Narrative:

We were flying the boids 9 arrival (dfw bpr boids 9) in an medium large transport. Our clearance was to depart boids (bpr 108 degree right/13 DME) heading 100 degrees, intercept the dfw ILS runway 13R localizer, descend to 5000'. As we departed boids at 5000' and began slowing from 250 KTS to 210, we were instructed to switch to 118.1. On 118.1 the controller told us to fly 090 degrees to intercept the ILS, maintain 4000'. I read back the clearance, set the altitude alert to 4000' while the first officer set 090 degrees in the heading selector and initiated a descent to 4000'. As we descended through 4300' the controller asked where we were going and said maintain 5000'. The first officer stopped the descent and I advised approach that he'd cleared us to 4000'. At that time we saw an small transport Y commuter aircraft at our 1 O'clock position at 4000' and approximately 4-5 mi. The small transport Y was northbound, reported us in sight and maintain visual sep. He crossed about 3 mi in front of our nose. We continued to 4000', intercepted the ILS for an uneventful landing. Both the first officer and myself, as well as another pilot in the jumpseat, believe we were cleared to 4000'. I called the approach facility and the supervisor on duty had already talked to the controller involved. Because the WX was VMC, and since both aircraft crews saw each other and were able to maintain visual sep, no further action is being considered. The controller involved did sound a little upset by the event. (This happened during an arrival complex the day following the air carrier departure accident.) the potential for a serious accident did exist.

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Original NASA ASRS Text

Title: APCH CTLR ISSUED AN AMBIGUOUS CLRNC AND MLG HAD ALT DEVIATION WITH POTENTIAL CONFLICT.

Narrative: WE WERE FLYING THE BOIDS 9 ARR (DFW BPR BOIDS 9) IN AN MLG. OUR CLRNC WAS TO DEPART BOIDS (BPR 108 DEG R/13 DME) HDG 100 DEGS, INTERCEPT THE DFW ILS RWY 13R LOC, DSND TO 5000'. AS WE DEPARTED BOIDS AT 5000' AND BEGAN SLOWING FROM 250 KTS TO 210, WE WERE INSTRUCTED TO SWITCH TO 118.1. ON 118.1 THE CTLR TOLD US TO FLY 090 DEGS TO INTERCEPT THE ILS, MAINTAIN 4000'. I READ BACK THE CLRNC, SET THE ALT ALERT TO 4000' WHILE THE F/O SET 090 DEGS IN THE HDG SELECTOR AND INITIATED A DSCNT TO 4000'. AS WE DSNDED THROUGH 4300' THE CTLR ASKED WHERE WE WERE GOING AND SAID MAINTAIN 5000'. THE F/O STOPPED THE DSCNT AND I ADVISED APCH THAT HE'D CLRED US TO 4000'. AT THAT TIME WE SAW AN SMT Y COMMUTER ACFT AT OUR 1 O'CLOCK POS AT 4000' AND APPROX 4-5 MI. THE SMT Y WAS NBND, RPTED US IN SIGHT AND MAINTAIN VISUAL SEP. HE CROSSED ABOUT 3 MI IN FRONT OF OUR NOSE. WE CONTINUED TO 4000', INTERCEPTED THE ILS FOR AN UNEVENTFUL LNDG. BOTH THE F/O AND MYSELF, AS WELL AS ANOTHER PLT IN THE JUMPSEAT, BELIEVE WE WERE CLRED TO 4000'. I CALLED THE APCH FAC AND THE SUPVR ON DUTY HAD ALREADY TALKED TO THE CTLR INVOLVED. BECAUSE THE WX WAS VMC, AND SINCE BOTH ACFT CREWS SAW EACH OTHER AND WERE ABLE TO MAINTAIN VISUAL SEP, NO FURTHER ACTION IS BEING CONSIDERED. THE CTLR INVOLVED DID SOUND A LITTLE UPSET BY THE EVENT. (THIS HAPPENED DURING AN ARR COMPLEX THE DAY FOLLOWING THE ACR DEP ACCIDENT.) THE POTENTIAL FOR A SERIOUS ACCIDENT DID EXIST.

Data retrieved from NASA's ASRS site as of August 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.