Narrative:

Captain misset altimeter, 28.87 inches instead of 29.87 inches (1000 ft difference). I did not do as I should have and look at all 4 numbers. After thousands of hours and tens of thousands of times setting the altimeter, usually the last 2 numbers I just failed to check the first 2 numbers. Now the reasons (read excuses): this was the fourth day of a long 4 day trip, each day with an early morning get up. I was tired. At my age these long hard time trips are really taking their toll. The aircraft had just come out of maintenance for an engine change and the altimeter was set at 28.90 inches when I got into the cockpit. Oddly, the standby altimeter was set correctly at 29.90 inches. When I arrived at the aircraft the first officer informed me that there was a question as to whether the #1 constant speed drive was, in fact, connected. We contacted maintenance who wanted us to start up the #1 engine to verify that it was connected. In order to do this without delaying our departure, we rushed through the 'originating' and 'before engine start' checklists. In each checklist it called for checking the altimeter, and each time we both said 29.87 and each time I looked at the altimeters (main and standby) and read 29.87. Gso is about 990 ft above sea level, as a result the 2 altimeter's big needles were pointing almost identically at 990 ft even though they were 1000 ft off. The main altimeter was also reading 'neg' in the window which should have set off a huge light in my head. My only excuse for this is that in pennsylvania, our home base, which is about 20 ft above sea level it is very common to see 'neg' in the altimeter window when the aircraft has been sitting all night and there has been a change in the barometric pressure. In this case I remember seeing the 'neg,' seeing the big needle just to the left of straight up and thinking, the altimeter setting is a little off and will be corrected when we get a new setting. Talk about situational awareness, where was I? I checked those altimeters 4 times at least, and never caught the error. As we climbed to our assigned altitude of 11000 ft and going through 10400 ft (my altimeter), the first officer gasped, compared altimeters (his was reading 11400 ft and climbing) and yelled for me to stop the climb. Thank goodness for a sharp first officer! Time for an evaluation of my altimeter setting practices and maybe more. Supplemental information from acn 317602: on departure I informed the PF I was going to tell the flight attendants to remain seated for WX and began to talk to the attendants via intercom. Flight had been cleared to 11000 ft. PF called 10000 ft for 11000 ft and when I looked back up my altimeter read 11700 ft. No traffic conflict occurred. Recommendations: check, double-check, xchk! Take your time, slow down, don't rush, particularly in the early morning hours and during high workload periods.

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Original NASA ASRS Text

Title: ALTDEV ALT OVERSHOT. WRONG ALT SETTING.

Narrative: CAPT MISSET ALTIMETER, 28.87 INCHES INSTEAD OF 29.87 INCHES (1000 FT DIFFERENCE). I DID NOT DO AS I SHOULD HAVE AND LOOK AT ALL 4 NUMBERS. AFTER THOUSANDS OF HRS AND TENS OF THOUSANDS OF TIMES SETTING THE ALTIMETER, USUALLY THE LAST 2 NUMBERS I JUST FAILED TO CHK THE FIRST 2 NUMBERS. NOW THE REASONS (READ EXCUSES): THIS WAS THE FOURTH DAY OF A LONG 4 DAY TRIP, EACH DAY WITH AN EARLY MORNING GET UP. I WAS TIRED. AT MY AGE THESE LONG HARD TIME TRIPS ARE REALLY TAKING THEIR TOLL. THE ACFT HAD JUST COME OUT OF MAINT FOR AN ENG CHANGE AND THE ALTIMETER WAS SET AT 28.90 INCHES WHEN I GOT INTO THE COCKPIT. ODDLY, THE STANDBY ALTIMETER WAS SET CORRECTLY AT 29.90 INCHES. WHEN I ARRIVED AT THE ACFT THE FO INFORMED ME THAT THERE WAS A QUESTION AS TO WHETHER THE #1 CONSTANT SPD DRIVE WAS, IN FACT, CONNECTED. WE CONTACTED MAINT WHO WANTED US TO START UP THE #1 ENG TO VERIFY THAT IT WAS CONNECTED. IN ORDER TO DO THIS WITHOUT DELAYING OUR DEP, WE RUSHED THROUGH THE 'ORIGINATING' AND 'BEFORE ENG START' CHKLISTS. IN EACH CHKLIST IT CALLED FOR CHKING THE ALTIMETER, AND EACH TIME WE BOTH SAID 29.87 AND EACH TIME I LOOKED AT THE ALTIMETERS (MAIN AND STANDBY) AND READ 29.87. GSO IS ABOUT 990 FT ABOVE SEA LEVEL, AS A RESULT THE 2 ALTIMETER'S BIG NEEDLES WERE POINTING ALMOST IDENTICALLY AT 990 FT EVEN THOUGH THEY WERE 1000 FT OFF. THE MAIN ALTIMETER WAS ALSO READING 'NEG' IN THE WINDOW WHICH SHOULD HAVE SET OFF A HUGE LIGHT IN MY HEAD. MY ONLY EXCUSE FOR THIS IS THAT IN PENNSYLVANIA, OUR HOME BASE, WHICH IS ABOUT 20 FT ABOVE SEA LEVEL IT IS VERY COMMON TO SEE 'NEG' IN THE ALTIMETER WINDOW WHEN THE ACFT HAS BEEN SITTING ALL NIGHT AND THERE HAS BEEN A CHANGE IN THE BAROMETRIC PRESSURE. IN THIS CASE I REMEMBER SEEING THE 'NEG,' SEEING THE BIG NEEDLE JUST TO THE L OF STRAIGHT UP AND THINKING, THE ALTIMETER SETTING IS A LITTLE OFF AND WILL BE CORRECTED WHEN WE GET A NEW SETTING. TALK ABOUT SITUATIONAL AWARENESS, WHERE WAS I? I CHKED THOSE ALTIMETERS 4 TIMES AT LEAST, AND NEVER CAUGHT THE ERROR. AS WE CLBED TO OUR ASSIGNED ALT OF 11000 FT AND GOING THROUGH 10400 FT (MY ALTIMETER), THE FO GASPED, COMPARED ALTIMETERS (HIS WAS READING 11400 FT AND CLBING) AND YELLED FOR ME TO STOP THE CLB. THANK GOODNESS FOR A SHARP FO! TIME FOR AN EVALUATION OF MY ALTIMETER SETTING PRACTICES AND MAYBE MORE. SUPPLEMENTAL INFO FROM ACN 317602: ON DEP I INFORMED THE PF I WAS GOING TO TELL THE FLT ATTENDANTS TO REMAIN SEATED FOR WX AND BEGAN TO TALK TO THE ATTENDANTS VIA INTERCOM. FLT HAD BEEN CLRED TO 11000 FT. PF CALLED 10000 FT FOR 11000 FT AND WHEN I LOOKED BACK UP MY ALTIMETER READ 11700 FT. NO TFC CONFLICT OCCURRED. RECOMMENDATIONS: CHK, DOUBLE-CHK, XCHK! TAKE YOUR TIME, SLOW DOWN, DON'T RUSH, PARTICULARLY IN THE EARLY MORNING HRS AND DURING HIGH WORKLOAD PERIODS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.