It's not exactly what the OP is looking for, but on the LAX website (http://www.lawa.org/lax/welcomeLAX.cfm), if you go to "airlines and flights", you can put in any arrival city and any date, and it will tell you all airlines' schedules for that arrival city from LA area airports in chronological order. I tried JFK for fun, and there were indeed no flights leaving after midnight from LAX.

I wonder if it's an LA curfew thing and not a UA thing. On my last UA flight into LAX, the plane was scheduled to get in at 12:20, and the pilot mentioned the curfew on the PA. Said the airport turns itself around after midnight for noise abatement, and if we had to land west to east, it would take us another XX additional minutes to get set up for landing.