The Egyptian officials said the aircraft was cruising at 36,000 feet (about 11,000 meters) when contact with air traffic controllers was lost. Militants in northern Sinai have not to date shot down commercial airliners or fighter jets. There have been media reports that they have acquired Russian shoulder-fired, anti-aircraft missiles. But these types of missiles can only be effective against low-flying aircraft or helicopters. In January 2014, Sinai-based militants claimed to have shot down a military helicopter; Egyptian officials at the time acknowledged the helicopter had crashed, but gave no reason.