Vgt controller described a go around event caused by an aircraft taking off without authorization.

Narrative:

Aircraft X called up ready to depart. I told him 'runway 12R; taxi via golf; cross runway 7.' he responded with; 'roger; crossing runway 7; runway 12 right.' I had aircraft Y on short final for runway 12 right. I then witnessed aircraft X departing runway 12 right without authorization. I told aircraft Y to go around. I then told aircraft X that he was not given a takeoff clearance. He said he was sorry; but he thought I cleared him for takeoff after the cherokee. I then told him of a possible pilot deviation and switched him to nellis departure.

Original NASA ASRS Text

Title: VGT Controller described a go around event caused by an aircraft taking off without authorization.

Narrative: Aircraft X called up ready to depart. I told him 'Runway 12R; taxi via Golf; cross Runway 7.' He responded with; 'Roger; crossing Runway 7; Runway 12 right.' I had Aircraft Y on short final for Runway 12 right. I then witnessed Aircraft X departing Runway 12 right without authorization. I told Aircraft Y to go around. I then told Aircraft X that he was not given a takeoff clearance. He said he was sorry; but he thought I cleared him for takeoff after the Cherokee. I then told him of a possible pilot deviation and switched him to Nellis Departure.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	943974
Time
Date	201104
Local Time Of Day	1801-2400
Place
Locale Reference	VGT.Tower
State Reference	NV
Aircraft 1
Make Model Name	Cessna 210 Centurion / Turbo Centurion 210C 210D
Flight Plan	VFR
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	Conflict Ground Conflict Critical Deviation - Procedural Clearance Ground Incursion Runway