Narrative:

On a flight from aspen, co, to denver, denver TRACON notified us of level 4 and 5 thunderstorms over the airport and were given the option to proceed or hold. We elected to hold at the bjc VOR until the WX permitted an approach. As we entered the hold at 11000 ft, TRACON had us exit and proceed northeast around the WX to try to make it in on runway 26. When we established a downwind to runway 26, an air carrier flight had just refused an approach due to microburst on the field. At this point, TRACON had us climb back up to 12000 ft to hold at the OM grasp of runway 26. My first officer was the PF while we entered holding. 3 other carriers were holding under us at this fix. At approximately XB28Z, TRACON had us turn to a heading of 360 degrees and to descend to 11000 ft. At this point, we were north of the grasp OM when we noticed a target on TCASII climbing rapidly into our assigned altitude while we were IMC. TRACON then noticed the closure and commanded a rapid descent to 11000 ft while we were at 11500 ft. This contradicted the TCASII climb and my judgement to begin a leveloff and immediate climb. I immediately assumed control of the aircraft and began a rapid climb and hard right turn to avoid the closure of 2 F18's into my altitude. As I began the right bank and climb, we broke out of IMC conditions where I saw 2 F18's pass under our left wing at approximately 250 ft. The other aircraft under us had also been vectored north and had to evade the traffic also. The near miss occurred north of grasp on vectors. In passing the F18's, I reported to approach control that I had performed a TCASII climb. After we were handed off to another sector, I requested the watch commander's number and why the situation had occurred. They apologized for putting us in jeopardy. Due to the WX, we diverted to our alternate to refuel. I contacted the watch commander, who immediately apologized for the incident and putting us in harm's way. He explained that TRACON was at total fault for the situation and that they were immediately investigating the breakdown in communication between 2 controllers. He said that neither controller was communicating with each other about the closing aircraft, and neither knew what the F18's were doing. The commander said and we agreed that if I had not performed the TCASII climb and evasive maneuvers that we would have had a head-on collision with the F18's. I immediately reported to my flight control and director of operations of the incident. If not for the awareness of the crew and the immediate action following the TCASII RA, this could have been a report by the NTSB. Thanks to the advancement of TCASII and the training to react to its commands, my crew and I will continue to fly in a safer environment even when human error happens.

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Original NASA ASRS Text

Title: ACR D328 FLC, RESPONDING TO A TCASII RA, INITIATES EVASIVE MANEUVERS WHILE HOLDING FOR WX AT DEN RWY 26 OM. TRACON APCH CTLRS HAVE BREAKDOWN WITH INTRAFAC COORD AND F18'S FLY THROUGH HOLDING STACK OF 4 ACFT.

Narrative: ON A FLT FROM ASPEN, CO, TO DENVER, DENVER TRACON NOTIFIED US OF LEVEL 4 AND 5 TSTMS OVER THE ARPT AND WERE GIVEN THE OPTION TO PROCEED OR HOLD. WE ELECTED TO HOLD AT THE BJC VOR UNTIL THE WX PERMITTED AN APCH. AS WE ENTERED THE HOLD AT 11000 FT, TRACON HAD US EXIT AND PROCEED NE AROUND THE WX TO TRY TO MAKE IT IN ON RWY 26. WHEN WE ESTABLISHED A DOWNWIND TO RWY 26, AN ACR FLT HAD JUST REFUSED AN APCH DUE TO MICROBURST ON THE FIELD. AT THIS POINT, TRACON HAD US CLB BACK UP TO 12000 FT TO HOLD AT THE OM GRASP OF RWY 26. MY FO WAS THE PF WHILE WE ENTERED HOLDING. 3 OTHER CARRIERS WERE HOLDING UNDER US AT THIS FIX. AT APPROX XB28Z, TRACON HAD US TURN TO A HDG OF 360 DEGS AND TO DSND TO 11000 FT. AT THIS POINT, WE WERE N OF THE GRASP OM WHEN WE NOTICED A TARGET ON TCASII CLBING RAPIDLY INTO OUR ASSIGNED ALT WHILE WE WERE IMC. TRACON THEN NOTICED THE CLOSURE AND COMMANDED A RAPID DSCNT TO 11000 FT WHILE WE WERE AT 11500 FT. THIS CONTRADICTED THE TCASII CLB AND MY JUDGEMENT TO BEGIN A LEVELOFF AND IMMEDIATE CLB. I IMMEDIATELY ASSUMED CTL OF THE ACFT AND BEGAN A RAPID CLB AND HARD R TURN TO AVOID THE CLOSURE OF 2 F18'S INTO MY ALT. AS I BEGAN THE R BANK AND CLB, WE BROKE OUT OF IMC CONDITIONS WHERE I SAW 2 F18'S PASS UNDER OUR L WING AT APPROX 250 FT. THE OTHER ACFT UNDER US HAD ALSO BEEN VECTORED N AND HAD TO EVADE THE TFC ALSO. THE NEAR MISS OCCURRED N OF GRASP ON VECTORS. IN PASSING THE F18'S, I RPTED TO APCH CTL THAT I HAD PERFORMED A TCASII CLB. AFTER WE WERE HANDED OFF TO ANOTHER SECTOR, I REQUESTED THE WATCH COMMANDER'S NUMBER AND WHY THE SIT HAD OCCURRED. THEY APOLOGIZED FOR PUTTING US IN JEOPARDY. DUE TO THE WX, WE DIVERTED TO OUR ALTERNATE TO REFUEL. I CONTACTED THE WATCH COMMANDER, WHO IMMEDIATELY APOLOGIZED FOR THE INCIDENT AND PUTTING US IN HARM'S WAY. HE EXPLAINED THAT TRACON WAS AT TOTAL FAULT FOR THE SIT AND THAT THEY WERE IMMEDIATELY INVESTIGATING THE BREAKDOWN IN COM BTWN 2 CTLRS. HE SAID THAT NEITHER CTLR WAS COMMUNICATING WITH EACH OTHER ABOUT THE CLOSING ACFT, AND NEITHER KNEW WHAT THE F18'S WERE DOING. THE COMMANDER SAID AND WE AGREED THAT IF I HAD NOT PERFORMED THE TCASII CLB AND EVASIVE MANEUVERS THAT WE WOULD HAVE HAD A HEAD-ON COLLISION WITH THE F18'S. I IMMEDIATELY RPTED TO MY FLT CTL AND DIRECTOR OF OPS OF THE INCIDENT. IF NOT FOR THE AWARENESS OF THE CREW AND THE IMMEDIATE ACTION FOLLOWING THE TCASII RA, THIS COULD HAVE BEEN A RPT BY THE NTSB. THANKS TO THE ADVANCEMENT OF TCASII AND THE TRAINING TO REACT TO ITS COMMANDS, MY CREW AND I WILL CONTINUE TO FLY IN A SAFER ENVIRONMENT EVEN WHEN HUMAN ERROR HAPPENS.

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.