THE PILOT MISSED THE BANNER PICKUP ON THE FIRST PASS. HE STATED THAT AS HE TURNED DOWNWIND IN A 60 DEGREE BANK, HE APPLIED 'HARD LEFT RUDDER' TO CHECK THE GRAPPLE FOR TANGLES AND THE AIRPLANE ENTERED A STALL. WITNESSES STATED THAT THE ANGLE OF BANK WAS 90 DEGREES AND THE ALTITUDE WAS LESS THAN 100 FEET AGL. THEY OBSERVED THE AIRPLANE ROLL BACK WINGS LEVEL, THEN ENTER A RIGHT NOSE DOWN ATTITUDE UNTIL IMPACT. NO EVIDENCE OF PRE-IMPACT ENGINE POWER LOSS WAS FOUND DURING THE INVESTIGATION.