Narrative:

We were flying a photo mission in the roc class C airspace and were heading to the north near the shores of lake ontario. We had been talking with approach and advising them of changes in direction and altitude. I was aware that there were 2 or 3 airliners approaching roc. I was at 4500 ft, but as I turned sbound I needed to descend to maintain VFR. I told approach that I was descending to 4000 ft. I then heard approach tell me there was traffic 11 O'clock less than 1 mi. I thought it was an MD80, but I am not sure. My co-worker spotted traffic at 1 O'clock position, but I looked at 11 O'clock position and saw an air carrier descending in front of me. Approach had told me to descend to 4000 ft and I thought I heard them restrict the air carrier to 4500 ft. Air carrier may have thought the 'descend to 4000 ft' call was for them. They were 300-500 ft from me when I descended to avoid them. Air carrier may have thought they were cleared to descend to 4000 ft. Also from their vantage point, I was under a layer of clouds so it was difficult to see. For my part, I will have more situational awareness of airliners when I am operating in class C airspace.

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Original NASA ASRS Text

Title: C172 PLT ON A PHOTO OP IN CLASS C AIRSPACE HAS NMAC WITH AN MD80 DSNDING IN FRONT OF HIM. APCH CTLR HAD ISSUED TA FOR THE MD80.

Narrative: WE WERE FLYING A PHOTO MISSION IN THE ROC CLASS C AIRSPACE AND WERE HEADING TO THE N NEAR THE SHORES OF LAKE ONTARIO. WE HAD BEEN TALKING WITH APCH AND ADVISING THEM OF CHANGES IN DIRECTION AND ALT. I WAS AWARE THAT THERE WERE 2 OR 3 AIRLINERS APCHING ROC. I WAS AT 4500 FT, BUT AS I TURNED SBOUND I NEEDED TO DSND TO MAINTAIN VFR. I TOLD APCH THAT I WAS DSNDING TO 4000 FT. I THEN HEARD APCH TELL ME THERE WAS TFC 11 O'CLOCK LESS THAN 1 MI. I THOUGHT IT WAS AN MD80, BUT I AM NOT SURE. MY CO-WORKER SPOTTED TFC AT 1 O'CLOCK POS, BUT I LOOKED AT 11 O'CLOCK POS AND SAW AN ACR DSNDING IN FRONT OF ME. APCH HAD TOLD ME TO DSND TO 4000 FT AND I THOUGHT I HEARD THEM RESTRICT THE ACR TO 4500 FT. ACR MAY HAVE THOUGHT THE 'DSND TO 4000 FT' CALL WAS FOR THEM. THEY WERE 300-500 FT FROM ME WHEN I DSNDED TO AVOID THEM. ACR MAY HAVE THOUGHT THEY WERE CLRED TO DSND TO 4000 FT. ALSO FROM THEIR VANTAGE POINT, I WAS UNDER A LAYER OF CLOUDS SO IT WAS DIFFICULT TO SEE. FOR MY PART, I WILL HAVE MORE SITUATIONAL AWARENESS OF AIRLINERS WHEN I AM OPERATING IN CLASS C AIRSPACE.

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.