Narrative:

Apa is known for being extremely busy with student pilot and training activity. I made contact with apa tower (after receiving ATIS) at a standard visual chkpoint/reference directly east of the field, approximately 8-10 NM out, from an altitude of 7000 ft MSL. The controller was busy and took a while to respond to my request for touch and goes. She told me to proceed at or about 7300 ft MSL to enter mid-field, in anticipation of the ability to join the left downwind leg of the pattern for runway 35L. Just prior to crossing runway 35R at mid-field, I was told that my traffic was a cessna, on the downwind leg of the pattern for runway 35L, and that I should report it in sight. I spotted it on the downwind leg, which appeared to be the position at which it was going to begin the base leg because it was in a slight left bank (that's how I spotted it), and reported it in sight. I was then given clearance to enter the standard left traffic (behind this cessna) on the downwind leg, at pattern altitude of 6800 ft MSL. I did so, all the while trying to keep my eye on the traffic ahead. In performing before landing checklists, I lost track of the cessna and was trying to relocate it when the controller cleared my base and touch and go on runway 35L. As I remained looking for the cessna, I realized I was having a difficult time because of the snow-spotted ground beneath the south end of the airspace. When I was past (south of) abeam the threshold, I saw an aircraft (possibly a twin cessna) just crossing the numbers. I continued downwind and turned base, then final, based on what I had seen the cessna before me (I thought) about to turn base. When I was approaching the threshold, approximately 200 ft AGL, a call was made from the cessna behind me that I immediately saw, then, on my right side (now higher than me). I obviously cut off this cessna, my traffic, and the controller told him to go around. I extended the ground roll of my touch and go to gain some spacing while the other pilot (flight instructor) asked where I came from. The controller said that I had said I had my traffic in sight. She was correct. I assumed my traffic was already ahead of me, and that's all I said during the touch and go when I realized that I had cut off the cessna (student). I maintained spacing and stayed in the pattern for one more touch and go, being controled (now) by a different controller. He instructed us to fly standard left traffic patterns, but the cessna ahead flew downwind so for that the final leg was 1 mi for each of us. This situation has, many times prior, occurred. Apa runs practice ILS approachs on the parallel runway 35R and puts all touch and goes on runway 35L when it is busy. While I should not have made the assumption that I did, I do think that (especially when it is busy) each pilot should be expected to fly a standard pattern, and that the tower should not mix touch and go traffic on runway 35L with transient traffic. These events, combined, led to the near-miss situation along with one that I was the victim of at apa (in a cessna) about 2 yrs ago.

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Original NASA ASRS Text

Title: C172 HAS NMAC WITH ANOTHER CESSNA WHEN SHE FOLLOWS THE WRONG ACFT IN THE TFC PATTERN.

Narrative: APA IS KNOWN FOR BEING EXTREMELY BUSY WITH STUDENT PLT AND TRAINING ACTIVITY. I MADE CONTACT WITH APA TWR (AFTER RECEIVING ATIS) AT A STANDARD VISUAL CHKPOINT/REF DIRECTLY E OF THE FIELD, APPROX 8-10 NM OUT, FROM AN ALT OF 7000 FT MSL. THE CTLR WAS BUSY AND TOOK A WHILE TO RESPOND TO MY REQUEST FOR TOUCH AND GOES. SHE TOLD ME TO PROCEED AT OR ABOUT 7300 FT MSL TO ENTER MID-FIELD, IN ANTICIPATION OF THE ABILITY TO JOIN THE L DOWNWIND LEG OF THE PATTERN FOR RWY 35L. JUST PRIOR TO XING RWY 35R AT MID-FIELD, I WAS TOLD THAT MY TFC WAS A CESSNA, ON THE DOWNWIND LEG OF THE PATTERN FOR RWY 35L, AND THAT I SHOULD RPT IT IN SIGHT. I SPOTTED IT ON THE DOWNWIND LEG, WHICH APPEARED TO BE THE POS AT WHICH IT WAS GOING TO BEGIN THE BASE LEG BECAUSE IT WAS IN A SLIGHT L BANK (THAT'S HOW I SPOTTED IT), AND RPTED IT IN SIGHT. I WAS THEN GIVEN CLRNC TO ENTER THE STANDARD L TFC (BEHIND THIS CESSNA) ON THE DOWNWIND LEG, AT PATTERN ALT OF 6800 FT MSL. I DID SO, ALL THE WHILE TRYING TO KEEP MY EYE ON THE TFC AHEAD. IN PERFORMING BEFORE LNDG CHKLISTS, I LOST TRACK OF THE CESSNA AND WAS TRYING TO RELOCATE IT WHEN THE CTLR CLRED MY BASE AND TOUCH AND GO ON RWY 35L. AS I REMAINED LOOKING FOR THE CESSNA, I REALIZED I WAS HAVING A DIFFICULT TIME BECAUSE OF THE SNOW-SPOTTED GND BENEATH THE S END OF THE AIRSPACE. WHEN I WAS PAST (S OF) ABEAM THE THRESHOLD, I SAW AN ACFT (POSSIBLY A TWIN CESSNA) JUST XING THE NUMBERS. I CONTINUED DOWNWIND AND TURNED BASE, THEN FINAL, BASED ON WHAT I HAD SEEN THE CESSNA BEFORE ME (I THOUGHT) ABOUT TO TURN BASE. WHEN I WAS APCHING THE THRESHOLD, APPROX 200 FT AGL, A CALL WAS MADE FROM THE CESSNA BEHIND ME THAT I IMMEDIATELY SAW, THEN, ON MY R SIDE (NOW HIGHER THAN ME). I OBVIOUSLY CUT OFF THIS CESSNA, MY TFC, AND THE CTLR TOLD HIM TO GAR. I EXTENDED THE GND ROLL OF MY TOUCH AND GO TO GAIN SOME SPACING WHILE THE OTHER PLT (FLT INSTRUCTOR) ASKED WHERE I CAME FROM. THE CTLR SAID THAT I HAD SAID I HAD MY TFC IN SIGHT. SHE WAS CORRECT. I ASSUMED MY TFC WAS ALREADY AHEAD OF ME, AND THAT'S ALL I SAID DURING THE TOUCH AND GO WHEN I REALIZED THAT I HAD CUT OFF THE CESSNA (STUDENT). I MAINTAINED SPACING AND STAYED IN THE PATTERN FOR ONE MORE TOUCH AND GO, BEING CTLED (NOW) BY A DIFFERENT CTLR. HE INSTRUCTED US TO FLY STANDARD L TFC PATTERNS, BUT THE CESSNA AHEAD FLEW DOWNWIND SO FOR THAT THE FINAL LEG WAS 1 MI FOR EACH OF US. THIS SIT HAS, MANY TIMES PRIOR, OCCURRED. APA RUNS PRACTICE ILS APCHS ON THE PARALLEL RWY 35R AND PUTS ALL TOUCH AND GOES ON RWY 35L WHEN IT IS BUSY. WHILE I SHOULD NOT HAVE MADE THE ASSUMPTION THAT I DID, I DO THINK THAT (ESPECIALLY WHEN IT IS BUSY) EACH PLT SHOULD BE EXPECTED TO FLY A STANDARD PATTERN, AND THAT THE TWR SHOULD NOT MIX TOUCH AND GO TFC ON RWY 35L WITH TRANSIENT TFC. THESE EVENTS, COMBINED, LED TO THE NEAR-MISS SIT ALONG WITH ONE THAT I WAS THE VICTIM OF AT APA (IN A CESSNA) ABOUT 2 YRS AGO.

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.