Narrative:

Leaving lax on the ventura 2 departure en route to santa rosa, ca. It was night and the sky was clear with approximately 7 mi visibility. We were instructed by tower to cross runway 24L and hold short at runway 24R. A jetstream was instructed to taxi onto runway 24L and we were then given position and hold on runway 24R. I was aware that often the lax tower will allow planes to depart from the lax north complex en route to a destination south of lax so as to save taxi time. This runway arrangement (aircraft Y on the left and us on the right) appeared tailor made for our wbound departure and an aircraft Y sbound departure. Aircraft Y was cleared for takeoff and immediately thereafter we were also cleared for takeoff with instructions to climb to 3000 ft and turn right to 270 degrees at the lax VOR. Immediately after rotating, tower asked if we had aircraft Y in sight. We replied that we did and were instructed to maintain visual separation and contact departure control. We contacted departure, brought the flaps up and began our turn with the appropriate airspeed to 270 degrees. At this time, departure asked us to verify aircraft Y in sight. We called them in sight and it became apparent that they were obviously heading in the same direction. They too were given a right turn abeam the VOR to 270 degrees in front of us. Our faster speed in the climb and in the turn put us near the jetstream that had already made the turn to 270 degrees. I had visual contact with the plane, however, at night the depth perception was difficult to judge having only their lights to go by. We were given further climb to 7000 ft. Departure advised aircraft Y that we were climbing above them and that they should stop climb at 4000 ft. We began to overtake them and I felt uncomfortable with the separation, as it became obvious they were either going in our same direction or heading northbound. I increased the rate of climb and about that time we got a TCASII alert. The alert quickly silenced as we climbed above them. At that time departure turned aircraft Y underneath us on a northbound heading. Shortly thereafter we were both instructed to contact the next sector frequencys.

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Original NASA ASRS Text

Title: EMB120 CREW RECEIVES TCASII TA DURING SIMULTANEOUS PARALLEL DEPS AT LAX.

Narrative: LEAVING LAX ON THE VENTURA 2 DEP ENRTE TO SANTA ROSA, CA. IT WAS NIGHT AND THE SKY WAS CLR WITH APPROX 7 MI VISIBILITY. WE WERE INSTRUCTED BY TWR TO CROSS RWY 24L AND HOLD SHORT AT RWY 24R. A JETSTREAM WAS INSTRUCTED TO TAXI ONTO RWY 24L AND WE WERE THEN GIVEN POS AND HOLD ON RWY 24R. I WAS AWARE THAT OFTEN THE LAX TWR WILL ALLOW PLANES TO DEPART FROM THE LAX NORTH COMPLEX ENRTE TO A DEST S OF LAX SO AS TO SAVE TAXI TIME. THIS RWY ARRANGEMENT (ACFT Y ON THE L AND US ON THE R) APPEARED TAILOR MADE FOR OUR WBOUND DEP AND AN ACFT Y SBOUND DEP. ACFT Y WAS CLRED FOR TKOF AND IMMEDIATELY THEREAFTER WE WERE ALSO CLRED FOR TKOF WITH INSTRUCTIONS TO CLB TO 3000 FT AND TURN R TO 270 DEGS AT THE LAX VOR. IMMEDIATELY AFTER ROTATING, TWR ASKED IF WE HAD ACFT Y IN SIGHT. WE REPLIED THAT WE DID AND WERE INSTRUCTED TO MAINTAIN VISUAL SEPARATION AND CONTACT DEP CTL. WE CONTACTED DEP, BROUGHT THE FLAPS UP AND BEGAN OUR TURN WITH THE APPROPRIATE AIRSPD TO 270 DEGS. AT THIS TIME, DEP ASKED US TO VERIFY ACFT Y IN SIGHT. WE CALLED THEM IN SIGHT AND IT BECAME APPARENT THAT THEY WERE OBVIOUSLY HEADING IN THE SAME DIRECTION. THEY TOO WERE GIVEN A R TURN ABEAM THE VOR TO 270 DEGS IN FRONT OF US. OUR FASTER SPD IN THE CLB AND IN THE TURN PUT US NEAR THE JETSTREAM THAT HAD ALREADY MADE THE TURN TO 270 DEGS. I HAD VISUAL CONTACT WITH THE PLANE, HOWEVER, AT NIGHT THE DEPTH PERCEPTION WAS DIFFICULT TO JUDGE HAVING ONLY THEIR LIGHTS TO GO BY. WE WERE GIVEN FURTHER CLB TO 7000 FT. DEP ADVISED ACFT Y THAT WE WERE CLBING ABOVE THEM AND THAT THEY SHOULD STOP CLB AT 4000 FT. WE BEGAN TO OVERTAKE THEM AND I FELT UNCOMFORTABLE WITH THE SEPARATION, AS IT BECAME OBVIOUS THEY WERE EITHER GOING IN OUR SAME DIRECTION OR HEADING NBOUND. I INCREASED THE RATE OF CLB AND ABOUT THAT TIME WE GOT A TCASII ALERT. THE ALERT QUICKLY SILENCED AS WE CLBED ABOVE THEM. AT THAT TIME DEP TURNED ACFT Y UNDERNEATH US ON A NBOUND HEADING. SHORTLY THEREAFTER WE WERE BOTH INSTRUCTED TO CONTACT THE NEXT SECTOR FREQS.

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.