Method and apparatus for continuously determining an interval of time during which an action must be taken

A method and apparatus for determining the time remaining for maximum control action to be taken in order to achieve a desired objective (i.e., the chronodrasic interval) is disclosed. The method and apparatus continuously determines the amount of a parameter (e.g., runway distance) required to achieve a desired objective (e.t., stop ping an aircraft before reaching the end of a runway on landing or accelerating an aircraft so that it reaches rotation speed before reaching the end of a runway on takeoff) if maximum control action is applied. The method and apparatus also continuously determines the total amount of the parameter remaining. The chronodrasic interval is then determined by deducting the amount of the parameter rerequired to achieve the desired objective if maximum control is taken from the total amount of the parameter maining; and, dividing the result by the present rate of a change of the parameter. The value of the chronodrasic interval, if below a predetermined value, is applied to a display to provide interactive information adapted to apprise a human operator of the need to take control action and the effectiveness of the control action taken. Alternatively, the value of the chronodrasic interval can be used to automatically regulate the amount of control action taken.