This research investigates the effects of a decision support system in the context of real-time, small group decision making. Following the March 1989 E m n Valdez oil spill, development of a real-time expert system (called the Shipboard Piloting Expert System, or SPES) was begun. The SPES is a prototype decision aid designed to add knowledge-based decision support functionalityto the integratedbridge system GDSS previously developed and fielded for Exxon Shipping Company.’ The SPES is a representative application of automated decision aids to hazardous real-time decision making situations (Grabowski and Sanboni 1992).