DC9 crew had TCASII RA.

Attributes
ACN	441767
Time
Date	199906
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : mdw.airport
State Reference	IL
Altitude	msl bound lower : 4000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : c90.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	climbout : vacating altitude
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp pilot : cfi
Experience	flight time last 90 days : 180 flight time total : 13300 flight time type : 4400
ASRS Report	441767
Person 2
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Events
Anomaly	conflict : airborne critical non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : took evasive action
Miss Distance	horizontal : 3000 vertical : 800
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Ord approach reported traffic at 1 O'clock at 3500 ft MSL heading northeast. We were descending to 4000 ft MSL, passing 4700 ft MSL when we received the TCASII RA. Had traffic on TCASII negative visual contact on traffic. It appeared the traffic started climbing on our TCASII. That's when we received the TCASII RA to climb. We stopped our descent at approximately 4700-4500 ft MSL and started a climb per RA instructions. Received a clear of conflict and at that time we were back at 5000 ft MSL. Advised ATC, and descended back to 4000 ft MSL. Landed without further incident.

Original NASA ASRS Text

Title: DC9 CREW HAD TCASII RA.

Narrative: ORD APCH RPTED TFC AT 1 O'CLOCK AT 3500 FT MSL HDG NE. WE WERE DSNDING TO 4000 FT MSL, PASSING 4700 FT MSL WHEN WE RECEIVED THE TCASII RA. HAD TFC ON TCASII NEGATIVE VISUAL CONTACT ON TFC. IT APPEARED THE TFC STARTED CLBING ON OUR TCASII. THAT'S WHEN WE RECEIVED THE TCASII RA TO CLB. WE STOPPED OUR DSCNT AT APPROX 4700-4500 FT MSL AND STARTED A CLB PER RA INSTRUCTIONS. RECEIVED A CLR OF CONFLICT AND AT THAT TIME WE WERE BACK AT 5000 FT MSL. ADVISED ATC, AND DSNDED BACK TO 4000 FT MSL. LANDED WITHOUT FURTHER INCIDENT.

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.