C182 PLT AT ASH MISTAKES; 'HOLD FOR RELEASE;' FOR 'POS AND HOLD.'

Narrative

INCIDENT WAS A RWY INCURSION ARISING OUT OF COMS BTWN THE PLT (ME) AND NASHUA TWR. THE FLT WAS PLANNED AS IFR FROM ASH TO ORF -- PURPOSE OF WHICH WAS PLEASURE. THERE WERE NO TIME PRESSURES ON ME FOR THIS FLT. I TAXIED OUT TO THE RAMP AREA OF ASH RWY 14; DID MY RUN-UP AS USUAL; AND THEN CALLED THE TWR RPTING OUR READINESS FOR TKOF. I HEARD 'POS AND HOLD.' EVIDENTLY; THE INSTRUCTION WAS 'HOLD FOR RELEASE.' I DON'T RECALL WHAT I READ BACK; BUT I BELIEVE IT WAS 'POS AND HOLD;' OTHERWISE I WOULD HAVE HELD FOR RELEASE. MOREOVER; I'D EXPECT THE TWR CTLR TO RESTATE THE INSTRUCTION IF THE READBACK WAS NOT CORRECT. AFTER THIS READBACK; I STARTED TAXIING FOR POS AND HOLD. AFTER XING THE HOLD LINE; BUT BEFORE REACHING THE RWY; THE TWR CALLED AND SAID TO HOLD; WHICH I DID. THERE WAS ANOTHER ACFT; WHICH I HAD NOT SEEN; WHICH WAS ON ABOUT A 1 MI FINAL. WHILE THE FIELD CONDITIONS WERE IFR; THE VISIBILITY SHOULD HAVE BEEN ADEQUATE FOR ME TO SEE THIS ACFT; BUT SINCE I BELIEVED I HAD BEEN CLRED TO 'POS AND HOLD;' I WASN'T REALLY LOOKING FOR TFC ON FINAL. SO; THIS INCIDENT WAS A 'NEAR' RWY INCURSION. THIS ERRONEOUS ACTION ON MY PART ALSO WOULD HAVE BEEN INSIDE THE ILS NO-TAXI ZONE; BUT NO ILS HOLDS SEPARATE FROM THE RWY HOLD LINE ARE PRESENT AT ASH. I'M FAIRLY EXPERIENCED WITH IFR AND HAVE NO EXPLANATION FOR MISINTERPING THE INSTRUCTION. I HEARD (AND I BELIEVE READ BACK) 'POS AND HOLD;' AND THAT'S WHAT I WAS DOING UP TO THE CALL FROM TWR. THE SUGGESTED CORRECTIVE ACTION WILL BE ADDED VIGILANCE FOR ATC (TWR) INSTRUCTIONS; AND CLR READBACK TO BE SURE I'VE UNDERSTOOD CORRECTLY. PERHAPS COMPLACENCY AND EXPECTATIONS OF A RELATIVELY UNCHALLENGING FLT ENTERED INTO MY MISINTERP OF THE ATC INSTRUCTION. I HEARD WHAT I WAS EXPECTING TO HEAR. NOTE THAT I'M NOT CONFIDENT OF THE ACTUAL COM AND READBACK SINCE I WAS FAIRLY RATTLED AFTER MAKING THE MISTAKE.