Narrative:

I was the PF in VFR conditions; but I requested the ILS due to scattered layer of cumulus clouds with a base of 5000 ft and tops to 14000 ft. The ASOS for acv airport was reporting clear. I was issued a prior clearance to descend to 10000 ft. I then was issued a new clearance to cross yager intersection at or above 7000 ft; cleared for the ILS runway 32 at acv. I was on a right base to join the localizer; but at yager at 28.9 DME there was a small cumulus cloud with a top of 14000 ft. I asked the PNF to request if we could track left of the localizer (1 DOT) to stay in smooth air and VFR conditions. As the localizer needle was coming alive I was in a right bank to join and skirting the edge of the cumulus cloud while the PNF was transmitting my request. At that point I thought the centerline would be left of the cumulus cloud; but I wanted permission to track left of the course just in case the centerline was in the middle of the cloud. For the 5 mi prior to joining the localizer; my GS indicator was showing that I was on the glidepath altitude. After the PNF finished asking for my request I was still in a right turn; but now 1 to 1 1/2 DOT left of the centerline proceeding inbound. The controller replied back; 'negative; traffic alert; you have opposite direction traffic at your same altitude; 8200 ft.' I couldn't see the traffic visually; but then our TCAS showed the traffic as a yellow TA advisory. I immediately deployed the air brakes and descended to our new cleared altitude of 6000 ft. We then saw the traffic to our right and it was approximately on the centerline of the localizer tracking outbound and climbing. I couldn't figure out why the climbing traffic was on the centerline outbound when we were cleared inbound. The climbing traffic was in VFR conditions.

Google
 

Original NASA ASRS Text

Title: DA50 FLT CREW ON ILS APCH TO ACV RPTS CONFLICT WITH OPPOSITE DIRECTION C208.

Narrative: I WAS THE PF IN VFR CONDITIONS; BUT I REQUESTED THE ILS DUE TO SCATTERED LAYER OF CUMULUS CLOUDS WITH A BASE OF 5000 FT AND TOPS TO 14000 FT. THE ASOS FOR ACV ARPT WAS RPTING CLR. I WAS ISSUED A PRIOR CLRNC TO DSND TO 10000 FT. I THEN WAS ISSUED A NEW CLRNC TO CROSS YAGER INTXN AT OR ABOVE 7000 FT; CLRED FOR THE ILS RWY 32 AT ACV. I WAS ON A R BASE TO JOIN THE LOC; BUT AT YAGER AT 28.9 DME THERE WAS A SMALL CUMULUS CLOUD WITH A TOP OF 14000 FT. I ASKED THE PNF TO REQUEST IF WE COULD TRACK L OF THE LOC (1 DOT) TO STAY IN SMOOTH AIR AND VFR CONDITIONS. AS THE LOC NEEDLE WAS COMING ALIVE I WAS IN A R BANK TO JOIN AND SKIRTING THE EDGE OF THE CUMULUS CLOUD WHILE THE PNF WAS XMITTING MY REQUEST. AT THAT POINT I THOUGHT THE CTRLINE WOULD BE L OF THE CUMULUS CLOUD; BUT I WANTED PERMISSION TO TRACK L OF THE COURSE JUST IN CASE THE CTRLINE WAS IN THE MIDDLE OF THE CLOUD. FOR THE 5 MI PRIOR TO JOINING THE LOC; MY GS INDICATOR WAS SHOWING THAT I WAS ON THE GLIDEPATH ALT. AFTER THE PNF FINISHED ASKING FOR MY REQUEST I WAS STILL IN A R TURN; BUT NOW 1 TO 1 1/2 DOT L OF THE CTRLINE PROCEEDING INBOUND. THE CTLR REPLIED BACK; 'NEGATIVE; TFC ALERT; YOU HAVE OPPOSITE DIRECTION TFC AT YOUR SAME ALT; 8200 FT.' I COULDN'T SEE THE TFC VISUALLY; BUT THEN OUR TCAS SHOWED THE TFC AS A YELLOW TA ADVISORY. I IMMEDIATELY DEPLOYED THE AIR BRAKES AND DSNDED TO OUR NEW CLRED ALT OF 6000 FT. WE THEN SAW THE TFC TO OUR R AND IT WAS APPROX ON THE CTRLINE OF THE LOC TRACKING OUTBOUND AND CLBING. I COULDN'T FIGURE OUT WHY THE CLBING TFC WAS ON THE CTRLINE OUTBOUND WHEN WE WERE CLRED INBOUND. THE CLBING TFC WAS IN VFR CONDITIONS.

Data retrieved from NASA's ASRS site as of January 2009 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.