Latent Threats: When training bites back. This blog is about Latent Threats. Threats that lurk undetected in training systems, procedures and practice.

In a previous blog post, Threat Managers: Rethinking Risk, we described the approach of Threat and Error Management. Specifically we described threats as being inherent in mountaineering, the need to manage them, and in turn respond to events.

Threats can also be latent. Often undetected, difficult to observe or even insidious, latent threats are often only obvious with the benefit of hindsight.

AAIB investigation to Schleicher ASW 24, G-CHBB

Although this blog is about mountaineering we have sometimes diverted into aviation. In this case we do so again, examining a report from the Air Accident Investigation Branch (AAIB) into a fatality during an aerotow launch of a glider from Dunstable Airfield. This was a tragic incident in which a single pilot lost their life. The reason why we examine this report here, is to allow you to consider the latent threats involved and draw parallels to other areas of work, namely instructional and guiding work.

Schleicher ASW 24 (G-CHBB), loss of control during failed aerotow, Dunstable Airfield, Bedfordshire, 16 August 2023:

The accident occurred during an aerotow launch from Dunstable Airfield. Eyewitnesses reported that, at an early stage in the launch, the glider’s vertical positioning behind the tug was unstable. While the pilot appeared to regain some control over the instability, shortly after the towing aircraft lifted off, witnesses noticed the tow rope had become detached from the glider, which was below 50 ft agl at the time. Despite the lack of traction from the towing aircraft, the glider continued to climb to between 50 and 100 ft agl before it entered a steep left turn with low and reducing airspeed. Shortly after entering the turn the glider yawed left and autorotated into an incipient spin before striking the ground nose first. Witnesses on the airfield arrived at the glider within 80 seconds of the accident but nothing could be done to save the pilot who had suffered fatal injuries during the accident sequence. AAIB Report

Context for non-glider pilots

It makes sense to try and add some context for non-pilots and those unfamiliar with gliding. Although there seems to be a growing number of instructors and guides who fly paragliders or speed wings.

• Gliders or sailplanes are in most cases engineless and gain height by winch or aerotows (effectively towed by another aircraft).
• Gliders are often single seat with a solo pilot. In the case of fatalities like this one, uncertainty as to the pilots actions will always remain.
• A situation like that experienced by the pilot of this aircraft is extremely challenging. Coming off aerotow at low altitude, only gives the pilot seconds to recognise the situation and choose an appropriate course of action. Turning back through 180 degrees to land on the runway is extremely hazardous and has a high fatality rate in all aspects of aviation. Tragically the pilot did not have enough height to achieve this manoeuvre successfully.

With the glider no longer connected to the towing aircraft, the accident pilot found himself in a challenging position, possibly suffering from the negative performance shaping effects of startle and/or surprise. With little height or speed available to him he needed to quickly decide on an appropriate course of action. That he decided to turn back toward the airfield indicates he did not consider landing ahead was a viable option. Tragically, at the height and speed he found himself, turning back proved unachievable. AAIB Report.

Key Facts in the investigation

The investigation did not identify any mechanical issues which could have led to the unintentional release of the aerotow rope. No defects were found with the glider that would have posed a problem. The pilot had an appropriate license and hours of flying time on the type of glider. This was effectively a check to demonstrate competence and currency. How often are Mountain Professionals demonstrably competent? It could be said that in the vast majority of cases the same circumstances apply, Mountain Professionals are frequently current in their practice and with current experience. Yet the challenge for us is that still incidents occur.

The summary report can be read here at: AAIB investigation to Schleicher ASW 24, G-CHBB. The full reports PDF can be found here at: https://assets.publishing.service.gov.uk/media/6650914d7b792ffff71a83d2/Schleicher_ASW_24_G-CHBB_07-24.pdf

The pilot

The circumstances of this incident give a window into single pilot decision making.

• The pilot was in an extremely challenging position with low height, a low energy glider with limited options.
• The report describes how they may have been suffering from the negative performance shaping factors of startle and or surprise.
• The decision to choose an appropriate course of action was pressured, and arguably made in extremis.

This accident serves to highlight how challenging it is to make effective decisions when something goes wrong unexpectedly at a critical stage of flight. While pilots may verbalise their intentions as part of an eventualities brief, being able to enact the plan when startled, surprised and under extreme pressure, is not necessarily assured. AAIB Report.

The Mountain Professional

This is of interest to the Mountain Professional for a couple of reasons. Firstly, we are often faced with making decisions where goal conflicts exist, although we often get a bit more time. These decisions are sometimes made under the pressure of challenging environmental conditions.

Secondly, in pressurised situations we default to the quality of our training. Especially if we think we have experienced the problem before. For glider pilots a situation such as an a rope break form part of training. In the same way that improvised rescue, route choice in avalanche terrain, or companion rescue appear in our training and continuing professional development courses.

Latent Threats – Training

Techniques for the safe handling of gliders during launch failures are regularly practiced. But in many situations there are subtle differences between training and practice. There are different ways of thinking about this, one approach would be to use to lens of varieties of work. Steven Shorrock provides a detailed insight into the understanding and improvement of human work here in his blog: https://humanisticsystems.com/2016/12/05/the-varieties-of-human-work/

In the diagram above we see four elements (proxies) that overlap. But what if we consider just two that are not totally aligned? There is often a difference between the situations that we imagine (Work-as-Imagined) a situation looks like, versus what actually happens (Work-as-Done). The generic term ‘work’ is used here, but we could view that as work, task or a training task for a particular scenario. Latent threats may exist in the gap between these proxies of work.

Use the accordions below if you want to find out more:

Latent Threats – Launch Failure

Glider pilots are trained that before a tow commences, they should have in mind a cut off or decision point during the launch. Where the first option of landing and stopping within the airfield boundary is no longer possible, the decision has to be to “land out”. Landing out means outwith the airfield, this becoming the main goal, the second of two options. In many gliding clubs this is captured in guidance, inevitably written by experienced instructors with plenty of time to imagine the perfect solution to this scenario.

Latent Threats – In Practice

Cable breaks either on winch or aerotow are frequently practiced in training and check flights. However, due to the additional risks and inconvenience of landing outside the airfield simulated emergencies are often initiated when the glider can safely land ahead or, is high enough to fly a circuit back to the airfield. This makes perfect sense. But consider the case, such as in this fatality where the pilot is under extreme pressure.

They will inevitably have done what made sense to them at the time. One explanation is that they attempted to turn back to the airfield as this was exactly what they had trained and flown previously. To do so was a well practised response to an emergency that they were familiar with. The pilots mental model is likely to have been framed by this familiar scenario, except this time essential parameters were different. The height and energy of the glider were much lower than normal.

Latent Threats – In the Awards

But what does this have to do with working in the mountains? In the broadest sense we all know that training and assessment courses cannot include everything, there will always be syllabus areas which address general principles leaving candidates to address these in their own professional practice. In the same way that we are not assessed driving on a motorway on a practical driving test. While the test might involve driving on dual carriageways and in different traffic conditions, motorways are excluded although driving theory tests may include questions on motorway driving and legislation.

The syllabus for the Mountaineering Instructor awards is also long established and static, being subject to only periodic change. This makes perfect sense, but the work environment for many Mountain Instructors in the UK has changed substantially from when the awards were originally conceived.

In the past newly qualified instructors worked for organisations perhaps in the form of Local Education Authority (LEA) centres. Fast forward to and these centres, often with experienced and highly qualified staff are few and far between. The majority of instructors qualifying now are working in a freelance capacity or are single person owner operators of their own businesses.

For example, despite the UK remit of the awards it is difficult to adequately prepare people to guide Cuillin Ridge traverses in North Wales through the training and assessment process alone. The principles are generic but style of these longer ridge traverses is closer to an alpine environment. The gap that exists presents a latent threat which needs to be addressed by humility and reflection in the autonomous practitioner. Of course it isn’t all about the awards and continuing professional development and mentoring may address these gaps in the short term.

Latent Threats – In scenario based training

At a more fundamental level there are also latent threats in scenario based training. One such example is that of avalanche companion rescue training. Many readers of this blog will be familiar with the use of an avalanche transceiver, avalanche probe and shovel to locate and quickly dig out a companion buried in an avalanche.

When we set up these quick scenarios they are often a secondary objective for the day. For convenience small areas are often used, which are far smaller than the debris tip of most avalanches. Frequently, rescuers are positioned close so that the majority of their practice time is taken up by the coarse and fine search phases with the aid of a transceiver. But the reality of even a simple rescue situation is that the victims transceiver could well be out of range. This requires a well practiced signal search.

Combine this with the limitations of a Scottish snowpack, or even a sparse alpine one early season, and we may be burying the “victims” transceiver at a depth less than one metre. Many guides will bury a spare transceiver in a skin bag or stuff sac, because nobody wants an avalanche probe through the contents of their rucksack. The result is a low reading on the transceiver, when a real rescue might result in a deeper burial with a correspondingly higher figure. The target for a probe strike is also much smaller resulting in the temptation for the rescuer to reduce the distance between the probe holes.

What this represents is a significant difference between Work-as-Imagined, Work-as-Prescribed and Work-as-Done. The way in which we then describe this scenario is often as one of success (Word-as-Disclosed), rather than highlighting the limitations and the latent threats that remain.

Latent Threats: A summary

Mountain Professionals = Threat Managers. If you have read this far you might want a quick latent threats summary.

• Threats and Errors always exist, if we accept this then we have agency over how we manage them. Read more in the previous blog Threat Managers: Rethinking Risk.
• We need to actively manage situations, and our behaviour in response to problems.
• Latent threats can be difficult to identify. Review past incident reports, listen to colleagues and foster open discussions when things don’t go to plan.
• Foster a strong safety culture that addresses organisational issues and contributes to community of practice. Organisations and associations don’t change or learn, people do.
• Incorporate threats into briefings.
• Reflect on the threats to your day in post trip reviews and debriefs.

If you liked this article you may wish to check out Assured Training or the Threat and Error Management section in Mountain CRM (e-learning). This is publicly available as a preview. Alternatively you may wish to download the Threat and Error Management (TEM) Booklet [Coming soon].

Note: I would like to thank the safety and risk professionals out there who have contributed to my thoughts on these issues. Particularly Professor Philip Ebert and Neil Richardson MRAeS.