MD88 crew had near midair collision with a light twin in ZTL class a.

Attributes
ACN	441820
Time
Date	199907
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : atl.vortac
State Reference	GA
Altitude	msl single value : 20000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl.artcc
Operator	common carrier : air carrier
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : macey 2 arrival
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : ztl.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : multi engine
Experience	flight time last 90 days : 175 flight time total : 10000 flight time type : 5000
ASRS Report	441820
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 20000 flight time type : 2200
ASRS Report	441620
Events
Anomaly	conflict : nmac non adherence : required legal separation
Independent Detector	aircraft equipment : tcas
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 500 vertical : 0
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Shortly after receiving clearance to descend (to be at 'womac at 13000 ft') and around FL200, we received a TCASII RA with traffic symbol below and at our 1 O'clock position. We immediately responded to the RA and shortly visually spotted the traffic. The aircraft was definitely on a collision course with us. We stopped the descent and pulled up, missing the traffic by an estimated 500 ft horizontally and 0-200 ft vertically. Several passenger commented upon leaving, that they saw the traffic and that it was 'very close.' it was a light twin that appeared to be in level flight passing from our right to our left, under our nose. We reported to the center that we were responding to an RA and had traffic in sight. We asked him if he was working the other traffic and he said he was and 'thanks for the help.' I truly believe the TCASII prevented a collision in this case, unless we would have been lucky enough to see him in time (unlikely).

Original NASA ASRS Text

Title: MD88 CREW HAD NMAC WITH A LIGHT TWIN IN ZTL CLASS A.

Narrative: SHORTLY AFTER RECEIVING CLRNC TO DSND (TO BE AT 'WOMAC AT 13000 FT') AND AROUND FL200, WE RECEIVED A TCASII RA WITH TFC SYMBOL BELOW AND AT OUR 1 O'CLOCK POS. WE IMMEDIATELY RESPONDED TO THE RA AND SHORTLY VISUALLY SPOTTED THE TFC. THE ACFT WAS DEFINITELY ON A COLLISION COURSE WITH US. WE STOPPED THE DSCNT AND PULLED UP, MISSING THE TFC BY AN ESTIMATED 500 FT HORIZLY AND 0-200 FT VERTLY. SEVERAL PAX COMMENTED UPON LEAVING, THAT THEY SAW THE TFC AND THAT IT WAS 'VERY CLOSE.' IT WAS A LIGHT TWIN THAT APPEARED TO BE IN LEVEL FLT PASSING FROM OUR R TO OUR L, UNDER OUR NOSE. WE RPTED TO THE CTR THAT WE WERE RESPONDING TO AN RA AND HAD TFC IN SIGHT. WE ASKED HIM IF HE WAS WORKING THE OTHER TFC AND HE SAID HE WAS AND 'THANKS FOR THE HELP.' I TRULY BELIEVE THE TCASII PREVENTED A COLLISION IN THIS CASE, UNLESS WE WOULD HAVE BEEN LUCKY ENOUGH TO SEE HIM IN TIME (UNLIKELY).

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.