not be set then step 330 determines if the aircraft accessory monitor 230 is communicating with a test set such as a test set used for atp if not then characterization mode ends at step 342 otherwise test set commands are entered by a user in step 332 for both setting parameters in step 336 and organizing data acquisition for the parameters set in step 334 in other embodiments step 334 may follow step 336 linearly in other embodiments the parameters may all be set in step 336 and then different test set commands from step 332 may cause step 334 to be executed for all set parameters the validity of the parameters set in step 336 and associated with data streams in step 334 may be tested in step 338 by verifying that each parameter has an associated data stream that does represent the parameter and that each desired parameter has been set these parametric data streams may be used to fill in the structure of the baseline model 320 in step 340 the baseline model is based upon the data acquired during atp and provides parameters representing the actual performance of the specific aircraft accessory under test the baseline model 320 may be associated with other models for example six sigma limits from the six sigma model derived from previous tests of all similar aircraft accessories may be added to the baseline model 320 to provide an estimate of the six sigma limits of the specific aircraft accessory under test any.