Narrative:

ATC facility: dfw tower. Location: 110.3/on localizer and GS beam for runway 17C dfw 2-3 DME. During simultaneous visual approachs to runway 17L/17C at dfw we were vectored above and behind traffic to runway 17L to intercept final for a visual approach to runway 17C. We were able to observe the other aircraft and verify its TCASII symbol throughout this event. Established on final with visibility unrestr we could monitor our relative position to the other aircraft. The comment was made that the other aircraft appeared closer than it should be. Its symbol on the TCASII display was too close to ours to judge distance. It maintained a position 200-300 ft above us at 2-3 mi without a 'traffic' call, we got a 'descend' command from TCASII with a vsi red/green command of 1500- 2000 FPM. After a hasty survey of our circumstances and continued close monitoring of our boogey at 9 O'clock position we insured our own separation and continued the approach to a landing. Even though ideal circumstances for parallel approachs existed, a TCASII command occurred that I feel was grossly inappropriate and dangerous. We had been visually monitoring the conflicting traffic since downwind. Had we been IMC, we would have been presented with an unresolvable RA.

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Original NASA ASRS Text

Title: FLC OF S80 HAS TCASII RA TO DSND WHEN CLOSE IN ON FINAL OF VISUAL APCH. THEY HAVE TFC IN SIGHT AND DO NOT RESPOND TO THE TCASII RA.

Narrative: ATC FACILITY: DFW TWR. LOCATION: 110.3/ON LOC AND GS BEAM FOR RWY 17C DFW 2-3 DME. DURING SIMULTANEOUS VISUAL APCHS TO RWY 17L/17C AT DFW WE WERE VECTORED ABOVE AND BEHIND TFC TO RWY 17L TO INTERCEPT FINAL FOR A VISUAL APCH TO RWY 17C. WE WERE ABLE TO OBSERVE THE OTHER ACFT AND VERIFY ITS TCASII SYMBOL THROUGHOUT THIS EVENT. ESTABLISHED ON FINAL WITH VISIBILITY UNRESTR WE COULD MONITOR OUR RELATIVE POS TO THE OTHER ACFT. THE COMMENT WAS MADE THAT THE OTHER ACFT APPEARED CLOSER THAN IT SHOULD BE. ITS SYMBOL ON THE TCASII DISPLAY WAS TOO CLOSE TO OURS TO JUDGE DISTANCE. IT MAINTAINED A POS 200-300 FT ABOVE US AT 2-3 MI WITHOUT A 'TFC' CALL, WE GOT A 'DSND' COMMAND FROM TCASII WITH A VSI RED/GREEN COMMAND OF 1500- 2000 FPM. AFTER A HASTY SURVEY OF OUR CIRCUMSTANCES AND CONTINUED CLOSE MONITORING OF OUR BOOGEY AT 9 O'CLOCK POS WE INSURED OUR OWN SEPARATION AND CONTINUED THE APCH TO A LNDG. EVEN THOUGH IDEAL CIRCUMSTANCES FOR PARALLEL APCHS EXISTED, A TCASII COMMAND OCCURRED THAT I FEEL WAS GROSSLY INAPPROPRIATE AND DANGEROUS. WE HAD BEEN VISUALLY MONITORING THE CONFLICTING TFC SINCE DOWNWIND. HAD WE BEEN IMC, WE WOULD HAVE BEEN PRESENTED WITH AN UNRESOLVABLE RA.

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.