FO REPORTS CAPTAIN FAILED TO REQUIRE REPAIR OF FAULTY ISI GAUGE PRIOR TO DEP.

Narrative

THE EVENT TOOK PLACE TODAY DURING THE PREFLT AT ZZZ. THE ACFT WAS DARK WITH GATE PWR AVAILABLE WHEN I CAME TO THE ACFT. I WAS THE FIRST ONE ON BOARD THE ACFT; AND STARTED UP USING FIRST GATE PWR; AND SINCE IT WAS COLD; SUBSEQUENTLY STARTED THE APU. AS THE PLANE WAS POWERING UP; THE ISI CAME ON; AND I NOTICED THAT THE TOP HALF OF THE ISI WAS MIRRORED DOWN ONTO THE LOWER HALF OF THE ISI; NOT GIVING A FULL VIEW. PITCH VIEW DOWN WAS LIMITED TO APPROX 2 DEGS NOSE DOWN; AND NO BACKUP NAV SOURCE WAS DISPLAYED; NO LOC COULD HAVE BEEN TRACKED. I POINTED THIS OUT TO THE CAPT WHO RESPONDED THAT HE HAD SEEN THIS THING BEFORE AND AFTER THE PLANE WARMED UP IT WOULD GO AWAY. AFTER COMPLETING MY PREFLT; I RETURNED TO THE FLT DECK; STILL TO FIND THE ISI INFO UN-VIEWABLE ON THE BOTTOM HALF. AFTER A FEW MINS; I ASKED HIM HIS INTENTIONS; AND HE ASSURED ME THAT IT WOULD BE FINE. I EXPLAINED WHY I WAS CONCERNED THAT THE ISI WAS NOT WORKING PROPERLY; IT IS IMPORTANT; NOT MEL'ABLE; AND NO ACTION WAS TAKEN. WE DEPARTED AND AFTER THE AIRPLANE ARRIVED AT CRUISE ALT; HE BROUGHT OUT THE LOGBOOK AND FILLED OUT A MAINT SLIP FOR AN INFLT MECHANICAL; AND CALLED IN RANGE TO NOTIFY THEM OF THE PROB. IT WAS CORRECTED IN ZZZ1. WE NEVER SHOULD HAVE TAKEN OFF. IF I WOULD HAVE DONE MY JOB; I WOULD HAVE INSISTED THAT WE NEVER DEPART WITHOUT HAVING OUR ISI FUNCTIONING PROPERLY. IF THE CAPT HAD DONE HIS JOB; WE NEVER WOULD HAVE DEPARTED IN VIOLATION OF FAR'S/SOP'S.