B737-700 CREW HAS LESS THAN LEGAL SEPARATION FROM A LEARJET IN LAS CLASS E AIRSPACE.

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ON THE TRALR 1 DEP OUT OF LAS; WE RECEIVED AN RA WHILE LEVEL AT 7000 FT. WE SHOWED THE INTRUDING ACFT (A LEARJET) WITHIN THE 2.5 MI RANGE ON OUR MAP DISPLAY. UP TO THIS POINT; THE CTLR ASKED THE LEARJET IF HE HAD US IN SIGHT. THE CTLR WENT SO FAR AS TO TELL LEARJET NOT TO PASS US ON THE DEP; AND AGAIN ASKED HIM IF HE HAD US IN SIGHT; TO WHICH HE RESPONDED THAT HE DID. UPON RECEIVING A DSND RA; THE FO DISCONNECTED THE AUTOPLT AND RESPONDED TO THE 1500-2000 FPM RA. BECAUSE WE WERE ONLY ABOUT 3000 FT AGL AND DSNDING IN HIGH TERRAIN; WE TURNED THE ACFT OFF COURSE TOWARDS A VALLEY (LOWER TERRAIN). AS SOON AS WE DSNDED 500-1000 FT; THE RA WAS COMPLETE. AT THIS POINT; THE INTRUDING ACFT WAS AT OUR 7-8 O'CLOCK POS AT APPROX 2 MI; 1000 FT ABOVE US. WE IMMEDIATELY NOTIFIED THE CTLR THAT WE HAD RESPONDED TO A TCASII RA AND WERE APPROX 2 MI TO THE R OF COURSE. THE CTLR ACKNOWLEDGED US AND ASKED THE LEARJET IF HE HAD PASSED US ON THE DEP. THE LEAR RESPONDED THAT WE 'HAD GONE WIDE R' ON THE DEP. AS A RESULT OF THE LEARJET'S POS ROUGHLY ABEAM US; THE CTLR GAVE HIM AN IMMEDIATE VECTOR NBOUND AWAY FROM US. I AM CONVINCED THAT UP UNTIL THIS POINT; THE LEAR DID NOT HAVE US IN SIGHT. WE REJOINED THE DEP AND I INFORMED THE CTLR THAT THE REASON WE WERE WIDE WAS BECAUSE OF THE DSCNT TOWARDS THE HIGH TERRAIN. WE CONTINUED THE DEP UNEVENTFULLY. PRIMARY FACTOR: I BELIEVE THE PRIMARY FACTOR IN THIS TCASII RA INCIDENT WAS THE FACT THAT THE LEARJET LOST SIGHT OF US ON THE DEP AND FAILED TO INFORM TRACON. CONTRIBUTING FACTORS: 1) TWR CTLR SHOULD HAVE ALLOWED MORE TIME BTWN DEPS CONSIDERING THE LEAR'S CLB AND ACCELERATION PERFORMANCE. 2) WE WERE FLYING AT AROUND 240 KIAS AND UPON NOTICING THE LEAR'S CLOSURE RATE ON THE TCASII; WE SHOULD HAVE INCREASED OUR AIRSPD TO 250 KIAS. 3) DUE TO THE CTLR'S HIGH WORKLOAD; HE WAS UNABLE TO ADEQUATELY ASCERTAIN THE LEARJET'S CLOSURE RATE TOWARDS OUR ACFT. TO HIS CREDIT; HE DID ASK THE LEARJET AT LEAST TWICE IF HE HAD US IN SIGHT AND NOT TO PASS US. 4) THE PRIMARY CTLR'S SUPVR SHOULD HAVE BEEN MONITORING AND INTERVENED. SUPPLEMENTAL INFO FROM ACN 636298: DEP CTL GAVE BOTH ACFT VECTORS FOR THE REST OF THE DEP. AFTER A CALL BACK TO APCH; WE FOUND OUT THAT THE LEARJET HAD BEEN GIVEN TKOF CLRNC WHILE WE WERE STILL ON THE RWY; AND WE WERE BOTH ON THE TRALR 1 DEP. THE LEARJET OUT CLBED AND OUTPERFORMED A 131K LB B737; AND FROM HIS NEGATIVE ANSWER AS TO WHETHER OR NOT HE HAD PASSED US ON THE DEP (WHEN HE CLRLY HAD); I THINK HE DID NOT HAVE US IN SIGHT.