Cno local controller issued parallel runway traffic to an aircraft turning base late. The aircraft t...

Narrative:

Traffic in the airspace. Aircraft X south pattern runway 26L. Aircraft Y 4 mile final; VOR approach; south of course for runway 26R. I told aircraft X extend upwind runway 26L to follow an aircraft inbound from the south. [That aircraft] checks in and was given left traffic runway 26L. Aircraft Y checks in on the VOR 4 mile final; 1/2 south of course as that is what VOR takes them to. Sct hands off aircraft Z 6 miles straight in runway 26R with over a 100 knot overtake on aircraft Y. Aircraft Z checks in for runway 26R tell him straight in runway 26R and issue the traffic for aircraft Y ahead on to his left on VOR runway 26R. Tell aircraft Y that he will be following aircraft Z overtaking him off of his right and higher. Aircraft X is left downwind runway 26L. I tell him that he is number 2 to follow the aircraft on a mile final. He acknowledges his clearance. I then issue traffic to aircraft X for aircraft Y who is on a 3 mile final for runway 26R and advise him that aircraft Y is south of course tracking the VOR. Aircraft X responds with looking. Approximately 1 minute later aircraft X responds with that it was close with the VOR traffic and that they had to maneuver to avoid the aircraft.I was distracted with aircraft Y on a 4 mile final with an aircraft with over a 100 knot overtake 2 miles in trail. I was trying to get the conflict resolved between the aircraft Z and aircraft Y in front resolved that I wasn't able to provide the best positive control between the other two aircraft. It would help if when sct hands off aircraft they put the faster aircraft in front instead of just dumping both on the tower to resolve the conflict. Another method would have been to extend the upwind of aircraft X more than I did.

Original NASA ASRS Text

Title: CNO Local Controller issued parallel runway traffic to an aircraft turning base late. The aircraft told the Controller they had to maneuver to avoid the traffic.

Narrative: Traffic in the airspace. Aircraft X south pattern Runway 26L. Aircraft Y 4 mile final; VOR Approach; south of course for Runway 26R. I told Aircraft X extend upwind Runway 26L to follow an aircraft inbound from the south. [That aircraft] checks in and was given left traffic Runway 26L. Aircraft Y checks in on the VOR 4 mile final; 1/2 south of course as that is what VOR takes them to. SCT hands off Aircraft Z 6 miles straight in Runway 26R with over a 100 Knot overtake on Aircraft Y. Aircraft Z checks in for Runway 26R tell him straight in Runway 26R and issue the traffic for Aircraft Y ahead on to his left on VOR Runway 26R. Tell Aircraft Y that he will be following Aircraft Z overtaking him off of his right and higher. Aircraft X is left downwind Runway 26L. I tell him that he is number 2 to follow the aircraft on a mile final. He acknowledges his clearance. I then issue traffic to Aircraft X for Aircraft Y who is on a 3 mile final for Runway 26R and advise him that Aircraft Y is south of course tracking the VOR. Aircraft X responds with looking. Approximately 1 minute later Aircraft X responds with that it was close with the VOR traffic and that they had to maneuver to avoid the aircraft.I was distracted with Aircraft Y on a 4 mile final with an aircraft with over a 100 knot overtake 2 miles in trail. I was trying to get the conflict resolved between the Aircraft Z and Aircraft Y in front resolved that I wasn't able to provide the best positive control between the other two aircraft. It would help if when SCT hands off aircraft they put the faster aircraft in front instead of just dumping both on the tower to resolve the conflict. Another method would have been to extend the upwind of Aircraft X more than I did.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1379171
Time
Date	201608
Local Time Of Day	1801-2400
Place
Locale Reference	CNO.Tower
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	None
Flight Plan	VFR
Aircraft 2
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Flight Plan	VFR
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 2
Events
Anomaly	ATC Issue All Types Conflict NMAC

Cno local controller issued parallel runway traffic to an aircraft turning base late. The aircraft told the controller they had to maneuver to avoid the traffic.