Despite the fact that there is unimaginable technological achievement in communication, navigation, surveillance, computation and control, the ATM system suffers from the lack of automation abilities. Almost all main processes of ATM are based on a rigidly structured airspace and centralized human-operated system architecture, but increasing the level of automation we could improve the efficiency of ATM and the human-operator tasks could be simplified. The core objective of any ATM is to guarantee safety and efficiency. The main purpose of this work is to provide theoretical investigation of serious questions in ATC system and in ATC working process. This publication is a continuation of previous work on concept of expert systems that could be used in ATC. Using appropriate knowledge in ATC physics, procedures and technology processes the ways to increase efficiency of Air Traffic Control (ATC) are found that do not destroy the safety level of whole ATM. The analysis of conflict characteristics, collisions and avoiding actions will be a knowledge base for future ATC expert system. Logical expert systems are similar to human operators that are using own knowledge bases, not mathematical functions, and are flexible for solving different typical problems of normal life.