Narrative:

The event occurred because ATC was too busy. I made a comment to the captain as we were approaching mkg that we were higher than usual at this point in the flight. Finally ZAU gave us 24000 ft and handed us off to another chicago frequency. They continued to leave us higher than usual. As I mentioned that we should ask for lower they came on and gave us lower mentioning that they had left us high. I began a descent of about 3000 FPM down to 14000 ft. They then assigned us an altitude of 10000 ft; 210 KTS; and a heading of 270 degrees as ATC was lining us up for the ILS runway 7R. We were level at 10000 ft for almost 1 min as we were entering the terminal area from the east. I was flying the aircraft. I noticed on TCAS that an aircraft appeared to be approaching our flight path 500 ft below us. He appeared to be following the shoreline south as we were headed west. We tried to alert ATC but he was so busy that we never had an opportunity to talk to him. The distance between our aircraft continued to decrease. We received a traffic caution. The aircraft was now showing 300 ft below us. I finally saw the airplane as we received the RA warning to climb. I immediately disconnected the autoplt; increased the power; and pitched up for the green on the vsi. I climbed about 500 ft before it stated that we were clear of the event. At that point I disconnected the climb. We advised ATC of our RA and deviation and returned back to our assigned altitude as soon as we determined it safe to do so. ATC acknowledged and told us to descend down to 7000 ft. We asked ATC if they were talking to the other aircraft and they stated that they were not talking to them. From my brief look at the other aircraft it appeared small; more than likely that of a GA aircraft. The WX was not too bad. Some scattered layers and maybe even a higher broken layer. There was a scattered layer reported at 600 ft. Therefore aircraft were shooting the ILS into runway 7R.

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Original NASA ASRS Text

Title: D328 EXPERIENCES NMAC WITH VFR TRAFFIC WHILE DESCENDING INTO MKG.

Narrative: THE EVENT OCCURRED BECAUSE ATC WAS TOO BUSY. I MADE A COMMENT TO THE CAPT AS WE WERE APCHING MKG THAT WE WERE HIGHER THAN USUAL AT THIS POINT IN THE FLT. FINALLY ZAU GAVE US 24000 FT AND HANDED US OFF TO ANOTHER CHICAGO FREQ. THEY CONTINUED TO LEAVE US HIGHER THAN USUAL. AS I MENTIONED THAT WE SHOULD ASK FOR LOWER THEY CAME ON AND GAVE US LOWER MENTIONING THAT THEY HAD LEFT US HIGH. I BEGAN A DSCNT OF ABOUT 3000 FPM DOWN TO 14000 FT. THEY THEN ASSIGNED US AN ALT OF 10000 FT; 210 KTS; AND A HDG OF 270 DEGS AS ATC WAS LINING US UP FOR THE ILS RWY 7R. WE WERE LEVEL AT 10000 FT FOR ALMOST 1 MIN AS WE WERE ENTERING THE TERMINAL AREA FROM THE E. I WAS FLYING THE ACFT. I NOTICED ON TCAS THAT AN ACFT APPEARED TO BE APCHING OUR FLT PATH 500 FT BELOW US. HE APPEARED TO BE FOLLOWING THE SHORELINE S AS WE WERE HEADED W. WE TRIED TO ALERT ATC BUT HE WAS SO BUSY THAT WE NEVER HAD AN OPPORTUNITY TO TALK TO HIM. THE DISTANCE BTWN OUR ACFT CONTINUED TO DECREASE. WE RECEIVED A TFC CAUTION. THE ACFT WAS NOW SHOWING 300 FT BELOW US. I FINALLY SAW THE AIRPLANE AS WE RECEIVED THE RA WARNING TO CLB. I IMMEDIATELY DISCONNECTED THE AUTOPLT; INCREASED THE PWR; AND PITCHED UP FOR THE GREEN ON THE VSI. I CLBED ABOUT 500 FT BEFORE IT STATED THAT WE WERE CLR OF THE EVENT. AT THAT POINT I DISCONNECTED THE CLB. WE ADVISED ATC OF OUR RA AND DEV AND RETURNED BACK TO OUR ASSIGNED ALT AS SOON AS WE DETERMINED IT SAFE TO DO SO. ATC ACKNOWLEDGED AND TOLD US TO DSND DOWN TO 7000 FT. WE ASKED ATC IF THEY WERE TALKING TO THE OTHER ACFT AND THEY STATED THAT THEY WERE NOT TALKING TO THEM. FROM MY BRIEF LOOK AT THE OTHER ACFT IT APPEARED SMALL; MORE THAN LIKELY THAT OF A GA ACFT. THE WX WAS NOT TOO BAD. SOME SCATTERED LAYERS AND MAYBE EVEN A HIGHER BROKEN LAYER. THERE WAS A SCATTERED LAYER RPTED AT 600 FT. THEREFORE ACFT WERE SHOOTING THE ILS INTO RWY 7R.

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.