HF COM NOT POSSIBLE DURING AN OCEANIC FLT WHEN CREW FINDS THEY CAN HEAR BUT NOT XMIT.

Narrative

PRIOR TO ENTERING NEW YORK OCEANIC AIRSPACE ON A FLT FROM TEB TO TNCM (ST MAARTEN); I TUNED OUR HF TO THE PRIMARY FREQ AND HEARD OTHER ACFT TALKING TO ZNY. I ASSUMED THAT THE RADIO WAS WORKING PROPERLY. AT THIS POINT I DID NOT TRY TO XMIT ON THE FREQ. AT THE BACUS INTXN RADAR SVC WAS TERMINATED AND WE WERE INSTRUCTED TO CALL NEW YORK OCEANIC ON HF. AFTER SEVERAL ATTEMPTS ON THE PRIMARY AND SECONDARY FREQS; WE FOUND THAT WE WERE UNABLE TO ESTABLISH COMS WITH NEW YORK OCEANIC. WE THEN CONTINUED VIA OUR CLRNC. AFTER A FEW MINS WE ESTABLISHED CONTACT WITH AN AIRLINER ON AIR-TO-AIR FREQ. HE WAS ABLE TO RELAY OUR POS TO NEW YORK OCEANIC FOR US. HE THEN TOLD US TO CALL ZMA ON VHF AT THE LETON INTXN. AT LETON WE ESTABLISHED COMS WITH MIAMI AND THE FLT THEN PROCEEDED NORMALLY TO OUR DEST. AS YOU CAN IMAGINE; WE WERE A LITTLE CONCERNED FLYING SEVERAL HUNDRED MI OVER WATER UNABLE TO TALK TO ATC. THE WHOLE PROB BEGAN WHEN WE ASSUMED THAT THE HF WAS WORKING PROPERLY DUE TO THE FACT THAT WE COULD HEAR OTHER ACFT TALKING. I SHOULD HAVE ATTEMPTED TO XMIT AT THAT TIME; THUS PROVING THE RADIO TO BE FUNCTIONAL. WE LEARNED OUR LESSON. IN THE FUTURE; I WILL PERFORM A COMPLETE FUNCTIONAL CHK OF HF EQUIP BEFORE NEEDING IT.