Narrative:

I was on a VFR flight plan from tus to prc with a flight plan altitude of 10580 ft. I was under FAA ATC for the entire flight. First tus tower, then tus approach on 125.1. They terminated by radar service 45 NM northwest of tus. I then went directly to ZAB on 125.4, and was provided radar service. 30 NM southeast of phx, they handed me off to phx TRACON. At the time of the incident, I was on my second phx TRACON frequency (119.2) and approximately 20 northwest of phx. I was at 10500 ft MSL, on a current phx altimeter issued by the controller, and verified by phx ATIS. My DFGS also showed I was at 10500 ft as did my mode C, based on the controller issuing me as traffic to other aircraft. Additionally, an air carrier jet, restr to 10000 ft during his climb, passed below me and my eye balls confirmed he was, in fact, 500 ft below me. A few mins after that, an air carrier B757 was issued traffic as 'a cessna, nwbound, at 10500 ft and restr to 10000 ft on his climb.' I knew that was referring to me, so I searched for the traffic. I located the B757 at my 8 O'clock position and he appeared to be at 10000 ft in a slight right turn. When I returned my scan (10 or 15 seconds later) to his position, he appeared to be in a climbing right turn in my 9 O'clock position at 1 1/2 mi. At this point he appeared to be above 10000 ft and coming directly at me. At the time, I had a ground speed of 108 KTS, with a true airspeed of 116 KTS. The B757 appeared to be traveling at approximately 250 KTS. To avoid overreacting, I continued to observe the B757. At a point when he appeared to be less than 1/2 mi and still pointed directly at me, I pulled back at 2 1/2 'G' climb. At approximately 11000 ft, at 50 KIAS, the aircraft shuddered on the edge of a power-on stall and I let it fall off on the left wing and recovered. As I did, I saw the B757 pass directly below at what appeared to be at least 10500 ft. The B757 pilot had a TCASII RA and told the controller he went to 9700 ft. A TRACON supervisor reviewed both the radar and voice tapes and said they had no mode C hits on the B757 above 10000 ft. I have lots of experience in the vicinity of large air carrier aircraft and I pride myself on the ability to judge the position and altitude of other aircraft. I also have 37 yrs of air traffic experience. I find it very hard to believe this aircraft did not climb above his assigned altitude.

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Original NASA ASRS Text

Title: A C150 PLT RPTED AN NMAC WITH A B757 20 NM NW OF PHX.

Narrative: I WAS ON A VFR FLT PLAN FROM TUS TO PRC WITH A FLT PLAN ALT OF 10580 FT. I WAS UNDER FAA ATC FOR THE ENTIRE FLT. FIRST TUS TWR, THEN TUS APCH ON 125.1. THEY TERMINATED BY RADAR SVC 45 NM NW OF TUS. I THEN WENT DIRECTLY TO ZAB ON 125.4, AND WAS PROVIDED RADAR SVC. 30 NM SE OF PHX, THEY HANDED ME OFF TO PHX TRACON. AT THE TIME OF THE INCIDENT, I WAS ON MY SECOND PHX TRACON FREQ (119.2) AND APPROX 20 NW OF PHX. I WAS AT 10500 FT MSL, ON A CURRENT PHX ALTIMETER ISSUED BY THE CTLR, AND VERIFIED BY PHX ATIS. MY DFGS ALSO SHOWED I WAS AT 10500 FT AS DID MY MODE C, BASED ON THE CTLR ISSUING ME AS TFC TO OTHER ACFT. ADDITIONALLY, AN ACR JET, RESTR TO 10000 FT DURING HIS CLB, PASSED BELOW ME AND MY EYE BALLS CONFIRMED HE WAS, IN FACT, 500 FT BELOW ME. A FEW MINS AFTER THAT, AN ACR B757 WAS ISSUED TFC AS 'A CESSNA, NWBOUND, AT 10500 FT AND RESTR TO 10000 FT ON HIS CLB.' I KNEW THAT WAS REFERRING TO ME, SO I SEARCHED FOR THE TFC. I LOCATED THE B757 AT MY 8 O'CLOCK POS AND HE APPEARED TO BE AT 10000 FT IN A SLIGHT R TURN. WHEN I RETURNED MY SCAN (10 OR 15 SECONDS LATER) TO HIS POS, HE APPEARED TO BE IN A CLBING R TURN IN MY 9 O'CLOCK POS AT 1 1/2 MI. AT THIS POINT HE APPEARED TO BE ABOVE 10000 FT AND COMING DIRECTLY AT ME. AT THE TIME, I HAD A GND SPD OF 108 KTS, WITH A TRUE AIRSPD OF 116 KTS. THE B757 APPEARED TO BE TRAVELING AT APPROX 250 KTS. TO AVOID OVERREACTING, I CONTINUED TO OBSERVE THE B757. AT A POINT WHEN HE APPEARED TO BE LESS THAN 1/2 MI AND STILL POINTED DIRECTLY AT ME, I PULLED BACK AT 2 1/2 'G' CLB. AT APPROX 11000 FT, AT 50 KIAS, THE ACFT SHUDDERED ON THE EDGE OF A PWR-ON STALL AND I LET IT FALL OFF ON THE L WING AND RECOVERED. AS I DID, I SAW THE B757 PASS DIRECTLY BELOW AT WHAT APPEARED TO BE AT LEAST 10500 FT. THE B757 PLT HAD A TCASII RA AND TOLD THE CTLR HE WENT TO 9700 FT. A TRACON SUPVR REVIEWED BOTH THE RADAR AND VOICE TAPES AND SAID THEY HAD NO MODE C HITS ON THE B757 ABOVE 10000 FT. I HAVE LOTS OF EXPERIENCE IN THE VICINITY OF LARGE ACR ACFT AND I PRIDE MYSELF ON THE ABILITY TO JUDGE THE POS AND ALT OF OTHER ACFT. I ALSO HAVE 37 YRS OF AIR TFC EXPERIENCE. I FIND IT VERY HARD TO BELIEVE THIS ACFT DID NOT CLB ABOVE HIS ASSIGNED ALT.

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.