Narrative:

I was flying left closed traffic for runway 29 at slo on sunday in small aircraft X. There was no ceiling, the visibility was 30 mi and there was light turbulence. I had already made 6 lndgs and was on downwind when I saw small aircraft Y pass behind me at my 7 O'clock position within 200' at my altitude (1200' MSL), inbound to the airport at about a 45 degree angle. I had no idea this aircraft would pass so close to me, based on the position reports provided by him. The tower also provided no position reports for this traffic based on the original callup position report from small aircraft Y. This aircraft reported abeam laguna lake just as I was about to turn from a crosswind to downwind. Laguna lake is north of the airport and is a common reporting point when arriving from the north. The tower asked small aircraft Y to report crossing the 101 freeway to enter an extended left downwind for 29. Within seconds after I turned downwind, small aircraft Y reported 'inbound on the 45.' the tower told small aircraft Y he was #2 to follow me. I was almost 45 degrees to the tower at that point, so I increased my scan, beginning to look at my 3 O'clock back to my 5 O'clock. I had no visual contact and was about to report that fact to the tower when I spotted small aircraft Y passing behind me at my 7 O'clock position on a shallow descent. This aircraft continued toward the tower and turned downwind with 1/4 mi from the runway at an altitude of approximately 500'. The tower had no visual contact with small aircraft Y until turning downwind. At this point the tower indicated that I was #2 to follow 'the small aircraft Y on short final.' small aircraft Y's transition from downwind to base to final was nothing more than a 180 degree turn of at least 30 degrees of bank less than 500' AGL. In short, an aircraft came less than 200' of me in the pattern. Based on the angle of the aircraft, I estimate that small aircraft Y came within 100' horizontal and 25' vertical. This aircraft never reported me in sight, even though I must have been clearly visible crossing from left to right. Based on this aircraft's erroneous position report, failure to comply with ATC instructions and dangerous pattern behavior, I believe that the pilot of small aircraft Y was operating his aircraft in a careless and reckless manner. However, there is more to this story. I was tempted to report this incident on the frequency, but decided to discuss it personally with the tower personnel instead. After making 2 more touch and go's, I made a full stop and taxied to the base of the tower. The controllers there recommended that I fill out this form and to contact the tower chief on monday. The air traffic manager told me that there was basically nothing I could do after the fact. The lesson of this story is to announce the near miss on frequency when it happens. Then the tower personnel can talk with both pilots afterward to figure what went wrong, and hopefully keep it from happening again.

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Original NASA ASRS Text

Title: NMAC BETWEEN SMA X AND SMA Y IN TRAFFIC PATTERN AT SLO.

Narrative: I WAS FLYING LEFT CLOSED TFC FOR RWY 29 AT SLO ON SUNDAY IN SMA X. THERE WAS NO CEILING, THE VISIBILITY WAS 30 MI AND THERE WAS LIGHT TURB. I HAD ALREADY MADE 6 LNDGS AND WAS ON DOWNWIND WHEN I SAW SMA Y PASS BEHIND ME AT MY 7 O'CLOCK POS WITHIN 200' AT MY ALT (1200' MSL), INBND TO THE ARPT AT ABOUT A 45 DEG ANGLE. I HAD NO IDEA THIS ACFT WOULD PASS SO CLOSE TO ME, BASED ON THE POS RPTS PROVIDED BY HIM. THE TWR ALSO PROVIDED NO POS RPTS FOR THIS TFC BASED ON THE ORIGINAL CALLUP POS RPT FROM SMA Y. THIS ACFT RPTED ABEAM LAGUNA LAKE JUST AS I WAS ABOUT TO TURN FROM A XWIND TO DOWNWIND. LAGUNA LAKE IS N OF THE ARPT AND IS A COMMON RPTING POINT WHEN ARRIVING FROM THE N. THE TWR ASKED SMA Y TO RPT XING THE 101 FREEWAY TO ENTER AN EXTENDED LEFT DOWNWIND FOR 29. WITHIN SECS AFTER I TURNED DOWNWIND, SMA Y RPTED 'INBND ON THE 45.' THE TWR TOLD SMA Y HE WAS #2 TO FOLLOW ME. I WAS ALMOST 45 DEGS TO THE TWR AT THAT POINT, SO I INCREASED MY SCAN, BEGINNING TO LOOK AT MY 3 O'CLOCK BACK TO MY 5 O'CLOCK. I HAD NO VISUAL CONTACT AND WAS ABOUT TO RPT THAT FACT TO THE TWR WHEN I SPOTTED SMA Y PASSING BEHIND ME AT MY 7 O'CLOCK POS ON A SHALLOW DSNT. THIS ACFT CONTINUED TOWARD THE TWR AND TURNED DOWNWIND WITH 1/4 MI FROM THE RWY AT AN ALT OF APPROX 500'. THE TWR HAD NO VISUAL CONTACT WITH SMA Y UNTIL TURNING DOWNWIND. AT THIS POINT THE TWR INDICATED THAT I WAS #2 TO FOLLOW 'THE SMA Y ON SHORT FINAL.' SMA Y'S TRANSITION FROM DOWNWIND TO BASE TO FINAL WAS NOTHING MORE THAN A 180 DEG TURN OF AT LEAST 30 DEGS OF BANK LESS THAN 500' AGL. IN SHORT, AN ACFT CAME LESS THAN 200' OF ME IN THE PATTERN. BASED ON THE ANGLE OF THE ACFT, I ESTIMATE THAT SMA Y CAME WITHIN 100' HORIZ AND 25' VERT. THIS ACFT NEVER RPTED ME IN SIGHT, EVEN THOUGH I MUST HAVE BEEN CLEARLY VISIBLE XING FROM L TO R. BASED ON THIS ACFT'S ERRONEOUS POS RPT, FAILURE TO COMPLY WITH ATC INSTRUCTIONS AND DANGEROUS PATTERN BEHAVIOR, I BELIEVE THAT THE PLT OF SMA Y WAS OPERATING HIS ACFT IN A CARELESS AND RECKLESS MANNER. HOWEVER, THERE IS MORE TO THIS STORY. I WAS TEMPTED TO RPT THIS INCIDENT ON THE FREQ, BUT DECIDED TO DISCUSS IT PERSONALLY WITH THE TWR PERSONNEL INSTEAD. AFTER MAKING 2 MORE TOUCH AND GO'S, I MADE A FULL STOP AND TAXIED TO THE BASE OF THE TWR. THE CTLRS THERE RECOMMENDED THAT I FILL OUT THIS FORM AND TO CONTACT THE TWR CHIEF ON MONDAY. THE AIR TFC MGR TOLD ME THAT THERE WAS BASICALLY NOTHING I COULD DO AFTER THE FACT. THE LESSON OF THIS STORY IS TO ANNOUNCE THE NEAR MISS ON FREQ WHEN IT HAPPENS. THEN THE TWR PERSONNEL CAN TALK WITH BOTH PLTS AFTERWARD TO FIGURE WHAT WENT WRONG, AND HOPEFULLY KEEP IT FROM HAPPENING AGAIN.

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.