PLT OF SMA NORAC FLEW OVER AIR CARRIER AT END OF RWY CLRED FOR TKOF.

Narrative

FLT WAS RUNNING LATE SO EVERYTHING WAS HURRIED INCLUDING TAXI. AS WE APCHED THE END OF THE TAXIWAY (HOLD SHORT LINE) THE FO WENT OFF RADIO AND ON TO PA TO ADVISE FLT ATTENDANTS TO BE SEATED FOR TKOF. SIMULTANEOUSLY; AN MLG CROSSED OVER THE THRESHOLD SO I ADVISED THE TWR THAT WE WERE READY FOR TKOF AND WE WERE CLRED INTO 'POS AND HOLD.' WITHOUT STOPPING; I TAXIED ONTO RWY AS THE MLG CLRED DOWNFIELD. WHILE ENTERING RWY AND BEFORE LINING UP I GLANCED QUICKLY DOWN THE FINAL APCH PATH AND SAW NO ACFT. FO AND I COMPLETED 'LINE UP CHKLIST.' AS MLG CLRED RWY WE WERE CLRED FOR TKOF BUT AT THAT MOMENT A SHADOW PASSED OVER THE ACFT AND A SECOND LATER THE SMA X THAT CREATED IT CAME INTO VIEW ABOVE US. WE HELD IN POS AS THE X FLEW DOWN THE RWY AS IT PERFORMED A GAR. CTLR THANKED US FOR HOLDING; THEN ADVISED US THAT THE X HAD NOT BEEN IN SIGHT FROM THE TWR NOR HAD IT MADE RADIO CONTACT. THE X THEN CAME ON THE RADIO TO ADVISE THAT IT WAS ABORTING LNDG FOR TFC. PLT SOUNDED LIKE EITHER A STUDENT OR INEXPERIENCED PLT ON RADIO. TWR ASKED X IF HE HAD CALLED THE TWR BUT THE X PLT SEEMED CONFUSED AND DID NOT ANSWER THE QUESTION; INSTEAD REPEATING THAT HE WAS 'ABORTING.' TWR ASSIGNED THE X A HDG FOR XWIND/DOWNWIND AND AS X CLRED THE DEP PATH WE WERE AGAIN CLRED FOR TKOF. LESSONS LEARNED ARE: JUST BECAUSE AN ACFT HAS COME OVER THRESHOLD; DON'T ASSUME THERE IS NOT ANOTHER CLOSE BEHIND. DON'T ASSUME THAT ALL ACFT ARE IN CONTACT WITH THE TWR EVEN IF THEY SHOULD BE. DON'T ASSUME THAT THE LCL CTLR IS AWARE OF ALL ACFT IN THE ATA. DON'T EVER TAKE POS ON RWY WITHOUT A GOOD LOOK (NOT A QUICK ONE) DOWN THE FINAL AT ANY ARPT.