Potential conflict that came near to being an near midair collision as a B777 climbs on a TCASII RA to avoid crossing VFR traffic at 12500 ft that was not reported to them by ARTCC radar controller at ZAU, il.

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Attributes
ACN	553438
Time
Date	200207
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	msl single value : 12500
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zau.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Route In Use	enroute airway : v170.airway
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	553438
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : airborne critical non adherence : published procedure non adherence : far non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took evasive action other
Consequence	faa : reviewed incident with flight crew other
Miss Distance	horizontal : 3000 vertical : 0
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During climb out after takeoff from ord, we received a TA followed immediately by an RA. The specifics are as follows: the aircraft was climbing to FL230. Passing between 12000 ft and 13000 ft, approximately position was 4246.1N 08724.1W and following 'traffic, traffic' followed immediately by an RA and 'maintain vertical speed.' the TCASII traffic was shown to be off to our right and 400 ft above us on my pfd. The vertical guidance from the RA was followed and all 3 pilots' attention was focused on visually identing the traffic. The effort was unsuccessful. Shortly after the aural clear of conflict was received, we immediately questioned the ATC controller who told us that he now had VFR traffic behind us at 12000 ft, but was not on his scope earlier, prior to the RA event. With my understanding of what constitutes an near midair collision, not sure whether this RA event satisfies the criteria. Our TCASII information showed the other aircraft at approximately level as he passed behind our aircraft. The lateral TCASII display, however, showed the 2 aircraft passing each other at approximately 1/2 mi.

Original NASA ASRS Text

Title: POTENTIAL CONFLICT THAT CAME NEAR TO BEING AN NMAC AS A B777 CLBS ON A TCASII RA TO AVOID XING VFR TFC AT 12500 FT THAT WAS NOT RPTED TO THEM BY ARTCC RADAR CTLR AT ZAU, IL.

Narrative: DURING CLBOUT AFTER TKOF FROM ORD, WE RECEIVED A TA FOLLOWED IMMEDIATELY BY AN RA. THE SPECIFICS ARE AS FOLLOWS: THE ACFT WAS CLBING TO FL230. PASSING BTWN 12000 FT AND 13000 FT, APPROX POS WAS 4246.1N 08724.1W AND FOLLOWING 'TFC, TFC' FOLLOWED IMMEDIATELY BY AN RA AND 'MAINTAIN VERT SPD.' THE TCASII TFC WAS SHOWN TO BE OFF TO OUR R AND 400 FT ABOVE US ON MY PFD. THE VERT GUIDANCE FROM THE RA WAS FOLLOWED AND ALL 3 PLTS' ATTN WAS FOCUSED ON VISUALLY IDENTING THE TFC. THE EFFORT WAS UNSUCCESSFUL. SHORTLY AFTER THE AURAL CLR OF CONFLICT WAS RECEIVED, WE IMMEDIATELY QUESTIONED THE ATC CTLR WHO TOLD US THAT HE NOW HAD VFR TFC BEHIND US AT 12000 FT, BUT WAS NOT ON HIS SCOPE EARLIER, PRIOR TO THE RA EVENT. WITH MY UNDERSTANDING OF WHAT CONSTITUTES AN NMAC, NOT SURE WHETHER THIS RA EVENT SATISFIES THE CRITERIA. OUR TCASII INFO SHOWED THE OTHER ACFT AT APPROX LEVEL AS HE PASSED BEHIND OUR ACFT. THE LATERAL TCASII DISPLAY, HOWEVER, SHOWED THE 2 ACFT PASSING EACH OTHER AT APPROX 1/2 MI.

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.