Health Risk Bow Tie Model

John FRANKLIN • 22 September 2020
in community Air Operations

This article and the attached bow tie (as PNG and Bow Tie XP files) are intended to help anyone working at an airport or airline who is implementing COVID-19 health measures as part of the EASA/ ECDC Aviation Health Safety Protocol (AHSP).

The main takeaways from this article are:

-           Read the article to understand the purpose of this Bow Tie model and how it can help you to manage the health risks as part of implementing the AHSP. 

-           Download the Bow Tie XP as an image file at the bottom of the article or email us at to get a copy of the Bow Tie XP file. Use it as part of your own health management processes – the idea is to save you time having to build your own. 

-           Tell us more about your implementation challenges and any solutions you think others could learn from - either in the comments section below or by email to

The purpose of the Bow Tie Model

These bow ties were developed to Map the risk of Covid-19 transmission through the transport of passengers, during their journey through the airport and on the aircraft. It can be used by you to understand your risks as an organization, it has also been used as a resource by EASA to ensure that the AHSP is complete, and to develop a monitoring framework for the implementation of the AHSP.

Bow tie models are used to understand risks, they are a useful way of visualizing a risk and developing mitigating actions. They help users to clearly identify the “top event” that they wish to prevent, the threats that may lead to this event and the consequences. Once these are in place, preventive barriers can be identified, in order to reduce the severity or likelihood of the top event. Recovery barriers can also be identified, to reduce the severity or likelihood of the consequences. The barriers can be categorized according to the type of mitigating action, for example how effective it is or whether it is a behavioural, socio-technical or hardware related barrier. Each barrier can also have “escalating factors”, which describe threats to reducing the effectiveness of the barrier, and these escalating factors in themselves have barriers.

Scenarios/ Top Events Covered in the Bow Tie

The bow tie has been set up to cover the most common types of COVID-19 transmission that are likely to occur during the normal passenger’s journey through the departure airport onto the aircraft and out of the arrival airport at the other end. It covers the following situations with barriers (mitigations), types of barriers, and their effectiveness in limiting the spread of the virus. 

-           Member of the public spreads the virus onboard the aircraft.

-           Member of the public spreads the virus at the airport.

-           Airport staff spread the virus.

-           Aircrew spread the virus onboard the aircraft. 

-           Suspected case during the flight.

-           Ground crew spread the virus through contact with other people. 

-           Ground crew spread the virus through surface contact. 

-           Contaminated aircraft surfaces.

What to do with this Bow Tie Model?

If you have Bowtie XP then you can download the .btf file and use within your own system to help with your risk assessment and mitigation work.  If you use another tool or process then you can download the .png file to help save you time with understanding the health risks that you should be trying to manage. 

Tell us your challenges and share your solutions!  

It is vital that we work together to help combat the spread of COVID-19 and to protect our passengers, crew and staff members from harm. As you work to implement the ASHP in your airport, airline or other organization please share your experiences with us – either through the comments section below or by emailing the Together4Safety team at

We would love to understand more about your challenges and particularly what has helped you and your organization to keep people safe.  The more practical information we can provide to help everyone with implementing the protocol and enabling people to fly with more confidence the better. 



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