According to the Russian Ministry of Defense, air traffic controllers were forced to give two airliners instructions to avoid a possible conflict with a U.S. Air Force reconnaissance aircraft over the Sea of Japan.
On May 22, a U.S. Air Force Boeing RC-135 plane departed from the Kadena Air Base, Japan to carry out a reconnaissance flight over the Sea of Japan at an altitude of 10,000 meters (32800 ft) with a switched-off transponder, according to the Russian Ministry of Defense.
The aircraft reportedly crossed international airways. The airways were being used by several international passenger flights, originating from Tokyo-Narita Airport, Japan. Two flights were mentioned by the defense ministry: a KLM and a Swiss flight bound for Europe.
KLM flight KL862, a Boeing 777-306ER, registration PH-BVP departed Narita at 10:34 hours local (JST) time (01:34 UTC), bound for Amsterdam, the Netherlands. Swiss International Air Lines flight LX161, an Airbus A340-313, registration HB-JMI, departed Narita at 10:37 hours local (JST) time (01:37 UTC), bound for Zurich, Switzerland.
Flight KL862 entered the Khabarovsk FIR at 02:30 UTC and started following airway A333. ADS-B data as captured by Flightradar24 show the aircraft descending briefly from 32000 feet to 31ooo feet inside the Khabarovsk FIR about 02:41 UTC. The flight then climbed back to 32000 feet, reaching that altitude again at 02:49 UTC.
A Defense spokesman was quoted by RT.com saying: “The Swiss crew asked Russian dispatchers of the Vladivostok air traffic control regional center for visual observation of the four-engined aircraft of unknown origin moving towards them.” At 12:41 hours local (Vladivivostok) time (02:41 UTC) the controller instructed the aircraft to descend to a lower altitude. Likely the KLM flight was meant instead of the Swiss flight as the mentioned times and descent profile only match the KLM flight.
Swiss 161 only entered Russian airspace at 02:49 UTC via the AVGOK waypoint, following airway R211. The flight remained at 30000 feet for the entire flight through the Khabarovsk FIR.