C206 PLT IS GIVEN CLRNC TO TAXI AROUND A HELI AND SUBSEQUENTLY MAKES A SUDDEN STOP AFTER BEING COMMANDED TO HOLD SHORT OF OCCUPIED RWY 21 AT SMO.

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I WAS MOVING MY ACFT FROM A MAINT SHOP ON THE S SIDE OF SANTA MONICA'S RWY 21/3; W END. THE TWR IS ON THE N SIDE; NEAR E END. TAXI CLRNC WAS GIVEN ME; BUT AS I DREW ABEAM A HELI WHOSE BLADE WAS ROTATING; MY CLRNC WAS AMENDED; BUT JUMBLED BY SIMILAR N-NUMBERS TO MINE; AND THE FACT THAT I WAS UNAWARE OF AN ACFT HOLDING IN POS AT THE FAR E END OF RWY 21. I WAS ON THE CTRLINE OF THE TXWY PARALLEL TO THE RWY; MOVING E. THE CTLR THEN INSTRUCTED ME TO ANGLE PAST; OR AROUND; THE HELI AND 'HOLD SHORT OF RWY 21.' THIS AMENDED CLRNC MUDDLED THE SIT FOR ALL CONCERNED EXCEPT FOR THE SMALL JET HOLDING IN POS; VIRTUALLY INVISIBLE TO ME AT THE TIME. THE HELI CAUSED SEVERAL PROBS. FIRST; THE CTLR WAS FORCED TO 'LOOK OUR FOR ME.' I NEVER LEARNED OF THE JET IN POS. THE GND CTLR; CONCERNED WITH THE HELI; MIGHT HAVE INDICATED THAT SHE HAD AN ACFT IN POS -- AND THIS WOULD HAVE SOLVED EVERYTHING. I BELIEVE THERE WERE 3 ACFT ON FREQ WHEN I WAS INSTRUCTED TO 'TAXI AROUND; OR PAST; OR ANGLE AWAY FROM THE HELI.' WHAT HAPPENED NEXT WAS COMPLICATED BY THE CIRCUMSTANCES OF THE NOISE OF THE CHOPPER; AND THE AMENDED CLRNC I RECEIVED FROM THE CTLR AT THE SAME MOMENT. THAT ANOTHER ACFT HAD A VERY SIMILAR CALL SIGN TO MINE DID NOT HELP EITHER. I UNDERSTOOD MY CLRNC; OR SO I THOUGHT; 'MOVE AWAY FROM; OR ANGLE...AND HOLD SHORT OF 21.' THE PROB THUS CREATED FOR ME WAS TO DISCERN MY 'HOLD SHORT' POINT. HOW CLOSE TO THE RWY? AS I ROLLED TOWARD THE RWY; THE CTLR ISSUED A SHARP; DIRECT ORDER; 'ACFT X HOLD SHORT!' I HIT THE BRAKES IN COMPLIANCE. I WAS ON THE WIDE APRON THAT SEPARATES THE TXWY FROM THE RWY. NO HOLD SHORT LINES EXIST IN THAT NO-MANS-LAND; AS THEY DO AT FORMAL XING POINTS LIKE BRAVO 1 OR 2. BUT I ALWAYS KNEW FULL WELL THAT I WAS TO HOLD SHORT OF RWY 21. ALL WAS WELL AFTER THAT. THE JET DEPARTED. I WAS INSTRUCTED TO CROSS RWY 21; AND I TAXIED TO MY HANGAR. TAXI INSTRUCTIONS FOR THE AREA WHEN THE HELI IS SPOOLING UP WOULD BEST GUIDE THE PLT IF THERE WERE RE-WORDED TO; 'ACFT X; TAXI AROUND THE HELI AND IMMEDIATELY RETURN TO THE TXWY CTRLINE AND CONTINUE AS CLRED.' IN A SIT SUCH AS THE ONE I DESCRIBED ABOVE; IT IS USEFUL IF EVERYONE BEING WORKED FULLY UNDERSTANDS; 'ACFT HOLDING IN POS ON RWY 21.'