Narrative:

I was the sole occupant of a low wing aircraft (X). I had returned to boi, my home base after a short cross country flight. When I was handed off to the tower, I requested multiple touch and goes, which was approved. On my second approach, I was advised that I would be #2, following an arrow (Y). As I was approximately abeam the approach end of runway 10R on a right downwind, I observed a low wing aircraft on what appeared to be an approach. I extended my downwind and continued to watch that aircraft as it descended on the approach. I had also heard other traffic being cleared to land on runway 10L and wanted to be certain that the aircraft I was watching was headed for runway 10R. As I continued downwind, it appeared that the aircraft I was watching landed on runway 10R, at which time I advised the tower that I had the landing aircraft in sight. I was cleared to turn base at my discretion, which I did almost immediately. I was also cleared to land on runway 10R. Shortly after I turned on final, the tower advised me to hold my altitude, which was approximately 3800 ft MSL at the time. I acknowledged and maintained altitude. The tower then advised another aircraft to turn 20 degrees left for final to runway 10L. I looked out and down from my left window and observed a t-tailed low wing aircraft (Z) banking to the left below and slightly behind me. I estimated the aircraft was about 300 ft below me and only slightly behind. I was then cleared to descend for landing. As I was descending, the tower called a cherokee (Y), which had performed a touch and go behind me on my first landing. I had previously heard the tower tell that aircraft to extend his downwind. The tower called the cherokee and asked if he had turned base, which he acknowledged. The tower then told the cherokee to turn to a south heading and continue downwind. I looked to my right and saw the cherokee turning away from me at a distance which I estimated to be 700-800 ft and at approximately the same altitude. I then continued to a touch and go landing. After completing a third landing, I parked my airplane. Although I had not been asked to call the tower, after thinking about the situation, I decided to call to find out what had happened. The tower supervisor advised me that he was only aware of the second situation. Apparently, the cherokee had not acknowledged the first instruction to continue downwind, and had instead turned base. The supervisor explained that the controller on duty was relatively new, and was not used to working heavy traffic. He apologized for the incident and stated that they (the tower) should have been providing better service. I told him my intent was just to find out what had happened and to make sure I had not done something wrong. He told me that it did not appear that I had done anything wrong, but rather it was an error in the tower. He stated that he would look into the first incident, which he was not familiar with, and call me back within 10 mins if he needed any more information from me or had any concerns. He also stated that he would not call unless there was a need to do so. I never heard back from him. My perception was that the first incident may have been caused by a pilot who overshot the approach path to runway 10L. That perception is based on radio traffic which indicated to that pilot to turn back to the approach for runway 10L, rather than having one of us break off the approach to runway 10R.

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Original NASA ASRS Text

Title: PLT OF GA ACFT EXPERIENCES TWO CLOSE ENCOUNTERS IN THE CIRCUIT AT BOI.

Narrative: I WAS THE SOLE OCCUPANT OF A LOW WING ACFT (X). I HAD RETURNED TO BOI, MY HOME BASE AFTER A SHORT XCOUNTRY FLT. WHEN I WAS HANDED OFF TO THE TWR, I REQUESTED MULTIPLE TOUCH AND GOES, WHICH WAS APPROVED. ON MY SECOND APCH, I WAS ADVISED THAT I WOULD BE #2, FOLLOWING AN ARROW (Y). AS I WAS APPROX ABEAM THE APCH END OF RWY 10R ON A R DOWNWIND, I OBSERVED A LOW WING ACFT ON WHAT APPEARED TO BE AN APCH. I EXTENDED MY DOWNWIND AND CONTINUED TO WATCH THAT ACFT AS IT DSNDED ON THE APCH. I HAD ALSO HEARD OTHER TFC BEING CLRED TO LAND ON RWY 10L AND WANTED TO BE CERTAIN THAT THE ACFT I WAS WATCHING WAS HEADED FOR RWY 10R. AS I CONTINUED DOWNWIND, IT APPEARED THAT THE ACFT I WAS WATCHING LANDED ON RWY 10R, AT WHICH TIME I ADVISED THE TWR THAT I HAD THE LNDG ACFT IN SIGHT. I WAS CLRED TO TURN BASE AT MY DISCRETION, WHICH I DID ALMOST IMMEDIATELY. I WAS ALSO CLRED TO LAND ON RWY 10R. SHORTLY AFTER I TURNED ON FINAL, THE TWR ADVISED ME TO HOLD MY ALT, WHICH WAS APPROX 3800 FT MSL AT THE TIME. I ACKNOWLEDGED AND MAINTAINED ALT. THE TWR THEN ADVISED ANOTHER ACFT TO TURN 20 DEGS L FOR FINAL TO RWY 10L. I LOOKED OUT AND DOWN FROM MY L WINDOW AND OBSERVED A T-TAILED LOW WING ACFT (Z) BANKING TO THE L BELOW AND SLIGHTLY BEHIND ME. I ESTIMATED THE ACFT WAS ABOUT 300 FT BELOW ME AND ONLY SLIGHTLY BEHIND. I WAS THEN CLRED TO DSND FOR LNDG. AS I WAS DSNDING, THE TWR CALLED A CHEROKEE (Y), WHICH HAD PERFORMED A TOUCH AND GO BEHIND ME ON MY FIRST LNDG. I HAD PREVIOUSLY HEARD THE TWR TELL THAT ACFT TO EXTEND HIS DOWNWIND. THE TWR CALLED THE CHEROKEE AND ASKED IF HE HAD TURNED BASE, WHICH HE ACKNOWLEDGED. THE TWR THEN TOLD THE CHEROKEE TO TURN TO A S HEADING AND CONTINUE DOWNWIND. I LOOKED TO MY R AND SAW THE CHEROKEE TURNING AWAY FROM ME AT A DISTANCE WHICH I ESTIMATED TO BE 700-800 FT AND AT APPROX THE SAME ALT. I THEN CONTINUED TO A TOUCH AND GO LNDG. AFTER COMPLETING A THIRD LNDG, I PARKED MY AIRPLANE. ALTHOUGH I HAD NOT BEEN ASKED TO CALL THE TWR, AFTER THINKING ABOUT THE SIT, I DECIDED TO CALL TO FIND OUT WHAT HAD HAPPENED. THE TWR SUPVR ADVISED ME THAT HE WAS ONLY AWARE OF THE SECOND SIT. APPARENTLY, THE CHEROKEE HAD NOT ACKNOWLEDGED THE FIRST INSTRUCTION TO CONTINUE DOWNWIND, AND HAD INSTEAD TURNED BASE. THE SUPVR EXPLAINED THAT THE CTLR ON DUTY WAS RELATIVELY NEW, AND WAS NOT USED TO WORKING HVY TFC. HE APOLOGIZED FOR THE INCIDENT AND STATED THAT THEY (THE TWR) SHOULD HAVE BEEN PROVIDING BETTER SVC. I TOLD HIM MY INTENT WAS JUST TO FIND OUT WHAT HAD HAPPENED AND TO MAKE SURE I HAD NOT DONE SOMETHING WRONG. HE TOLD ME THAT IT DID NOT APPEAR THAT I HAD DONE ANYTHING WRONG, BUT RATHER IT WAS AN ERROR IN THE TWR. HE STATED THAT HE WOULD LOOK INTO THE FIRST INCIDENT, WHICH HE WAS NOT FAMILIAR WITH, AND CALL ME BACK WITHIN 10 MINS IF HE NEEDED ANY MORE INFO FROM ME OR HAD ANY CONCERNS. HE ALSO STATED THAT HE WOULD NOT CALL UNLESS THERE WAS A NEED TO DO SO. I NEVER HEARD BACK FROM HIM. MY PERCEPTION WAS THAT THE FIRST INCIDENT MAY HAVE BEEN CAUSED BY A PLT WHO OVERSHOT THE APCH PATH TO RWY 10L. THAT PERCEPTION IS BASED ON RADIO TFC WHICH INDICATED TO THAT PLT TO TURN BACK TO THE APCH FOR RWY 10L, RATHER THAN HAVING ONE OF US BREAK OFF THE APCH TO RWY 10R.

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.