Narrative:

Left latrobe, PA, for a VFR flight at 17500 ft to miv, nj. Return trip climbed to 17500 ft, leveled off. Landed at miv and was instructed to call ZNY. Talked to center and they advised us we showed altitude of FL195. We advised them we were at 17500 ft VFR and would have our encoder checked as soon as practical. We were told that they vectored some traffic around us because we showed FL195. We saw the traffic above us about 3000 ft and turned left of their course as a courtesy with lights on. They passed us at about 3 or 4 mi to our right above us, about 3000 ft to 2000 ft. There was no conflict to us of any kind. ZNY had seen us showing on radar as an encoded altitude of FL195. We assured them we were level at 17500 ft on both of our altimeters. We advised them we would have our transponder encoder checked. In the future, I plan to always get advisories from center when flying above 15000 ft at VFR.

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Original NASA ASRS Text

Title: AFTER LNDG, BE60 PLT IS ASKED TO CALL TO CONFIRM ALT IN PCA. MODE C SHOWED FL195 AT ZNY. CTL ACTIONS REQUIRED TO VECTOR AROUND, WHAT TURNED OUT TO BE AN UNVERIFIED MODE C ERROR.

Narrative: LEFT LATROBE, PA, FOR A VFR FLT AT 17500 FT TO MIV, NJ. RETURN TRIP CLBED TO 17500 FT, LEVELED OFF. LANDED AT MIV AND WAS INSTRUCTED TO CALL ZNY. TALKED TO CTR AND THEY ADVISED US WE SHOWED ALT OF FL195. WE ADVISED THEM WE WERE AT 17500 FT VFR AND WOULD HAVE OUR ENCODER CHKED AS SOON AS PRACTICAL. WE WERE TOLD THAT THEY VECTORED SOME TFC AROUND US BECAUSE WE SHOWED FL195. WE SAW THE TFC ABOVE US ABOUT 3000 FT AND TURNED L OF THEIR COURSE AS A COURTESY WITH LIGHTS ON. THEY PASSED US AT ABOUT 3 OR 4 MI TO OUR R ABOVE US, ABOUT 3000 FT TO 2000 FT. THERE WAS NO CONFLICT TO US OF ANY KIND. ZNY HAD SEEN US SHOWING ON RADAR AS AN ENCODED ALT OF FL195. WE ASSURED THEM WE WERE LEVEL AT 17500 FT ON BOTH OF OUR ALTIMETERS. WE ADVISED THEM WE WOULD HAVE OUR XPONDER ENCODER CHKED. IN THE FUTURE, I PLAN TO ALWAYS GET ADVISORIES FROM CTR WHEN FLYING ABOVE 15000 FT AT VFR.

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.