AN A320 FLT IS TOLD TO CLR THE RWY AND BE RESEQUENCED FOR TKOF. THE CREW HAD REFUSED A TKOF CLRNC WITH LESS THAN 2 MINS AND LESS THAN 5 MI BEHIND A DEP B747-400 THAT HAD LIFTED OFF THE RWY JUST 30 SECONDS PRIOR TO TKOF CLRNC AT LAX; CA.

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WE WERE OPERATING AS FLT XYZ FROM LAX TO BOS. WE WERE SEQUENCED BY GND CTL TO FOLLOW A B747-400. WHEN TWR GAVE THE B747 THEIR TKOF CLRNC; WE STARTED TIMING FROM THE BEGINNING OF THEIR TKOF ROLL. WE WERE CLRED INTO POS AND HOLD ON RWY 25R. AFTER 50 SECONDS; THE B747 BECAME AIRBORNE. AN E120 WAS CLRED TO CROSS THE RWY DOWNFIELD. IMMEDIATELY AFTER THE E120 CLRED; WE WERE GIVEN OUR TKOF CLRNC; THAT WAS 1 MIN 10 SECONDS AFTER THE B747 STARTED THEIR ROLL. WE REFUSED AND TOLD CTLR THAT WE WANTED 2 MINS FOR WAKE TURB AVOIDANCE. CTLR WAS VERY UPSET AT OUR REFUSAL; SAYING THAT WE DID HAVE STANDARD WAKE TURB SEPARATION OF 5 NM (ABSOLUTELY NOT -- THE ACFT WAS ONLY AIRBORNE FOR APPROX 20-30 SECONDS!); AND THAT WE SHOULD HAVE TOLD HIM BEFOREHAND OF OUR REQUEST FOR 2 MINS SEPARATION. WHY? WITH ALL THE INFO ON WAKE TURB NOWADAYS; SHOULDN'T IT BE AUTOMATIC TO RECEIVE 5 NM AND/OR 2 MINS SEPARATION? CTLR MADE US TAXI DOWN ON RWY 25R AND EXIT ON TXWY F FOR RESEQUENCING (WHICH WE DID). THIS SORT OF PLT PUSHING WILL ONE DAY RESULT IN A SERIOUS ACCIDENT WHEN A CREW IS NOT WILLING TO TAKE A DELAY AND SUFFERS THE CONSEQUENCES OF WAKE TURB ENCOUNTER AT VERY LOW ALT.