B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 125; Flight Crew Type 11000
Communication Breakdown; Situational Awareness; Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Human Factors
Another carrier was told to line up and wait on Runway 24R after being asked if he could accept that runway and he said yes. Suspect he did not change runway in his NAV database. We were told to maintain visual separation and cleared for takeoff on Runway 24L right after the other carrier was cleared for takeoff on 24R. After takeoff; he started to drift toward us and I started altering course slightly left to stay away from him.  About that time; we got the RA and complied. Either he didn't switch runway in his database or ATC gave an incorrect clearance to one or both of us. Departure seemed like they had no idea why we were both cleared for takeoff nearly in formation. I am curious myself as after both DLREY and FABRA the route takes both planes to ENNEY. We maintained visual separation until the RA but as we were basically cleared to takeoff on very close parallel runways at the same time we were very close to start with. We expected the other carrier or us would be given a turn away from each other after takeoff.
LAX air carrier departure described a developing conflict with parallel runway departure traffic after takeoff; the reporter suspecting the conflicting aircraft may not have changed database after a last minute runway change.