B737 DEP FROM ONT BEGINS TKOF WITHOUT ATC CLRNC.

Narrative

HOLDING SHORT AT RWY 26R ONT; HAD BEEN THERE 15 MINS; WATCHED 6-7 ACFT LAND. TWR GAVE SEVERAL 2-3 MIN CALLS TO US TO EXTEND WAIT. VERY SUDDENLY; IN A HURRIED VOICE; TWR CALLED; COMPANY FLT NUMBER; FLY HEADING 280 DEGS; CLB TO 14000 FT; NEED YOUR BEST RATE THROUGH 6000 FT; CLRED WITH DEP INSTRUCTIONS AT THE HOLD SHORT LINE. I ASSUMED; WITH AN URGENCY IN THE VOICE; CLRED FOR TKOF. THE CALL ACTUALLY WAS CLRED INTO POS AND HOLD. I HAVE NEVER RECEIVED DEP INSTRUCTIONS; THEN A POS AND HOLD. YOU ALWAYS RECEIVE; TAXI INTO POS AND HOLD; THEN RECEIVE DEP INSTRUCTIONS WITH A TKOF CLRNC. THE INSTRUCTIONS WERE DIFFERENT. I WAS EXPECTING THE POMONA DEP AS ALWAYS -- WITH A VECTOR AND A HIGHER THAN NORMAL ALT. IN A HURRIED VOICE IT CAME ACROSS AS AN EXPEDITED CLRNC. WATCHING PLANES LAND IN A HAZY SKY; I DIDN'T KNOW IF THERE WAS TFC ON APCH. THE WHOLE SEQUENCE WAS NOT NORMAL. THE ABORT WAS UNEVENTFUL; MINIMUM BRAKING. TAXIED BACK AND DEPARTED WITH A NORMAL CLRNC. I FEEL THAT I WAS SET UP AND I TOOK THE BAIT. SUPPLEMENTAL INFO FROM ACN 584866: AS WE STARTED OUR TKOF; TWR SAID TO HOLD OUR POS. AIRSPD WAS MINIMAL. ACFT WAS BRAKED AND WE EXITED THE RWY.