Air carrier Y descent through occupied altitude TCASII TA RA had less than standard separation from ...

Attributes
ACN	210797
Time
Date	199205
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : atl
State Reference	GA
Altitude	msl bound lower : 3000 msl bound upper : 3400
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 12
ASRS Report	210797
Person 2
Affiliation	government : faa
Function	controller : handoff position
Qualification	controller : radar
Experience	controller radar : 11
ASRS Report	210803
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : investigated faa : reviewed incident with flight crew
Miss Distance	horizontal : 4200 vertical : 100
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Inter Facility Coordination Failure

Narrative:

Small transport X was vectored over atl in an IFR corridor northbound into fty at 5000 ft. The sector was becoming very busy at the time with various departures and arrs. The arrs into fty were of various type performance. Through the assistance of a handoff controller coordination was implemented to turn and descend the small transport X early towards the ILS 8 final. After arriving over the top of a ledge of airspace (3000 ft to surface) used for fty's localizer, the controller turned small transport X on a downwind heading towards final. In the meantime, an air carrier Y inbound to atl was vectored over the top and descended early for an ILS approach for runway 8L. The splitting off of final sectors for atl and the busy traffic of satellite contributed to a hurried vector from the controller. Supplemental information from acn 210803: I was working a handoff position. My radar controller had traffic sbound climbing to 6000. The other aircraft was northbound at 5000. I coordinated a heading and descent through another controller airspace which was approved. Supplemental information from acn 210889: I was flying air carrier Y on downwind (270 degree heading) for runway 8L in atl at 7000 ft MSL and instructed to descend to 4000 ft then further instructed to descend to 2800 ft. Spdbrakes were extended to increase descent rate. Descending through 4500 ft, I was instructed to turn left to 180 degrees (base leg). At approximately 3600-3800 ft MSL and turning through 230 degrees, a TCASII TA followed by the appearance of an aircraft symbol (10 mi range) below us and climbing. This was followed by a RA monitor descent followed by another RA climb/climb. Power was added, climb attitude was established and spdbrakes were stowed. Autoplt was disconnected when climb/climb advisory was received. We climbed to approximately 3800 ft, then ATC told us to maintain 3600 ft. After landing, I spoke with the approach control supervisor and he said we missed small transport X by about 100 ft vertical. TCASII worked well and gave us our first indication of the other aircraft.

Original NASA ASRS Text

Title: ACR Y DSCNT THROUGH OCCUPIED ALT TCASII TA RA HAD LTSS FROM SMT X. EVASIVE ACTION TAKEN CLB. SYS ERROR.

Narrative: SMT X WAS VECTORED OVER ATL IN AN IFR CORRIDOR NBOUND INTO FTY AT 5000 FT. THE SECTOR WAS BECOMING VERY BUSY AT THE TIME WITH VARIOUS DEPS AND ARRS. THE ARRS INTO FTY WERE OF VARIOUS TYPE PERFORMANCE. THROUGH THE ASSISTANCE OF A HDOF CTLR COORD WAS IMPLEMENTED TO TURN AND DSND THE SMT X EARLY TOWARDS THE ILS 8 FINAL. AFTER ARRIVING OVER THE TOP OF A LEDGE OF AIRSPACE (3000 FT TO SURFACE) USED FOR FTY'S LOC, THE CTLR TURNED SMT X ON A DOWNWIND HDG TOWARDS FINAL. IN THE MEANTIME, AN ACR Y INBOUND TO ATL WAS VECTORED OVER THE TOP AND DSNDED EARLY FOR AN ILS APCH FOR RWY 8L. THE SPLITTING OFF OF FINAL SECTORS FOR ATL AND THE BUSY TFC OF SATELLITE CONTRIBUTED TO A HURRIED VECTOR FROM THE CTLR. SUPPLEMENTAL INFO FROM ACN 210803: I WAS WORKING A HDOF POS. MY RADAR CTLR HAD TFC SBOUND CLBING TO 6000. THE OTHER ACFT WAS NBOUND AT 5000. I COORDINATED A HDG AND DSCNT THROUGH ANOTHER CTLR AIRSPACE WHICH WAS APPROVED. SUPPLEMENTAL INFO FROM ACN 210889: I WAS FLYING ACR Y ON DOWNWIND (270 DEG HDG) FOR RWY 8L IN ATL AT 7000 FT MSL AND INSTRUCTED TO DSND TO 4000 FT THEN FURTHER INSTRUCTED TO DSND TO 2800 FT. SPDBRAKES WERE EXTENDED TO INCREASE DSCNT RATE. DSNDING THROUGH 4500 FT, I WAS INSTRUCTED TO TURN L TO 180 DEGS (BASE LEG). AT APPROX 3600-3800 FT MSL AND TURNING THROUGH 230 DEGS, A TCASII TA FOLLOWED BY THE APPEARANCE OF AN ACFT SYMBOL (10 MI RANGE) BELOW US AND CLBING. THIS WAS FOLLOWED BY A RA MONITOR DSCNT FOLLOWED BY ANOTHER RA CLB/CLB. PWR WAS ADDED, CLB ATTITUDE WAS ESTABLISHED AND SPDBRAKES WERE STOWED. AUTOPLT WAS DISCONNECTED WHEN CLB/CLB ADVISORY WAS RECEIVED. WE CLBED TO APPROX 3800 FT, THEN ATC TOLD US TO MAINTAIN 3600 FT. AFTER LNDG, I SPOKE WITH THE APCH CTL SUPVR AND HE SAID WE MISSED SMT X BY ABOUT 100 FT VERT. TCASII WORKED WELL AND GAVE US OUR FIRST INDICATION OF THE OTHER ACFT.

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.

Air carrier Y descent through occupied altitude TCASII TA RA had less than standard separation from small transport X. Evasive action taken climb. System error.