Narrative:

Returning to my home field (harvey), I was showing the seattle area to my passenger. It was a beautiful day and I had in my mind that the floor of the class B airspace was at 5000 ft on my planned course returning to harvey. I was approximately over the winslow ferry dock when I again checked my terminal area chart. I realized the floor of the class B airspace was only 3000 ft MSL. I immediately descended to below 3000 ft. I fly almost daily out of seatac for an airline. I have just recently returned to VFR 'small airplane' flying. Being that my part 121 flying is all IFR, dealing with the class B/D airspace is somewhat of a new experience in the VFR environment. What caused this problem (and I am not positive I did penetrate the class B, but if not I sure came close -- too close!) was not devoting 100% attention to my location and rechking -- again and again -- my planned altitude for going under the class B. It was a situation where I had made a plan to be at 3500 ft, then I checked the class B floor and confirmed it was 5000 ft. Then I did not realize my actual course was farther south and one that would be in the area where the floor was only 3000 ft.

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Original NASA ASRS Text

Title: A HIGHLY EXPERIENCED PLT, WITH VERY LOW TIME IN A C182 BLUNDERED INTO SEA CLASS B AIRSPACE WHILE SIGHTSEEING WITH A PAX.

Narrative: RETURNING TO MY HOME FIELD (HARVEY), I WAS SHOWING THE SEATTLE AREA TO MY PAX. IT WAS A BEAUTIFUL DAY AND I HAD IN MY MIND THAT THE FLOOR OF THE CLASS B AIRSPACE WAS AT 5000 FT ON MY PLANNED COURSE RETURNING TO HARVEY. I WAS APPROX OVER THE WINSLOW FERRY DOCK WHEN I AGAIN CHKED MY TERMINAL AREA CHART. I REALIZED THE FLOOR OF THE CLASS B AIRSPACE WAS ONLY 3000 FT MSL. I IMMEDIATELY DSNDED TO BELOW 3000 FT. I FLY ALMOST DAILY OUT OF SEATAC FOR AN AIRLINE. I HAVE JUST RECENTLY RETURNED TO VFR 'SMALL AIRPLANE' FLYING. BEING THAT MY PART 121 FLYING IS ALL IFR, DEALING WITH THE CLASS B/D AIRSPACE IS SOMEWHAT OF A NEW EXPERIENCE IN THE VFR ENVIRONMENT. WHAT CAUSED THIS PROB (AND I AM NOT POSITIVE I DID PENETRATE THE CLASS B, BUT IF NOT I SURE CAME CLOSE -- TOO CLOSE!) WAS NOT DEVOTING 100% ATTN TO MY LOCATION AND RECHKING -- AGAIN AND AGAIN -- MY PLANNED ALT FOR GOING UNDER THE CLASS B. IT WAS A SIT WHERE I HAD MADE A PLAN TO BE AT 3500 FT, THEN I CHKED THE CLASS B FLOOR AND CONFIRMED IT WAS 5000 FT. THEN I DID NOT REALIZE MY ACTUAL COURSE WAS FARTHER S AND ONE THAT WOULD BE IN THE AREA WHERE THE FLOOR WAS ONLY 3000 FT.

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.