"We fly over remnants of Ukraine, where Banderovtsi and other filth lives," Kaco quoted the pilot as saying in a Twitter message.
Banderovtsi, which is derived from the name of controversial Ukrainian nationalist Stepan Bandera (1909-1959), is often used in Russia as a derogative umbrella term for nationalist Ukrainians. Aeroflot confirmed in a Tweet on Thursday that the pilot had taken the Russo-Ukrainian war of words to the skies, but noted he had violated company rules by expressing his personal opinion while on duty.
The company also said an internal investigation had been launched, but abstained at this point from offering any apologies to the parties concerned. Russia annexed Ukraine's Crimean peninsula in March, and is accused of fostering an ongoing pro-Russian insurgency in Ukrainian Donetsk and Luhansk regions.
While Moscow has officially denied backing the rebels, the separatists have been glorified by the Russia's state-run media, which has also vilified the Ukrainian government, frequently dubbed it a quasi-fascist junta.