ACR MLG ALT DEVIATION OVERSHOT DURING CLIMB AS FLT CREW STUDIED THE ACFT RADAR RETURN FOR A SOFT ROUTE THROUGH THE ENROUTE TSTM WX ACTIVITY.

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CLBING OUT OF BOS ENRTE TO ORD. ASKED BOS ARTCC FOR SOUTHERLY DEVIATION ON INITIAL CONTACT IN ORDER TO AVOID STORMS TO THE WNW AND N OF OUR ROUTE. REQUEST DENIED ACCOUNT TFC. CENTER SAID A HDG OF 330 DEGS SHOULD AVOID THE WX AND SAID THAT PREVIOUS FLTS HAD NO PROB. WE PROCEEDED TO CLB ON OR CLOSE TO A HDG OF 330 DEGS. THE ALT CLRNC LIMIT WAS FL230. WE ENTERED IMC ABOUT 16000' IN THE CLB AND TURNED ENG ANTI-ICE ON. BOTH OF US BECAME VERY BUSY NAVIGATING VIA THE ON BOARD WX RADAR. I WAS HAND FLYING RATHER THAN USING ALL OF THE AUTOMATIC FLT SYSTEMS. I DON'T RECALL HEARING THE ALT ALERT AS WE PASSED THROUGH FL221 AND DON'T RECALL SEEING THE ALT ALERT LIGHT EITHER. FOR SOME REASON; I RECALL THINKING THAT WE WERE CLRED TO FL240. LEAVING FL233 THE ALT ALERT SOUNDED AND THE LIGHT BEGAN FLASHING. I INTERPRETED THIS AS THE WARNING APCHING FL240 AND HAD JUST BEGUN A SLIGHT THROTTLE REDUCTION PRIOR TO THE ALERT. AT FL234 I MADE A SLIGHTLY GREATER THROTTLE REDUCTION AS THE F/O SAID; 'HEY! 230; WE'RE ONLY CLRED TO 230!' I RECOGNIZED THE ERROR AT THAT POINT AND MADE A POSITIVE CORRECTION TOWARD FL230. THE ACFT REACHED FL236 BEFORE THE CORRECTION WAS EFFECTIVE. SEVERAL FACTORS PROBABLY CONTRIBUTED TO THE BUST. (1) BOTH OF US WERE SOMEWHAT FATIGUED. IT WAS THE LAST LEG OF A DAY THAT BEGAN WITH A WAKE-UP. (2) I WAS HAND FLYING. THE BUST WOULDN'T HAVE OCCURRED IF I'D HAD THE AUTOMATICS ENGAGED. (3) BOTH OF US WERE CONSTANTLY REFERRING TO THE RADAR. (4) SAME OLD STORY ABOUT THE ALT ALERT BEING USED AS AN EVERYDAY COMMONPLACE WARNING AND THEN BEING OVERLOOKED WHEN IT REALLY MEANS SOMETHING. IF YOU KNEW IN FRONT THAT FATIGUE MIGHT AFFECT YOUR PERFORMANCE; YOU MIGHT BE ABLE TO CHANGE SOMETHING. I WILL CERTAINLY CONSIDER USING THE AUTO FLT SYSTEM DURING PERIODS OF FATIGUE OR OTHER ANOMALIES IN THE FUTURE. I WASN'T TRYING TO TORTURE MYSELF OR PROVE A POINT BY HAND FLYING. I NORMALLY HAND FLY AT LEAST TO CRUISE BECAUSE I REFUSE TO FORGET HOW TO FLY JUST BECAUSE THERE'S A MACHINE THAT CAN DO IT AS WELL OR BETTER THAN I. IN FACT; I FELT QUITE COMFORTABLE RIGHT UNTIL THE F/O MADE HIS WARNING. THE ALT ALERT SITUATION SHOULD REALLY BE CORRECTED. HOW ABOUT JUST A LIGHT FOR THE ALERT APCHING THE ASSIGNED ALT AND RESERVE THE AURAL WARNING FOR POTENTIAL BUSTS? ANYBODY SUGGESTED THIS BEFORE?? I ALREADY KNOW THE ANSWER...JUST WONDER HOW LONG IT WILL TAKE. SUPPLEMENTAL INFO FROM ACN 91717. I DON'T REMEMBER MAKING THE 1000 REMAINING CALL. I BELIEVE THE PRIMARY CAUSE OF THE BUST WAS OVER ATTN TO THE RADAR. THE ACFT RADAR IS FANTASTIC AND WHEN SUPERIMPOSED OVER THE MAP MODE GIVES AN AMAZING AMOUNT OF INFO.