Narrative:

On may/xx/97 I was the PF, first officer, on air carrier flight approaching lax from the east in an A320. Prior to civet we were slowed to 250 KTS and given several delay vectors. Once cleared for the civet arrival, it was at 'maximum forward speed 330 KTS or greater.' ATC (socal) was extremely busy, and upon reaching arnes at 10000 ft MSL we did not yet have approach clearance. At approximately 27 DME from lax, clearance was received 'slow now to 170 KTS, cleared ILS runway 25L, 170 KTS to limma.' the aircraft was quickly slowed and configured to gear down, flaps full and a steep descent was hand flown at a selected speed of 170 KTS to intercept glide path from above. The runway 25L ILS was idented and displayed on the pfd. The aircraft was aligned with runway 25L. At approximately gaate MD80 traffic was called out to the north by ATC. I did not ever see the MD80 but did visually acquire a B737 abeam us proceeding to the north complex (runways 24). I was also aware of a commuter aircraft behind us that was asked to 'call the airbus in sight.' I assumed him to be a few mi behind following us to runway 25L. He never reported a visual on us and to the best of my knowledge did not see us. Between hunda and limma as we approached the vertical profile descent was reduced to 400-500 FPM and TCASII gave us a 'traffic' call. The TCASII symbol was very close and I assumed it was the MD80 or B737 going to the parallel runway. Shortly thereafter, an RA 'descend' was issued which we complied with, followed by a 'monitor vertical speed.' TCASII indicated an aircraft 500 ft above and slightly behind and left (south) of our aircraft which I believe was the 'commuter' aircraft. Almost immediately thereafter, we were issued a clearance for the visual to runway 25R. An uneventful landing on runway 25R followed. Lessons learned: 1) TCASII works. Do what it says. At the time of the RA I thought my situational awareness was perfect and I knew where all my traffic was. My first impression was 'it's the B737 to the north' and then as I looked at the display 'it's a false target' because it was so close and not moving. I now believe it was the commuter aircraft behind us. Fortunately we followed the RA and evaluated while we were getting vertical separation. 2) the socal controllers were maxed out. ATC was doing their best to handle all the traffic but the controllers were task saturated. I was task saturated at 10000 ft inside arnes as a new A320 first officer trying to slow the aircraft and get back on profile. I am sure (in my mind) that we were cleared for the ILS to runway 25L and that was the readback. If we were cleared for the right runway, we missed it and socal did not catch the incorrect readback. 3) even though the WX was excellent (by los angeles standards) visibility looking west (into the sun, haze, and ocean glare) was poor. The commuter would have had a very hard time seeing us in the conditions. Relying on pilots to maintain visual separation in these conditions probably is not a good idea. Even if you report 'traffic in sight,' are you sure it's the right one and not one of the numerous other aircraft operating to 4 closely spaced parallel runways? In my opinion, there was too much traffic for the current system to handle at the time. ATC was so busy they did not have time to wait for readbacks in many cases, let alone ensure the readbacks were correct. TCASII is a good system, but when we need to use it for separation we are getting too close to the 'edge of the envelope.' we all want on time arrs, but the current system can only handle so much traffic safely. Until we have data link or some other system in place, radio communications are critical to ensure safe aircraft separation. We all must adhere to proper procedures and radio discipline to insure clrncs are understood and complied with. If we have to hold airplanes somewhere to do this, so be it.

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Original NASA ASRS Text

Title: A320 ACFT ON DSCNT AND APCH TO LAX, HVY TFC, FREQ CONGESTION, RESTR VISIBILITY, RESULTED IN RPTR ACFT RECEIVING TCASII RA WHICH THEY FOLLOWED.

Narrative: ON MAY/XX/97 I WAS THE PF, FO, ON ACR FLT APCHING LAX FROM THE E IN AN A320. PRIOR TO CIVET WE WERE SLOWED TO 250 KTS AND GIVEN SEVERAL DELAY VECTORS. ONCE CLRED FOR THE CIVET ARR, IT WAS AT 'MAX FORWARD SPD 330 KTS OR GREATER.' ATC (SOCAL) WAS EXTREMELY BUSY, AND UPON REACHING ARNES AT 10000 FT MSL WE DID NOT YET HAVE APCH CLRNC. AT APPROX 27 DME FROM LAX, CLRNC WAS RECEIVED 'SLOW NOW TO 170 KTS, CLRED ILS RWY 25L, 170 KTS TO LIMMA.' THE ACFT WAS QUICKLY SLOWED AND CONFIGURED TO GEAR DOWN, FLAPS FULL AND A STEEP DSCNT WAS HAND FLOWN AT A SELECTED SPD OF 170 KTS TO INTERCEPT GLIDE PATH FROM ABOVE. THE RWY 25L ILS WAS IDENTED AND DISPLAYED ON THE PFD. THE ACFT WAS ALIGNED WITH RWY 25L. AT APPROX GAATE MD80 TFC WAS CALLED OUT TO THE N BY ATC. I DID NOT EVER SEE THE MD80 BUT DID VISUALLY ACQUIRE A B737 ABEAM US PROCEEDING TO THE N COMPLEX (RWYS 24). I WAS ALSO AWARE OF A COMMUTER ACFT BEHIND US THAT WAS ASKED TO 'CALL THE AIRBUS IN SIGHT.' I ASSUMED HIM TO BE A FEW MI BEHIND FOLLOWING US TO RWY 25L. HE NEVER RPTED A VISUAL ON US AND TO THE BEST OF MY KNOWLEDGE DID NOT SEE US. BTWN HUNDA AND LIMMA AS WE APCHED THE VERT PROFILE DSCNT WAS REDUCED TO 400-500 FPM AND TCASII GAVE US A 'TFC' CALL. THE TCASII SYMBOL WAS VERY CLOSE AND I ASSUMED IT WAS THE MD80 OR B737 GOING TO THE PARALLEL RWY. SHORTLY THEREAFTER, AN RA 'DSND' WAS ISSUED WHICH WE COMPLIED WITH, FOLLOWED BY A 'MONITOR VERT SPD.' TCASII INDICATED AN ACFT 500 FT ABOVE AND SLIGHTLY BEHIND AND L (S) OF OUR ACFT WHICH I BELIEVE WAS THE 'COMMUTER' ACFT. ALMOST IMMEDIATELY THEREAFTER, WE WERE ISSUED A CLRNC FOR THE VISUAL TO RWY 25R. AN UNEVENTFUL LNDG ON RWY 25R FOLLOWED. LESSONS LEARNED: 1) TCASII WORKS. DO WHAT IT SAYS. AT THE TIME OF THE RA I THOUGHT MY SITUATIONAL AWARENESS WAS PERFECT AND I KNEW WHERE ALL MY TFC WAS. MY FIRST IMPRESSION WAS 'IT'S THE B737 TO THE N' AND THEN AS I LOOKED AT THE DISPLAY 'IT'S A FALSE TARGET' BECAUSE IT WAS SO CLOSE AND NOT MOVING. I NOW BELIEVE IT WAS THE COMMUTER ACFT BEHIND US. FORTUNATELY WE FOLLOWED THE RA AND EVALUATED WHILE WE WERE GETTING VERT SEPARATION. 2) THE SOCAL CTLRS WERE MAXED OUT. ATC WAS DOING THEIR BEST TO HANDLE ALL THE TFC BUT THE CTLRS WERE TASK SATURATED. I WAS TASK SATURATED AT 10000 FT INSIDE ARNES AS A NEW A320 FO TRYING TO SLOW THE ACFT AND GET BACK ON PROFILE. I AM SURE (IN MY MIND) THAT WE WERE CLRED FOR THE ILS TO RWY 25L AND THAT WAS THE READBACK. IF WE WERE CLRED FOR THE R RWY, WE MISSED IT AND SOCAL DID NOT CATCH THE INCORRECT READBACK. 3) EVEN THOUGH THE WX WAS EXCELLENT (BY LOS ANGELES STANDARDS) VISIBILITY LOOKING W (INTO THE SUN, HAZE, AND OCEAN GLARE) WAS POOR. THE COMMUTER WOULD HAVE HAD A VERY HARD TIME SEEING US IN THE CONDITIONS. RELYING ON PLTS TO MAINTAIN VISUAL SEPARATION IN THESE CONDITIONS PROBABLY IS NOT A GOOD IDEA. EVEN IF YOU RPT 'TFC IN SIGHT,' ARE YOU SURE IT'S THE RIGHT ONE AND NOT ONE OF THE NUMEROUS OTHER ACFT OPERATING TO 4 CLOSELY SPACED PARALLEL RWYS? IN MY OPINION, THERE WAS TOO MUCH TFC FOR THE CURRENT SYS TO HANDLE AT THE TIME. ATC WAS SO BUSY THEY DID NOT HAVE TIME TO WAIT FOR READBACKS IN MANY CASES, LET ALONE ENSURE THE READBACKS WERE CORRECT. TCASII IS A GOOD SYS, BUT WHEN WE NEED TO USE IT FOR SEPARATION WE ARE GETTING TOO CLOSE TO THE 'EDGE OF THE ENVELOPE.' WE ALL WANT ON TIME ARRS, BUT THE CURRENT SYS CAN ONLY HANDLE SO MUCH TFC SAFELY. UNTIL WE HAVE DATA LINK OR SOME OTHER SYS IN PLACE, RADIO COMS ARE CRITICAL TO ENSURE SAFE ACFT SEPARATION. WE ALL MUST ADHERE TO PROPER PROCS AND RADIO DISCIPLINE TO INSURE CLRNCS ARE UNDERSTOOD AND COMPLIED WITH. IF WE HAVE TO HOLD AIRPLANES SOMEWHERE TO DO THIS, SO BE IT.

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.