B757 FLC LOSS OF COMRDO WITH ATC DUE TO THE ACFT LOGBOOK PLACED ON THE CTR CONSOLE WHEN THE CABIN ATTENDANT SAT ON JUMP SEAT WHILE THE FLC TOOK TURNS USING THE LAVATORY.

Narrative

LOCATION: 130 DEG RADIAL FROM MIA. ENRTE APPROX 50 MINS BEFORE LNDG AT MIA; I HAD A FLT ATTENDANT COME TO THE COCKPIT TO MAN THE DOOR AS THE COPLT AND I TOOK TURNS USING THE LAVATORY. WHEN SHE SAT ON THE JUMP SEAT; THE LOGBOOK WAS PLACED ON THE CTR CONSOLE TOGGLING ALL OF OUR RADIO VOLUME SWITCHES DOWN. I DID NOT DISCOVER THIS UNTIL ASKING FOR OUR DSCNT INTO MIA. AT THAT TIME ZMA INFORMED US THAT THEY HAD BEEN TRYING TO CONTACT US FOR THE PAST 100 MI. I APOLOGIZED AND INFORMED THEM THAT OUR VOLUME SWITCHED HAD BEEN INADVERTENTLY TOGGLED DOWN. WHEN WE USED ACARS FOR ATIS WE DISCOVERED THAT OUR ACARS PAPER WAS JAMMED SO THAT DISPATCH'S ATTEMPTS TO GET US TO CONTACT MIA HAD ALSO FAILED. WHAT ALSO CONTRIBUTED TO US NOT RECOGNIZING THE PROB SOONER WAS THAT THE FREQ HAD SO LITTLE TFC EARLIER WE HAD ASKED SAN JUAN FOR A RADIO CHK. HE INFORMED US THAT THERE WERE ONLY 4 ACFT ON FREQ. WE WERE WITH MIA AT THE TIME OF THE INCIDENT; BUT WERE EXPECTING QUIETER THAN NORMAL RADIO TFC DUE TO OUR EARLIER RADIO CHK. THE COPLT AND I RECOGNIZE THE IMPORTANCE OF MAINTAINING RADIO CONTACT WITH ATC -- ESPECIALLY POST 9/TUE/01; AND MUST MAKE SURE NOTHING IS PLACED ON THE CTR CONSOLE THAT MAY AFFECT THE RADIOS AND MUST BE MORE CAREFUL MONITORING THE RADIOS.