The advent of EROPS extended-range flights by twin-engined aircraft demonstrated the need for a computer program to draw charts to assist the flight planner in operational decision-making. An EROPS Planning Aid program (EROPA) was written by the author to run on a desktop computer. This article briefly describes the EROPS rules, and how EROPA is used. Then the subject of chart-drawing using a desktop computer is discussed, and other related applications are considered.