MD88 MISTAKENLY STARTED TAXIING INTO POS FOR TKOF AFTER TWR CTLR INSTRUCTED THEM TO PULL UP BEHIND A B757 THAT WAS AHEAD TAKING THE RWY. TWR SENT ANOTHER ACFT AROUND AND CLRED RPTRS FOR TKOF SINCE THEY WERE OVER THE HOLD SHORT LINE.

Narrative

TAXIING FOR TKOF ON RWY 18L IN CVG; GND CTLR TOLD US TO FOLLOW THE B757 AHEAD. I WAS TIRED; HAD NOT SLEPT WELL NIGHT BEFORE EARLY MORNING SIGN-IN AND WE WERE ON OUR THIRD LEG OF THE DAY. B757 AHEAD TAXIED ONTO RWY 18L AND DEPARTED. WE SWITCHED TO LCL FREQ. CAPT CALLED FOR BEFORE TKOF CHKLIST; WHICH I INITIATED. AS I WAS ACCOMPLISHING BEFORE TKOF ITEMS; I LOOKED UP; NOTICED WE WERE BEYOND RWY HOLD SHORT LINES AND ASKED THE CAPT 'ARE WE CLRED INTO POS AND HOLD?' (WE WERE NOT.) THE CAPT STOPPED THE ACFT. WE HAD TAXIED ABOUT 50-75 FT BEYOND THE HOLD SHORT LINE AT THE TKOF END OF RWY 18L. THIS PUT US ABOUT 50-60 FT FROM THE EDGE OF THE RWY AND ABOUT 125-135 FT FROM RWY CTR (150 FT WIDE RWY). A DORNIER 328 WAS ON A 2 MI FINAL; YET WAS NOT A FACTOR. CAPT TOLD ME TO RPT OUR ERROR TO TWR. WE DID. TWR SENT THE DORNIER AROUND; THEN CLRED US FOR TKOF. BOTH OF US WERE TIRED. I HAD MENTIONED THIS TO CAPT IN THE MORNING; AND I FLEW ONLY THE MIDDLE LEG AS A RESULT. CAPT WAS TIRED ALSO. GND CTLR TOLD US TO FOLLOW B757 AHEAD AND QUITE LITERALLY WE DID. CTLR NEITHER STATED HOLD SHORT OF RWY 18L NOR DID HE SWITCH US TO TWR FREQ. EVEN THOUGH IT IS OBVIOUS TO ANYONE THAT YOU DO NOT TAXI ONTO AN ACTIVE RWY WITHOUT CLRNC; BUT A QUICK 'HOLD SHORT RWY 18L' FROM GND CTLR LIKELY WOULD HAVE LEFT QUITE A DIFFERENT IMPRESSION ON US AS OPPOSED TO 'FOLLOW THE B757.' STANDARD PHRASEOLOGY. ACCOMPLISHMENT OF CHKLIST WHILE MOVING CLOSE TO A RWY DISTR ME FROM BEING AS VIGILANT AS I MIGHT HAVE BEEN. MAINTAIN VIGILANCE; REDUCE DISTRS AT CRITICAL JUNCTURES. I FELT COMFORTABLE WITH MY CAPT. HE WAS COMPETENT; CONFIDENT; BUT HE IS HUMAN. TRUST -- BUT VERIFY. WE WENT OVER THE HOLD SHORT LINE; BUT NOT ONTO THE RWY. HOWEVER; I CAN SEE HOW DISASTROUS THIS SIT CAN BE. I WILL BE MUCH MORE RELUCTANT TO ACCOMPLISH CHKLISTS WHEN APCHING ACTIVE RWYS FOR TKOF OR AFTER LNDG. IN FACT; MINIMUM ACTIVITY (EYES OUTSIDE) APCHING AN ACTIVE RWY SOUNDS LIKE THE BEST ALTERNATIVE TO ME. SUPPLEMENTAL INFO FROM ACN 594323: WHILE AWAITING TKOF AT CVG; TWR ADVISED US TO 'PULL UP BEHIND THAT B757.' THE B757 WAS TAKING THE RWY AND CLRED FOR TKOF. I KNEW WE WERE NEXT FOR TKOF; BUT DIDN'T REALIZE THAT TWR WAS PLANNING FOR A TURBOPROP COMMUTER ACFT TO LAND PRIOR TO OUR DEP. RIGHT AFTER WE BEGAN TAXIING PAST THE HOLD SHORT LINE; THE FO LOOKED UP FROM THE CHKLIST HE WAS COMPLETING AND ASKED IF WE HAD BEEN CLRED INTO POS AND HOLD. AT THIS POINT I REALIZED THAT WE HAD NOT AND I IMMEDIATELY STOPPED THE ACFT AND WE ADVISED TWR THAT WE HAD STOPPED PAST THE HOLD SHORT LINE. THE ACFT WAS STRADDLING THE HOLD SHORT LINE. I ESTIMATE THAT THE NOSE OF THE ACFT WAS 40 FT PAST THE HOLD SHORT LINE AND 30 FT AWAY FROM THE WHITE RWY EDGE LINE. TWR DIRECTED THE TURBOPROP TO DISCONTINUE HIS APCH AND CLRED US FOR TKOF. THE REST OF THE FLT WAS UNEVENTFUL. 2 FACTORS CONTRIBUTED TO THIS EVENT. THE FIRST WAS THE TWR CTLR'S FAILURE TO USE THE WORDS 'HOLD SHORT.' HAD THESE WORDS BEEN SPOKEN; I HAVE NO DOUBT WHATSOEVER THAT I WOULD NOT HAVE TAXIED PAST THE HOLD SHORT LINE. THE SECOND WAS FATIGUE. I HAD BEEN UP SINCE EARLY MORNING AND THE FO HAD BEEN UP SINCE EARLY MORNING HRS. THIS WAS OUR THIRD LEG OF THE DAY.