Complexity in autopilot logic design and confusion involved in its mode transition is one of the major reasons for the accidents in highly automated airliner. In this paper we present the usage of a recently proposed array logic based technique for designing the autopilot mode transition logic for a commercial aircraft in the lateral direction. This designing technique helps to reduce the design effort in the development of an autopilot. Ease to understand and very concise way to specify a large number of transitions in simple tabular column is one the highlight of this method. This paper provides some observations about lateral modes and logic concerning lateral mode transition in a less complex way compared to the prevailing methods for autopilot design. Here various mode possibilities of lateral mode transition in an autopilot is mentioned along with specification criteria's that bound these transition and these possible transitions were given a frame work using MATLAB software.