Sibir Airlines, the parent company of S7, has been fined 30,000 rubles ($930) for bumping a passenger from an overbooked flight.
The passenger was illegally turned away from an S7 flight from Omsk to Moscow after arriving on time and with a valid ticket, prosecutors said in a statement Thursday.
The practice of overbooking flights is common among airlines, but most ask passengers to voluntarily give up their seats in return for some form of compensation. It was not clear whether S7 had offered compensation.
In January, Sibir was fined an identical sum for canceling a regularly scheduled flight from Novosibirsk to Phuket, Thailand.
Kemerovo region authorities slapped the company with an additional 1.3 million rubles ($40,000) in fines in July for illegally raising prices on flights to Moscow.
Sibir is Russia's fourth-largest airline in terms of passengers, behind Aeroflot, Transaero and UTair.