What was found
IAD/IND - FLT 6724 - DURING CRUISE ON 10-30-98 AT 1400 HOURS, EXPERIENCED AN ANTI-ICE DUCT WARNING LIGHT ON THE MASTER CAUTION PANEL. AIRCRAFT CONTACTED MAINTENANCE CONTROL AND DISPATCH. DECISION TO CONTINUE TO IND WAS MADE. UPON ARRIVAL AT IND, ACFT LANDED, AFTER DECLARING AN EMERGENCY AS A PRECAUTIONARY MEASURE, WITH NO FURTHER INCIDENT. MAINTENANCE TROUBLESHOT SYSTEM AND PERFORMED GROUND RUNS, BUT COULD NOT DUPLICATE DISCREPANCY. ALL PERTINENT CHECKS ACCOMPLISHED. ACFT RELEASED FOR SERVICE. THERE HAS BEEN NO FURTHER DISCREPANCIES WITH THE SYSTEM SINCE THIS ONE OCCURRENCE. (X)