Narrative:

On approximately 1 mile final to 27L atl; tower controller issued traffic advisory for helicopter traffic; passing overhead from right to left at 2;000 ft. Our altitude was approximately 1;600 descending on glide slope. I looked for traffic and didn't see it above our position. I quickly checked TCAS display and saw a target 'pop up' to our right indicating -02. I then looked below our position and saw the helicopter; on a converging course with our flight. I informed the tower that the traffic was apparently below our position and headed for us. We were now at approximately 1;500 to 1;400 MSL. The helicopter was on another frequency and we could not hear the instructions issued to him. But he began to climb and passed directly over our airplane by approximately 200 to 400 ft.we would have impacted the helicopter had he not taken evasive actions. On taxi in; the controller informed us that the helicopter was assigned 2;000 to transition through the traffic pattern. The helicopter was at approximately 1;200. The error was not caught until we gained visual contact with the helicopter; ascertained that he was not at 2;000 and informed the tower controller. 1. I identified traffic being out of compliance with assigned altitude and informed tower.2. Controller issued swift corrective instructions to the helicopter to climb above our position. 3. The captain's excellent situational awareness to not initiate a go-around. Had he done that; we would have climbed right into the helicopter as he returned to his assigned altitude. As he was on another frequency; we could not hear the instructions issued to him. But by looking out the window; the captain continued the approach which became the only clear path available to us to avoid the helicopter. We were too low to safely descend to avoid the traffic. This incident began and ended quickly; in approximately 10 to 20 seconds; so there was no time for discussion or analysis. Our reactions were quick and coordinated and worked well. I'm not sure how a mode C helicopter could penetrate so deeply into atl airspace; so far off of its assigned altitude. But mode C awareness would help and the TCAS display was what guided my vision to the true location of the traffic which was what avoided a potential collision. Why not transition overflying traffic midfield instead of at the airport perimeter?

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Original NASA ASRS Text

Title: Air carrier flight crew reports NMAC with helicopter at 1;000 FT AGL during approach to Runway 27L at ATL. Helicopter crew; apparently not at assigned altitude; is instructed to climb.

Narrative: On approximately 1 mile final to 27L ATL; Tower Controller issued traffic advisory for helicopter traffic; passing overhead from right to left at 2;000 FT. Our altitude was approximately 1;600 descending on glide slope. I looked for traffic and didn't see it above our position. I quickly checked TCAS display and saw a target 'pop up' to our right indicating -02. I then looked below our position and saw the helicopter; on a converging course with our flight. I informed the Tower that the traffic was apparently below our position and headed for us. We were now at approximately 1;500 to 1;400 MSL. The helicopter was on another frequency and we could not hear the instructions issued to him. But he began to climb and passed directly over our airplane by approximately 200 to 400 FT.We would have impacted the helicopter had he not taken evasive actions. On taxi in; the Controller informed us that the helicopter was assigned 2;000 to transition through the traffic pattern. The helicopter was at approximately 1;200. The error was not caught until we gained visual contact with the helicopter; ascertained that he was not at 2;000 and informed the Tower Controller. 1. I identified traffic being out of compliance with assigned altitude and informed Tower.2. Controller issued swift corrective instructions to the helicopter to climb above our position. 3. The Captain's excellent situational awareness to NOT initiate a go-around. Had he done that; we would have climbed right into the helicopter as he returned to his assigned altitude. As he was on another frequency; we could not hear the instructions issued to him. But by looking out the window; the Captain continued the approach which became the only clear path available to us to avoid the helicopter. We were too low to safely descend to avoid the traffic. This incident began and ended quickly; in approximately 10 to 20 seconds; so there was no time for discussion or analysis. Our reactions were quick and coordinated and worked well. I'm not sure how a Mode C helicopter could penetrate so deeply into ATL airspace; so far off of its assigned altitude. But Mode C awareness would help and the TCAS display was what guided my vision to the true location of the traffic which was what avoided a potential collision. Why not transition overflying traffic midfield instead of at the airport perimeter?

Data retrieved from NASA's ASRS site as of April 2012 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.