LOC DME APCH STARTED; THEN CLRED FOR VOR DME APCH. CLRED AS REQUESTED.

Narrative

APCHING GUA FROM SJD (SAN JOSE; COSTA RICA) WE WERE CLRED FOR THE LOC DME ARC RWY 1 APCH. WE HAD JUST STARTED THE APCH TURNING FROM THE AIRWAY TO INTERCEPT THE 7 DME ARC; WHEN APCH CLRED US FOR THE VOR DME RWY 1 APCH. THE PNF ADVISED WE HAD STARTED THE OTHER APCH AND ASKED HOW SHOULD WE TRANSITION. I INTERRUPTED AND SAID TO JUST REQUEST THE DME ARC APCH. THE PNF DID SO AND APCH IMMEDIATELY CLRED US TO CONTINUE THE ARC APCH ALL RELATIVELY BENIGN EXCEPT ON LATER DISCUSSION. NEITHER OF US WERE SURE THAT WE HAD EVER RECEIVED THE INITIAL 'ARC APCH' CLRNC. I THOUGHT WE HAD; ELSE WHY WOULD WE HAVE THE ARC PLATE OUT. HOWEVER THE FO IS NOT SO SURE; THINKING WE MAY HAVE ONLY HAD IT OUT BECAUSE WE HAD BEEN BRIEFED (BY A RTE CHK PLT) THAT WE WOULD MOST LIKELY GET THAT APCH. THE BIGGEST PROB HERE WAS HIGH MENTAL WORKLOAD BECAUSE OF MINIMAL FAMILIARITY WITH THE RTE AND AREA; AND CONTINUOUS ATC LANGUAGE DIFFICULTIES. IT WAS THE FIRST FLT INTO GUATEMALA OR COSTA RICA BY BOTH PLTS. WE HAD A RTE CHK PLT WITH US FROM LAX-GUA; BUT WERE NOW ON OUR OWN. ALSO CONTRIBUTING -- THE CAPT RECEIVED A LATE WAKE UP AT THE HOTEL AND IN HIS HASTE; LEFT HIS APCH PLATES IN THE ROOM (HE HAD BEEN STUDYING THEM THE NIGHT BEFORE). THIS ADDED TO THE WORKLOAD; AS BOTH PLTS THEN HAD TO SHARE THE FO PLATES. VERY AWKWARD.