Air crews of Russia’s Aerospace Forces have trained in-flight refueling (IFR) in Central Russia's Lipetsk Region, the Russian Defense Ministry’s press service said.

"More than 10 crews of newest Su-35S fighter jets, as well as Su-24 strike fighters and Su-24M attack aircraft performed the most complicated element of the flight training, alone and in pairs" the ministry said. "The training flights took place in daylight and nighttime"

The air-to-air refueling took place at altitudes of 5,000-6,000 meters, at speeds of about 600 kmph. The distance between the planes and Il-78 tanker aircraft was less than 20 meters.