Narrative:

I was returning to my home base, deer valley (dvt) from casa grande. Not having approached the class B in this vicinity before, I was trying to check the chart for both the boundary and altitude. As soon as I realized I was close to the boundary, over sun lakes, I called phx approach and requested a VFR transition, known as the 'biltmore' giving my exact position over the charted landmark, sun lakes. The controller gave me a transponder code. Not receiving any other control instruction, and not realizing my altitude was the floor of the class B (4000 ft) until I had crossed the B boundary and the controller then issued the clearance with the remark 'already in class B', although I was not at the time of my request. If I had realized that I was at the floor, I would have descended below it to stay clear until receiving the clearance. This is an unusual segment to have the floor that low (2500 ft AGL) at the 30 mi radius of the class B. The controller about 10 mi later remarked that I was tracking east of the biltmore corridor. While a general route is depicted I was not aware if was considered to have hard boundaries, and in all previous uses of the corridor had come from locations further east, where I was directed to the ahwatakee golf course to initial the north/south route over the center of sky harbor. So I was proceeding to this same landmark as I had been instructed in the past. I have thoroughly reviewed the class B chart for phx to ensure I will strictly comply with the boundaries and rtes in the future.

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Original NASA ASRS Text

Title: PLT OF C170B ATTEMPTING TO CONTACT APCH CTL TO TRANSIT CLASS B AIRSPACE ENTERS THE AIRSPACE PRIOR TO RECEIVING CLRNC.

Narrative: I WAS RETURNING TO MY HOME BASE, DEER VALLEY (DVT) FROM CASA GRANDE. NOT HAVING APCHED THE CLASS B IN THIS VICINITY BEFORE, I WAS TRYING TO CHK THE CHART FOR BOTH THE BOUNDARY AND ALT. AS SOON AS I REALIZED I WAS CLOSE TO THE BOUNDARY, OVER SUN LAKES, I CALLED PHX APCH AND REQUESTED A VFR TRANSITION, KNOWN AS THE 'BILTMORE' GIVING MY EXACT POS OVER THE CHARTED LANDMARK, SUN LAKES. THE CTLR GAVE ME A XPONDER CODE. NOT RECEIVING ANY OTHER CTL INSTRUCTION, AND NOT REALIZING MY ALT WAS THE FLOOR OF THE CLASS B (4000 FT) UNTIL I HAD CROSSED THE B BOUNDARY AND THE CTLR THEN ISSUED THE CLRNC WITH THE REMARK 'ALREADY IN CLASS B', ALTHOUGH I WAS NOT AT THE TIME OF MY REQUEST. IF I HAD REALIZED THAT I WAS AT THE FLOOR, I WOULD HAVE DSNDED BELOW IT TO STAY CLR UNTIL RECEIVING THE CLRNC. THIS IS AN UNUSUAL SEGMENT TO HAVE THE FLOOR THAT LOW (2500 FT AGL) AT THE 30 MI RADIUS OF THE CLASS B. THE CTLR ABOUT 10 MI LATER REMARKED THAT I WAS TRACKING E OF THE BILTMORE CORRIDOR. WHILE A GENERAL RTE IS DEPICTED I WAS NOT AWARE IF WAS CONSIDERED TO HAVE HARD BOUNDARIES, AND IN ALL PREVIOUS USES OF THE CORRIDOR HAD COME FROM LOCATIONS FURTHER E, WHERE I WAS DIRECTED TO THE AHWATAKEE GOLF COURSE TO INITIAL THE N/S RTE OVER THE CTR OF SKY HARBOR. SO I WAS PROCEEDING TO THIS SAME LANDMARK AS I HAD BEEN INSTRUCTED IN THE PAST. I HAVE THOROUGHLY REVIEWED THE CLASS B CHART FOR PHX TO ENSURE I WILL STRICTLY COMPLY WITH THE BOUNDARIES AND RTES IN THE FUTURE.

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.