Narrative:

ZLA asked for a highspeed (330K) penetration on 25L profile descent to accommodate following traffic and vectored me across 'civet corner' presumably for same purpose. On interception of 25L localizer I was asked to maintain 250K below 10000' and turned over to lax approach. They immediately asked me to slow to 180K and cleared me '25L approach after fueler'. Inside fueler I watched large transport Y approach the localizer from sli VOR (at 90 degree to localizer) pass approximately 2 miles in front of me. As he approached the localizer I heard 'clicks' on the frequency (124.9). I attempted, twice, to contact approach on 124.9 but the frequency was silent so I immediately contacted lax approach on 124.5 and explained that I had lost contact with the approach controller on 124.9 and received an acknowledgement. When large transport Y crossed the localizer he was still quite fast with only a small flap setting showing and because he made no attempt to 'lead in' I assumed he was aiming for 24R. We were in the clear with heavy haze below, topping at 2000'. I watched large transport Y turn in toward lax. I was instructed by the approach controller to follow large transport Y but informed him that I was unable. The controller acknowledged and instructed me to maintain 4000'. I saw large transport Y commence a descending left turn towards me and he passed directly below me approximately 1000' lower and crossing right to left. At this time I was above the glide slope. I informed the controller that I no longer had large transport Y in sight. I proceeded to lax at 4000' on the localizer and was vectored for another approach. I suggest that close in transitions be designed at less than 90 degree intercepts so that in the event of radio failure with high performance aircraft, and the loss of 'lead-in' vectors, that the traffic on parallel runway approachs not be jeopardized, nor, as in this case, following traffic. Large transport Y was finally contacted by lax approach through commercial radio, showing initiative on the part of large transport Y crew radio handling. Callback conversation with reporter revealed the following information: after landing the reporter called approach control to find what happened. The large transport that crossed their path had 'stuck microphone' and approach control on 124.9 was effectively out of service. By the time reporter decided that this was true, the other aircraft had already started to cross their path and standard sep had been lost. As stated in the narrative, the crew of large transport did not regain contact with approach control until they were contacted through commercial radio and advised that they were the aircraft with the stuck microphone. Reporter stated that he had seen the other aircraft well before it came close and at no time did he feel that any danger existed.

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Original NASA ASRS Text

Title: FREQ BLOCKAGE CAUSED AN ACR LGT TO PASS THROUGH THE FINAL APCH COURSE AND COME INTO CONFLICT WITH AN ACR HVT INBOUND ON THE ILS.

Narrative: ZLA ASKED FOR A HIGHSPEED (330K) PENETRATION ON 25L PROFILE DESCENT TO ACCOMMODATE FOLLOWING TFC AND VECTORED ME ACROSS 'CIVET CORNER' PRESUMABLY FOR SAME PURPOSE. ON INTERCEPTION OF 25L LOC I WAS ASKED TO MAINTAIN 250K BELOW 10000' AND TURNED OVER TO LAX APCH. THEY IMMEDIATELY ASKED ME TO SLOW TO 180K AND CLRED ME '25L APCH AFTER FUELER'. INSIDE FUELER I WATCHED LGT Y APCH THE LOC FROM SLI VOR (AT 90 DEG TO LOC) PASS APPROX 2 MILES IN FRONT OF ME. AS HE APCHED THE LOC I HEARD 'CLICKS' ON THE FREQ (124.9). I ATTEMPTED, TWICE, TO CONTACT APCH ON 124.9 BUT THE FREQ WAS SILENT SO I IMMEDIATELY CONTACTED LAX APCH ON 124.5 AND EXPLAINED THAT I HAD LOST CONTACT WITH THE APCH CTLR ON 124.9 AND RECEIVED AN ACKNOWLEDGEMENT. WHEN LGT Y CROSSED THE LOC HE WAS STILL QUITE FAST WITH ONLY A SMALL FLAP SETTING SHOWING AND BECAUSE HE MADE NO ATTEMPT TO 'LEAD IN' I ASSUMED HE WAS AIMING FOR 24R. WE WERE IN THE CLEAR WITH HEAVY HAZE BELOW, TOPPING AT 2000'. I WATCHED LGT Y TURN IN TOWARD LAX. I WAS INSTRUCTED BY THE APCH CTLR TO FOLLOW LGT Y BUT INFORMED HIM THAT I WAS UNABLE. THE CTLR ACKNOWLEDGED AND INSTRUCTED ME TO MAINTAIN 4000'. I SAW LGT Y COMMENCE A DESCENDING LEFT TURN TOWARDS ME AND HE PASSED DIRECTLY BELOW ME APPROX 1000' LOWER AND XING RIGHT TO LEFT. AT THIS TIME I WAS ABOVE THE GLIDE SLOPE. I INFORMED THE CTLR THAT I NO LONGER HAD LGT Y IN SIGHT. I PROCEEDED TO LAX AT 4000' ON THE LOC AND WAS VECTORED FOR ANOTHER APCH. I SUGGEST THAT CLOSE IN TRANSITIONS BE DESIGNED AT LESS THAN 90 DEG INTERCEPTS SO THAT IN THE EVENT OF RADIO FAILURE WITH HIGH PERFORMANCE ACFT, AND THE LOSS OF 'LEAD-IN' VECTORS, THAT THE TFC ON PARALLEL RWY APCHS NOT BE JEOPARDIZED, NOR, AS IN THIS CASE, FOLLOWING TFC. LGT Y WAS FINALLY CONTACTED BY LAX APCH THROUGH COMMERCIAL RADIO, SHOWING INITIATIVE ON THE PART OF LGT Y CREW RADIO HANDLING. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING INFORMATION: AFTER LNDG THE REPORTER CALLED APCH CTL TO FIND WHAT HAPPENED. THE LGT THAT CROSSED THEIR PATH HAD 'STUCK MIKE' AND APCH CTL ON 124.9 WAS EFFECTIVELY OUT OF SERVICE. BY THE TIME RPTR DECIDED THAT THIS WAS TRUE, THE OTHER ACFT HAD ALREADY STARTED TO CROSS THEIR PATH AND STANDARD SEP HAD BEEN LOST. AS STATED IN THE NARRATIVE, THE CREW OF LGT DID NOT REGAIN CONTACT WITH APCH CTL UNTIL THEY WERE CONTACTED THROUGH COMMERCIAL RADIO AND ADVISED THAT THEY WERE THE ACFT WITH THE STUCK MICROPHONE. RPTR STATED THAT HE HAD SEEN THE OTHER ACFT WELL BEFORE IT CAME CLOSE AND AT NO TIME DID HE FEEL THAT ANY DANGER EXISTED.

Data retrieved from NASA's ASRS site as of August 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.