Narrative:

We normally set up our navigation 1 hour out and brief the approach just before descent. At most airports you can tell what runway you will get; but at lax you never know until approach control gives you the runway and at the same time starts you down a challenging profile descent; with several descent altitudes. If you did not 'guess' correctly it now starts a 'fire drill' in the cockpit as one pilot starts descending to the first altitude as the other pilot reprograms the FMC; sets and idents the radios. Briefs the new missed approach; sets the new decision ht; and briefs the runway exit plan. In all of this; we ended up slightly right of course because we both switched the ILS frequency; ending up on the original frequency; then reset. I called approach later. He said no conflict was caused.

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Original NASA ASRS Text

Title: A B757-200 FLT CREW ON APCH TO LAX GOT A LATE CHANGE TO THEIR RWY ASSIGNMENT AND DEVIATED R OF COURSE WHILE THEY REPROGRAMMED THE FMC.

Narrative: WE NORMALLY SET UP OUR NAV 1 HR OUT AND BRIEF THE APCH JUST BEFORE DSCNT. AT MOST ARPTS YOU CAN TELL WHAT RWY YOU WILL GET; BUT AT LAX YOU NEVER KNOW UNTIL APCH CTL GIVES YOU THE RWY AND AT THE SAME TIME STARTS YOU DOWN A CHALLENGING PROFILE DSCNT; WITH SEVERAL DSCNT ALTS. IF YOU DID NOT 'GUESS' CORRECTLY IT NOW STARTS A 'FIRE DRILL' IN THE COCKPIT AS ONE PLT STARTS DSNDING TO THE FIRST ALT AS THE OTHER PLT REPROGRAMS THE FMC; SETS AND IDENTS THE RADIOS. BRIEFS THE NEW MISSED APCH; SETS THE NEW DECISION HT; AND BRIEFS THE RWY EXIT PLAN. IN ALL OF THIS; WE ENDED UP SLIGHTLY R OF COURSE BECAUSE WE BOTH SWITCHED THE ILS FREQ; ENDING UP ON THE ORIGINAL FREQ; THEN RESET. I CALLED APCH LATER. HE SAID NO CONFLICT WAS CAUSED.

Data retrieved from NASA's ASRS site as of January 2009 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.