0119116/

[3] https://www.easa.europa.eu/en/newsroom-and-events/press-releases/easa-publishes-results-first-eu-study-citizens-acceptance-urban

[4] https://verticalmag.com/news/nasa-public-awareness-acceptance-of-aam-is-a-big-challenge/