CL65 crew received a TCASII RA during descent into dtw.

Attributes
ACN	550819
Time
Date	200206
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : dtw.airport
State Reference	MI
Altitude	msl single value : 17000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors arrival star : ns
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zob.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise : level
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 2560 flight time type : 1100
ASRS Report	550819
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne critical non adherence : required legal separation non adherence : published procedure non adherence : far
Independent Detector	atc equipment other atc equipment : radar mode c aircraft equipment : tcas other controllera
Resolutory Action	controller : issued advisory flight crew : took evasive action
Miss Distance	horizontal : 3000 vertical : 300
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance Airspace Structure
Primary Problem	Ambiguous

Narrative:

During our arrival into dtw we were vectored and speed restr several times by ZOB. We were then given a descent. As we were descending, ATC gave us a TA for a nearby aircraft. We reduced the range on TCASII to look closer and we noticed an aircraft at about our 2 O'clock position at an altitude below our current altitude, but at or above our clearance altitude. This aircraft was passing from right to left directly in front of our flight path. The captain tried to query ATC several times, but the frequency was very busy. ATC then gave us another very casual TA of the other aircraft's location and altitude. Realizing this was not going to work, I began an aggressive leveloff to avoid a potential collision as our descent would have taken us through the intruding aircraft's altitude at approximately the same position. At the same time, TCASII issued a TA, followed very shortly by an RA instructing us to climb. I disconnected the autoplt and began an aggressive climb. ATC gave us another casual TA and we responded we were climbing. I leveled the aircraft after TCASII reported 'clear of conflict.' then we began our descent to our original cleared altitude once again.

Original NASA ASRS Text

Title: CL65 CREW RECEIVED A TCASII RA DURING DSCNT INTO DTW.

Narrative: DURING OUR ARR INTO DTW WE WERE VECTORED AND SPD RESTR SEVERAL TIMES BY ZOB. WE WERE THEN GIVEN A DSCNT. AS WE WERE DSNDING, ATC GAVE US A TA FOR A NEARBY ACFT. WE REDUCED THE RANGE ON TCASII TO LOOK CLOSER AND WE NOTICED AN ACFT AT ABOUT OUR 2 O'CLOCK POS AT AN ALT BELOW OUR CURRENT ALT, BUT AT OR ABOVE OUR CLRNC ALT. THIS ACFT WAS PASSING FROM R TO L DIRECTLY IN FRONT OF OUR FLT PATH. THE CAPT TRIED TO QUERY ATC SEVERAL TIMES, BUT THE FREQ WAS VERY BUSY. ATC THEN GAVE US ANOTHER VERY CASUAL TA OF THE OTHER ACFT'S LOCATION AND ALT. REALIZING THIS WAS NOT GOING TO WORK, I BEGAN AN AGGRESSIVE LEVELOFF TO AVOID A POTENTIAL COLLISION AS OUR DSCNT WOULD HAVE TAKEN US THROUGH THE INTRUDING ACFT'S ALT AT APPROX THE SAME POS. AT THE SAME TIME, TCASII ISSUED A TA, FOLLOWED VERY SHORTLY BY AN RA INSTRUCTING US TO CLB. I DISCONNECTED THE AUTOPLT AND BEGAN AN AGGRESSIVE CLB. ATC GAVE US ANOTHER CASUAL TA AND WE RESPONDED WE WERE CLBING. I LEVELED THE ACFT AFTER TCASII RPTED 'CLR OF CONFLICT.' THEN WE BEGAN OUR DSCNT TO OUR ORIGINAL CLRED ALT ONCE AGAIN.

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.