GA SMA ON TCA CLRNC GIVEN VECTOR INTO RISING TERRAIN. OPERROR.

Narrative

I WAS GIVEN A CLRNC TO DEPART THE TCA VIA HDG 110 DEG AND TO MAINTAIN 3500' MSC. UPON CONTACTING DEPARTURE CONTROL; I WAS INSTRUCTED TO FLY HEADING 150 DEG FROM A POINT ABOUT 4 MILES SOUTH OF THE AIRPORT. THIS HEADING TOOK ME TOWARD HILLS SE OF THE LAS VOR WHICH ARE SHOWN ON THE CHART AS RISING TO 4069'. THE RADIO CHANNEL WAS EXTREMELY BUSY AT THE TIME--IT WAS NOT POSSIBLE FOR ME TO ASK ATC FOR A HIGH ALTITUDE. ALTHOUGH I ATTEMPTED TO CONTACT THEM SEVERAL TIMES. FINALLY; WHEN WITHIN ONE HALF MILE OF THE TERRAIN; I EXERCISED MY EMER AUTHORITY AND CLIMBED TO 4;300' TO CROSS THE RIDGES. I FELT THAT THIS WAS SAFER THAN A COURSE DEVIATION SINCE A NORTHERLY TURN MIGHT CAUSE A CONFLICT WITH INBOUND TFC AND A SOUTHERLY TURN WAS TOWARD MORE TERRAIN. SHORTLY AFTER REACHING 4300' ATC CLRED BY TO 5000' AND DIRECT BOULDER CITY--I DID NOT MENTION MY PREDICAMENT DUE TO FREQUENCY CONGESTION. I THINK MAYBE SOMEBODY NEEDS TO VERIFY THE MINIMUM VECTORING ALTITUDES SE OF LAS AND VERIFY THAT LOW ALTITUDE ALERT FEATURES OF THE RADAR SYSTEM SOFTWARE ARE FUNCTIONAL.