Narrative:

Flying scheduled flight from mry to sfo, our IFR flight plan cleared us to 6000 ft. After receiving clearance (route and altitude, departure frequency and squawk) shut off radio and waited until passenger boarding. Prior to doing so had set 6000 ft in electronic altitude alerter. Though I had plenty of sleep the night before, I was slightly tired but still safe to fly this flight of day. Once we boarded we restarted engines, finished all checklists and taxied. Conducted takeoff without incident. We hadn't noticed that altitude encoder had indicated 7000 ft when we put avionics master back on, and in our climb we were proceeding to what we thought was our assigned altitude of 7000 ft. We hadn't thought to rechk it. When queried by oakland center as to our 7000 ft, were corrected (by this time we were at 6700 ft) and we returned to 6000 ft. For most of the morning we attempted to determine whether we had erred, but on our 4TH leg that day we caught the electronic altitude alerter transpose numbers again after startup, then we were aware of the problem. This situation would have been avoided by doublechking all electronically stored navigation data stored prior to startup - again after startup to ensure accuracy, and not to assume these are infallible instruments. This shall not become a regular part of my departure briefing.

Google
 

Original NASA ASRS Text

Title: FLC OF COMMUTER SMT CLBED TO WRONG ALT.

Narrative: FLYING SCHEDULED FLT FROM MRY TO SFO, OUR IFR FLT PLAN CLRED US TO 6000 FT. AFTER RECEIVING CLRNC (ROUTE AND ALT, DEP FREQ AND SQUAWK) SHUT OFF RADIO AND WAITED UNTIL PAX BOARDING. PRIOR TO DOING SO HAD SET 6000 FT IN ELECTRONIC ALT ALERTER. THOUGH I HAD PLENTY OF SLEEP THE NIGHT BEFORE, I WAS SLIGHTLY TIRED BUT STILL SAFE TO FLY THIS FLT OF DAY. ONCE WE BOARDED WE RESTARTED ENGINES, FINISHED ALL CHKLISTS AND TAXIED. CONDUCTED TKOF WITHOUT INCIDENT. WE HADN'T NOTICED THAT ALT ENCODER HAD INDICATED 7000 FT WHEN WE PUT AVIONICS MASTER BACK ON, AND IN OUR CLB WE WERE PROCEEDING TO WHAT WE THOUGHT WAS OUR ASSIGNED ALT OF 7000 FT. WE HADN'T THOUGHT TO RECHK IT. WHEN QUERIED BY OAKLAND CENTER AS TO OUR 7000 FT, WERE CORRECTED (BY THIS TIME WE WERE AT 6700 FT) AND WE RETURNED TO 6000 FT. FOR MOST OF THE MORNING WE ATTEMPTED TO DETERMINE WHETHER WE HAD ERRED, BUT ON OUR 4TH LEG THAT DAY WE CAUGHT THE ELECTRONIC ALT ALERTER TRANSPOSE NUMBERS AGAIN AFTER STARTUP, THEN WE WERE AWARE OF THE PROBLEM. THIS SITUATION WOULD HAVE BEEN AVOIDED BY DOUBLECHKING ALL ELECTRONICALLY STORED NAV DATA STORED PRIOR TO STARTUP - AGAIN AFTER STARTUP TO ENSURE ACCURACY, AND NOT TO ASSUME THESE ARE INFALLIBLE INSTRUMENTS. THIS SHALL NOT BECOME A REGULAR PART OF MY DEP BRIEFING.

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.