In the current Airlines Air Traffic Management (ATM), the Air Traffic Control Operators (ATCO), with the Air Traffic Control systems (ATC), operate air traffic paths with a small number of fixed routes. Problems of fixed routes appear such that even when they reduce the chance for conflict, they also produce flight paths plans that do not reduce flight time or fuel usage. In nowadays Airlines are heavily overloaded and anxious to minimize the aircrafts fuel usage costs, increase airplanes, and optimize the paths or the flight routes in order to find the most optimal suitable flight paths. This paper presents a new path planning method that deal with such problem effectively, the idea was to produce flights routes by allowing the ATCO, or the pilot to select better fuel-efficient routes with reducing flight time. This work has been done by using modified 'Rapidly Exploring Random Tree' (RRT) path planning algorithm in dynamic cluttered environment with collision avoidance. The experiment of the developed algorithm simulation experiment shows promising result for future research.