A310 TURNS ON COURSE VICE REQUIRED 250 DEG HDG AFTER TKOF AT LAX.

Narrative

OUR FLT WAS FROM LAX TO BUR. OUR PDC CLRNC WAS 'LAX LAXM1 BUR; MAINTAIN 5000 FT.' WHILE TAXIING INTO POS RWY 25R; TWR CLRED US FOR TKOF. TWR DID NOT GIVE US A HDG TO MAINTAIN; SO I ASSUMED WE WERE CLRED TO FLY THE LAXM1 ROUTING; WHICH WAS TO TURN R TO INTERCEPT THE LAX 316 DEG RADIAL TO 'SILEX.' THEREFORE; ONCE SAFELY AIRBORNE; I BEGAN A R-HAND TURN TO INTERCEPT THE LAX 316 DEG RADIAL. WHEN WE CHKED IN WITH SOCAL DEP; THE CTLR ADVISED US THAT WE SHOULD HAVE MAINTAINED A 250 DEG HDG AFTER TKOF. I WAS UNABLE TO FIND ANYTHING IN OUR FLT PUBS WHICH DIRECTED US TO MAINTAIN A 250 DEG HDG WHEN ASSIGNED THE LAXM1 PROC. TO PREVENT CONFUSION IN THE FUTURE; I WOULD LIKE THE LAXM1 ROUTING TO INCLUDE A STATEMENT SAYING TO MAINTAIN A 250 DEG HDG UNTIL TOLD OTHERWISE BY ATC. ALSO; IT WOULD HAVE BEEN HELPFUL IF TWR WOULD HAVE DIRECTED US TO MAINTAIN A 250 DEG HDG WHEN WE WERE CLRED FOR TKOF. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: WE (THE FLT CREW) HAD TO SEARCH OUR MANUALS EXTENSIVELY TO DISCOVER EXACTLY WHAT LAXM1 MEANT. IT WAS NOT A SID LISTED UNDER OUR LAX AERO CHARTS BUT RATHER IN AN ENRTE PORTION OF THE MANUALS WHICH LISTED COMMON OR 'CANNED' RTES FOR VERY SHORT FLTS. WHEN WE RECEIVED NO INDEPENDENT ASSIGNMENT OF A SID WE INTERPED THE CLRNC TO REQUIRE A TURN ON COURSE; IE; A R TURN TO INTERCEPT THE LAX 316 DEG RADIAL PER THE LAXM1 ROUTING.