On goshen arrival to mdw, flight crew of B737-300 encounter uncontrolled traffic. Receive TCASII RA ...

Attributes
ACN	616617
Time
Date	200405
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : gsh.vortac
State Reference	IN
Altitude	msl single value : 10000
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude descent : approach
Route In Use	arrival star : goshen
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zau.artcc
Make Model Name	Small Aircraft, Low Wing, 2 Eng, Retractable Gear
Flight Phase	cruise : level
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	616617
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	616619
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne critical non adherence : clearance non adherence : published procedure
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 50 vertical : 700
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure ATC Human Performance Aircraft
Primary Problem	ATC Human Performance

Narrative:

At 10000 ft on the goshen arrival, we received a TCASII RA. It indicated an aircraft approaching from approximately 12 O'clock position and 300 ft below. The captain was flying the aircraft with the autoplt engaged. As the RA was sounded, he disconnected the autoplt and initiated a climb as directed by the TCASII. At the same time, the controller gave us a descent to 9000 ft. The captain told me to inform center that we were climbing. I did this and the controller seemed unaware that there was another aircraft there until I queried him about it. He stumbled for a moment and then said to maintain 10000 ft. As the light twin passed by and approximately 700 ft below, I told the controller that we had him in sight and were clear. He subsequently gave us a descent clearance to 9000 ft and a turn to 250 degrees. He soon switched us to approach control and the rest of the flight went uneventfully.

Original NASA ASRS Text

Title: ON GOSHEN ARR TO MDW, FLT CREW OF B737-300 ENCOUNTER UNCTLED TFC. RECEIVE TCASII RA AND COMPLY.

Narrative: AT 10000 FT ON THE GOSHEN ARR, WE RECEIVED A TCASII RA. IT INDICATED AN ACFT APCHING FROM APPROX 12 O'CLOCK POS AND 300 FT BELOW. THE CAPT WAS FLYING THE ACFT WITH THE AUTOPLT ENGAGED. AS THE RA WAS SOUNDED, HE DISCONNECTED THE AUTOPLT AND INITIATED A CLB AS DIRECTED BY THE TCASII. AT THE SAME TIME, THE CTLR GAVE US A DSCNT TO 9000 FT. THE CAPT TOLD ME TO INFORM CTR THAT WE WERE CLBING. I DID THIS AND THE CTLR SEEMED UNAWARE THAT THERE WAS ANOTHER ACFT THERE UNTIL I QUERIED HIM ABOUT IT. HE STUMBLED FOR A MOMENT AND THEN SAID TO MAINTAIN 10000 FT. AS THE LIGHT TWIN PASSED BY AND APPROX 700 FT BELOW, I TOLD THE CTLR THAT WE HAD HIM IN SIGHT AND WERE CLR. HE SUBSEQUENTLY GAVE US A DSCNT CLRNC TO 9000 FT AND A TURN TO 250 DEGS. HE SOON SWITCHED US TO APCH CTL AND THE REST OF THE FLT WENT UNEVENTFULLY.

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.

On goshen arrival to mdw, flight crew of B737-300 encounter uncontrolled traffic. Receive TCASII RA and comply.