Drone flying

Posted 04/05/22

What is BowTie and why should the drone industry care?

The unmanned industry is at a hugely exciting time with technology and innovation growing at a spectacular rate.

Stories of vertiports, air taxis, High Altitude Pseudo Satellites and cargo UAVs are making daily news. But with that comes the inevitable uncertainty and learning that goes hand in hand with a high growth industry. Regulators are balancing keeping the skies safe without stifling innovation. A task that’s been a challenge since the dawn of aviation.

“It has not always been easy to administer the Regulations so as to secure the safety of the public without handicapping the expansion of [the industry]” F H Sykes (the first Controller General of Civil Aviation Air Ministry), Synopsis, 31 October 1919

The good news is that the unmanned industry doesn’t need to reinvent the wheel. Developed over many years, manned aviation has established guidance materials, safety and risk management best practices, and a regulatory framework that have made it incredibly safe. As unmanned operations continue to evolve into more complex use cases, of course we should be adopting appropriate elements from manned aviation into the unmanned industry to help move it forward in a safe and sustainable way. What is BowTie? When it comes to flight operations, ‘BowTie’ is the benchmark for risk management best practice. It’s used by, and recommended by, organisations like ICAO and many regulators around the world as a preferred methodology to understand, manage and communicate safety risk. BowTie looks at the cause-and-effect relationships that create pathways to accidents, and the ways we seek to interrupt those pathways to keep our operations safe. It puts the information into an easy to interpret picture that starts by identifying the Hazard (the potential source of harm) and then it flows from left to right, identifying the Threats that cause a loss of control (referred to as the Top Event) and the potential Consequences that result from a loss of control. It then adds the Barriers that are intended to keep the operation safe and finally, it looks at the reasons why the barriers might fail and how we manage those problems (known as Escalation Factors and Escalation Barriers). Depending on how detailed you want your assessments to be, or what issues you need to focus on, there will be likely be more than one BowTie.

Examples of typical Top Events for UAS operations include events like

  • Inability to maintain the desired flight path
  • Loss of normal separation with terrain/obstacles
  • Loss of normal separation with manned aircraft

You’ll see from the diagram below why it’s called BowTie:

Why BowTie and not a Risk Table?

There are many reasons, but first and foremost is the ease of interpretation, where a picture can quite literally tell a thousand words. Here’s just one example - in the BowTie we can clearly see where the Barriers have their effect i.e. before or after the loss of control event. In aviation we want to ensure that we remain in control in the first instance and if we saw a lack of Barriers before the Top Event, with most of them sitting after the Top Event, we would be looking at a Hazard that is likely to get out of control quite frequently and then be heavily reliant on recovery measures to prevent an accident – clearly not where we would want to be. If we put the same information a simple tabular risk assessment, we just don’t have that sort of clarity.

What are the other benefits of using BowTie? Why is it so widely used in manned aviation?

1. Understanding your risk landscape

BowTie is a thorough risk analysis tool. As already mentioned, it looks at where the Barriers have their effect, but on top of that, it considers how they might be degraded and how those issues are being managed. This in turn leads to realistic evaluations of effectiveness for the individual barriers, meaning we can generate an easily interpreted picture of where strengths and weakness exist within the various scenarios being considered.

2. Identifying where resources are best spent

No-one has an unlimited budget, and for startups it can be particularly challenging to work out exactly where safety effort should be directed. Having clarity from the BowTie models will pinpoint exactly where resources, both people and financial, should be focused.

3. Engagement with stakeholders

Engaging with, and getting support from, stakeholders with your own organisation can be one of the biggest challenges that a safety manager will face. Having an easily interpreted visual tool is a great way to communicate and help build a healthy safety culture. Engagement with external stakeholders, such as the presentation of safety cases to regulators, is also made simple by using a tool that’s well recognised within the aviation industry.

4. Better and faster decision making across the business

Having the right information at your fingertips helps managers at all levels of the organisation make decisions with clarity and a solid evidence base rather than just guesswork. It’s worth noting that Bowtie can be applied to all kinds of risks not just those around flight operations. Risks related to issues like project timelines and budgets, for example, can also be modelled very successfully with this tool.

5. Closing the loop on safety management

BowTieXP software (my preferred platform) holds a lot of information beyond the basic diagrams. The diagram elements can be used as the framework for the targeted collection of Safety Performance Indicators through barrier-based auditing and the integration of information available via occurrence reporting systems. This allows for the continuous feedback of safety intelligence into a ‘live’ safety management process, providing a realistic representation of what’s actually happening in your operation. Seems like a lot of work. Why would I bother? Hopefully it’s a given that we all want to assure the safety of our operations, so really it’s a question of how do we do it efficiently and effectively. Moving beyond a box ticking exercise is what this methodology is all about and at the end of the day this is what allows for sustainable operations in any aviation business.

How do I find out more? Visit our BowTie page


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