Narrative:

Air carrier X was cleared from a heading direct altur NDB 210 KTS at 11000 ft. We were approximately 20 mi out from denver VOR. We were asked by approach if we had the airport at 1 O'clock and commuter traffic at 2 O'clock for runway 25. We replied we have the airport but negative contact on the traffic. At approximately 3 mi east of altur, we saw a commuter above us at 10 O'clock heading southeast. We asked to slow down to configure but controller said hold 210 to altur cleared the visual runway 26R. We again advised that we did not see the traffic. Controller replied he's at 2 O'clock speed your discretion contact tower. Captain contacted tower and advised negative on the traffic. Tower also advised an medium large transport on ILS for 26L. TCASII showed 2 aircraft. The medium large transport and the sebound commuter. Captain asked tower if commuter at 10 O'clock was our traffic. The tower did not respond to us but said to the commuter turn back right cleared 25 visual, traffic is an medium large transport for 26L. He did not advise him of us. An large transport for runway 26R. We could see we were in his blind side as he turned back to the field. The captain then said to tower 'we are on the visual for 26R' we identify ourselves by the proper call sign. The TCASII reported 'traffic' for the medium large transport on runway 26L. The tower again did not respond to us but said to the commuter 'tighten the turn now, cleared 25.' the commuter was over 26L centerline and above us. He went to a very steep bank perhaps 45 degree. Our TCASII now called 'traffic' for the commuter. We knew the conflict was going to occur due to the sudden and pronounced turn and descent. He did not see us and to line up properly for 25 he cut right across 26R centerline and held steep descent to get down for the runway. We could not do a go around as we might have flown into him. We could not turn left due to the medium large transport on ILS for runway 26L. The only way to avoid this aircraft was to do a formation descent with him. The captain called out on the radio 'he is descending on top of us.' the tower did not respond. I could see him on the left of us. I increased descent to 2500 FPM. I saw him through the eyebrow windows. If I did anything else at this point my tail could have hit him or my wings could have hit him. If I did not lock onto him in a formation descent he would have hit us. As he cleared us to the right I arrested the descent. This occurred inside altur. We stabilized the aircraft on the approach, slowed to approach speed to accommodate an medium large transport on short final 26R, and made an uneventful landing at denver.

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Original NASA ASRS Text

Title: ACR X TCASII TA HAD NMAC WITH COMMUTER Y. VISUAL APCH EVASIVE ACTION TAKEN . SEE AND AVOID CONCEPT.

Narrative: ACR X WAS CLRED FROM A HDG DIRECT ALTUR NDB 210 KTS AT 11000 FT. WE WERE APPROX 20 MI OUT FROM DENVER VOR. WE WERE ASKED BY APCH IF WE HAD THE ARPT AT 1 O'CLOCK AND COMMUTER TFC AT 2 O'CLOCK FOR RWY 25. WE REPLIED WE HAVE THE ARPT BUT NEGATIVE CONTACT ON THE TFC. AT APPROX 3 MI E OF ALTUR, WE SAW A COMMUTER ABOVE US AT 10 O'CLOCK HDG SE. WE ASKED TO SLOW DOWN TO CONFIGURE BUT CTLR SAID HOLD 210 TO ALTUR CLRED THE VISUAL RWY 26R. WE AGAIN ADVISED THAT WE DID NOT SEE THE TFC. CTLR REPLIED HE'S AT 2 O'CLOCK SPD YOUR DISCRETION CONTACT TWR. CAPT CONTACTED TWR AND ADVISED NEGATIVE ON THE TFC. TWR ALSO ADVISED AN MLG ON ILS FOR 26L. TCASII SHOWED 2 ACFT. THE MLG AND THE SEBOUND COMMUTER. CAPT ASKED TWR IF COMMUTER AT 10 O'CLOCK WAS OUR TFC. THE TWR DID NOT RESPOND TO US BUT SAID TO THE COMMUTER TURN BACK R CLRED 25 VISUAL, TFC IS AN MLG FOR 26L. HE DID NOT ADVISE HIM OF US. AN LGT FOR RWY 26R. WE COULD SEE WE WERE IN HIS BLIND SIDE AS HE TURNED BACK TO THE FIELD. THE CAPT THEN SAID TO TWR 'WE ARE ON THE VISUAL FOR 26R' WE IDENT OURSELVES BY THE PROPER CALL SIGN. THE TCASII RPTED 'TFC' FOR THE MLG ON RWY 26L. THE TWR AGAIN DID NOT RESPOND TO US BUT SAID TO THE COMMUTER 'TIGHTEN THE TURN NOW, CLRED 25.' THE COMMUTER WAS OVER 26L CENTERLINE AND ABOVE US. HE WENT TO A VERY STEEP BANK PERHAPS 45 DEG. OUR TCASII NOW CALLED 'TFC' FOR THE COMMUTER. WE KNEW THE CONFLICT WAS GOING TO OCCUR DUE TO THE SUDDEN AND PRONOUNCED TURN AND DSCNT. HE DID NOT SEE US AND TO LINE UP PROPERLY FOR 25 HE CUT RIGHT ACROSS 26R CENTERLINE AND HELD STEEP DSCNT TO GET DOWN FOR THE RWY. WE COULD NOT DO A GAR AS WE MIGHT HAVE FLOWN INTO HIM. WE COULD NOT TURN L DUE TO THE MLG ON ILS FOR RWY 26L. THE ONLY WAY TO AVOID THIS ACFT WAS TO DO A FORMATION DSCNT WITH HIM. THE CAPT CALLED OUT ON THE RADIO 'HE IS DSNDING ON TOP OF US.' THE TWR DID NOT RESPOND. I COULD SEE HIM ON THE L OF US. I INCREASED DSCNT TO 2500 FPM. I SAW HIM THROUGH THE EYEBROW WINDOWS. IF I DID ANYTHING ELSE AT THIS POINT MY TAIL COULD HAVE HIT HIM OR MY WINGS COULD HAVE HIT HIM. IF I DID NOT LOCK ONTO HIM IN A FORMATION DSCNT HE WOULD HAVE HIT US. AS HE CLRED US TO THE R I ARRESTED THE DSCNT. THIS OCCURRED INSIDE ALTUR. WE STABILIZED THE ACFT ON THE APCH, SLOWED TO APCH SPD TO ACCOMMODATE AN MLG ON SHORT FINAL 26R, AND MADE AN UNEVENTFUL LNDG AT DENVER.

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.