CFI WITH SPI FORGETS TO CHANGE TO GND FREQ. TAXIES ACROSS RWY WITH ACFT READY FOR TKOF.

Narrative

THE INCURSION HAPPENED PART WAY THROUGH A HOT; TIRING AND FRUSTRATING DAY; FOLLOWING A PERIOD IN WHICH I HAD HAD A TOTAL OF 4 DAYS OFF WORK IN THE PREVIOUS 2 MONTHS. I WAS PROGRAMMED FOR A PARTICULARLY BUSY 12 HR DAY; INCLUDING 5 INSTRUCTIONAL FLTS; AND MY SCHEDULE HAD BEEN DELAYED DUE TO A MGMNT OVERSIGHT. AT THE END OF MY THIRD FLT MY STUDENT HAD MADE A XWIND LNDG ON RWY 23 IN A VERY UNTIDY MANNER. AS WE CLRED THE RWY WE WERE TOLD TO CONTACT GND CTL; AND THE STUDENT ACKNOWLEDGED; HOWEVER WE DID NOT CHANGE FREQ. I IMMEDIATELY BEGAN TAXIING AND DEBRIEFING THE LNDG; AND CONTINUED TAXIING TOWARDS THE RAMP; WHICH INVOLVED XING RWY 5/23. MAYBE HAVING BEEN CLRED TO THE RAMP SO OFTEN IN THE LAST FEW DAYS I ASSUMED WE WERE CLRED AGAIN. ALTHOUGH I LOOKED BOTH WAYS I DID NOT SEE THE LIGHT ACFT WHICH HAD JUST BEEN CLRED FOR TKOF ON RWY 23; AND I TAXIED ONTO THE RWY. I SAW THE ACFT JUST AS ATC TOLD HIM TO HOLD HIS POS. I HAD NO CHOICE AT THAT STAGE BUT TO CONTINUE ACROSS RWY 23 TO CLR IT. THIS WAS A CLR CASE OF TIREDNESS OR FATIGUE FROM OVERWORK. FEAR OF BEING REPLACED OR LOSING MY STATUS AS A 'SENIOR' INSTRUCTOR IF I EASED UP IN A WORLD AWASH WITH INSTRUCTORS AND ALSO NEEDING THE MONEY FROM A POORLY PAID PIECE-WORK JOB WERE THE DRIVING FACTORS. IT TOOK THE INCURSION TO MAKE ME REALIZE HOW FAR I HAD A LLOWED MYSELF TO BE DRIVEN. I KNOW THE SOLUTION FOR ME -- A REST. MORE GENERALLY; MAYBE THE PROBS OF MIXING FATIGUE AND FLT COULD BE AIMED MORE PUBLICLY USING ACTUAL EXAMPLES -- MINE; FOR INSTANCE.