The challenge of integrating risks

The foundation of any safety management system (SMS) is the use of a robust methodology for risk assessment. No aviation organisation would consider their SMS complete without assessing the chance certain events will occur and how severe their consequences. But what do you do when you want to integrate different stakeholders with different risks and different consequences?

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The matrix dilemma

Aviation safety risk assessments follow the 5 x 5 risk assessment matrix published by ICAO in its Safety Management Manual. This ICAO matrix sorts event risks across three levels of acceptability that are colour-coded red, yellow and green.

The ICAO 5 x 5 risk assessment matrix (Source: ICAO Doc. 9859)

This basic matrix is often expanded to include injury and damage to assets, reputation and the environment.

The matrix risk scores dictate how much or how little an organisation must do about that risk. So how do you share severity and probability in an integrated safety system in a way that is still useful when an event has significantly different consequences for stakeholders?

The illogic of integrating risk

Let’s consider the situation at a large airport with shared taxiways, where there is a risk of an occasional aeroplane collision during push-back. The individual stakeholders in the integrated SMS might see their risk as follows:

  • ANSP – Not applicable, as we followed procedures, no people are injured or assets damaged (green zone)
  • Airport – Occasional event, minor severity from delays but damaged assets aren’t ours (4D yellow zone)
  • Airline – Occasional event, significant severity from damage, costs, delays (4C yellow zone)
  • Ground handling – Occasional event with serious (financial) consequences, (4B red zone)


The event results from an action by the push-back driver employed by the ground handling organisation. The high cost makes it a serious event. However, if all stakeholders in an integrated system were to adopt the highest score, for example, the other stakeholders must take actions that are probably unwarranted, as red risks are unacceptable.

This example considers a non-fatal incident on the apron. But what about a crash where an aeroplane undershoots and comes down just outside the airport fence? Aside from whether emergency services are adequate, this risk could also conceivably be ranked as negligible for the airport on the 5 x 5 matrix.

An alternative way to share

A negligible risk severity score for a serious, fatal accident simply cannot be right. But isn’t it just as incorrect for the airport to adopt the same catastrophic ranking the airline would apply? Risk assessments are intended to pinpoint where appropriate action should be taken so resources can be allocated effectively.

Making the step to a fully integrated risk assessment in which the risks are presented in an ‘honest’ manner means respecting each organisation’s own risk and showing clearly the different risk levels for individual stakeholders.

In our Risk Assessment* white paper, we suggest an alternative way to present risk in an integrated SMS.

For more on this topic, click here to download the whitepaper:

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About To70. To70 is one of the world’s leading aviation consultancies, founded in the Netherlands with offices in Europe, Australia, Asia, and Latin America. To70 believes that society’s growing demand for transport and mobility can be met in a safe, efficient, environmentally friendly and economically viable manner. To achieve this, policy and business decisions have to be based on objective information. With our diverse team of specialists and generalists to70 provides pragmatic solutions and expert advice, based on high-quality data-driven analyses. For more information, please refer to


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