Narrative:

Departed morristown airport, nj, VFR (cavu) en route to baltimore, md. Requested and tower approved runway 5, left downwind departure on course +/-250 degrees. Climbed at 500 FPM to 3500 ft en route. Checked new york sectional for floor of class B airspace and confused philadelphia 7000/4000 ft with new york 7000/3000 ft outer rings. Realized that on way inbound class B clearance was received at 3500 ft. Rechked map. Immediately descended below 3000 ft until clear of class B airspace.

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Original NASA ASRS Text

Title: PLT OF A C172 INADVERTENTLY PENETRATED CLASS B AIRSPACE DUE TO MISCALCULATING THE CLASS B FLOOR ALT UNDER WHICH HE DEPARTED ON A VFR FLT.

Narrative: DEPARTED MORRISTOWN ARPT, NJ, VFR (CAVU) ENRTE TO BALTIMORE, MD. REQUESTED AND TWR APPROVED RWY 5, L DOWNWIND DEP ON COURSE +/-250 DEGS. CLBED AT 500 FPM TO 3500 FT ENRTE. CHKED NEW YORK SECTIONAL FOR FLOOR OF CLASS B AIRSPACE AND CONFUSED PHILADELPHIA 7000/4000 FT WITH NEW YORK 7000/3000 FT OUTER RINGS. REALIZED THAT ON WAY INBOUND CLASS B CLRNC WAS RECEIVED AT 3500 FT. RECHKED MAP. IMMEDIATELY DSNDED BELOW 3000 FT UNTIL CLR OF CLASS B AIRSPACE.

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.