Medium large transport misses approach when they receive a TCASII RA from an aircraft that doesn't a...

Attributes
ACN	245794
Time
Date	199307
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : den
State Reference	CO
Altitude	msl bound lower : 6000 msl bound upper : 6000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : den
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 6000 flight time type : 800
ASRS Report	245794
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	other
Consequence	Other
Miss Distance	horizontal : 0 vertical : 100
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Turning final for runway 26L at den outside altur OM. We were given traffic both to follow and to the north. This is normal to these parallel runways. Prior to crossing altur we noticed traffic to the south on our TCASII. This is unusual. We kept looking visually for the traffic as well as using the TCASII on the 5 mi scale. The traffic appeared to be converging for a landing on our runway 26L. After crossing the marker we contacted the tower and were informed that our traffic was on short final. As the target got closer both vertical and horizontal, I flattened the approach rising 1 DOT above the GS. The target continued to converge until we got a TA on the TCASII. Still no visual or ATC confirmation. Separation was becoming critical and I leveled the aircraft holding 5800 ft MSL. We then got an RA on the TCASII and initiated an uneventful missed approach. I don't believe there was actually traffic there. No one landed that I am aware of, and ATC didn't seem to be concerned about a possible near miss on final approach. The TCASII is a wonderful tool, however, I wonder if this was a 'shadow' or TCASII 'anomaly.' we did have parallel traffic to runway 26R.

Original NASA ASRS Text

Title: MLG MISSES APCH WHEN THEY RECEIVE A TCASII RA FROM AN ACFT THAT DOESN'T APPEAR TO EXIST.

Narrative: TURNING FINAL FOR RWY 26L AT DEN OUTSIDE ALTUR OM. WE WERE GIVEN TFC BOTH TO FOLLOW AND TO THE N. THIS IS NORMAL TO THESE PARALLEL RWYS. PRIOR TO XING ALTUR WE NOTICED TFC TO THE S ON OUR TCASII. THIS IS UNUSUAL. WE KEPT LOOKING VISUALLY FOR THE TFC AS WELL AS USING THE TCASII ON THE 5 MI SCALE. THE TFC APPEARED TO BE CONVERGING FOR A LNDG ON OUR RWY 26L. AFTER XING THE MARKER WE CONTACTED THE TWR AND WERE INFORMED THAT OUR TFC WAS ON SHORT FINAL. AS THE TARGET GOT CLOSER BOTH VERT AND HORIZ, I FLATTENED THE APCH RISING 1 DOT ABOVE THE GS. THE TARGET CONTINUED TO CONVERGE UNTIL WE GOT A TA ON THE TCASII. STILL NO VISUAL OR ATC CONFIRMATION. SEPARATION WAS BECOMING CRITICAL AND I LEVELED THE ACFT HOLDING 5800 FT MSL. WE THEN GOT AN RA ON THE TCASII AND INITIATED AN UNEVENTFUL MISSED APCH. I DON'T BELIEVE THERE WAS ACTUALLY TFC THERE. NO ONE LANDED THAT I AM AWARE OF, AND ATC DIDN'T SEEM TO BE CONCERNED ABOUT A POSSIBLE NEAR MISS ON FINAL APCH. THE TCASII IS A WONDERFUL TOOL, HOWEVER, I WONDER IF THIS WAS A 'SHADOW' OR TCASII 'ANOMALY.' WE DID HAVE PARALLEL TFC TO RWY 26R.

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.

Medium large transport misses approach when they receive a TCASII RA from an aircraft that doesn't appear to exist.