A B737-700 executed a TCASII RA maneuver in response to climbing VFR traffic also talking to ATC.

Attributes
ACN	636913
Time
Date	200411
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : jot.vortac
State Reference	IL
Altitude	msl single value : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 200 flight time total : 5000 flight time type : 1500
ASRS Report	636913
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 250 flight time total : 23000 flight time type : 10000
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 2500 vertical : 100
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure
Primary Problem	Flight Crew Human Performance

Narrative:

ATC gave us descent to 7000 ft. Reported VFR traffic 1-2 O'clock at 6500 ft. Passing approximately 8000 ft, TCASII TA received. Target approximately 4 mi, 12-1 O'clock position on TCASII. Could not visually identify. Shortly after target disappeared from screen, ATC informed traffic was climbing towards our assigned altitude of 7000 ft. Reported traffic at 6500 ft. Seconds later, RA issued with target 2 - 2 1/2 mi on nose. I complied with RA climb of 2000 FPM. I never visually acquired the traffic. RA reduced climb to 500 FPM within 2-3 seconds after responding, captain reported visual with the traffic going down right side of aircraft 100 ft below and 1/2 mi off. ATC was informed of TCASII climb. I would have preferred ATC intervene immediately with altitude change or heading prior TCASII RA.

Original NASA ASRS Text

Title: A B737-700 EXECUTED A TCASII RA MANEUVER IN RESPONSE TO CLBING VFR TFC ALSO TALKING TO ATC.

Narrative: ATC GAVE US DSCNT TO 7000 FT. RPTED VFR TFC 1-2 O'CLOCK AT 6500 FT. PASSING APPROX 8000 FT, TCASII TA RECEIVED. TARGET APPROX 4 MI, 12-1 O'CLOCK POS ON TCASII. COULD NOT VISUALLY IDENT. SHORTLY AFTER TARGET DISAPPEARED FROM SCREEN, ATC INFORMED TFC WAS CLBING TOWARDS OUR ASSIGNED ALT OF 7000 FT. RPTED TFC AT 6500 FT. SECONDS LATER, RA ISSUED WITH TARGET 2 - 2 1/2 MI ON NOSE. I COMPLIED WITH RA CLB OF 2000 FPM. I NEVER VISUALLY ACQUIRED THE TFC. RA REDUCED CLB TO 500 FPM WITHIN 2-3 SECONDS AFTER RESPONDING, CAPT RPTED VISUAL WITH THE TFC GOING DOWN R SIDE OF ACFT 100 FT BELOW AND 1/2 MI OFF. ATC WAS INFORMED OF TCASII CLB. I WOULD HAVE PREFERRED ATC INTERVENE IMMEDIATELY WITH ALT CHANGE OR HDG PRIOR TCASII 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.