ACR MLG ALT DEV EXCURSION FROM CHARTED VISUAL APCH ALT INTO BUR.

Narrative

I HAD BEEN CLRED BY BUR APCH CTL FOR THE 4 STACKS VISUAL APCH TO RWY 15 AT BURBANK WITH THE STANDARD INSTRUCTION TO MAINTAIN 3000 FT UNTIL TURNING FINAL. APCH CTL HAD BEEN CALLING OUT TFC (PRETTY MUCH CONTINUOUSLY; AS USUAL; WHICH WE OBSERVED AND ACKNOWLEDGED). IN THE TURN WE WERE SWITCHED OVER TO BUR TWR. WHEN WE CAME UP ON FREQ; THE TWR CTLR TOLD US TO WATCH OUT FOR OTHER TFC BECAUSE WE WERE FLYING THROUGH THE WHITEMAN ARPT TFC PATTERN AT TFC PATTERN ALT! I OBSERVED 2 OTHER ACFT IN THE VICINITY THAT POSED NO THREAT TO US (ALTHOUGH WE PROBABLY HAD THEIR ATTN). I CONTINUED TO RWY 15 AND LANDED. I THEN SPOKE WITH THE BUR TWR SUPVR ABOUT WHAT HAD JUST HAPPENED. HE SAID I DID NOT STAY AT 3000 FT AS INSTRUCTED. WHAT DID JUST HAPPEN? IT WAS A VERY CLR NIGHT AND I HAD THE ARPT VISUALLY ABOUT 15 MI OUT. WHEN I STARTED MY TURN TO FINAL AND DSCNT OUT OF 3000 FT I WAS FURTHER OUT (AROUND 9 NM) THAN I THOUGHT (NO DME AT BUR). I QUICKLY REALIZED IT AND LEVELED OFF AROUND 2200-2300 FT JUST WAITING TO REINTERCEPT THE RWY 15 VASIS. I WAS NOT FLYING THE EXACT 'DEPICTED' GND TRACK ON THE APCH PLATE (WHICH IS RECOMMENDED ONLY ACCORDING TO THE CVF PROCS); IN FACT I WAS FLYING JUST INSIDE THE BROKEN ARROW DEPICTION. I DID; IN FACT; COMPLY WITH THE 3000 FT RESTRICTION AND DID NOT LEAVE IT UNTIL I STARTED MY TURN. THE RESTRICTION; I'M NOW CONVINCED; SHOULD PROBABLY BE WORDED SOMETHING LIKE 'MAINTAIN 3000 FT UNTIL INTERCEPTING FINAL;' WHICH LEAVES LESS ROOM FOR INTERPRETATION. WHITEMAN ARPT IS DEPICTED ON THE APCH CHART BUT THERE IS NOTHING THAT GIVES YOU A HEADS UP CALL THAT THEIR TFC PATTERN EXTENDS OUT SO CLOSE TO THE EXTENDED FINAL OF RWY 15 AT BUR. THAT'S THE REASON FOR THE 3000 FT RESTRICTION. HAD I KNOWN THAT THE WHITEMAN TFC PATTERN WAS EVEN THERE; I CERTAINLY WOULD NOT HAVE DRIVEN THROUGH IT INTENTIONALLY. I RECOMMENDED A NOTE BE ADDED TO THE CHART BRINGING ATTN TO THE WHITMAN ARPT TFC PATTERN AND CHANGING THE WORDING ON THE 3000 FT RESTRICTION.