A300 landing boi has conflict with preceding B757.

Attributes
ACN	578054
Time
Date	200304
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : boi.airport
State Reference	ID
Altitude	msl single value : 5000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : boi.tracon
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : boi.tracon
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 100 flight time total : 13000 flight time type : 900
ASRS Report	578054
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : investigated
Miss Distance	vertical : 600
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

We were being vectored to the east runway for a landing at boi. The first officer was flying to an assigned heading of 280 degrees (downwind) at 8000 ft MSL. The aircraft we were following was a B757. Just as we rolled out of the 280 degree heading the approach controller gave us a clearance to descend to 5000 ft MSL. The WX conditions were IMC (in and out of clouds) with visibilities 2-3 mi. As we were descending the B757 was given a 270 degrees left turn to set them up for a landing to the west. This was due to a sudden change in the surface winds. As this aircraft completed its turn the controller told us to level at 7000 ft MSL. By this time we were already at 5600 ft MSL descending to 5000 ft MSL. At this time the TCASII displayed an RA situation and commanded an immediate climb of 2000 ft or better. This was accomplished and the B757 stated that he was descending. After landing I called RAPCON and talked to the controller. He stated that 'he intended to have our aircraft descend to 7000 ft MSL versus 5000 ft MSL and have the B757 cross under us on his base leg.' the tapes were pulled and confirmed that we were given a clearance to 5000 ft versus 7000 ft MSL as he had intended.

Original NASA ASRS Text

Title: A300 LNDG BOI HAS CONFLICT WITH PRECEDING B757.

Narrative: WE WERE BEING VECTORED TO THE E RWY FOR A LNDG AT BOI. THE FO WAS FLYING TO AN ASSIGNED HEADING OF 280 DEGS (DOWNWIND) AT 8000 FT MSL. THE ACFT WE WERE FOLLOWING WAS A B757. JUST AS WE ROLLED OUT OF THE 280 DEG HDG THE APCH CTLR GAVE US A CLRNC TO DSND TO 5000 FT MSL. THE WX CONDITIONS WERE IMC (IN AND OUT OF CLOUDS) WITH VISIBILITIES 2-3 MI. AS WE WERE DSNDING THE B757 WAS GIVEN A 270 DEGS L TURN TO SET THEM UP FOR A LNDG TO THE W. THIS WAS DUE TO A SUDDEN CHANGE IN THE SURFACE WINDS. AS THIS ACFT COMPLETED ITS TURN THE CTLR TOLD US TO LEVEL AT 7000 FT MSL. BY THIS TIME WE WERE ALREADY AT 5600 FT MSL DSNDING TO 5000 FT MSL. AT THIS TIME THE TCASII DISPLAYED AN RA SIT AND COMMANDED AN IMMEDIATE CLB OF 2000 FT OR BETTER. THIS WAS ACCOMPLISHED AND THE B757 STATED THAT HE WAS DSNDING. AFTER LNDG I CALLED RAPCON AND TALKED TO THE CTLR. HE STATED THAT 'HE INTENDED TO HAVE OUR ACFT DSND TO 7000 FT MSL VERSUS 5000 FT MSL AND HAVE THE B757 CROSS UNDER US ON HIS BASE LEG.' THE TAPES WERE PULLED AND CONFIRMED THAT WE WERE GIVEN A CLRNC TO 5000 FT VERSUS 7000 FT MSL AS HE HAD INTENDED.

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.