Narrative:

I was working local control/ground control combined. The WX was VFR with scattered cumulo nimbus clouds. Runway 34 was in use. Aircraft X, a carj on a visual approach, was on left downwind. Approach control had positioned aircraft X on a close downwind approximately 2 mi west of the airport to assist the pilot in seeing the airport. I had cleared aircraft X to land. Aircraft Y, an AC69, was southeast, inbound for a visual approach, being vectored by approach control to follow aircraft X. Aircraft X was at approximately 4600 ft (field elevation 2165 ft) passing the airport, and continued sbound on downwind. When the aircraft was about 2 mi south, I encouraged a turn to base leg as soon as feasible, because approach control had traffic on right base to follow them. Aircraft X began a turn to base, and I projected that the aircraft would join final near the ennka OM. Approach control had turned aircraft Y, now about 6 mi southeast, southward to follow aircraft X. Aircraft X made a wide turn to base leg, and as I watched the rate of turn, I began to realize that the aircraft would fly across the final. They did in fact cross final 4-5 mi from the end of the runway. I issued traffic to aircraft X on aircraft Y. The aircraft X crew advised that they had seen the traffic on TCASII and added that they had been vectored too close to the airport to make that kind of turn. Aircraft X continued to 1 1/2 - 2 mi east of final, passing approximately 800 ft below and 1 mi north of aircraft Y. Aircraft Y saw aircraft X and followed the carj on a visual approach, extending approximately 2 mi west of final to space himself behind the carj. I believe the carj made an excessively wide turn to final, contributing to this situation. I should have anticipated the situation and advised aircraft X of the traffic on right base following him, and cautioned him to not fly through the final.

Related reports:

Google
 

Original NASA ASRS Text

Title: 2 IFR ACFT MAKING VISUAL APCHS TO AVL ARPT. IT'S NOT INDICATED, BUT THE VISIBILITY MAY HAVE BEEN A PROB. ACFT X WAS VECTORED A CLOSE DOWNWIND AND RELEASED TO THE TWR. ACFT Y WAS VECTORED ALMOST STRAIGHT-IN AND TURNED OVER TO THE TWR ABOUT 6 MI OUT.

Narrative: I WAS WORKING LCL CTL/GND CTL COMBINED. THE WX WAS VFR WITH SCATTERED CUMULO NIMBUS CLOUDS. RWY 34 WAS IN USE. ACFT X, A CARJ ON A VISUAL APCH, WAS ON L DOWNWIND. APCH CTL HAD POSITIONED ACFT X ON A CLOSE DOWNWIND APPROX 2 MI W OF THE ARPT TO ASSIST THE PLT IN SEEING THE ARPT. I HAD CLRED ACFT X TO LAND. ACFT Y, AN AC69, WAS SE, INBOUND FOR A VISUAL APCH, BEING VECTORED BY APCH CTL TO FOLLOW ACFT X. ACFT X WAS AT APPROX 4600 FT (FIELD ELEVATION 2165 FT) PASSING THE ARPT, AND CONTINUED SBOUND ON DOWNWIND. WHEN THE ACFT WAS ABOUT 2 MI S, I ENCOURAGED A TURN TO BASE LEG AS SOON AS FEASIBLE, BECAUSE APCH CTL HAD TFC ON R BASE TO FOLLOW THEM. ACFT X BEGAN A TURN TO BASE, AND I PROJECTED THAT THE ACFT WOULD JOIN FINAL NEAR THE ENNKA OM. APCH CTL HAD TURNED ACFT Y, NOW ABOUT 6 MI SE, SOUTHWARD TO FOLLOW ACFT X. ACFT X MADE A WIDE TURN TO BASE LEG, AND AS I WATCHED THE RATE OF TURN, I BEGAN TO REALIZE THAT THE ACFT WOULD FLY ACROSS THE FINAL. THEY DID IN FACT CROSS FINAL 4-5 MI FROM THE END OF THE RWY. I ISSUED TFC TO ACFT X ON ACFT Y. THE ACFT X CREW ADVISED THAT THEY HAD SEEN THE TFC ON TCASII AND ADDED THAT THEY HAD BEEN VECTORED TOO CLOSE TO THE ARPT TO MAKE THAT KIND OF TURN. ACFT X CONTINUED TO 1 1/2 - 2 MI E OF FINAL, PASSING APPROX 800 FT BELOW AND 1 MI N OF ACFT Y. ACFT Y SAW ACFT X AND FOLLOWED THE CARJ ON A VISUAL APCH, EXTENDING APPROX 2 MI W OF FINAL TO SPACE HIMSELF BEHIND THE CARJ. I BELIEVE THE CARJ MADE AN EXCESSIVELY WIDE TURN TO FINAL, CONTRIBUTING TO THIS SIT. I SHOULD HAVE ANTICIPATED THE SIT AND ADVISED ACFT X OF THE TFC ON R BASE FOLLOWING HIM, AND CAUTIONED HIM TO NOT FLY THROUGH THE FINAL.

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.