A NATO Northrop Grumman RQ-4D Phoenix strategic reconnaissance drone flying over Black Sea waters has signaled an air communications system failure while in the air, a source in the EU air traffic control services told TASS. "The drone is currently over the neutral waters of the Mediterranean Sea near Crete Island where it is following a square-shaped trajectory and signaling communications failure," the source said. "The aircraft was flying at an altitude of over 16 km without entering the airspace of any countries and outside the corridors for civil aircraft flight," the source said. The source did not specify the possible reasons for the drone’s communications system’s failure signal. He said, however, that one of the functions of the Northrop Grumman RQ-4D Phoenix drone, whose flight was last recorded over the Black Sea on July 17, is imaging of large areas and transmitting the data in real time.