Narrative:

We were on a photo mission needing photos at 5000 ft, 12000 ft, 15000 ft, and FL210. I had filed for an IFR flight clearance to be picked up in the air at the completion of the 15000 ft AGL photos. We were using flight following from sac TRACON and ZOA from the ground up. At 15000 ft, we asked for our clearance to FL210. Center advised us it would be 5+ mins before clearance would be available. I told them I would use the time to climb closer to FL180. The controller said to maintain VFR conditions. The airplane climbed better than I thought it would and I misread the altimeter as we were reaching 16900 ft. Moments later, I realized it was actually reading 17950 ft, at which time the controller asked our altitude. I told them FL180, as I pushed over to get down to 17500 ft. A few mins later, they gave us a clearance to FL210 for our photo work. Misreading of the altimeter could have been caused by many factors. The altimeter, though it is an approved type, is difficult to read. It is a single hand type with a mechanical odometer number display for the thousands of ft readout. It also is in a poor location, lower left corner of the pilot's panel where lighting conditions can sometimes blank it out. This is an older model cessna T206 which I just recently started flying 25 hours to date. Though I am well experience with the use of supplemental oxygen and operation at altitudes like this, it was the first time for many yrs. Over the yrs, you forget how stressful this type of flying is. Recent experience is so important, but for high altitude operations you don't do it unless there is a need. This flight provided my recurrency training in the high altitude operation of a light airplane. Callback conversation with reporter revealed the following information: reporter stated that the main reason for his mistake was the difficulty in reading the altimeter, as the one altimeter hand was covering the altimeter setting window and the sun was in his eyes. In addition, he was not used to the high altitude environment.

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Original NASA ASRS Text

Title: PLT OF A CESSNA T206 PHOTO SHOOT ENTERED CLASS B AIRSPACE DUE TO NOT HAVING SET THE COMMON ALTIMETER SETTING FOR FL180 AND ABOVE.

Narrative: WE WERE ON A PHOTO MISSION NEEDING PHOTOS AT 5000 FT, 12000 FT, 15000 FT, AND FL210. I HAD FILED FOR AN IFR FLT CLRNC TO BE PICKED UP IN THE AIR AT THE COMPLETION OF THE 15000 FT AGL PHOTOS. WE WERE USING FLT FOLLOWING FROM SAC TRACON AND ZOA FROM THE GND UP. AT 15000 FT, WE ASKED FOR OUR CLRNC TO FL210. CTR ADVISED US IT WOULD BE 5+ MINS BEFORE CLRNC WOULD BE AVAILABLE. I TOLD THEM I WOULD USE THE TIME TO CLB CLOSER TO FL180. THE CTLR SAID TO MAINTAIN VFR CONDITIONS. THE AIRPLANE CLBED BETTER THAN I THOUGHT IT WOULD AND I MISREAD THE ALTIMETER AS WE WERE REACHING 16900 FT. MOMENTS LATER, I REALIZED IT WAS ACTUALLY READING 17950 FT, AT WHICH TIME THE CTLR ASKED OUR ALT. I TOLD THEM FL180, AS I PUSHED OVER TO GET DOWN TO 17500 FT. A FEW MINS LATER, THEY GAVE US A CLRNC TO FL210 FOR OUR PHOTO WORK. MISREADING OF THE ALTIMETER COULD HAVE BEEN CAUSED BY MANY FACTORS. THE ALTIMETER, THOUGH IT IS AN APPROVED TYPE, IS DIFFICULT TO READ. IT IS A SINGLE HAND TYPE WITH A MECHANICAL ODOMETER NUMBER DISPLAY FOR THE THOUSANDS OF FT READOUT. IT ALSO IS IN A POOR LOCATION, LOWER L CORNER OF THE PLT'S PANEL WHERE LIGHTING CONDITIONS CAN SOMETIMES BLANK IT OUT. THIS IS AN OLDER MODEL CESSNA T206 WHICH I JUST RECENTLY STARTED FLYING 25 HRS TO DATE. THOUGH I AM WELL EXPERIENCE WITH THE USE OF SUPPLEMENTAL OXYGEN AND OP AT ALTS LIKE THIS, IT WAS THE FIRST TIME FOR MANY YRS. OVER THE YRS, YOU FORGET HOW STRESSFUL THIS TYPE OF FLYING IS. RECENT EXPERIENCE IS SO IMPORTANT, BUT FOR HIGH ALT OPS YOU DON'T DO IT UNLESS THERE IS A NEED. THIS FLT PROVIDED MY RECURRENCY TRAINING IN THE HIGH ALT OP OF A LIGHT AIRPLANE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE MAIN REASON FOR HIS MISTAKE WAS THE DIFFICULTY IN READING THE ALTIMETER, AS THE ONE ALTIMETER HAND WAS COVERING THE ALTIMETER SETTING WINDOW AND THE SUN WAS IN HIS EYES. IN ADDITION, HE WAS NOT USED TO THE HIGH ALT ENVIRONMENT.

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.