Air carrier on final for runway 27L at ord experienced conflict with traffic overshooting runway 28;...

Attributes
ACN	838285
Time
Date	200906
Local Time Of Day	0601-1200
Place
Locale Reference	ORD.Airport
State Reference	IL
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Heavy Transport
Operating Under FAR Part	Part 121
Flight Phase	Final Approach Descent
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Final Approach Descent
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Conflict NMAC

Narrative:

We were on final to runway 27L; on course and slope. At 3;500 ft; relief pilot called traffic at 11 o'clock; an MD80 we all thought he was on an intercept heading to runway 28. Shortly; it appeared he overshot or was on an assigned heading that put the MD80 on our flight path. I cleared us right and started a shallow right turn and a descent so we could keep the traffic in sight. Seconds later we received a TA followed immediately by an RA commanding a climb. I elected; with the captain's concurrence; to keep the descent so as to keep the MD80 in sight. A climb would have us losing visual; and I was worried they might elect to abort their approach and also start a climb or missed approach. We at no time received any information from the controllers; the MD80 started a turn back to the left to intercept runway 28 and after concurrence from tower; we re-intercepted the ILS to runway 27L and landed. This was the closest to a midair I have had in 18 years.

Original NASA ASRS Text

Title: Air carrier on final for Runway 27L at ORD experienced conflict with traffic overshooting Runway 28; reporting aircraft initiated a slow descent to avoid traffic; TCAS RA then commanded climb; flight crew elected to continue descent to keep traffic in sight.

Narrative: We were on final to Runway 27L; on course and slope. At 3;500 FT; Relief Pilot called traffic at 11 o'clock; an MD80 we all thought he was on an intercept heading to Runway 28. Shortly; it appeared he overshot or was on an assigned heading that put the MD80 on our flight path. I cleared us right and started a shallow right turn and a descent so we could keep the traffic in sight. Seconds later we received a TA followed immediately by an RA commanding a climb. I elected; with the Captain's concurrence; to keep the descent so as to keep the MD80 in sight. A climb would have us losing visual; and I was worried they might elect to abort their approach and also start a climb or missed approach. We at no time received any information from the Controllers; the MD80 started a turn back to the left to intercept Runway 28 and after concurrence from Tower; we re-intercepted the ILS to Runway 27L and landed. This was the closest to a midair I have had in 18 years.

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.

Air carrier on final for runway 27L at ord experienced conflict with traffic overshooting runway 28; reporting aircraft initiated a slow descent to avoid traffic; TCAS RA then commanded climb; flight crew elected to continue descent to keep traffic in sight.