Narrative:

During approach into den we were assigned the RNAV (rnp) Z runway 34R. Upon reaching himom (if) we were unable to continue the RNAV approach because we dropped LNAV and so we requested the visual approach to runway 34R. The controller cleared us for the visual approach to 34R then offered a runway change to 35L even though the controller stated that it might be 'a little late in the game to switch'. We accepted the runway change and decided to switch. I had already disconnected the autopilot and autothrottles in anticipation for landing on runway 34R. We were assigned a 080 heading for the visual to runway 35L. We were then given a subsequent turn to 020 to intercept final for runway 35L. Attempting to hand fly the aircraft and make sure the new approach was loaded by the captain; and acquire an electronic centerline to the new runway; my workload increased to a level I didn't anticipate. This caused me to inadvertently shallow my turn to final. While trying to work through this issue I lost situational awareness and was focused more on making sure the ILS was loaded for runway 35L instead of visually clearing my turn and getting established on final. During the turn to/through final we got an RA from TCAS that stated to level off. I leveled the aircraft and the captain notified ATC of the RA and they stated for us to fly the localizer for runway 35L. The controller then asked if we could continue the approach or if we needed to go missed approach. We were high and too close to continue the approach due to leveling off for the RA so we executed a missed approach and were given vectors for the missed. We were vectored for and flew the ILS to 35R and landed. After landing the ground controller gave us a number to contact denver TRACON. The captain [did so; and] discussed the events leading up to the approach.

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Original NASA ASRS Text

Title: B737NG First Officer reported executing a go-around after a last minute runway change led to an airborne conflict and an unstabilized approach.

Narrative: During approach into DEN we were assigned the RNAV (RNP) Z RWY 34R. Upon reaching HIMOM (IF) we were unable to continue the RNAV approach because we dropped LNAV and so we requested the visual approach to Runway 34R. The controller cleared us for the visual approach to 34R then offered a runway change to 35L even though the controller stated that it might be 'a little late in the game to switch'. We accepted the runway change and decided to switch. I had already disconnected the autopilot and autothrottles in anticipation for landing on Runway 34R. We were assigned a 080 heading for the visual to Runway 35L. We were then given a subsequent turn to 020 to intercept final for Runway 35L. Attempting to hand fly the aircraft and make sure the new approach was loaded by the Captain; and acquire an electronic centerline to the new runway; my workload increased to a level I didn't anticipate. This caused me to inadvertently shallow my turn to final. While trying to work through this issue I lost situational awareness and was focused more on making sure the ILS was loaded for RWY 35L instead of visually clearing my turn and getting established on final. During the turn to/through final we got an RA from TCAS that stated to level off. I leveled the aircraft and the Captain notified ATC of the RA and they stated for us to fly the LOC for Runway 35L. The controller then asked if we could continue the approach or if we needed to go missed approach. We were high and too close to continue the approach due to leveling off for the RA so we executed a missed approach and were given vectors for the missed. We were vectored for and flew the ILS to 35R and landed. After landing the Ground Controller gave us a number to contact Denver TRACON. The Captain [did so; and] discussed the events leading up to the approach.

Data retrieved from NASA's ASRS site 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.