Reduce the risks cost-effectively   The risks are unacceptable and must be reduced.   The risks are tolerable and risk mitigation is not required.   Avoid the vulnerability completely by using other airplane types

It seems like you're asking for a step-by-step guide on how to manage risks in an aviation context. Here's a general approach:

1. Risk Identification: The first step is to identify the risks. This could be technical failures, human errors, natural disasters, etc. In this case, the risk seems to be related to a specific type of airplane.

2. Risk Assessment: Once the risks are identified, they need to be assessed in terms of their potential impact and the likelihood of their occurrence. This can be done using various risk assessment tools and methodologies.

3. Risk Evaluation: After assessing the risks, they need to be evaluated to determine whether they are acceptable or not. If the risks are unacceptable, as stated in your question, they must be reduced.

4. Risk Mitigation: This is the process of developing strategies to reduce the impact of risk occurrence. Cost-effective risk mitigation strategies could include regular maintenance and inspection of the airplanes, training of staff, etc.

5. Alternative Solutions: If the risks are still unacceptable after mitigation, alternative solutions should be considered. In this case, it could be using other types of airplanes that do not have the same vulnerabilities.

6. Implementation and Monitoring: Once the strategies are decided, they need to be implemented and continuously monitored to ensure their effectiveness.

Remember, the goal is not to eliminate all risks (which is often impossible), but to reduce them to an acceptable level while balancing the costs and benefits.