NMAC BTWN A SINGLE ENG CESSNA AND A BELLANCA ON L BASE LEG CAUSED BY THE RPTING PLT OF THE CESSNA DOING AN UNAUTH 270 DEG R TURN OFF OF A L BASE TO AVOID A PIPER CUB RPTED BY TWR ON SHORT R BASE LEG.

Narrative

WHILE ON A L BASE APCH TO LAND ON RWY 7; THE TWR ADVISED ME OF OTHER TFC IN THE PATTERN; SPECIFICALLY A PIPER CUB ON 'SHORT R BASE' FOR RWY 7. AT THE TIME I WAS THE FIRST OF THREE IN LINE TO LAND; THE SECOND BEING A FASTER BELLANCA AND THE THIRD I BELIEVE TO BE A CESSNA OF THE SAME TYPE THAT I WAS FLYING; ALL INSTRUCTED TO LAND USING A L BASE APCH TO RWY 7. AS I CONTINUED MY APCH I SCANNED THE AREA NEAR THE THRESHOLD LOOKING FOR THE PIPER AND SEEING ONLY 4 OTHER ACFT ON THE GND AWAITING TO DEPART. AS I DSNDED THROUGH 700 FT MSL I THEN LEVELED OUT AND BEGAN A 270 DEG TURN TO THE R. I DID NOT AT THAT TIME REQUEST PERMISSION NOR INFORM ATC OF MY INTENTIONS. AFTER TURNING 180 DEGS I LEVELED MY WINGS TO CHK FOR TFC AND THE BELLANCA THAT WAS FOLLOWING ME WAS NOW AT MY 2 O'CLOCK POS WITHIN I ESTIMATE TO BE 500 FT. THE TWR THEN INSTRUCTED THE BELLANCA TO PROCEED TO LAND AND INSTRUCTED ME TO FOLLOW; WHICH I DID. AFTER LNDG AND EXITING THE RWY; GND CTL ASKED WHY I DEVIATED FROM MY APCH AND EXECUTED A TURN. I TOLD THEM I DID SO BECAUSE I DID NOT SEE THE PIPER ON SHORT BASE. GND CTL THEN SAID 'THE TWR CTLR SAYS THE PIPER ON SHORT BASE WAS ABOUT 2000 FT DOWN THE RWY MAKING A MID-FIELD APCH. YOU SHOULDN'T HAVE MADE YOUR TURN DUE TO POSSIBLE TFC CONFLICTS.' NOW THESE MAY NOT BE THE EXACT WORDS SPOKEN BY GND CTL; BUT WHAT STICKS OUT IN HIS STATEMENT IS THE FACT THAT THE PIPER WAS '2000 FT DOWN THE RWY MAKING A MID-FIELD APCH.'I THINK THIS IS KEY BECAUSE AT NO TIME DURING MY APCH ON L BASE DID THE TWR INFORM ME OF HIS EXACT POS IN RELATION TO THE RWY. IF THIS HAD BEEN THE CASE I WOULD MOST CERTAINLY HAVE CONTINUED IN TO LAND; ADJUSTING MY SPD DOWN AS NECESSARY TO KEEP FROM OVERRUNNING THE PIPER. IN REFLECTING ON THE EVENTS THAT OCCURRED; SEVERAL THINGS NEED TO BE ADDRESSED. THE FIRST ONE IS INACTION ON MY PART TO FURTHER INQUIRE OF THE EXACT LOCATION OF THE PIPER. IF I HAD CONTINUED MY APCH AND DETERMINED THAT A CONFLICT WITH THE PIPER WOULD OCCUR; SIMPLY FLYING UPWIND WOULD BE AN ACCEPTABLE ALTERNATIVE; RE-ENTERING THE PATTERN ON DOWNWIND. THE OTHER THING I NEGLECTED TO DO WAS INFORM THE TWR OF MY INTENTIONS; REQUEST PERMISSION TO CIRCLE; OR EVEN TO EXTEND MY BASE LEG. AFTER REVIEWING FAR 91.123 (C); I CLRLY DID NOT FULFILL MY RESPONSIBILITY TO INFORM THE TWR OF MY INTENTIONS. I MADE THE DECISION TO CIRCLE BASED ON THE FACTS THAT I KNEW AT THE TIME; AND I DID NOT FEEL COMPELLED TO FLY WHERE I WAS UNABLE TO DETERMINE THE POS OF OTHER ACFT IN THE AREA. AS FAR AS THE BELLANCA IS CONCERNED; I'M SURE THAT HE ADJUSTED HIS FLT PATH IN ORDER TO AVOID ME AS I HAVE IN THE PAST HAD TO DO FOR OTHERS. I THINK THAT IN THIS INSTANCE THE TWR CTLR IS ALSO PARTLY RESPONSIBLE FOR NOT SUPPLYING ME WITH COMPLETE INFO. IF HE HAD SAID THE PIPER WAS MAKING A MID- FIELD APCH INSTEAD OF ONE ON SHORT BASE; I WOULD NOT HAVE HESITATED TO LAND. THE TFC AT THE TIME BOTH IN THE AIR AND ON THE GND WAS VERY BUSY AND THIS COULD HAVE BEEN A FACTOR TO CHOOSE WHAT I CONSIDER TO BE THE INCORRECT VERBIAGE.