Narrative:

I was with my wife on an IFR flight to pdk airport. I was radar vectored (by atl approach) to the northeast of pdk and told to expect the visual to runway 20L. At approximately 8 mi from the airport, I was told to contact the tower. On my second attempt, the tower acknowledged me and I was told to 'proceed.' shortly thereafter, I was told that I was '#3 for runway 20L.' at that distance, I could not see the runway environment well, so I intercepted the localizer to runway 20L and tracked it inbound. By radio communication, it was obvious that there were multiple planes in the pattern, both runway 20L&right were in use and that the controller was very busy. I was given no further information from the tower (dispatch) about the identify and location of the #1 and #2 aircraft. I assumed that they were in the pattern, left traffic, but I could not see them. Sometime thereafter, I saw a plane on short final for runway 20L. I assumed that it was the '#2 plane' and that the '#1 plane' had landed. In short order, I began to worry about assumption. At the point that I was about to query the tower, (at less than 1 mi final, 800 ft AGL) a C152 turned into my flight path from a left base to final approach. We were so close that I could see the rivets on his fuselage. This necessitated a hard right descending bank that put me (it seemed rather quickly) into the approach course for runway 20R. Once I was sufficiently below and behind him, I shouted 'whoa' into the microphone and made a left turn to the southeast out of the runway 20R course. I then said 'tower, aircraft X.' he asked if I was now behind the C152, to which I responded in the affirmative. He then directed me to do a left 280/360 degree turn and cleared me to land on runway 20L. We landed without incident. I do not believe that I was ever seen by the C152. My evasive maneuver certainly caused a third aircraft on the approach to runway 20R to do a go around. My perception is that I did an inadequate job of visualizing the #1 and #2 aircraft and should have queried the tower earlier about their position. I was lulled by the fact that I was on an IFR flight plan within and then under class B airspace and was radar contact. I realize that it is the pilot's responsibility to see and avoid other aircraft while IFR in a VFR environment. It is also incredible to me that this could be allowed to happen in a radar environment and I feel that the aircraft spacing was obviously inadequate.

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Original NASA ASRS Text

Title: C182 ON VISUAL APCH TO PDK EXPERIENCED NMAC WITH TFC TURNING FINAL AHEAD AT APPROX 800 FT.

Narrative: I WAS WITH MY WIFE ON AN IFR FLT TO PDK ARPT. I WAS RADAR VECTORED (BY ATL APCH) TO THE NE OF PDK AND TOLD TO EXPECT THE VISUAL TO RWY 20L. AT APPROX 8 MI FROM THE ARPT, I WAS TOLD TO CONTACT THE TWR. ON MY SECOND ATTEMPT, THE TWR ACKNOWLEDGED ME AND I WAS TOLD TO 'PROCEED.' SHORTLY THEREAFTER, I WAS TOLD THAT I WAS '#3 FOR RWY 20L.' AT THAT DISTANCE, I COULD NOT SEE THE RWY ENVIRONMENT WELL, SO I INTERCEPTED THE LOC TO RWY 20L AND TRACKED IT INBOUND. BY RADIO COM, IT WAS OBVIOUS THAT THERE WERE MULTIPLE PLANES IN THE PATTERN, BOTH RWY 20L&R WERE IN USE AND THAT THE CTLR WAS VERY BUSY. I WAS GIVEN NO FURTHER INFO FROM THE TWR (DISPATCH) ABOUT THE IDENT AND LOCATION OF THE #1 AND #2 ACFT. I ASSUMED THAT THEY WERE IN THE PATTERN, L TFC, BUT I COULD NOT SEE THEM. SOMETIME THEREAFTER, I SAW A PLANE ON SHORT FINAL FOR RWY 20L. I ASSUMED THAT IT WAS THE '#2 PLANE' AND THAT THE '#1 PLANE' HAD LANDED. IN SHORT ORDER, I BEGAN TO WORRY ABOUT ASSUMPTION. AT THE POINT THAT I WAS ABOUT TO QUERY THE TWR, (AT LESS THAN 1 MI FINAL, 800 FT AGL) A C152 TURNED INTO MY FLT PATH FROM A L BASE TO FINAL APCH. WE WERE SO CLOSE THAT I COULD SEE THE RIVETS ON HIS FUSELAGE. THIS NECESSITATED A HARD R DSNDING BANK THAT PUT ME (IT SEEMED RATHER QUICKLY) INTO THE APCH COURSE FOR RWY 20R. ONCE I WAS SUFFICIENTLY BELOW AND BEHIND HIM, I SHOUTED 'WHOA' INTO THE MIKE AND MADE A L TURN TO THE SE OUT OF THE RWY 20R COURSE. I THEN SAID 'TWR, ACFT X.' HE ASKED IF I WAS NOW BEHIND THE C152, TO WHICH I RESPONDED IN THE AFFIRMATIVE. HE THEN DIRECTED ME TO DO A L 280/360 DEG TURN AND CLRED ME TO LAND ON RWY 20L. WE LANDED WITHOUT INCIDENT. I DO NOT BELIEVE THAT I WAS EVER SEEN BY THE C152. MY EVASIVE MANEUVER CERTAINLY CAUSED A THIRD ACFT ON THE APCH TO RWY 20R TO DO A GAR. MY PERCEPTION IS THAT I DID AN INADEQUATE JOB OF VISUALIZING THE #1 AND #2 ACFT AND SHOULD HAVE QUERIED THE TWR EARLIER ABOUT THEIR POS. I WAS LULLED BY THE FACT THAT I WAS ON AN IFR FLT PLAN WITHIN AND THEN UNDER CLASS B AIRSPACE AND WAS RADAR CONTACT. I REALIZE THAT IT IS THE PLT'S RESPONSIBILITY TO SEE AND AVOID OTHER ACFT WHILE IFR IN A VFR ENVIRONMENT. IT IS ALSO INCREDIBLE TO ME THAT THIS COULD BE ALLOWED TO HAPPEN IN A RADAR ENVIRONMENT AND I FEEL THAT THE ACFT SPACING WAS OBVIOUSLY INADEQUATE.

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.