Potentially new ways to improve civil aircraft fuel efficiency, based on the aircraft maintenance process optimization are considered. The data confirming the advisability of their further in-depth study and implementation in civil aviation airlines activity is given.It is shown that one of the reasons provoking the increase of fuel consumption at the cruising flight stage might be the necessity of the bypass of meteorological areas and of the flight altitude or airspeed change. These events are occasional. At the same time the most advantageous methods aimed at improving fuel efficiency are continuous aircraft climb or descent.One of these research directions is the implementation of continuous descent mode, rational routes of approach to the airfield, climb, choice of optimal flight modes in flights. This program is called “SESAR”. While its realization within the framework of the EC it is planned to reduce fuel consumption by 5 million tons a year due to its economy by 10 % after each flight. The similar program “NextGen” of air traffic optimization is accepted and is realized nowadays in the USA. The purpose of this program is annual improvement of fuel efficiency not less than by 2 % a year.Based on the conducted research the expanded list of recommendations for the realization of aircraft continuous descent system in flight, providing renunciation of horizontal flight areas at idling engines is presented.