1. A method of constructing a behavior model of an identified airplane engine, in order to track the operation of the engine, the method comprising a training step for training at least one statistical regression function in connection with a generic database containing data issued from a plurality of airplane engines in order to establish a generic behavior model of a plurality of airplane engines, wherein the method further comprises a step of resetting the generic behavior model in connection with data stored in a specific database which is specific to said identified airplane engine, in order to establish a specific behavior model that takes into account features specific to said identified airplane engine, the respective generic and specific databases comprising degradation indicators (t) and context variables (v i ), wherein the training step comprises the following sub-steps: a/ for at least one obtained degradation indicators (t) of the generic database, determining a regression function (f i ) for each context variable (v i ) having an influence on said at least one degradation indicator; b/ modeling each degradation indicator by optimizing regression functions determined in sub-step a/; and wherein the resetting step has a sub-step of optimizing each degradation indicator by an additional statistical regression in connection with said specific database, leaving only an affine resetting as degrees of freedom.