NMAC.

Narrative

PICKED UP BANNER FROM WINDSOR ARPT. ON CLBOUT; NOTICED VERY SLUGGISH PERFORMANCE. CLB WAS 100 FPM OR LESS AND EXPERIENCED SEVERAL SETTLING SESSIONS AS IF A VERY LONG BANNER WAS BEING TOWED. AFTER DEBATING RELEASING THE BANNER; WAS ABLE TO WORK ALT UP TO 600 FT AGL. HEADED FOR STADIUM AREA EXPERIENCED SUBSTANTIAL (150-200 FT) LOSS OF ALT OVER RIVER AND INITIATED A GRADUAL TURN TO RETURN TO WINDSOR ARPT. 2/3 OF WAY THROUGH TURN I OBSERVED A HELI PASS TO MY R ABOUT 200 FT BELOW ME AND 200 FT AWAY. THIS DID NOT ALARM ME BECAUSE; IN TOWING BANNERS AROUND STADIUMS; WE FLY IN CLOSE PROX TO OTHER ACFT. ABOUT 1 MIN AFTERWARDS; I HAD INFORMED WINDSOR THAT I WAS RETURNING AND IMMEDIATELY THE HELI CONTACTED THE TWR AND TOLD THEM THAT WE HAD NEARLY COLLIDED. THE PLT OF THE HELI WAS VERY RUDE IN HIS RADIO MANNERS. HE HAD ALLEGED I HAD TRIED TO RUN HIM OVER. AT THE TIME; A BLIND; WOUNDED BIRD WOULD HAVE BEEN ABLE TO GET AWAY FROM ME DUE TO LACK OF PERFORMANCE OF THE ACFT. I HAVE TOWED MANY BANNERS LONGER THAN THE ONE INVOLVED ON WARMER DAYS; AND NEVER HAD ANY PROB. THIS BANNER WAS RETURNED; RELEASED AND 2 SMALLER BANNERS SUCCESSFULLY TOWED. LATER IN THE DAY; ANOTHER BANNER NEARLY THE SAME LENGTH WAS ATTEMPTED WITH THE SAME RESULTS; EXCEPT THAT I DID NOT VENTURE OUT OF THE IMMEDIATE ARPT AREA. ACFT WILL BE INSPECTED TO DETERMINE REASON(S) FOR LACK OF PERFORMANCE.