Narrative:

Evasive maneuver at 800 ft AGL during go around from runway 4R at mdw to avoid potential midair collision with helicopter over midfield, night VMC. We were approximately 2 NM from touchdown on runway 4R at mdw when tower cleared an air carrier B737 for takeoff from runway 4R. Air carrier B737 was not rolling by the time we were at 200 ft AGL. We queried tower and were instructed to go around. The go around instruction did not initially include heading and altitude. The captain initiated a go around per the published missed approach procedure runway 4R ILS mdw. At approximately 800 ft AGL, I saw the lights of an aircraft slightly above us and to our right which appeared to be crossing our go around path from southeast to the northwest. I took control of the aircraft and initiated an aggressive left turn leveling the aircraft. During the evasive maneuver, ATC told us of the traffic. We queried ATC and were instructed to fly a 230 degree heading and climb to 2600 ft. We returned for landing on runway 4R at mdw. The captain contacted mdw tower after landing and was told the helicopter had us in sight and was maintaining visual separation. It appeared to me that we were within 500 ft of colliding with the helicopter. The captain was the PF and did not see the traffic and potential conflict because of his attention being focused on the go around maneuver. The potential conflict was due to mdw tower's trying to expedite traffic flow in and out of mdw on runway 4R. It was unfortunate timing that an aircraft was transitioning over the field during our go around.

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Original NASA ASRS Text

Title: AN A320 FO RPTED AN NMAC AT MDW WHICH WAS THE RESULT OF A B737 NOT DEPARTING FROM RWY 4R AS EXPEDITIOUSLY AS THE TWR HAD PLANNED. ON THE MISSED, THE CAPT FLEW THE MISSED APCH IN LIEU OF ALT AND HDG INSTRUCTIONS. THE RPTR TOOK OVER THE CTLS TO AVOID A HELI XING OVER THE A320'S FLT PATH.

Narrative: EVASIVE MANEUVER AT 800 FT AGL DURING GAR FROM RWY 4R AT MDW TO AVOID POTENTIAL MIDAIR COLLISION WITH HELI OVER MIDFIELD, NIGHT VMC. WE WERE APPROX 2 NM FROM TOUCHDOWN ON RWY 4R AT MDW WHEN TWR CLRED AN ACR B737 FOR TKOF FROM RWY 4R. ACR B737 WAS NOT ROLLING BY THE TIME WE WERE AT 200 FT AGL. WE QUERIED TWR AND WERE INSTRUCTED TO GO AROUND. THE GAR INSTRUCTION DID NOT INITIALLY INCLUDE HDG AND ALT. THE CAPT INITIATED A GAR PER THE PUBLISHED MISSED APCH PROC RWY 4R ILS MDW. AT APPROX 800 FT AGL, I SAW THE LIGHTS OF AN ACFT SLIGHTLY ABOVE US AND TO OUR R WHICH APPEARED TO BE XING OUR GAR PATH FROM SE TO THE NW. I TOOK CTL OF THE ACFT AND INITIATED AN AGGRESSIVE L TURN LEVELING THE ACFT. DURING THE EVASIVE MANEUVER, ATC TOLD US OF THE TFC. WE QUERIED ATC AND WERE INSTRUCTED TO FLY A 230 DEG HDG AND CLB TO 2600 FT. WE RETURNED FOR LNDG ON RWY 4R AT MDW. THE CAPT CONTACTED MDW TWR AFTER LNDG AND WAS TOLD THE HELI HAD US IN SIGHT AND WAS MAINTAINING VISUAL SEPARATION. IT APPEARED TO ME THAT WE WERE WITHIN 500 FT OF COLLIDING WITH THE HELI. THE CAPT WAS THE PF AND DID NOT SEE THE TFC AND POTENTIAL CONFLICT BECAUSE OF HIS ATTN BEING FOCUSED ON THE GAR MANEUVER. THE POTENTIAL CONFLICT WAS DUE TO MDW TWR'S TRYING TO EXPEDITE TFC FLOW IN AND OUT OF MDW ON RWY 4R. IT WAS UNFORTUNATE TIMING THAT AN ACFT WAS TRANSITIONING OVER THE FIELD DURING OUR GAR.

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.