LEAR-25 FLT CREW HAS A RWY INCURSION AT IWA.

Narrative

AFTER WE RECEIVED ATIS AND A CLRNC; WE TAXIED TO AND HELD SHORT OF RWY 30L FOR A FULL LENGTH DEP AT IWA. THERE WERE SEVERAL ACFT IN THE PATTERN; AND THE RADIO FREQS WERE BUSY; BUT THERE WERE NO OTHER ACFT IN THE PATTERN; AND THERE WERE NO OTHER ACFT THAT WE HEARD OR COULD SEE HOLDING SHORT OF RWY 30L. WE WAITED ABOUT 1 MIN AND RECEIVED WHAT WE THOUGHT WAS AN IMMEDIATE TKOF CLRNC FOR RWY 30L; WITH A CHEROKEE ON SHORT FINAL. I ACKNOWLEDGED THE CLRNC. THERE WERE NO OTHER ACFT IN THE AREA; AND WE COMPLETED OUR TKOF CHKLIST AND BEGAN OUR TKOF ROLL. AS WE LINED UP ON THE CTRLINE OF THE RWY; WE SAW A SINGLE ENG; PISTON ACFT TAKING OFF DOWNFIELD ON OUR RWY. THE FO AND I BOTH APPLIED BRAKES AS HE RETARDED THE THRUST LEVERS. AT THAT TIME; THE TWR TOLD US TO HOLD OUR POS AND CALLED A GAR FOR THE CHEROKEE. THE CTLR TOLD US THAT OUR LAST INSTRUCTION WAS TO HOLD SHORT. I INFORMED HIM THAT WE HAD; THEN ENTERED THE RWY AFTER RECEIVING OUR IMMEDIATE TKOF INSTRUCTION. HE TOLD US THAT IT HAD BEEN FOR A CIRRUS MAKING AN INTXN DEP. WE COULD NOT SEE THE ACFT AT THE INTXN AND DID NOT KNOW HE WAS THERE. THE CTLR WAS UNCLEAR ENOUGH TO MAKE US THINK THAT HE CALLED US INSTEAD OF THE CIRRUS. APPARENTLY MY XMISSION ACKNOWLEDGING OUR TKOF CLRNC HAD BEEN BLOCKED BY THE CIRRUS; AND THE TWR DID NOT NOTICE US TAKING THE ACTIVE RWY UNTIL WE WERE LINED UP AND MOVING DOWN THE RWY. SUPPLEMENTAL INFO FROM ACN 701224: THE FLT CREW ALLOWED THEMSELVES TO FEEL HURRIED BY THE 'IMMEDIATE' TKOF CLRNC. THERE WAS NO DOUBT IN MY MIND THAT THE TKOF CLRNC WAS FOR US AS THE CAPT READ IT BACK. WE HAD BEEN READY AT THE END FOR SOME TIME; AND WE WERE THE FIRST ACFT IN SEQUENCE AT THE END OF THE RWY. THE LACK OF ANY CORRECTION FROM THE TWR AFTER THE READBACK MADE ME ABSOLUTELY CONFIDENT WE WERE CLRED TO TAKE THE RWY AND DEPART.