Air carrier X TCASII RA descend had near midair collision with aircraft Y. See and avoid concept.

Attributes
ACN	245559
Time
Date	199306
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : aqn
State Reference	TX
Altitude	msl bound lower : 12500 msl bound upper : 12500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dfw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 8000 flight time type : 2500
ASRS Report	245559
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 200 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

Air carrier X on the AQN2 arrival to dfw. We were cleared to descend to 11000 ft and to cut the corner east of aqn to intercept the 040 degree radial outbound. At about 12500 ft and descending, we received a TCASII TA at 11 O'clock, about 7-8 mi (yellow intruder) at 1000 ft below our altitude. At about 4-5 mi we got the red RA and instructions to descend at a minimum of 1500 FPM. We responded accordingly while looking outside. We got a visual on the intruding light aircraft Y at about 1 mi. He passed above us at about 500 ft and maybe slightly behind us. At no time were we advised of this traffic by ATC. Only after we called it did the controller acknowledge it. Later phone call with sector supervisor indicated that the controller was extremely busy handling both acton and boids arrs to dfw and acknowledged that she simply missed the traffic. Otherwise we would never have been cleared to 11000 ft through the intruder's altitude. TCASII saved our bacon! It was very uncomfortable being directed to descend through a yet unseen (but very close) intruder's altitude, but TCASII obviously had it all figured out. Recommendation: properly staff busy sectors during peak hours to reduce chances of this type situation.

Original NASA ASRS Text

Title: ACR X TCASII RA DSND HAD NMAC WITH ACFT Y. SEE AND AVOID CONCEPT.

Narrative: ACR X ON THE AQN2 ARR TO DFW. WE WERE CLRED TO DSND TO 11000 FT AND TO CUT THE CORNER E OF AQN TO INTERCEPT THE 040 DEG RADIAL OUTBOUND. AT ABOUT 12500 FT AND DSNDING, WE RECEIVED A TCASII TA AT 11 O'CLOCK, ABOUT 7-8 MI (YELLOW INTRUDER) AT 1000 FT BELOW OUR ALT. AT ABOUT 4-5 MI WE GOT THE RED RA AND INSTRUCTIONS TO DSND AT A MINIMUM OF 1500 FPM. WE RESPONDED ACCORDINGLY WHILE LOOKING OUTSIDE. WE GOT A VISUAL ON THE INTRUDING LIGHT ACFT Y AT ABOUT 1 MI. HE PASSED ABOVE US AT ABOUT 500 FT AND MAYBE SLIGHTLY BEHIND US. AT NO TIME WERE WE ADVISED OF THIS TFC BY ATC. ONLY AFTER WE CALLED IT DID THE CTLR ACKNOWLEDGE IT. LATER PHONE CALL WITH SECTOR SUPVR INDICATED THAT THE CTLR WAS EXTREMELY BUSY HANDLING BOTH ACTON AND BOIDS ARRS TO DFW AND ACKNOWLEDGED THAT SHE SIMPLY MISSED THE TFC. OTHERWISE WE WOULD NEVER HAVE BEEN CLRED TO 11000 FT THROUGH THE INTRUDER'S ALT. TCASII SAVED OUR BACON! IT WAS VERY UNCOMFORTABLE BEING DIRECTED TO DSND THROUGH A YET UNSEEN (BUT VERY CLOSE) INTRUDER'S ALT, BUT TCASII OBVIOUSLY HAD IT ALL FIGURED OUT. RECOMMENDATION: PROPERLY STAFF BUSY SECTORS DURING PEAK HRS TO REDUCE CHANCES OF THIS TYPE SIT.

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.