A DC9 flight crew observed and received a TCASII RA from an opposite direction B737 at same altitude...

Attributes
ACN	453523
Time
Date	199910
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : atl.airport
State Reference	GA
Altitude	msl single value : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
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 : 15000 flight time type : 5000
ASRS Report	453523
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 210 flight time total : 12000 flight time type : 6400
ASRS Report	453374
Events
Anomaly	non adherence : clearance
Independent Detector	aircraft equipment : tcas other controllera other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	vertical : 0
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We noticed TCASII traffic at our altitude but could not immediately determine its direction of travel. Upon visual acquisition, still could not tell if coming or going away and assumed same direction of flight but kept watch of the target. Simultaneously, we were given a frequency change, we determined that the other aircraft was going straight at us and controller asked 'aircraft Y, where are you going?' I commanded an evasive left turn, as the first officer was flying, which he started when we got a TCASII RA to climb and the controller issued an immediate left turn. We were already in the turn and climbing slightly per the TCASII. The other aircraft (aircraft Y B737) passed to our right, also in a left bank. It appeared to be at least as close as one would get on a parallel ILS approach.

Original NASA ASRS Text

Title: A DC9 FLC OBSERVED AND RECEIVED A TCASII RA FROM AN OPPOSITE DIRECTION B737 AT SAME ALT.

Narrative: WE NOTICED TCASII TFC AT OUR ALT BUT COULD NOT IMMEDIATELY DETERMINE ITS DIRECTION OF TRAVEL. UPON VISUAL ACQUISITION, STILL COULD NOT TELL IF COMING OR GOING AWAY AND ASSUMED SAME DIRECTION OF FLT BUT KEPT WATCH OF THE TARGET. SIMULTANEOUSLY, WE WERE GIVEN A FREQ CHANGE, WE DETERMINED THAT THE OTHER ACFT WAS GOING STRAIGHT AT US AND CTLR ASKED 'ACFT Y, WHERE ARE YOU GOING?' I COMMANDED AN EVASIVE L TURN, AS THE FO WAS FLYING, WHICH HE STARTED WHEN WE GOT A TCASII RA TO CLB AND THE CTLR ISSUED AN IMMEDIATE L TURN. WE WERE ALREADY IN THE TURN AND CLBING SLIGHTLY PER THE TCASII. THE OTHER ACFT (ACFT Y B737) PASSED TO OUR R, ALSO IN A L BANK. IT APPEARED TO BE AT LEAST AS CLOSE AS ONE WOULD GET ON A PARALLEL ILS APCH.

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.