Narrative:

Training was in progress on local control. I was working ground control at the time. I was scanning out the window and saw two aircraft turning right base at the same time for runway 19R. It appeared the trailing aircraft was cutting off the leading aircraft. I attempted to verify with local control whether or not they wanted both aircraft on right base at the same time; essentially flying parallel each other with less than a mile apart and going to turn final for the same runway. The trainer on local control stated that they should not be on base at the same time; that the previously trailing aircraft was supposed to be on an extended downwind to follow the previously leading aircraft.I again pointed out that both aircraft were on base at the same time and I gave their relative position reference visual points of reference from the tower's view point as the trainer seemed unable to find either aircraft on base; though both were clearly visible even without binoculars. The trainer took over local control at this point and attempted to try and fix things by issuing aircraft X a left turn back to downwind. This was a very bad call because aircraft X was well established on base and approaching final as the lead aircraft with aircraft Y parallel to them on the right base approaching final as well. The controller in charge (controller in charge) attempted to point out the error of this instruction to aircraft X but the local controller either did not hear the controller in charge or still failed to see both aircraft. Both aircraft X and aircraft Y ended up continuing on the base through final probably due to the confusing instructions the local controller was attempting to have them do and thus subsequently flew through the final of runway 19L where aircraft Z was on final and local control was still trying to get aircraft X to turn left which would have put him flying nose to nose with aircraft Z. Aircraft X flew directly across aircraft Z's final and aircraft Y flew directly behind aircraft Z through runway 19L's final.later on the pilots of aircraft Z visited the tower to find out what happened and advised that one of the aircraft passed behind their tail by 100 feet or less. Local control eventually figured out which aircraft was which either because they finally listened to the controller in charge or saw both aircraft or both; I am not sure; but they turned both aircraft back towards runway 19R with left turns giving the then outside aircraft (aircraft Y) the turn first. All three aircraft completed their landings but local control never fully recovered the picture; continued to struggle (confusing call signs; making bad judgment calls; etc); and refused to give up the position when relief was offered.

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Original NASA ASRS Text

Title: CCR Tower Controllers reported two aircraft turned base from downwind simultaneously. A Controller confused the call signs and broke the wrong aircraft out. The confusion caused both aircraft to fly through the final approach course of the parallel runway where another aircraft was on short final.

Narrative: Training was in progress on Local Control. I was working Ground Control at the time. I was scanning out the window and saw two aircraft turning right base at the same time for RWY 19R. It appeared the trailing aircraft was cutting off the leading aircraft. I attempted to verify with Local Control whether or not they wanted both aircraft on right base at the same time; essentially flying parallel each other with less than a mile apart and going to turn final for the same runway. The trainer on Local Control stated that they should not be on base at the same time; that the previously trailing aircraft was supposed to be on an extended downwind to follow the previously leading aircraft.I again pointed out that both aircraft were on base at the same time and I gave their relative position reference visual points of reference from the tower's view point as the trainer seemed unable to find either aircraft on base; though both were clearly visible even without binoculars. The trainer took over Local Control at this point and attempted to try and fix things by issuing Aircraft X a left turn back to downwind. This was a very bad call because Aircraft X was well established on base and approaching final as the lead aircraft with Aircraft Y parallel to them on the right base approaching final as well. The Controller In Charge (CIC) attempted to point out the error of this instruction to Aircraft X but the Local Controller either did not hear the CIC or still failed to see both aircraft. Both Aircraft X and Aircraft Y ended up continuing on the base through final probably due to the confusing instructions the Local Controller was attempting to have them do and thus subsequently flew through the final of Runway 19L where Aircraft Z was on final and Local Control was still trying to get Aircraft X to turn left which would have put him flying nose to nose with Aircraft Z. Aircraft X flew directly across Aircraft Z's final and Aircraft Y flew directly behind Aircraft Z through Runway 19L's final.Later on the pilots of Aircraft Z visited the tower to find out what happened and advised that one of the aircraft passed behind their tail by 100 feet or less. Local Control eventually figured out which aircraft was which either because they finally listened to the CIC or saw both aircraft or both; I am not sure; but they turned both aircraft back towards Runway 19R with left turns giving the then outside aircraft (Aircraft Y) the turn first. All three aircraft completed their landings but Local Control never fully recovered the picture; continued to struggle (confusing call signs; making bad judgment calls; etc); and refused to give up the position when relief was offered.

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.