A major non-conformity means an identifiable deviation which poses a serious threat to the safety of personnel, the ship or to the environment that requires immediate corrective action or the lack of effective and systematic implementation of a requirement of the ISM Code.
A major non-conformity on ship audits requires downgrading to a non- conformity in order to allow the vessel to sail (Ref. MEPC/Circ. 1059 of 16-12-2002).
An additional audit (timed to verify the effectiveness of the corrective action) is required within 3 months to close out a downgraded major non-conformity.