Air carrier on visual approach to den experienced TCASII RA with ATC issued traffic.

Attributes
ACN	600170
Time
Date	200311
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : den.airport
State Reference	CO
Altitude	msl single value : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d01.tracon
Operator	common carrier : air carrier
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	climbout : takeoff
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 180 flight time total : 20000 flight time type : 600
ASRS Report	600170
Person 2
Function	flight crew : first officer
Events
Anomaly	conflict : airborne critical non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	Ambiguous

Narrative:

We were on approach to runway 35R at den. Approach control cleared us to 7500 ft and then cleared us for a visual approach. First officer descended to 7000 ft which is altitude for FAF (fronz). ATC called traffic which we did not see and then told us to turn left to 270 degree heading to avoid traffic. In the turn we got an RA to 'climb' and first officer started an immediate climb. I then saw a light aircraft below and straight ahead. It's possible that we were below the TCA floor or the light aircraft was in the class B airspace. Looking at the commercial chart page later on, I believe we were in an area with a 7000 ft floor (maybe even 6500 ft). Adding to the confusion was the fact that den changed our runway 2 times -- runway 26 to runway 35L to runway 35R. So we had a very high workload. Although ATC can be extremely busy, they are intimately familiar with their own airspace, and I would think we could be warned if we got too low. (Could the controller's screen give him a warning if we were too low?) we might only fly into any given airport a few times a yr, yet we are expected to dynamically interpretation the information from that small commercial chart page. (Impossible if you get 2 runway changes!)

Original NASA ASRS Text

Title: ACR ON VISUAL APCH TO DEN EXPERIENCED TCASII RA WITH ATC ISSUED TFC.

Narrative: WE WERE ON APCH TO RWY 35R AT DEN. APCH CTL CLRED US TO 7500 FT AND THEN CLRED US FOR A VISUAL APCH. FO DSNDED TO 7000 FT WHICH IS ALT FOR FAF (FRONZ). ATC CALLED TFC WHICH WE DID NOT SEE AND THEN TOLD US TO TURN L TO 270 DEG HDG TO AVOID TFC. IN THE TURN WE GOT AN RA TO 'CLB' AND FO STARTED AN IMMEDIATE CLB. I THEN SAW A LIGHT ACFT BELOW AND STRAIGHT AHEAD. IT'S POSSIBLE THAT WE WERE BELOW THE TCA FLOOR OR THE LIGHT ACFT WAS IN THE CLASS B AIRSPACE. LOOKING AT THE COMMERCIAL CHART PAGE LATER ON, I BELIEVE WE WERE IN AN AREA WITH A 7000 FT FLOOR (MAYBE EVEN 6500 FT). ADDING TO THE CONFUSION WAS THE FACT THAT DEN CHANGED OUR RWY 2 TIMES -- RWY 26 TO RWY 35L TO RWY 35R. SO WE HAD A VERY HIGH WORKLOAD. ALTHOUGH ATC CAN BE EXTREMELY BUSY, THEY ARE INTIMATELY FAMILIAR WITH THEIR OWN AIRSPACE, AND I WOULD THINK WE COULD BE WARNED IF WE GOT TOO LOW. (COULD THE CTLR'S SCREEN GIVE HIM A WARNING IF WE WERE TOO LOW?) WE MIGHT ONLY FLY INTO ANY GIVEN ARPT A FEW TIMES A YR, YET WE ARE EXPECTED TO DYNAMICALLY INTERP THE INFO FROM THAT SMALL COMMERCIAL CHART PAGE. (IMPOSSIBLE IF YOU GET 2 RWY CHANGES!)

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.