INTL FLC MISUNDERSTOOD CLRNC.

Narrative

AT XA11Z; ACFT X REQUESTED A CHANGE OF ALT FROM FL310 TO FL350. 14 MINS LATER; ZNY ISSUED THIS CLRNC: 'ATCC CTAM F320 RR UNABLE REQUESTED ALT DUE TFC.' THE RO DELIVERED THE CLRNC VERBATIM; BUT THE READBACK WAS INCORRECT. THE FLT READ BACK: 'ACFT X LEAVING 310; CLBING 330 RPT REACHING.' THE RO RESPONDED WITH: 'LEAVING FL310 CLBING TO FL330 YOU WILL RPT LEVEL.' AT XA35Z; THE FLT RPTED: '...LVL 330.' WHEN THE FLT RPTED LVL AT FL330; THE RO ACKNOWLEDGED SEEING FL320 IN THE ATC CLRNC THAT APPEARED IN THE LOWER PORTION OF THE DISPLAY. SHE SAID THAT SHE SAW THE DIFFERENCE BUT SHE THOUGHT THAT SHE HAD MADE A TYPING ERROR. INSTEAD OF TYPING THE WORDS THAT SHE HEARD THROUGH THE HEADSET (AS VERIFIED BY THE AUDIO TAPE); SHE THEN TYPED 'LVL FL320.' (IT WAS LATER RPTED TO NEW YORK MGMNT BY NEW YORK ARTCC; THAT THE CTLR WAS GETTING READY TO ASK ABOUT WHY THE READBACK SHOWED FL330 INSTEAD OF FL320; BUT UPON RECEIVING THE 'LVL FL320 RPT; HE/SHE DECIDED TO NOT CALL.) ACFT X CONTINUED A FL330 WITHOUT ADEQUATE SEPARATION FROM OTHER FLTS FOR 1 HR AND 9 MINS.