A method for synchronizing planning information in a high availability planning and scheduling architecture includes processing requests from one or more external systems (40) using an advanced planning and scheduling (APS) engine (22) included in a first primary high availability (HA) system (20a). The processing of requests includes modifying planning information stored in memory of the first primary HA system (20a) according to the requests. The method also includes storing change information reflecting the modifications to the planning information in a database (64) and extracting the change information from the database (64) at an extraction time. Furthermore, the method includes updating the planning information using the extracted change information and storing the updated planning information in memory of a second primary HA system (20a). In addition, the method includes identifying requests that were processed by the first primary HA system (20a) after the extraction time and updating the planning information stored in memory of the second primary HA system (20a) to account for these requests. The method also includes replacing the first primary HA system (20a) with the second primary HA system (20a).