The Integrated Closed Environmental Control System (ICECS) Program included design, analysis, fabrication and testing of an advanced environmental control system concept for military aircraft. Fuel was utilized as the primary heat sink of a vapor-cycle system with ram air augmentation. Through the use of closed-loop avionics cooling and maximum use of fuel as a heat sink, reductions in bleed air use reduced environmental control system (ECS)-related fuel penalties and, as a result, reduced life-cycle costs (LCC). Additionally, by providing a drier, more stable environment for avionics, significant reliability gains have been demonstrated when compared to the baseline open-loop ECS. The overall emphasis was to verify through test the benefits of an ICECS using primarily off-the-shelf hardware.