Narrative:

Made initial contact with tower while 6 mi east, told 'enter right downwind runway 7R, report on the 45.' pattern had numerous aircraft doing touch and goes, some obviously students. ATIS (10 min old) reported visibility 3 haze, flight visibility was closer to 1 mi in vicinity of airport. We called on 45, and entered following an small aircraft. After tower request to rock wings for identification, we were sequenced as '#3 for right, follow small aircraft ahead'. Just before turning base (we had extended downwind for spacing) I asked tower if we could change to runway 7L since our terminal was on north side of airport. After 5 second pause, tower said 'small aircraft X roger, change runways, clear to land runway 7L'. I acknowledged 'small aircraft X cleared on the left'. After turning 1 mi final, I could barely see airport (runway threshold). On 3/4 mi final. Spotted aircraft Y, which appeared to be on tight left base to 7L. I waited a few second to verify he wasn't just doing a 360. During that the he descended slightly below us and turned final, oblivious to our presence. By now we were on 1/4 mi final. I called tower with 'tower you've got 2 aircraft short final 7L, small aircraft X going around'. Frequency dead quiet for 5 second, then tower said 'small aircraft X thank you, aircraft Y are you on final for 7L?' aircraft Y replied affirmative, and tower told him to make it a full stop. During this time several more aircraft reported inbound to tower. Situation becoming a zoo and visibility poor. While on our left downwind back to 7L, new authoritative controller's voice came on and began untangling things. His workload extremely high. Landing accomplished without further incident. I believe there were several unsafe situations and contributing factors: 1) tower overly generous in visibility. (They are always reluctant to make field IFR. 2) student/inexperience tower controller let too many aircraft in closed traffic, considering it was a peak arrival hour, visibility poor, and many of the closed traffic pilots were students already at edge of their envelope due to low visibility. 3) supervising tower controller failed to detect the impending conflict when our change to left runway was approved. 4) realizing the controller was losing the situation, I should not have requested the last min runway change, realizing the additional stress on the struggling controller could cause an error. The real error was in not making the visibility report more realistic (maybe visibility 2 mi from ground, flight visibility approximately 1 mi). Under SVFR control, things would be much more orderly. Not mentioned was the high risk of a midair in the air traffic area with this many aircraft and poor visibility.

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Original NASA ASRS Text

Title: CONFLICT AIRBORNE BETWEEN SMA X AND ACFT Y IN ATA.

Narrative: MADE INITIAL CONTACT WITH TWR WHILE 6 MI E, TOLD 'ENTER RIGHT DOWNWIND RWY 7R, REPORT ON THE 45.' PATTERN HAD NUMEROUS ACFT DOING TOUCH AND GOES, SOME OBVIOUSLY STUDENTS. ATIS (10 MIN OLD) REPORTED VISIBILITY 3 HAZE, FLT VISIBILITY WAS CLOSER TO 1 MI IN VICINITY OF ARPT. WE CALLED ON 45, AND ENTERED FOLLOWING AN SMA. AFTER TWR REQUEST TO ROCK WINGS FOR ID, WE WERE SEQUENCED AS '#3 FOR RIGHT, FOLLOW SMA AHEAD'. JUST BEFORE TURNING BASE (WE HAD EXTENDED DOWNWIND FOR SPACING) I ASKED TWR IF WE COULD CHANGE TO RWY 7L SINCE OUR TERMINAL WAS ON N SIDE OF ARPT. AFTER 5 SEC PAUSE, TWR SAID 'SMA X ROGER, CHANGE RWYS, CLEAR TO LAND RWY 7L'. I ACKNOWLEDGED 'SMA X CLRED ON THE LEFT'. AFTER TURNING 1 MI FINAL, I COULD BARELY SEE ARPT (RWY THRESHOLD). ON 3/4 MI FINAL. SPOTTED ACFT Y, WHICH APPEARED TO BE ON TIGHT LEFT BASE TO 7L. I WAITED A FEW SEC TO VERIFY HE WASN'T JUST DOING A 360. DURING THAT THE HE DESCENDED SLIGHTLY BELOW US AND TURNED FINAL, OBLIVIOUS TO OUR PRESENCE. BY NOW WE WERE ON 1/4 MI FINAL. I CALLED TWR WITH 'TWR YOU'VE GOT 2 ACFT SHORT FINAL 7L, SMA X GOING AROUND'. FREQ DEAD QUIET FOR 5 SEC, THEN TWR SAID 'SMA X THANK YOU, ACFT Y ARE YOU ON FINAL FOR 7L?' ACFT Y REPLIED AFFIRMATIVE, AND TWR TOLD HIM TO MAKE IT A FULL STOP. DURING THIS TIME SEVERAL MORE ACFT REPORTED INBND TO TWR. SITUATION BECOMING A ZOO AND VISIBILITY POOR. WHILE ON OUR LEFT DOWNWIND BACK TO 7L, NEW AUTHORITATIVE CTLR'S VOICE CAME ON AND BEGAN UNTANGLING THINGS. HIS WORKLOAD EXTREMELY HIGH. LNDG ACCOMPLISHED WITHOUT FURTHER INCIDENT. I BELIEVE THERE WERE SEVERAL UNSAFE SITUATIONS AND CONTRIBUTING FACTORS: 1) TWR OVERLY GENEROUS IN VISIBILITY. (THEY ARE ALWAYS RELUCTANT TO MAKE FIELD IFR. 2) STUDENT/INEXPERIENCE TWR CTLR LET TOO MANY ACFT IN CLOSED TFC, CONSIDERING IT WAS A PEAK ARR HOUR, VISIBILITY POOR, AND MANY OF THE CLOSED TFC PLTS WERE STUDENTS ALREADY AT EDGE OF THEIR ENVELOPE DUE TO LOW VISIBILITY. 3) SUPERVISING TWR CTLR FAILED TO DETECT THE IMPENDING CONFLICT WHEN OUR CHANGE TO LEFT RWY WAS APPROVED. 4) REALIZING THE CTLR WAS LOSING THE SITUATION, I SHOULD NOT HAVE REQUESTED THE LAST MIN RWY CHANGE, REALIZING THE ADDITIONAL STRESS ON THE STRUGGLING CTLR COULD CAUSE AN ERROR. THE REAL ERROR WAS IN NOT MAKING THE VISIBILITY REPORT MORE REALISTIC (MAYBE VISIBILITY 2 MI FROM GND, FLT VISIBILITY APPROX 1 MI). UNDER SVFR CONTROL, THINGS WOULD BE MUCH MORE ORDERLY. NOT MENTIONED WAS THE HIGH RISK OF A MIDAIR IN THE ATA WITH THIS MANY ACFT AND POOR VISIBILITY.

Data retrieved from NASA's ASRS site as of August 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.