Narrative:

We were given position and hold 24L at lax. Tower asked if we had air carrier Y departing 25R in sight. I told him that we did not. He then gave us a takeoff clearance. I read back the clearance and told him that we now have the traffic in sight. He then asked us to maintain visual separation. After switching to departure and receiving a climb clearance to 13;000; we continued the climb. Passing around 5000 ft; departure gave the preceding air carrier Y a turn that would cross our departure path. I had lost sight of that aircraft under our nose; but the captain still had visual. It appeared to him that; given our close proximity (approximately 2.5 miles on the TCAS display); we may have a loss of separation and possible safety concern. As the captain began to deviate from our departure heading; I asked departure for another heading to avoid a conflict. He told us that we were still 3 miles in trail (with no conflict) and to ask for the heading before turning. We explained that from our vantage point (and very close proximity); a conflict could have easily happened. Air carrier Y continued its turn to the north and we continued our straight out climb with no conflict. I understand that ATC gives clearances with the information they have on their radar scopes and that info is very accurate. I also believe that it is ultimately our responsibility as pilots for the safe conduct of our flight. With a visual separation clearance; it was our responsibility to avoid hitting the preceding aircraft and I believe we did exactly that.

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Original NASA ASRS Text

Title: Air carrier departing LAX Runway 24L was instructed to maintain visual separation from a 25R departure; elected to turn from assigned heading to secure separation and was questioned by ATC.

Narrative: We were given position and hold 24L at LAX. Tower asked if we had Air Carrier Y departing 25R in sight. I told him that we did not. He then gave us a takeoff clearance. I read back the clearance and told him that we now have the traffic in sight. He then asked us to maintain visual separation. After switching to Departure and receiving a climb clearance to 13;000; we continued the climb. Passing around 5000 ft; Departure gave the preceding Air Carrier Y a turn that would cross our departure path. I had lost sight of that aircraft under our nose; but the Captain still had visual. It appeared to him that; given our close proximity (approximately 2.5 miles on the TCAS display); we may have a loss of separation and possible safety concern. As the Captain began to deviate from our departure heading; I asked Departure for another heading to avoid a conflict. He told us that we were still 3 miles in trail (with no conflict) and to ask for the heading BEFORE turning. We explained that from our vantage point (and very close proximity); a conflict could have easily happened. Air Carrier Y continued its turn to the north and we continued our straight out climb with no conflict. I understand that ATC gives clearances with the information they have on their radar scopes and that info is very accurate. I also believe that it is ultimately our responsibility as Pilots for the safe conduct of our flight. With a visual separation clearance; it was our responsibility to avoid hitting the preceding aircraft and I believe we did exactly that.

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.