Narrative:

We departed with minimum spacing (due to aircraft on short final) behind a beech 1900 turboprop, which had been assigned a departure heading of 330 degrees off runway 29R at msp. Our assigned heading was 300 degrees, a diverging course. Upon initial contact with departure control. We acknowledged visual contact with the preceding B-1900, and we were cleared to 7000 ft MSL on a 300 degree heading, and he advised the B-1900 would be nebound. As we climbed through 2500 ft MSL, it appeared that the B-1900 was beginning a left turn to the southwest, rather than a right turn to the northeast. As we realized we were converging, we told the controller, and he gave us a left turn to 270 degrees. I lost sight of the B-1900 as I began to roll the aircraft left, but the first officer said had the aircraft still in sight, converging, and he turned the TCASII control to TA only to avoid an RA, since we had the aircraft in sight. He did ask me to increase the climb rate for spacing, so I aborted the noise abatement procedure and applied climb thrust and increased pitch. The B-1900 passed directly under us approximately 200 ft below as estimated by the first officer. Upon return to msp 3 1/2 hours later, the ATC watch supervisor explained to me a misunderstanding between sector controllers as to the b- 1900's initial departure course. The B-1900 pilots were supposed to have us in sight as they turned left, but I suspect they must have confused us with someone else, as no one in their right mind would deliberately create such a collision hazard. Given sometimes complicated departure procedures with noise abatement maneuvers, it is common to dismiss IFR traffic. You have acknowledged visual contact with after being told they will comply with ATC directions that will result in increasing spacing, i.e., a turn away from you. In this case, the aircraft did not do what our controller anticipated, and luckily, we were still observing the traffic. Otherwise, this event might have had disastrous consequences.

Related reports:

Google
 

Original NASA ASRS Text

Title: NMAC BTWN A DEPARTING MLG AND AN LTT.

Narrative: WE DEPARTED WITH MINIMUM SPACING (DUE TO ACFT ON SHORT FINAL) BEHIND A BEECH 1900 TURBOPROP, WHICH HAD BEEN ASSIGNED A DEP HDG OF 330 DEGS OFF RWY 29R AT MSP. OUR ASSIGNED HDG WAS 300 DEGS, A DIVERGING COURSE. UPON INITIAL CONTACT WITH DEP CTL. WE ACKNOWLEDGED VISUAL CONTACT WITH THE PRECEDING B-1900, AND WE WERE CLRED TO 7000 FT MSL ON A 300 DEG HDG, AND HE ADVISED THE B-1900 WOULD BE NEBOUND. AS WE CLBED THROUGH 2500 FT MSL, IT APPEARED THAT THE B-1900 WAS BEGINNING A L TURN TO THE SW, RATHER THAN A R TURN TO THE NE. AS WE REALIZED WE WERE CONVERGING, WE TOLD THE CTLR, AND HE GAVE US A L TURN TO 270 DEGS. I LOST SIGHT OF THE B-1900 AS I BEGAN TO ROLL THE ACFT L, BUT THE FO SAID HAD THE ACFT STILL IN SIGHT, CONVERGING, AND HE TURNED THE TCASII CTL TO TA ONLY TO AVOID AN RA, SINCE WE HAD THE ACFT IN SIGHT. HE DID ASK ME TO INCREASE THE CLB RATE FOR SPACING, SO I ABORTED THE NOISE ABATEMENT PROC AND APPLIED CLB THRUST AND INCREASED PITCH. THE B-1900 PASSED DIRECTLY UNDER US APPROX 200 FT BELOW AS ESTIMATED BY THE FO. UPON RETURN TO MSP 3 1/2 HRS LATER, THE ATC WATCH SUPVR EXPLAINED TO ME A MISUNDERSTANDING BTWN SECTOR CTLRS AS TO THE B- 1900'S INITIAL DEP COURSE. THE B-1900 PLTS WERE SUPPOSED TO HAVE US IN SIGHT AS THEY TURNED L, BUT I SUSPECT THEY MUST HAVE CONFUSED US WITH SOMEONE ELSE, AS NO ONE IN THEIR R MIND WOULD DELIBERATELY CREATE SUCH A COLLISION HAZARD. GIVEN SOMETIMES COMPLICATED DEP PROCS WITH NOISE ABATEMENT MANEUVERS, IT IS COMMON TO DISMISS IFR TFC. YOU HAVE ACKNOWLEDGED VISUAL CONTACT WITH AFTER BEING TOLD THEY WILL COMPLY WITH ATC DIRECTIONS THAT WILL RESULT IN INCREASING SPACING, I.E., A TURN AWAY FROM YOU. IN THIS CASE, THE ACFT DID NOT DO WHAT OUR CTLR ANTICIPATED, AND LUCKILY, WE WERE STILL OBSERVING THE TFC. OTHERWISE, THIS EVENT MIGHT HAVE HAD DISASTROUS CONSEQUENCES.

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.