Narrative:

The flight involved was a 40 min flight between pao and 103. As often is the case in the bay area, overcast had developed overnight and was burning off during the morning hours. 1 hour prior to our scheduled departure, I checked the recorded WX information available at the oakland automated flight service station. Pao, sjs, and hwd were all reporting VFR conditions with ceilings around 1400-1500 ft. As we drove to the airport and preflted, the clouds were clearing over pao and to the south we could see sunshine over sunol pass, which was our intended route of flight. The ceilings were lower from hayward to the north. We departed pao using a standard 'right dumbarton' departure and contacted norcal approach for flight following and to establish 2-WAY radio contact in the event that our flight path took us into the northern corner of the sjc class C airspace. There was some miscom with ATC at this point. Rather than just ask for flight following, I mentioned the clearance through sjc class C. ATC asked if I was going to san jose and I replied, 'no, I was just transitioning south toward sunol pass to avoid the overcast.' ATC then granted clearance into class B airspace, which I neither requested nor needed. (In fact, this was not possible from my location due to the overcast above. The class B floor is 4000 ft in this area.) during this exchange, ATC noted my mode C altitude at 900 ft, and I realized that I had been focused on maintaining cloud clrncs above and had neglected to maintain the required 1000 ft AGL minimum clearance over the city. I confirmed his reading and climbed immediately to correct the situation. In doing so I found I was unable to remain 500 ft below the clouds. I had misjudged the cloud level in this area. Within 2-3 mi, the ceiling lifted, I reached the break in the overcast that I had observed from pao, and I was able to climb above the cloud layer in VFR conditions. At no time was my visibility less than 10 mi, but at some points I was only about 200-300 ft below the clouds. The rest of our flight was uneventful. I am generally a very conservative pilot. Most of my flying involves trips such as this one where I am transporting my family on a pleasure trip. We usually do not fly in rough or marginal WX. Based on 'iffy reports,' I have often cancelled flts and driven our car just to avoid getting into the situation described above. This time I believed that the overcast had cleared enough for us to transition this area safely while maintaining all of the appropriate clrncs. By the time I realized I was wrong, the safest option was to continue on and climb out. I am usually very alert to 'get-there-itis' and avoid that pitfall. However, in this case, I wonder if our plans for the holiday weekend caused me to push my limits beyond what I normally would have, or to misread the conditions prior to departure? In retrospect, I realize that I should have delayed our departure at least another 1/2 hour to 1 hour so that the overcast would not have been an issue. It is also possible that I could have obtained a 'special VFR clearance' for the transition, as VFR under those minimums was easily maintained, but this didn't occur to me since I thought I would be ok anyway.

Related reports:

Google
 

Original NASA ASRS Text

Title: A PA28 PLT WAS UNABLE TO MAINTAIN CLOUD CLRNC DURING A VFR FLT FROM PAO TO 103.

Narrative: THE FLT INVOLVED WAS A 40 MIN FLT BTWN PAO AND 103. AS OFTEN IS THE CASE IN THE BAY AREA, OVCST HAD DEVELOPED OVERNIGHT AND WAS BURNING OFF DURING THE MORNING HRS. 1 HR PRIOR TO OUR SCHEDULED DEP, I CHKED THE RECORDED WX INFO AVAILABLE AT THE OAKLAND AUTOMATED FLT SVC STATION. PAO, SJS, AND HWD WERE ALL RPTING VFR CONDITIONS WITH CEILINGS AROUND 1400-1500 FT. AS WE DROVE TO THE ARPT AND PREFLTED, THE CLOUDS WERE CLRING OVER PAO AND TO THE S WE COULD SEE SUNSHINE OVER SUNOL PASS, WHICH WAS OUR INTENDED RTE OF FLT. THE CEILINGS WERE LOWER FROM HAYWARD TO THE N. WE DEPARTED PAO USING A STANDARD 'R DUMBARTON' DEP AND CONTACTED NORCAL APCH FOR FLT FOLLOWING AND TO ESTABLISH 2-WAY RADIO CONTACT IN THE EVENT THAT OUR FLT PATH TOOK US INTO THE NORTHERN CORNER OF THE SJC CLASS C AIRSPACE. THERE WAS SOME MISCOM WITH ATC AT THIS POINT. RATHER THAN JUST ASK FOR FLT FOLLOWING, I MENTIONED THE CLRNC THROUGH SJC CLASS C. ATC ASKED IF I WAS GOING TO SAN JOSE AND I REPLIED, 'NO, I WAS JUST TRANSITIONING S TOWARD SUNOL PASS TO AVOID THE OVCST.' ATC THEN GRANTED CLRNC INTO CLASS B AIRSPACE, WHICH I NEITHER REQUESTED NOR NEEDED. (IN FACT, THIS WAS NOT POSSIBLE FROM MY LOCATION DUE TO THE OVCST ABOVE. THE CLASS B FLOOR IS 4000 FT IN THIS AREA.) DURING THIS EXCHANGE, ATC NOTED MY MODE C ALT AT 900 FT, AND I REALIZED THAT I HAD BEEN FOCUSED ON MAINTAINING CLOUD CLRNCS ABOVE AND HAD NEGLECTED TO MAINTAIN THE REQUIRED 1000 FT AGL MINIMUM CLRNC OVER THE CITY. I CONFIRMED HIS READING AND CLBED IMMEDIATELY TO CORRECT THE SIT. IN DOING SO I FOUND I WAS UNABLE TO REMAIN 500 FT BELOW THE CLOUDS. I HAD MISJUDGED THE CLOUD LEVEL IN THIS AREA. WITHIN 2-3 MI, THE CEILING LIFTED, I REACHED THE BREAK IN THE OVCST THAT I HAD OBSERVED FROM PAO, AND I WAS ABLE TO CLB ABOVE THE CLOUD LAYER IN VFR CONDITIONS. AT NO TIME WAS MY VISIBILITY LESS THAN 10 MI, BUT AT SOME POINTS I WAS ONLY ABOUT 200-300 FT BELOW THE CLOUDS. THE REST OF OUR FLT WAS UNEVENTFUL. I AM GENERALLY A VERY CONSERVATIVE PLT. MOST OF MY FLYING INVOLVES TRIPS SUCH AS THIS ONE WHERE I AM TRANSPORTING MY FAMILY ON A PLEASURE TRIP. WE USUALLY DO NOT FLY IN ROUGH OR MARGINAL WX. BASED ON 'IFFY RPTS,' I HAVE OFTEN CANCELLED FLTS AND DRIVEN OUR CAR JUST TO AVOID GETTING INTO THE SIT DESCRIBED ABOVE. THIS TIME I BELIEVED THAT THE OVCST HAD CLRED ENOUGH FOR US TO TRANSITION THIS AREA SAFELY WHILE MAINTAINING ALL OF THE APPROPRIATE CLRNCS. BY THE TIME I REALIZED I WAS WRONG, THE SAFEST OPTION WAS TO CONTINUE ON AND CLB OUT. I AM USUALLY VERY ALERT TO 'GET-THERE-ITIS' AND AVOID THAT PITFALL. HOWEVER, IN THIS CASE, I WONDER IF OUR PLANS FOR THE HOLIDAY WEEKEND CAUSED ME TO PUSH MY LIMITS BEYOND WHAT I NORMALLY WOULD HAVE, OR TO MISREAD THE CONDITIONS PRIOR TO DEP? IN RETROSPECT, I REALIZE THAT I SHOULD HAVE DELAYED OUR DEP AT LEAST ANOTHER 1/2 HR TO 1 HR SO THAT THE OVCST WOULD NOT HAVE BEEN AN ISSUE. IT IS ALSO POSSIBLE THAT I COULD HAVE OBTAINED A 'SPECIAL VFR CLRNC' FOR THE TRANSITION, AS VFR UNDER THOSE MINIMUMS WAS EASILY MAINTAINED, BUT THIS DIDN'T OCCUR TO ME SINCE I THOUGHT I WOULD BE OK ANYWAY.

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.