Narrative:

Large transport on takeoff, bna, runway 20R. Instructions: 'cleared for takeoff, turn left to 180 degrees, maintain 5M.' we made takeoff and started left turn at 300' AGL as per company policy. I cleared area as I started turn and saw an light transport who had just taken off on parallel 20L, abreast and about 150' lower. I rolled back to 210 degrees and asked first officer to tell tower that I was maintaining that heading until clear of traffic. Female controller again told an light transport to turn left to 130 degrees, and then told us to turn to 180 degrees. I waited until light transport started diverging before I turned. The same thing happened about 6 months before at dfw departing runway 36L with large transport traffic departing 36R unexpectedly. At least that time it was about 1500' between runways. That time we also had to worry about departing traffic on 35R. Both times I heard another aircraft being cleared for takeoff at about the same time I started takeoff roll. For some reason the time in dfw I rationalized that it was on the other side of the airport, although I knew that was another frequency. The other aircraft's relative position just didn't register until I saw another aircraft in formation with me--not good west/O a pretkof briefing when you are turning into the guy. This time in bna the closer than normal spacing was due to being cleared for takeoff a little early (we were about 40 seconds from takeoff) and controller's inexperience. Specifically, inexperience with acceleration of different aircraft types. Had I complied with tower's instructions, I would have passed a lot closer to the light transport than I like. I probably would not have been able to see him nor him me until we merged to about 100'.

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Original NASA ASRS Text

Title: POTENTIAL CONFLICT AIRBORNE BETWEEN ACR-LGT AND UNK-LTT ON INITIAL CLIMB AFTER TKOF PARALLEL RWYS.

Narrative: LGT ON TKOF, BNA, RWY 20R. INSTRUCTIONS: 'CLRED FOR TKOF, TURN LEFT TO 180 DEGS, MAINTAIN 5M.' WE MADE TKOF AND STARTED LEFT TURN AT 300' AGL AS PER COMPANY POLICY. I CLRED AREA AS I STARTED TURN AND SAW AN LTT WHO HAD JUST TAKEN OFF ON PARALLEL 20L, ABREAST AND ABOUT 150' LOWER. I ROLLED BACK TO 210 DEGS AND ASKED F/O TO TELL TWR THAT I WAS MAINTAINING THAT HDG UNTIL CLR OF TFC. FEMALE CTLR AGAIN TOLD AN LTT TO TURN LEFT TO 130 DEGS, AND THEN TOLD US TO TURN TO 180 DEGS. I WAITED UNTIL LTT STARTED DIVERGING BEFORE I TURNED. THE SAME THING HAPPENED ABOUT 6 MONTHS BEFORE AT DFW DEPARTING RWY 36L WITH LGT TFC DEPARTING 36R UNEXPECTEDLY. AT LEAST THAT TIME IT WAS ABOUT 1500' BTWN RWYS. THAT TIME WE ALSO HAD TO WORRY ABOUT DEPARTING TFC ON 35R. BOTH TIMES I HEARD ANOTHER ACFT BEING CLRED FOR TKOF AT ABOUT THE SAME TIME I STARTED TKOF ROLL. FOR SOME REASON THE TIME IN DFW I RATIONALIZED THAT IT WAS ON THE OTHER SIDE OF THE ARPT, ALTHOUGH I KNEW THAT WAS ANOTHER FREQ. THE OTHER ACFT'S RELATIVE POS JUST DIDN'T REGISTER UNTIL I SAW ANOTHER ACFT IN FORMATION WITH ME--NOT GOOD W/O A PRETKOF BRIEFING WHEN YOU ARE TURNING INTO THE GUY. THIS TIME IN BNA THE CLOSER THAN NORMAL SPACING WAS DUE TO BEING CLRED FOR TKOF A LITTLE EARLY (WE WERE ABOUT 40 SECS FROM TKOF) AND CTLR'S INEXPERIENCE. SPECIFICALLY, INEXPERIENCE WITH ACCELERATION OF DIFFERENT ACFT TYPES. HAD I COMPLIED WITH TWR'S INSTRUCTIONS, I WOULD HAVE PASSED A LOT CLOSER TO THE LTT THAN I LIKE. I PROBABLY WOULD NOT HAVE BEEN ABLE TO SEE HIM NOR HIM ME UNTIL WE MERGED TO ABOUT 100'.

Data retrieved from NASA's ASRS site as of August 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.