Internationally recognised good practice in management system auditing, as set in ISO 17011, require an audit team to include skills and expertise that cover the scope of the audit.
The breadth of topics covered by the CHS makes it unlikely to find this expertise in one individual only. An adequate combination of skills (thematic expertise, languages, geographical coverage, experience of particular organisational set ups, etc) allows for a more efficient coverage of the different functions, contexts and ways of working of an organisation. The combination of skills of several persons helps minimise the information uncertainty and therefore improves the reliability of audit outcomes.
With the exception of maintenance audits, HQAI audit teams are composed of at least two auditors chosen for the complementarity of their skills and experience, trying to find compositions that minimise costs.