LR31 DEPARTS LAS WITHOUT ATC TKOF CLRNC.

Narrative

THE COPLT REQUESTED TAXI CLRNC FROM THE LAS VEGAS RAMP; HAD DIFFICULTY BEING HEARD BY GND CTL. HAVING FLOWN IN AND OUT OF LAS VEGAS MANY TIMES IN THE PAST; I HAD THE COPLT SWITCH TO THE #2 COM RADIO; WHICH WAS HEARD BETTER. GND CTL GAVE US INSTRUCTIONS TO FOLLOW ANOTHER LEAR 31A COMING OUT OF THE LAS VEGAS EXECUTIVE RAMP; AND TO TAXI TO AND HOLD SHORT OF RWY 19R. THEY ALSO SUGGESTED THAT WE SHOULD TRY ANOTHER RADIO. WE ADVISED THEM THAT WE HAD ALREADY SWITCHED THE RADIOS AND THAT WE WERE CLRED TO TAXI TO AND HOLD SHORT OF RWY 19R. THE TAXI FROM RAMP FOR RWY 19R IS EXTREMELY SHORT; WHICH MEANS THERE IS A MINIMAL AMOUNT OF TIME TO COMPLETE THE TAXI CHKLIST. LAS VEGAS TWR IS FREQUENTLY CALLING YOUR N-NUMBER TO ASK IF YOU ARE READY FOR TKOF OR ISSUING TKOF CLRNC AS YOU COME ON FREQ. THIS FACT ADDS A DEGREE OF URGENCY TO COMPLETE ALL THE CHKLISTS; PRIOR TO SWITCHING TO THE TWR FREQ. THE LEAR 31A AHEAD OF US WAS THEN ASKED BY THE TWR 'HOW MUCH OF A PROB WOULD IT BE TO REPROGRAM THE FMS TO DEPART ON THE IDALE2 RNAV DEP FROM RWY 19L?' WE WERE THEN #1 HOLDING SHORT OF RWY AND WERE ASKED BY THE TWR CTLR IF WE COULD REPROGRAM THE FMS FOR A RWY 19L RNAV DEP. I BELIEVE THAT WE RESPONDED THAT WE COULD DO THAT. AN EMBRAER TWIN TURBOPROP COMMUTER ACR X HAD JUST LANDED ON RWY 19R AND THE TWR CTLR THEN INSTRUCTED US TO TAXI INTO POS ON RWY 19R AND HOLD. THE COPLT REPLIED FOR LEAR JET XXXXX; 'TAXI INTO POS AND HOLD RWY 19R.' THERE WAS A SUBSTANTIAL AMOUNT OF RADIO COMS TAKING PLACE. AN ACR Y HAD BEEN DIRECTED TO TAXI INTO POS ON RWY 19L. I ASKED FOR THE 'RWY LINEUP CHKLIST.' WHILE RUNNING THE CHKLIST; I NOTED THAT THE ACR Y HAD BEGUN ITS TKOF ROLL AND THAT THE EMBRAER WAS CLRING RWY 19R. WHILE COMPLETING THE CHKLIST; MY COPLT RADIOED BACK WITH 'LEAR XXXXX CLRED FOR TKOF.' I ASKED HIM IF WE WERE CLRED FOR TKOF AND HE RESPONDED WITH 'YES WE ARE CLRED FOR TKOF.' ONCE AIRBORNE; THE TWR TOLD US THAT WE HAD NOT RECEIVED TKOF CLRNC AND ASKED IF WE HAD THE ACR Y IN SIGHT. WE RESPONDED THAT WE DID; AND THEY THEN GAVE US A DIVERGENT HDG AND A FREQ CHANGE TO DEP CTL. DEP CTL THEN CONTINUED TO HANDLE US AND ALSO GAVE US A TELEPHONE NUMBER TO CALL UPON LNDG. I CALLED AND SPOKE TO MR X AT LAS. I RELATED MY RECOLLECTION OF THE EVENTS TO MR X AND WAS INFORMED BY HIM THAT HE HAD LISTENED TO THE TWR TAPES AND THAT THE TKOF CLRNC HAD BEEN ISSUED TO THE ACR Y AND NOT TO US! CONTRIBUTING FACTORS: 1) COMPRESSED TIME DUE TO PROX OF RAMP AND RWY. 2) POOR RADIO COMS. 3) PERCEIVED URGENCY ON THE PART OF THE TWR. 4) UNCERTAINTY AS TO WHICH DEP/RWY TO EXPECT. 5) FAILURE TO ASK COPLT TO CONFIRM THE TKOF CLRNC IF ANY DOUBT EXITS. 6) PREOCCUPATION WITH ENSURING THAT ACFT AND CREW ARE READY FOR TKOF. 7) POSSIBLE FATIGUE COMPONENT.