Your Auditor will let you know exactly who needs to be available and when, but typically you will need to make the person who is coordinating Travelife Certification available for the entire audit.  You can also expect the Auditor to want to speak to various other department heads and to conduct private interviews with at least three different staff of their choosing.  When you join Travelife you will be find more information about how to prepare for an audit in the Member Zone.