ALTIMETER SETTING WAS NOT UPDATED; AND ACFT DEVIATED FROM ASSIGNED ALT.

Narrative

ACFT WAS ON A FLT FROM DTW TO RFD. AT THE TIME OF THE INCIDENT; THE PLTS WERE IN CONTACT WITH ZAU. THE ACFT HAD JUST PASSED OVER PMM VOR. THE CTLR HAD NOT GIVEN THE CURRENT ALTIMETER SETTING WHEN THE CREW CHKED IN ON THE NEW FREQ. THE CREW DID NOT CATCH THIS OMISSION. AFTER A SHORT PERIOD OF TIME; THE CTLR STATED HE SAW THE ACFT 400 FT OFF ALT AND GAVE THE CHICAGO ALTIMETER SETTING TO THEM. THERE HAD BEEN QUITE A CHANGE IN THE LAST 50 MI. THE CREW PUT THIS NEW ALTIMETER SETTING IN AND THE FLT PROCEEDED WITHOUT INCIDENT. FACTORS INVOLVED IN THIS ERROR INCLUDED THE CTLR'S INITIAL OMISSION OF THE ALTIMETER SETTING AND THE CREW'S SUBSEQUENT FAILURE TO CATCH THIS MISTAKE. THERE WERE NO DISTRS IN THE COCKPIT. MOREOVER; THE CREW WAS ALERT AND NO EXTRANEOUS COM OR ACTIVITY WAS OCCURRING AT THE TIME. THE CAPT WAS WELL AWARE OF THE ACFT'S POS BUT FAILED TO CATCH THE MISTAKE ON THE PART OF THE CTLR. THE CREW DISCUSSED THE INCIDENT AT LENGTH. THE CAPT ASSUMED FULL RESPONSIBILITY FOR THE ERROR BUT THE FO STATED HE WAS EQUALLY RESPONSIBLE FOR FAILING TO CATCH THE MISTAKE. COCKPIT RESOURCE MGMNT WAS ACTIVELY USED THE ENTIRE DAY BY THE CREW AND THEY BOTH HAVE WORKED WELL TOGETHER ON NUMEROUS OCCASIONS. SUPPLEMENTAL INFO FROM ACN 294742: IN RETROSPECT; I REALIZED THAT COMPLACENCY WAS THE CAUSE FOR THE ERROR. THE CAPT AND I WERE VERY FAMILIAR WITH THE RTE; THE ACFT AND EACH OTHER BECAUSE OF OUR FAMILIARITY WITH ONE ANOTHER; WE CONSTANTLY CONVERSE AT ALT. ALTHOUGH WE DO NOT NORMALLY MISS ATC CALLS AND ALWAYS PRACTICE PROPER COCKPIT RESOURCE MGMNT; WE ALLOWED OUR CONCENTRATION TO LAPSE.