ACRP Report 65: Guidebook for Airport Irregular Operations (IROPS) Contingency Planning is a practical guidebook for commercial passenger service airports of all sizes to develop, continually evaluate, and update their contingency plans for procedures pertaining to IROPS that may cause significant disruptions to customers. This guidebook assists aviation system partners in improving their response to customer care during a broad array of IROPS conditions and with step by step templates for the preparation of contingency plans that include necessary communications, collaboration, and coordination to address customer needs. A specific focus on the needs of smaller airports has been included in the development of the guidebook.