Narrative:

Plting aircraft X doing pattern work. On climb out after touch-and-go, I heard another aircraft (Y) calling 1.5 mi final. I turned crosswind, then downwind, announcing my location at all times. On downwind, opposite landing end of runway 15, before starting descent, I saw an aircraft low and on approximately 1/4 mi final. So I assumed this was the aircraft who previously had advised a 1.5 mi final. I descended and announced base. At approximately 500 ft, started to turn final when I saw another aircraft, already on final and descending towards me. I immediately stopped the turn to final and descended rapidly for approximately 75 ft and exited the pattern to the upwind side. Aircraft Z responded by a go around, after I had called on radio warning of danger. Pilot of aircraft #2 was a student pilot who advised had announced the 1.5 mi final. Problem arose due to insufficient communication from aircraft #2. I made 3 position calls, while aircraft Z was silent on long final. If aircraft Z had advised still on final, I could have extended downwind leg. Aircraft Z was probably on a 2.5 mi final, possibly due to inexperience of the student pilot, distance was inaccurately estimated, and position not updated. Corrective action: to make it a practice to update position on final, especially when extended final and other traffic in the pattern.

Related reports:

Google
 

Original NASA ASRS Text

Title: A LOW TIME PLT HAD AN NMAC WITH A STUDENT PLT AT IWS.

Narrative: PLTING ACFT X DOING PATTERN WORK. ON CLBOUT AFTER TOUCH-AND-GO, I HEARD ANOTHER ACFT (Y) CALLING 1.5 MI FINAL. I TURNED XWIND, THEN DOWNWIND, ANNOUNCING MY LOCATION AT ALL TIMES. ON DOWNWIND, OPPOSITE LNDG END OF RWY 15, BEFORE STARTING DSCNT, I SAW AN ACFT LOW AND ON APPROX 1/4 MI FINAL. SO I ASSUMED THIS WAS THE ACFT WHO PREVIOUSLY HAD ADVISED A 1.5 MI FINAL. I DSNDED AND ANNOUNCED BASE. AT APPROX 500 FT, STARTED TO TURN FINAL WHEN I SAW ANOTHER ACFT, ALREADY ON FINAL AND DSNDING TOWARDS ME. I IMMEDIATELY STOPPED THE TURN TO FINAL AND DSNDED RAPIDLY FOR APPROX 75 FT AND EXITED THE PATTERN TO THE UPWIND SIDE. ACFT Z RESPONDED BY A GAR, AFTER I HAD CALLED ON RADIO WARNING OF DANGER. PLT OF ACFT #2 WAS A STUDENT PLT WHO ADVISED HAD ANNOUNCED THE 1.5 MI FINAL. PROB AROSE DUE TO INSUFFICIENT COM FROM ACFT #2. I MADE 3 POS CALLS, WHILE ACFT Z WAS SILENT ON LONG FINAL. IF ACFT Z HAD ADVISED STILL ON FINAL, I COULD HAVE EXTENDED DOWNWIND LEG. ACFT Z WAS PROBABLY ON A 2.5 MI FINAL, POSSIBLY DUE TO INEXPERIENCE OF THE STUDENT PLT, DISTANCE WAS INACCURATELY ESTIMATED, AND POS NOT UPDATED. CORRECTIVE ACTION: TO MAKE IT A PRACTICE TO UPDATE POS ON FINAL, ESPECIALLY WHEN EXTENDED FINAL AND OTHER TFC IN THE PATTERN.

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.