An Aeroflot Airbus A330-300, on a flight 501 between Tel Aviv and Moscow, had to alter its altitude by 2,000 feet (600 meters) to avoid NATO reconnaissance aircraft, Russian aviation authority Rosaviatsia announced. 

The incident took place on December 3, above the Black Sea.  

Rosaviatsia spokesperson told Russian news agency RIA Novosti that the aircraft, a CL-600, also known as ISR Artemis, had suddenly changed its altitude from 11,000 meters (approx. 36,000 feet) to 9,200 meters (approx. 30,000 feet), and intersected the path of the civilian flight. 

According to the spokesperson, Russian flight controllers tried to communicate with the military jet, but received no response. As a result, they requested the Aeroflot flight to change its altitude. 

According to Flightradar24 data, AFL501 began descending at 6:55 UTC when it was approximately 70 kilometers (37 nautical miles) from the Turkish coast, and changed its altitude from 35,000 feet (10,670 meters) to 31,000 feet (9,450 meters), before starting the climb to 36,000 feet (11,000 meters) at 7:04 UTC. 

RIA Novosti reported that the flight was carrying 142 passengers. According to a Rosaviatsia spokesperson, Aeroflot pilots could visually identify the American airplane at the moment when both aircraft passed each other. 

The aviation authority also said it will initiate a protest note in regards to the incident. According to Rosaviatsia, intensive flights of NATO aircraft near the Russian border pose a risk to civilian aircraft. 

Russian state news agency TASS also announced that on the same day Sukhoi Su-27 and Su-30 fighter jets were scrambled to intercept two NATO reconnaissance aircraft, a CL-600 Artemis and a Boeing RC-135, over the Black Sea. According to Russian Defense Ministry information, quoted by TASS, the fighter jets have prevented the American planes from violating the Russian border and returned to base.  

The information may have referred to the same flight of the CL-600 Artemis. 

The US Army currently operates one aircraft of this type in Europe. Registered as N488CR, it has been based at Romania’s Constanta Mihail Kogălniceanu Airport (CND). 

Due to its nature, the aircraft is not tracked by popular flight tracking services, such as Flightradar24 and Radarbox. However, its flights are visible on websites that display ADS-B data directly, such as ADS-B Exchange and PlaneRadar.  

According to both services, in the morning of December 3, N488CR was performing a flight over Gerogian territory along the border of Armenia and Azerbaijan. While the trajectory of the aircraft over the Black Sea intersected with the one of AFL501, the services do not show the extreme change in altitude, which, according to Rosaviatsia, was the main reason for the avoidance maneuver initiated by the Aeroflot flight.  

ADS-B Exchange data shows N488CR cruising at 38,500 feet throughout the entirety of its flight over the Black Sea. However, due to fragmented coverage of the ADS-B system away from the coast, the data is incomplete and features significant gaps.