SMA CROSSED ACTIVE RWY WITHOUT CLRNC FORCING AN ABORTED TKOF BY ANOTHER SMA.

Narrative

MONITORED ATIS (126.75) AT POU. THEN SPOKE TO GND FOR PERMISSION TO TAXI TO THE ACTIVE RWY. I RECEIVED AND ACKNOWLEDGED A HOLD SHORT RWY 33 ON ALPHA TAXIWAY. I TAXIED TO THE HOLD LINE AND STOPPED THE ACFT. I WAS WEARING A RADIO HEADSET. MY INSTRUCTOR TOLD ME HE HAD THE AIRPLANE. I ASSUMED HE HEARD THE ATIS AND THE EXCHANGE BETWEEN GND CTL AND ME. I SHOULD HAVE REPEATED GND INSTRUCTIONS TO HIM. I DID NOT. I WAS READING THE APCH PLATE WHEN I HEARD GND ASK 'SMA X WHAT ARE YOU DOING?' WHEN I LOOKED UP I SAW THAT THE INSTRUCTOR HAD TAXIED ACROSS RWY 33 TOWARDS A RWY WE HAD TAKEN OFF AND LANDED ON EARLIER IN THE DAY. HE EXPECTED THE SAME RWY TO BE IN USE. SUPPLEMENTAL INFORMATION FROM ACN #86701: I WATCHED SMA X COME TO A STOP AND HOLD SHORT OF RWY 33. AFTER A DEP I WAS PLANNING TO COORDINATE A BACK TAXI ON 33. I TOLD AN MDT TO TAXI AND HOLD SHORT OF RWY 33. SECONDS LATER I SAW SMA X XING RWY 33 AS SMA Y WAS ABORTING TAKEOFF. SMA Y PLT WAS THE ONLY ONE OF US TO SEE THE INCIDENT IN TIME TO DO ANYTHING ABOUT IT.