Narrative:

We were descending to 9000 ft on the janesville 4 arrival to ord in VFR conditions. I was the PF and the captain was the PNF. We set our altimeters to; if I remember correctly 30.23. I am not sure exactly if it was 30.21 or 30.23. All I remember it was higher than standard. About 3-4 mi before krena we leveled off at 9000 ft. ATC told us to contact chicago approach. Before the captain could talk to chicago approach; approach called for us to see if we were on the frequency. The captain replied with; checking in at 9000 ft with ATIS. ATC came back with there is an aircraft at 8500 ft unverified and fast moving. I thought to myself; who would be out here close to chicago and be a fast mover? We were both looking for the aircraft and that's when the TCAS system told us to 'climb climb.' I looked down and saw a 2000 FPM climb. I disconnected the autoplt and pushed up the thrust levers and at the exact time the captain called ATC to let them know we were in a climb due to an RA. It was a smooth climb and at about 9300 ft the RA said to 'monitor vertical speed' at a lower climb rate of about 300 ft or so. I started to push forward a little to keep from climbing so fast. At that time the intruder was at our 11-12 O'clock position. The FMS moved on to the next waypoint so I started to turn to ord. I happened to look down at the TCAS and I noticed that the intruder aircraft was only 300 ft below and climbing. It was a red box with an up arrow. The captain spotted the aircraft and it was not one; but 2 F-16's flying in formation. About then I looked again at our altitude and it was about 9400 ft. That should have put them at about 9000 ft to 9100 ft. They passed under our wing at about the 10 O'clock position. I caught a glimpse of the two fly right under the wing. They just looked like they owned the sky and made no move to get out of the way or make a course correction.

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Original NASA ASRS Text

Title: E145 HAS CONFLICT WITH VFR F16S OVER KRENA INTERSECTION AT 9000 MSL. TCAS RA SAVES THE DAY.

Narrative: WE WERE DSNDING TO 9000 FT ON THE JANESVILLE 4 ARR TO ORD IN VFR CONDITIONS. I WAS THE PF AND THE CAPT WAS THE PNF. WE SET OUR ALTIMETERS TO; IF I REMEMBER CORRECTLY 30.23. I AM NOT SURE EXACTLY IF IT WAS 30.21 OR 30.23. ALL I REMEMBER IT WAS HIGHER THAN STANDARD. ABOUT 3-4 MI BEFORE KRENA WE LEVELED OFF AT 9000 FT. ATC TOLD US TO CONTACT CHICAGO APCH. BEFORE THE CAPT COULD TALK TO CHICAGO APCH; APCH CALLED FOR US TO SEE IF WE WERE ON THE FREQ. THE CAPT REPLIED WITH; CHKING IN AT 9000 FT WITH ATIS. ATC CAME BACK WITH THERE IS AN ACFT AT 8500 FT UNVERIFIED AND FAST MOVING. I THOUGHT TO MYSELF; WHO WOULD BE OUT HERE CLOSE TO CHICAGO AND BE A FAST MOVER? WE WERE BOTH LOOKING FOR THE ACFT AND THAT'S WHEN THE TCAS SYS TOLD US TO 'CLB CLB.' I LOOKED DOWN AND SAW A 2000 FPM CLB. I DISCONNECTED THE AUTOPLT AND PUSHED UP THE THRUST LEVERS AND AT THE EXACT TIME THE CAPT CALLED ATC TO LET THEM KNOW WE WERE IN A CLB DUE TO AN RA. IT WAS A SMOOTH CLB AND AT ABOUT 9300 FT THE RA SAID TO 'MONITOR VERT SPD' AT A LOWER CLB RATE OF ABOUT 300 FT OR SO. I STARTED TO PUSH FORWARD A LITTLE TO KEEP FROM CLBING SO FAST. AT THAT TIME THE INTRUDER WAS AT OUR 11-12 O'CLOCK POS. THE FMS MOVED ON TO THE NEXT WAYPOINT SO I STARTED TO TURN TO ORD. I HAPPENED TO LOOK DOWN AT THE TCAS AND I NOTICED THAT THE INTRUDER ACFT WAS ONLY 300 FT BELOW AND CLBING. IT WAS A RED BOX WITH AN UP ARROW. THE CAPT SPOTTED THE ACFT AND IT WAS NOT ONE; BUT 2 F-16'S FLYING IN FORMATION. ABOUT THEN I LOOKED AGAIN AT OUR ALT AND IT WAS ABOUT 9400 FT. THAT SHOULD HAVE PUT THEM AT ABOUT 9000 FT TO 9100 FT. THEY PASSED UNDER OUR WING AT ABOUT THE 10 O'CLOCK POS. I CAUGHT A GLIMPSE OF THE TWO FLY RIGHT UNDER THE WING. THEY JUST LOOKED LIKE THEY OWNED THE SKY AND MADE NO MOVE TO GET OUT OF THE WAY OR MAKE A COURSE CORRECTION.

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.