Insufficiency in showing errors in aviation ergatic system is understood to be a situation when there is no available information about the system or some of the board information is unreliable. With the use of the method of automatic diagnosis it is possible to analyse the symptoms of analytical redundancy. Residual differences, i.e. residuents, which are the final value expression of the consequences (effects) of function observation, which are measured on obtained mathematical model, are the keystones of this method. The content of the mathematical model application contains generator of residuents, i.e. signals, which carry the information about the incorrectness (errors) and aviation ergatic system (AES) failures.