Approach controller gave descent instructions for traffic, TCASII said climb. Flight crew followed c...

Attributes
ACN	193372
Time
Date	199110
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 3000 msl bound upper : 4000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord tower : tys
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 9000 flight time type : 2000
ASRS Report	193372
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 7000 flight time type : 2500
ASRS Report	193480
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

On localizer at 4000 ft, heard 'air carrier 3000.' clearance cut-out by TCASII calling 'traffic, traffic.' first officer called to confirm clearance and we were directed to 'turn right immediately and descend immediately to 3000.' seeing proximity of other aircraft I rolled into a 50 degree bank and started descent. TCASII then called 'climb crossing climb.' I continued descent and turn. I do not know how close we came to the other aircraft. The volume of the 'traffic, traffic' is too loud if it cuts out ATC. I feel that if I had leveled wings to climb as TCASII instructed and our operating manual specifies, we may have well hit the other aircraft. Supplemental information from acn 193480. Medium large transport was established on localizer at 4000 ft and cleared for the approach. ATC issued clearance 'air carrier descend/ maintain 3000.' however, the call sign was partially covered by the cockpit TCASII issuing a loud 'traffic, traffic' warning. Copilot set in 3000 ft in altitude armed window, but aircraft remained at 4000 ft while the copilot called ATC to verify 3200 ft was for medium large transport. An ATC supervisor came abruptly on line and told medium large transport to descend immediately to 3000 ft immediate right turn to 270 degree. Captain began exactly that, using 50 degree right bank and pushing nose down. At this point the TCASII warned 'monitor vertical speed' and the came was covered in red lights except for green lights at 1500 FPM climb. Captain says TCASII also issued 'climb, crossover climb', but I do not recall that. I feel once beginning the evasive descending right turn, the flight crew was committed to that course of action and at that point going from steep descent to a climb would have been a hazardous course of action. Question: although you may deviate (are required to by company) from ATC instructions due to a TCASII RA, who do you follow when both are giving different evasive courses of action? And do you stop midway through one course of action to follow another?

Original NASA ASRS Text

Title: APCH CTLR GAVE DSCNT INSTRUCTIONS FOR TFC, TCASII SAID CLB. FLC FOLLOWED CTLR CLRNC, ACFT PASS IN CLOSE PROX.

Narrative: ON LOC AT 4000 FT, HEARD 'ACR 3000.' CLRNC CUT-OUT BY TCASII CALLING 'TFC, TFC.' FO CALLED TO CONFIRM CLRNC AND WE WERE DIRECTED TO 'TURN R IMMEDIATELY AND DSND IMMEDIATELY TO 3000.' SEEING PROX OF OTHER ACFT I ROLLED INTO A 50 DEG BANK AND STARTED DSCNT. TCASII THEN CALLED 'CLB XING CLB.' I CONTINUED DSCNT AND TURN. I DO NOT KNOW HOW CLOSE WE CAME TO THE OTHER ACFT. THE VOLUME OF THE 'TFC, TFC' IS TOO LOUD IF IT CUTS OUT ATC. I FEEL THAT IF I HAD LEVELED WINGS TO CLB AS TCASII INSTRUCTED AND OUR OPERATING MANUAL SPECIFIES, WE MAY HAVE WELL HIT THE OTHER ACFT. SUPPLEMENTAL INFO FROM ACN 193480. MLG WAS ESTABLISHED ON LOC AT 4000 FT AND CLRED FOR THE APCH. ATC ISSUED CLRNC 'ACR DSND/ MAINTAIN 3000.' HOWEVER, THE CALL SIGN WAS PARTIALLY COVERED BY THE COCKPIT TCASII ISSUING A LOUD 'TFC, TFC' WARNING. COPLT SET IN 3000 FT IN ALT ARMED WINDOW, BUT ACFT REMAINED AT 4000 FT WHILE THE COPLT CALLED ATC TO VERIFY 3200 FT WAS FOR MLG. AN ATC SUPVR CAME ABRUPTLY ON LINE AND TOLD MLG TO DSND IMMEDIATELY TO 3000 FT IMMEDIATE R TURN TO 270 DEG. CAPT BEGAN EXACTLY THAT, USING 50 DEG R BANK AND PUSHING NOSE DOWN. AT THIS POINT THE TCASII WARNED 'MONITOR VERT SPD' AND THE CAME WAS COVERED IN RED LIGHTS EXCEPT FOR GREEN LIGHTS AT 1500 FPM CLB. CAPT SAYS TCASII ALSO ISSUED 'CLB, CROSSOVER CLB', BUT I DO NOT RECALL THAT. I FEEL ONCE BEGINNING THE EVASIVE DSNDING R TURN, THE FLC WAS COMMITTED TO THAT COURSE OF ACTION AND AT THAT POINT GOING FROM STEEP DSCNT TO A CLB WOULD HAVE BEEN A HAZARDOUS COURSE OF ACTION. QUESTION: ALTHOUGH YOU MAY DEVIATE (ARE REQUIRED TO BY COMPANY) FROM ATC INSTRUCTIONS DUE TO A TCASII RA, WHO DO YOU FOLLOW WHEN BOTH ARE GIVING DIFFERENT EVASIVE COURSES OF ACTION? AND DO YOU STOP MIDWAY THROUGH ONE COURSE OF ACTION TO FOLLOW ANOTHER?

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.

Approach controller gave descent instructions for traffic, TCASII said climb. Flight crew followed controller clearance, aircraft pass in close proximity.