In praise of the Empirical

There’s a lot of people busying themselves and tying themselves up in knots trying to work out how to ensure that new aviation developments fly safely. Making possible the safe introduction of new air vehicles into an already complex system occupies meeting after meeting across the globe.

Advanced Air Mobility (AAM)[1] will mean full time aviation activities in unfamiliar places. There’s a such a complex maelstrom of interacting bits and pieces that it’s not easy to see the light at the end of the tunnel. This is driving innovation and a fresh look at how the business of safety assessment and assurance is done.

Since the first days of my working in an engineering department, I’ve been a supporter of a systematic approach. Over the decades this has paid handsome dividends. I don’t think there would ever have been a civil fly-by-wire aircraft in service if it was not for systematic engineering.

This does require a great deal of characterising and parameterising of measurable items. This is to distinguish, down to a fine level, technical attributes that can be verified and validated. In fact, the concept of verification and validation (abbreviated as V&V[2]) is upheld with almost religious passion.

The emphasis coming from the advocates of AAM is often on flexibility, openness to latest ideas and speed of working. The emphasis coming from public authorities is on maintaining or enhancing existing levels of flight safety[3]. Both are right and bridging the gap is quite doable.

What is most dangerous is to see this equation as purely binary. That is to discard a systematic approach in favour of a more try it and see, empirical approach. Innovation isn’t about throwing away the past. It’s about building on the past. All aviation activities involve safety risk. There are 3 things that can be done with risk: eliminate it, mitigate it, or live with it. To do any of these 3 things it’s first necessary to understand it.

So, I’m putting my finger on the greatest difficulty and that’s anticipating the future. To understand AAM[4] risks requires an appreciation of the combinations and permutations of different interactions that can exist in an aviation system with fast vehicles in dense environments. This is where classical V&V has limitations. It because of the vast, and I mean vast number of different live scenarios that can exist. Afterall the flight operations of AAM are supposed to be wide-ranging and unconstrained.

Hence my title. Not only do we need empirical means of proving systems, but existing means need to be improved. Going off and doing a bit of flying just doesn’t cut it.


[2] These are critical components of a quality management system such as ISO 9000



The case for future media

In my last post, I advocated protected image recording in civil aviation. Its introduction has been long delayed despite a great number of safety recommendations that such recording be adopted. Delays occur but the world doesn’t stand still. Notwithstanding all the worldwide successes of achieving excellent safety performance, fatal aviation accidents continue to happen.

Emerging technologies arrive with faster introduction and adoption in every walk of life. For example, streaming media is growing at a pace far faster than past technological changes. There have been adventurous proposals that all civil aircraft should stream large amounts of data to a ground-based network for every moment of flight. The idea is not so wild. Conventional technology already allows manufactures, like Rolls-Royce to monitor the performance of their in-service aero engines across the globe[1]. The collection of data is paid for by the benifits gained in performance and understanding of the operational life of engines.

Could this be a replacement for dedicated on-board protected accident recording? My answer is: “no”.

Communication technofixes will help provide supporting information and be greatly valued. However, the benefits of protected on-board accident recording are in its incorruptibility and that it can preserve the last microseconds of an event. This is especially true when the event in question has unique attributes or is mysterious in some way.

Before the bombing of Pan Am Flight 103 over Lockerbie, Scotland[2], few had thought of using a Cockpit Area Microphone (CAM) for explosion detection. There were faint noises at the end of the accident recording that needed careful analysis.

The conventional technology we use is rapidly being superseded. Obsolescence is inevitable. Computational speed is increasing, as is memory capacity. So, on-board aircraft systems will be advancing in one way or another. That progress needs to include protected aircraft accident recording.

Telling the story of an accident must be authentic. The means to do it needs to be incorruptible.

Thus, it’s reasonable that a degree of conservatism will prevail. In other words, accident recording equipment should be based on reliable fully proven technology. Adoption of the state-of-the-art may be attractive but extensive proving should be undertaken first.

The need for progress is primarily to improve how lessons are learned. That’s the fundamental. Data recovered post-accident is turned into information that can be effectively used to improve safety. Shortening the time between aquiring data and taking safety action must be an aim.

The industry and the authorities could make a leap forward in protected image recording, in civil aviation by making those images 3-dimensional. Carefully placed cameras can provide a wraparound view of a cockpit in all conditions. Then 3D video recording on replay could provide a virtual reality experience.

Already available, this technical capability could then provide investigators with all the details of an event in 360-degree wraparound virtual reality detail. The post-accident learning possibilities are great. Study and investigation could become an immersive event. A well-constructed and selectively edited 3D views could be used as a training aids. This subject should be researched.



The case for video

Everyone recognises that accident investigation has played a big role in increasing aviation safety. Gathering evidence is a key part of that process. The continuous development of accident flight recorders has, from a basic capability in the 1960s, transformed what can be learnt from serious incidents and accidents. This is true worldwide.

In the days when accident flight recorders transitioned from tape-based recording to solid-state recording the opportunity to increase capability advanced further. Good quality audio, more aircraft parameters and better survivability have resulted.

In 1989, British Midland Airways Flight 092, Boeing 737-400[1], crashed onto the motorway embankment in the UK[2]. Post investigation the safety recommendations included a discussion of external image display[3]. The UK CAA fully accepted the recommendation.

I was part of the research effort that looked at the practicalities of introducing video image display in the cockpit. The ruggedised video cameras available at the time were bulky, expensive, and low resolution. British Airways fitted external cameras to a Boeing 747 classic aircraft as a trial. That system was flown and information gathered from normal operations.

This was an idea before its time. Today, external cameras are installed on several common aircraft types. These cameras make images available to the cockpit for an operational purpose, or to passengers as part of an in-flight entertainment system experience.

The Boeing 777-300 and -300ER can have external cameras fitted. One in the leading edge of each side of the tailplane facing the main gear and one belly-mounted, facing the nosewheel. The AIRBUS A340-600 and A340-500’s can have cameras. Pilots use them for taxying, observing cargo loading, refuelling, parking, and manoeuvring. The AIRBUS A380 has a camera on the tail looking forward.

Despite the acceptance of cameras and displays in numerous places on an aircraft there is no mandatory requirement to record the images that they present.

Internationally, aviation accident investigators are in favour of crash-protected image recording systems. The US NTSB did have a published list of “most-wanted” transportation safety improvements that included a call for the introduction of mandatory cockpit video recorders.

After the loss of Air France AF447 in 2009, the French aviation accident investigators recommended that ICAO require that aircraft undertaking public transport flights with passengers be equipped with an image recorder that makes it possible to observe the whole of the instrument panel.

Some arguments against installed cameras that made sense in an era before the iPhone mobile, iPad and GOPRO camera now seem insubstantial. Commercial off the shelf equipment can provide powerful image display and recoding capabilities. This is in the context of a world where passengers and crew regularly carry mobile devices with high quality cameras.

Today, the inclusion of a crash-protected cockpit image recording system on commercial aircraft is not a radical step.

One argument against installed cameras remains. Those who have been part of a fatal aircraft accident investigation know that the impact of seeing human remains is not to be underestimated. A legitimate concern is that a cockpit video recording, that continues throughout an accident scenario may record the injuries suffered by those covered by installed cameras. In such a case the protection of the accident recordings is a matter of extreme sensitivity.

Should such sensitive recordings be released into the public domain a great deal of harm may be done. Thus, a decision to mandate cockpit video recording must fully consider the special needs to protect the confidentiality of accident recordings. Whereas in the past the means to afford high levels of protection was at the limits of the available technology, now advancements make this possible.

There are both aviation safety and security aspect to cockpit video recording. Aviation accidents are not normally crime scenes. However, disruptive behaviour or hijacking by a passenger or a wilful malicious act by a crew member can be examples of aviation crimes[4][5][6].

There has been a strong objection to video recording in aviation but the arguments against are falling away. Protecting the confidentiality of downloaded accident recordings is vital but it can be done. The technical pros and cons have been explored in detail[7].

Frequent recommendations have already been made on this subject over a decade without significant progress having been made. Surely, it’s now time to act.



[3] 4.19 The CAA should expedite current research into methods of providing flight deck crews of public transport aircraft with visual information on the status of their aircraft by means of external and internal closed circuit television monitoring and the recording/recall of such monitoring, including that associated with flight deck presentations, with a view towards producing a requirement for all UK public transport aircraft to be so equipped (Made 30 March 1990).




[7] CAP 762. CAA Research Project. The Effectiveness of Image Recorder Systems in Accident Investigations.