Narrative:

As local control in charge of both runway 8L and 8R I was moderately busy. Air carrier X landed runway 8L and was issued detailed taxi instructions to cross runway 8R. Air carrier X acknowledged these instructions. As local controller for the departure runway, I issued 'taxi into position' instructions to air carrier Y, which was still several hundred ft from the approach end of this runway. The crew acknowledged the instructions for taxiing into position and hold. Scanning the runway to ensure that air carrier X was clear gave indication to me, as the local controller, that air carrier X was complying with instructions. Air carrier X was in center of runway with the nose still at 90 degree angle to runway. Taxiway was in full view to the crew. I then observed air carrier Y taxi onto runway 8R at an intersection. This seemed very unusual, however, it created no problem. From the time air carrier X was observed progressing across the runway in a normal fashion to the time air carrier Y was actually in position for departure was about 1 min. I proceeded to issue departure clearance to air carrier Y when I observed unusual movement through my peripheral vision. Air carrier X had made a hard 90 degree turn and was taxiing on the runway. This only proves a controller's job is never completed. We must watch every aircraft and be aware of the pilots who make mistakes.

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Original NASA ASRS Text

Title: ACR X NON ADHERENCE TO ATC INSTRUCTIONS MADE TURN BACK ONTO ACTIVE RWY WITH ACR Y CLRED FOR TKOF. PLTDEV SYS ERROR.

Narrative: AS LCL CTL IN CHARGE OF BOTH RWY 8L AND 8R I WAS MODERATELY BUSY. ACR X LANDED RWY 8L AND WAS ISSUED DETAILED TAXI INSTRUCTIONS TO CROSS RWY 8R. ACR X ACKNOWLEDGED THESE INSTRUCTIONS. AS LCL CTLR FOR THE DEP RWY, I ISSUED 'TAXI INTO POS' INSTRUCTIONS TO ACR Y, WHICH WAS STILL SEVERAL HUNDRED FT FROM THE APCH END OF THIS RWY. THE CREW ACKNOWLEDGED THE INSTRUCTIONS FOR TAXIING INTO POS AND HOLD. SCANNING THE RWY TO ENSURE THAT ACR X WAS CLR GAVE INDICATION TO ME, AS THE LCL CTLR, THAT ACR X WAS COMPLYING WITH INSTRUCTIONS. ACR X WAS IN CTR OF RWY WITH THE NOSE STILL AT 90 DEG ANGLE TO RWY. TAXIWAY WAS IN FULL VIEW TO THE CREW. I THEN OBSERVED ACR Y TAXI ONTO RWY 8R AT AN INTXN. THIS SEEMED VERY UNUSUAL, HOWEVER, IT CREATED NO PROBLEM. FROM THE TIME ACR X WAS OBSERVED PROGRESSING ACROSS THE RWY IN A NORMAL FASHION TO THE TIME ACR Y WAS ACTUALLY IN POS FOR DEP WAS ABOUT 1 MIN. I PROCEEDED TO ISSUE DEP CLRNC TO ACR Y WHEN I OBSERVED UNUSUAL MOVEMENT THROUGH MY PERIPHERAL VISION. ACR X HAD MADE A HARD 90 DEG TURN AND WAS TAXIING ON THE RWY. THIS ONLY PROVES A CTLR'S JOB IS NEVER COMPLETED. WE MUST WATCH EVERY ACFT AND BE AWARE OF THE PLTS WHO MAKE MISTAKES.

Data retrieved from NASA's ASRS site as of July 2007 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.