Narrative:

I was on a VFR cross country from rockport, tx (rkp) to georgetown, tx (gtu). We were VFR over the top and were handed off from ZHU on austin approach level at 6500 ft MSL. Cloud tops were 5500 ft MSL with bases reported at 3500 ft AGL. The clouds had large breaks which would permit a VFR descent. Our location, when handed off to approach control, was approximately 20 mi southeast of austin bergstrom airport. We told austin approach that we were going to begin a VFR descent and we were told to maintain VFR at or above 4500 ft MSL. We informed approach that we would need at least 3500 ft MSL and that seemed to be approved and we continued the VFR descent to 3500 ft MSL. At 3500 ft MSL the visibility was VFR but not great, so I requested further descent to 2500 ft MSL. At that point austin approach put us on a northeasterly vector, presumably to remain clear of other traffic and remain well clear of the class C airspace which I was never told to remain clear of. After a short period of time, I was told to resume normal navigation to georgetown, tx (gtu). It is not known if our descent caused a problem for austin approach due to our continuing requests for a lower altitude. We remained VFR throughout the maneuver and our track between victoria VORTAC (vct) and the centex VORTAC (cwx), a course of 357 degrees to cwx, appeared to keep us outside the class C airspace to the east of austin. Approach did not say anything to us that would have indicated any problems at the time. In retrospect, we probably should have waited until we were well north of the austin area before commencing out descent. The duty runways at austin bergstrom. Were runways 18L and 18R so we thought that most of the traffic would have been routed to the north for the visual approach to bergstrom, a descent in a location to the southeast and outside of class C would have been the ideal place to accomplish the descent. The break we descended through was a very large elongated area that permitted compliance with all the VFR requirements in the regulations. When approach told us to maintain VFR at or above 4500 ft, we complied but the area we were in was not going to permit that forever which is why we requested 3500 ft. In the future I will not begin my descent in this kind of situation until approach can approve descent to below the bases in one shot. By descending to 4500 ft, I was below the tops and above the bases in an area that was not going to last forever and could have been in a situation eventually of asking for emergency IFR handling. We did not get close to that because austin was able to approve our requests, but had that not been the case, we would not have been in a great place.

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Original NASA ASRS Text

Title: A C172 PLT MAY HAVE VIOLATED CLASS C AIRSPACE AT AUS, AS WELL AS VFR CLOUD CLRNCS.

Narrative: I WAS ON A VFR XCOUNTRY FROM ROCKPORT, TX (RKP) TO GEORGETOWN, TX (GTU). WE WERE VFR OVER THE TOP AND WERE HANDED OFF FROM ZHU ON AUSTIN APCH LEVEL AT 6500 FT MSL. CLOUD TOPS WERE 5500 FT MSL WITH BASES RPTED AT 3500 FT AGL. THE CLOUDS HAD LARGE BREAKS WHICH WOULD PERMIT A VFR DSCNT. OUR LOCATION, WHEN HANDED OFF TO APCH CTL, WAS APPROX 20 MI SE OF AUSTIN BERGSTROM ARPT. WE TOLD AUSTIN APCH THAT WE WERE GOING TO BEGIN A VFR DSCNT AND WE WERE TOLD TO MAINTAIN VFR AT OR ABOVE 4500 FT MSL. WE INFORMED APCH THAT WE WOULD NEED AT LEAST 3500 FT MSL AND THAT SEEMED TO BE APPROVED AND WE CONTINUED THE VFR DSCNT TO 3500 FT MSL. AT 3500 FT MSL THE VISIBILITY WAS VFR BUT NOT GREAT, SO I REQUESTED FURTHER DSCNT TO 2500 FT MSL. AT THAT POINT AUSTIN APCH PUT US ON A NORTHEASTERLY VECTOR, PRESUMABLY TO REMAIN CLR OF OTHER TFC AND REMAIN WELL CLR OF THE CLASS C AIRSPACE WHICH I WAS NEVER TOLD TO REMAIN CLR OF. AFTER A SHORT PERIOD OF TIME, I WAS TOLD TO RESUME NORMAL NAV TO GEORGETOWN, TX (GTU). IT IS NOT KNOWN IF OUR DSCNT CAUSED A PROB FOR AUSTIN APCH DUE TO OUR CONTINUING REQUESTS FOR A LOWER ALT. WE REMAINED VFR THROUGHOUT THE MANEUVER AND OUR TRACK BTWN VICTORIA VORTAC (VCT) AND THE CENTEX VORTAC (CWX), A COURSE OF 357 DEGS TO CWX, APPEARED TO KEEP US OUTSIDE THE CLASS C AIRSPACE TO THE E OF AUSTIN. APCH DID NOT SAY ANYTHING TO US THAT WOULD HAVE INDICATED ANY PROBS AT THE TIME. IN RETROSPECT, WE PROBABLY SHOULD HAVE WAITED UNTIL WE WERE WELL N OF THE AUSTIN AREA BEFORE COMMENCING OUT DSCNT. THE DUTY RWYS AT AUSTIN BERGSTROM. WERE RWYS 18L AND 18R SO WE THOUGHT THAT MOST OF THE TFC WOULD HAVE BEEN ROUTED TO THE N FOR THE VISUAL APCH TO BERGSTROM, A DSCNT IN A LOCATION TO THE SE AND OUTSIDE OF CLASS C WOULD HAVE BEEN THE IDEAL PLACE TO ACCOMPLISH THE DSCNT. THE BREAK WE DSNDED THROUGH WAS A VERY LARGE ELONGATED AREA THAT PERMITTED COMPLIANCE WITH ALL THE VFR REQUIREMENTS IN THE REGS. WHEN APCH TOLD US TO MAINTAIN VFR AT OR ABOVE 4500 FT, WE COMPLIED BUT THE AREA WE WERE IN WAS NOT GOING TO PERMIT THAT FOREVER WHICH IS WHY WE REQUESTED 3500 FT. IN THE FUTURE I WILL NOT BEGIN MY DSCNT IN THIS KIND OF SIT UNTIL APCH CAN APPROVE DSCNT TO BELOW THE BASES IN ONE SHOT. BY DSNDING TO 4500 FT, I WAS BELOW THE TOPS AND ABOVE THE BASES IN AN AREA THAT WAS NOT GOING TO LAST FOREVER AND COULD HAVE BEEN IN A SIT EVENTUALLY OF ASKING FOR EMER IFR HANDLING. WE DID NOT GET CLOSE TO THAT BECAUSE AUSTIN WAS ABLE TO APPROVE OUR REQUESTS, BUT HAD THAT NOT BEEN THE CASE, WE WOULD NOT HAVE BEEN IN A GREAT PLACE.

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.