C150 TAXIED ONTO DEP RWY WITHOUT ATC CLRNC AT VGT ARPT.

Narrative

I WAS ACTING AS THE PIC OF A CESSNA 150M. I WAS THE SOLE OCCUPANT OF THE ACFT AND THE INTENT OF THE FLT WAS TO PERFORM TOUCH AND GOES AT THE NORTH LAS VEGAS ARPT (VGT) FOR APPROX ONE HR. AFTER PERFORMING THE NECESSARY PRFLT CHKS AND OBTAINING THE VGT AWOS; I CONTACTED THE VGT GND CTLR AT ABOUT XA15 LCL TIME AND ADVISED HIM OF MY INTENT. THE VGT GND CTLR CLRED ME TO TAXI TO RWY 7. UPON REACHING AND HOLDING SHORT OF RWY 7 AT TXWY GULF; I CONTACTED THE VGT TWR AND ADVISED HIM OF MY LOCATION AND THAT I WAS READY FOR DEP. THE VGT TWR CTLR ADVISED ME TO TAXI TO RWY 12R. AFTER VISUALLY CHKING FOR CONFLICTING GND OR AIRBORNE TFC I CROSSED RWY 7 AND CONTINUED ONTO RWY 12R WHERE I POSITIONED THE AIRPLANE AT OR ABOVE THE RWY IDENTIFICATION MARKINGS AT THE APCH END OF RWY 12R. UPON BRINGING THE ACFT TO A COMPLETE STOP I IMMEDIATELY REALIZED THAT I HAD MISTAKENLY TAXIED INTO A 'POS AND HOLD' DEP POSTURE; ON THE RWY; WHEN I HAD ACTUALLY ONLY BEEN CLRED TO TAXI TO THE RWY. WITHIN SECONDS OF REALIZING THIS MISTAKE I HEARD TFC VIA THE RADIO ASKING THE VGT TWR IF THEY WANTED HIM TO 'GO AROUND;' BECAUSE OF TFC ON THE RWY. THE VGT CTLR ADVISED THE TFC TO GAR AND THEN CONTACTED ME VIA THE RADIO. THE CTLR ASKED IF I UNDERSTOOD WHAT I HAD DONE AND I INDICATED THAT I UNDERSTOOD HIS PREVIOUS TAXIING INSTRUCTIONS AND NOW REALIZED THAT I HAD MADE A MISTAKE. THE VGT CTLR THEN CLRED ME FOR TKOF AND THE PREVIOUS TFC I OBSTRUCTED CONTINUED AROUND THE TFC PATTERN AND LANDED UNEVENTFULLY AFTER MY TKOF. AFTER SEVERAL TOUCH AND GOES AT VGT THE CTLR ASKED ME TO CONTACT THE TWR VIA PHONE UPON COMPLETING MY FLT FOR THE EVENING. I THEN CONCLUDED MY FLT; SECURED THE AIRPLANE AND CONTACTED THE VGT TWR VIA PHONE AS REQUESTED. I EXPLAINED TO THE CTLR THAT I FULLY UNDERSTOOD HIS EARLIER TAXI CLRNC AND THAT FOR UNKNOWN REASONS I CONTINUED TO TAXI ONTO THE RWY. I APOLOGIZED TO THE CTLR AND TOLD HIM THAT I COULD OFFER NO EXPLANATION FOR THE ERROR I HAD MADE OTHER THAN MOMENTARY HUMAN ERROR. I THEN PROVIDED THE CTLR WITH MY CONTACT INFO AS WELL AS MY LICENSING INFO.