In this paper a modified form of Euler integration is described which, when applied to the six-degree of freedom flight equations, retains and enhances many of the advantages of AB-2 integration and at the same time eliminates the disadvantages. The scheme is based on the Euler integration formula, but with the state-variable derivative represented at the midpoint of each integration step. In this case the conventional first-order Euler method actually becomes second order, with a very small accompanying error coefficient. To apply this method to the six-degree-of-freedom flight equations it is necessary to define velocity states at half-integer frame times and position states at integer frame times. It is shown through dynamic error analysis that the modified Euler method has an error coefficient which is one-tenth that associated with AB-2. The method also exhibits minimal output delay in response to transient inputs. The modified Euler method may also be useful in the integration of state and costate equations in real-time mechanization of Kalrnan filters for navigation and control systems. The ever increasing complexity of the math models used as a basis for real time flight simulation has continued to apply pressure on digital processor speed requirements for such simulations. More effective numerical integration algorithms can help relieve some of this pressure. The most popular method currently in use for flight simulation is the AdamsBashforth second-order predictor method, usually referred to as AB-2. Its advantages include second-order accuracy with respec1 to integration step size, only one required pass through the state equations per integration step, and compatibility with real-time inputs. Disadvantages include stability problems associated with extraneous roots and response delays of one or two frames following transient inputs. In the next section we consider AB-2 along with two other second-order integration methods suitable for real-time simulation of dynamic systems. The first is a two-pass realtime predictor-corrector algorithm and the second is a singlepass version of the same. We then introduce the modifiedEuler method and describe its application to the flight equations. The accuracy of the various methods is compared by means of time-history plots of the dynamic error in simulating aircraft response to a control-surface input.