Narrative:

During takeoff in a 150000 pound aircraft at ord on runway 09R another aircraft on approach to runway 04R executed a go around. At approximately 120 KTS ord tower canceled our takeoff clearance, captain replied unable. Shortly after lift-off we commenced our assigned turn to 140 degrees and immediately gained visual contact with conflicting traffic at very close range, 1 O'clock, and slightly high. Captain lowered nose and we passed beneath without incident. Concern is that we disregarded a controller instruction without declaring an emergency and a loss of separation resulted. Supplemental information from acn 329518: on takeoff roll at about 100 KTS, first officer flying, heard aircraft transmit, 'going around.' tower issued go around instructions to that aircraft followed quickly by instructions to us to cancel takeoff clearance. We were now approaching 130 KTS, weight was 149500 pounds. I PNF, immediately responded negative, unable, we're going due to the high speed and heavy gross weight. At this point we were at lift-off and aircraft on go around on runway 04R was sighted climbing on the go around. It was apparent that we would be able to fly under and/or behind this aircraft which we were able to do with normal bank and slightly lower climb angle than normal. Our aircraft passed about 1/2 mi behind and approximately 400 ft beneath the other aircraft. I don't know that anyone can be faulted for this occurrence. We probably need to look at intersecting runway operations again. One concern I need to address is not complying with ATC instructions to abort the takeoff. In this situation my judgement was that we would be in more peril by aborting than by continuing takeoff and maintaining visual separation.

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Original NASA ASRS Text

Title: DURING TKOF AT ORD RWY 09R ANOTHER ACFT ON APCH TO RWY 04R COMMENCED A GAR. AT APPROX 120 KTS ORD TWR CANCELED TKOF CLRNC. CAPT REPLIED UNABLE. SHORTLY AFTER LIFT-OFF HE TURNED TO ASSIGNED 140 DEGS. SAW TFC 1 O'CLOCK HIGH, LOWERED NOSE AND PASSED BENEATH WITHOUT INCIDENT.

Narrative: DURING TKOF IN A 150000 LB ACFT AT ORD ON RWY 09R ANOTHER ACFT ON APCH TO RWY 04R EXECUTED A GAR. AT APPROX 120 KTS ORD TWR CANCELED OUR TKOF CLRNC, CAPT REPLIED UNABLE. SHORTLY AFTER LIFT-OFF WE COMMENCED OUR ASSIGNED TURN TO 140 DEGS AND IMMEDIATELY GAINED VISUAL CONTACT WITH CONFLICTING TFC AT VERY CLOSE RANGE, 1 O'CLOCK, AND SLIGHTLY HIGH. CAPT LOWERED NOSE AND WE PASSED BENEATH WITHOUT INCIDENT. CONCERN IS THAT WE DISREGARDED A CTLR INSTRUCTION WITHOUT DECLARING AN EMER AND A LOSS OF SEPARATION RESULTED. SUPPLEMENTAL INFO FROM ACN 329518: ON TKOF ROLL AT ABOUT 100 KTS, FO FLYING, HEARD ACFT XMIT, 'GOING AROUND.' TWR ISSUED GAR INSTRUCTIONS TO THAT ACFT FOLLOWED QUICKLY BY INSTRUCTIONS TO US TO CANCEL TKOF CLRNC. WE WERE NOW APCHING 130 KTS, WT WAS 149500 LBS. I PNF, IMMEDIATELY RESPONDED NEGATIVE, UNABLE, WE'RE GOING DUE TO THE HIGH SPD AND HVY GROSS WT. AT THIS POINT WE WERE AT LIFT-OFF AND ACFT ON GAR ON RWY 04R WAS SIGHTED CLBING ON THE GAR. IT WAS APPARENT THAT WE WOULD BE ABLE TO FLY UNDER AND/OR BEHIND THIS ACFT WHICH WE WERE ABLE TO DO WITH NORMAL BANK AND SLIGHTLY LOWER CLB ANGLE THAN NORMAL. OUR ACFT PASSED ABOUT 1/2 MI BEHIND AND APPROX 400 FT BENEATH THE OTHER ACFT. I DON'T KNOW THAT ANYONE CAN BE FAULTED FOR THIS OCCURRENCE. WE PROBABLY NEED TO LOOK AT INTERSECTING RWY OPS AGAIN. ONE CONCERN I NEED TO ADDRESS IS NOT COMPLYING WITH ATC INSTRUCTIONS TO ABORT THE TKOF. IN THIS SIT MY JUDGEMENT WAS THAT WE WOULD BE IN MORE PERIL BY ABORTING THAN BY CONTINUING TKOF AND MAINTAINING VISUAL SEPARATION.

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.