ALT XING RESTR -- THE ACR WAS HIGH AT THE ASSIGNED VOR XING.

Narrative

WE RECEIVED A XING RESTR FOR OXI PLUS OR MINUS 60 DME OUT AND STARTED TO DSND OUT OF 14000 FT AT 500 FPM. DURING THIS PROLONGED DSCNT THE FO WENT OFF THE AIR TO PICK UP ORD ATIS. THE L PACK WAS DEFERRED AND THE COCKPIT TEMP WAS UNCOMFORTABLY HIGH. I TRIED TO MAKE ADJUSTMENTS TO THE AIR CONDITIONING SYS; WHILE FLYING AND DOING RADIOS AND FAILED TO NOTICE OUR PROX TO OXI VOR AND DIDN'T REALIZE THE MISTAKE UNTIL ATC QUERIED US. FAILURE TO PROPERLY DIVIDE COCKPIT DUTIES WAS THE PRIMARY CAUSE OF THE INCIDENT WITH; UNCOMFORTABLE TEMP DUE TO DEFERRAL AS A CONTRIBUTING FACTOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CAPT WAS FLYING AN ATR- 72 AT THE TIME AND HE SET UP A SHALLOW DSCNT BECAUSE 'I INTERPRETED THE INSTRUCTIONS AS TO START DSCNT NOW; BUT CROSS OXI AT 9000 FT.' THIS WAS MUCH TOO EARLY FOR A NORMAL DSCNT SO HE STARTED DOWN AT 500 FPM AND THEN GOT DISTRACTED. HE THINKS THAT HE WAS AT 9700 FT AT OXI; BUT THE CTLR DID NOT ASK HIM ABOUT THE XING UNTIL MUCH LATER AND AFTER HE WAS LEVEL AT 9000 FT. THE CAPT; WHO HAS ABOUT 6000 HRS IN THE ATR-72; SAID THAT HE WAS AWARE OF THE INSIDIOUS NATURE OF THESE SLOW DSCNTS.