B757 has TCASII RA and traffic conflict at atl when another aircraft is vectored across flight path.

Attributes
ACN	455730
Time
Date	199911
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : atl.airport
State Reference	GA
Altitude	msl single value : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other Other
Flight Phase	descent : approach
Route In Use	approach other arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other Other
Flight Phase	descent : approach
Route In Use	approach other arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp pilot : multi engine
Experience	flight time last 90 days : 200 flight time total : 15000 flight time type : 2000
ASRS Report	455730
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : atp
ASRS Report	455329
Events
Anomaly	conflict : airborne critical non adherence : published procedure non adherence : required legal separation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 6000 vertical : 0
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

We were on left downwind for runway 8L at atl at 11000 ft, 210 KTS. ATC cleared us to 7000 ft, slow to 170 KTS. Controller then told us to maintain 210 KTS and frequency change. Final controller cleared us to 5000 ft with 5 degree right turn (275 degree heading). We were about 2 mi behind another B757 who was at our 1 O'clock position. I expedited the descent to 5000 ft expecting to be turned in first. I was uncomfortable with the spacing and began to slow to 180 KTS. ATC then turned the other aircraft to 180 degrees across our path. He was still descending to 5000 ft but our TCASII commanded 'climb.' I turned about 15 degrees right to fly behind him rather than pull up into him straight ahead. Once clear, I returned to my assigned heading. I believe the final controller assumed we were at 170 KTS not 210 KTS and was unaware of the decreased separation. Had we been directly behind the lead aircraft, the problem would not have been as great. Supplemental information from acn 455329: the controller should have noted our overtake, then either issue us a slower speed, or could have turned us to base leg first. Additionally, a more timely TA would have helped. It really didn't do much to help with the traffic directly in front of us and an RA going off at the same time.

Original NASA ASRS Text

Title: B757 HAS TCASII RA AND TFC CONFLICT AT ATL WHEN ANOTHER ACFT IS VECTORED ACROSS FLT PATH.

Narrative: WE WERE ON L DOWNWIND FOR RWY 8L AT ATL AT 11000 FT, 210 KTS. ATC CLRED US TO 7000 FT, SLOW TO 170 KTS. CTLR THEN TOLD US TO MAINTAIN 210 KTS AND FREQ CHANGE. FINAL CTLR CLRED US TO 5000 FT WITH 5 DEG R TURN (275 DEG HDG). WE WERE ABOUT 2 MI BEHIND ANOTHER B757 WHO WAS AT OUR 1 O'CLOCK POS. I EXPEDITED THE DSCNT TO 5000 FT EXPECTING TO BE TURNED IN FIRST. I WAS UNCOMFORTABLE WITH THE SPACING AND BEGAN TO SLOW TO 180 KTS. ATC THEN TURNED THE OTHER ACFT TO 180 DEGS ACROSS OUR PATH. HE WAS STILL DSNDING TO 5000 FT BUT OUR TCASII COMMANDED 'CLB.' I TURNED ABOUT 15 DEGS R TO FLY BEHIND HIM RATHER THAN PULL UP INTO HIM STRAIGHT AHEAD. ONCE CLR, I RETURNED TO MY ASSIGNED HDG. I BELIEVE THE FINAL CTLR ASSUMED WE WERE AT 170 KTS NOT 210 KTS AND WAS UNAWARE OF THE DECREASED SEPARATION. HAD WE BEEN DIRECTLY BEHIND THE LEAD ACFT, THE PROB WOULD NOT HAVE BEEN AS GREAT. SUPPLEMENTAL INFO FROM ACN 455329: THE CTLR SHOULD HAVE NOTED OUR OVERTAKE, THEN EITHER ISSUE US A SLOWER SPD, OR COULD HAVE TURNED US TO BASE LEG FIRST. ADDITIONALLY, A MORE TIMELY TA WOULD HAVE HELPED. IT REALLY DIDN'T DO MUCH TO HELP WITH THE TFC DIRECTLY IN FRONT OF US AND AN RA GOING OFF AT THE SAME TIME.

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.