An engine control system includes an engine controller configured to execute an open-loop model of the engine control system. The open-loop model receives a measured effector and boundary condition parameter vector and generates a synthesized engine operating parameter based on the measured effector and boundary condition parameter vector. The engine controller calculates a corrector error value between the synthesized engine operating parameter and a measured engine operating parameter, and determines an open loop corrector error calculated as a difference between the corrector error and a vector-matrix product of corrector state vector and a gain map/function. The engine controller applies the gain map/function to the open loop corrector error to determine an effector and boundary condition error vector of the measured effector and boundary condition parameter vector.