A LOW TIME CFII; BASED OUT OF PFN; VIOLATED PFN CLASS D AIRSPACE.

Narrative

I WAS SCHEDULED TO TAKE A CUSTOMER IN A C152 ON AN AERIAL PHOTOGRAPHY SHOOT ON SEP/XA/99. I AM A FLT INSTRUCTOR AT PANAMA CITY; BAY COUNTY INTL MUNICIPAL ARPT. WE DEPARTED PFN; CLASS D AIRSPACE; TO THE E WHERE THE CUSTOMER WISHED TO TAKE PHOTOGRAPHS. I WAS TOLD BY TWR TO SWITCH FREQS TO TYNDALL APCH WHEN ABOUT 4 MI OUT. I MONITORED APCH FREQ; AND THE CUSTOMER TOOK PHOTOS IN THIS AREA (ABOUT 4 MI E OF PFN). VISUALLY; I ESTIMATED MY POS AS BEING ABOUT 4 MI; ALTHOUGH I HAD NO DME TO CONFIRM THIS. UPON RETURNING TO PFN; THE TWR INFORMED ME I HAD VIOLATED THEIR AIRSPACE. I DID NOT REALIZE THAT PFN EXTENDED 5 MI FROM THE ARPT. RATHER; I THOUGHT IT EXTENDED ONLY 4 MI; AS MANY CLASS D ARPTS DO. THIS AIRSPACE VIOLATION COULD HAVE BEEN PREVENTED IF TWR DID NOT ASK ME TO SWITCH FREQS UNTIL I WAS CLR OF THEIR AIRSPACE; AS TELLING ME TO SWITCH FREQS AT THE 4 MI POINT MEANT TO ME THAT I WAS CLR OF THE CLASS D AIRSPACE. ALSO; THE SECTIONAL SHOULD GIVE RADII OF AIRSPACE; AS IT IS UNCLR. THIS WOULD MORE CLRLY DEFINE THE DIMENSIONS OF AIRSPACE. BEING AT 500 FT AGL; I THOUGHT I WAS IN CLASS G AIRSPACE; WHERE NO RADIO CALL WOULD HAVE BEEN NECESSARY.