B767-300 FO IS COERCED INTO FLYING A MULTI-DAY TRIP WITH ONLY 3 HRS SLEEP WHEN THE ORIGINAL SCHEDULE ON RESERVE ONLY SHOWED A SINGLE DAY OF AVAILABILITY.

Narrative

THE ISSUE AROSE IN THE TIMEFRAME PRECEDING THE TRIP. I WAS ON RESERVE ONLY MAR/XX; BUT CONTACTED APPROX XA00 BY THE CREW DESK TO CANCEL MY DAY OFF AND ASSIGN AN XJ35 DEP ON MAR/XA. I INDICATED 'FATIGUE' AND ASKED ABOUT OTHER ALTERNATIVES AND LEGALITIES. AT THE TIME OF THE CALL; I WOULD ONLY HAVE A MAX OF 5 HRS TO SLEEP UNDER PERFECT CONDITIONS. THE CREW DESK DENIED MY 'FATIGUE' STATEMENT AND INDICATED I HAD ENOUGH TIME TO SLEEP PRECEDING THE ASSIGNMENT. I SPOKE WITH THE DUTY MGR; WHO INDICATED THE TRIP WAS LEGAL AND I MUST FLY. AFTER PACKING AND THE STRESS OF CANCELING MAJOR PLANS; I COULD ONLY MANAGE 3 HRS OF SLEEP. UPON DEP; I MISSED RADIO CALLS; ROUTINE ITEMS; AND FOUGHT TO STAY AWAKE. I WAS NOT AN ASSET TO THE CAPT AND UNFIT TO FLY. MY SLEEP WAS ALSO COMPROMISED BY THE NEED TO PACK AND OTHER ITEMS NOT ANTICIPATED WHEN SCHEDULED FOR 1 DAY OF RESERVE AND SUBSEQUENTLY ASSIGNED A MULTI-DAY TRIP. DESPITE MY INDICATION OF STATING FATIGUE; THE CREW DESK COMPELLED ME TO FLY IN CONDITION WHERE I CLRLY FELT UNFIT FOR DUTY. ALTHOUGH THERE WASN'T A SPECIFIC SOP OR FAR VIOLATION; I ACTED IN CONTRAST TO THE FARS; WHICH REQUIRE I RPT RESTED AND FIT FOR DUTY.