GLONASS stands for Globalnaya navigatsionnaya sputnikovaya sistema or Global Navigation Satellite System, an initiative of Soviet Union. GLONASS is a space based satellite system used by Soviet Union Defense forces. During the long autonomous flight, drones totally depend upon Global Positioning System to continue its way-points. If G.P.S receiver fails to receive signals in any situation, Drone moves to fail safe aka landing mode to secure it. But recovery of drone is too much difficult in that above the line of sight situation. And G.P.S loss is very normal situation for different types of low altitude mini or micro drones due to the changing latitude. These types of G.P.S disturbances known as ionospheric disturbances, which includes loss of G.P.S lock and noise level increment.
GLONASS provides an alternative to G.P.S. Many updated versions of G.P.S integrated with GLONASS and the result of it, providing very low H.D.O.P and more satellites visible to it. Position of the drone can be locked more quickly and precisely, mostly in built up places and mountain areas where visibility of the G.P.S satellites getting to hard due to obstacles. In October 2011, the full orbital constellation of 24 satellites was restored, and providing the full global coverage. The latest version of it named as GLONASS-K. As per the accuracy point of view, Integrated GLONASS with G.P.S is more effective rather than using alone. Because integrated version with G.P.S provides more than 50 satellites availability to it and greatly improved accuracy.