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Both VMAtm answer and Skott K assumptions are wrong here.

So, you could try to get back to Russia by plane, as there is border check in the airports.

Yes, there is border check in the airport but you won't be allowed to enter Belarus anyway. Russian visa gives no allowance to do that and Belarusian Consular Office in airport don't make visas to foreigners who arrive from Russian flights.
So you won't be able to obtain visa even in airport, you should get it prior to your arrival!

All possible grounds when you are excused from obtaining transit visas are listed in paragraph four of the Resolution of Council of Ministers of Belarus about transit, and RU-BY flights (and vice versa) are not among them.

If you are not eligible to any of this grounds you need Belarussian visa (either transit or entry), no matter of way you arrive Belarus (ground or air).

UPDATE: what concerns Russian or non-Russian planes (as suggested by pnuts), Russian Embassy in Belarus gives zero clarification about this:

Пассажирам, следующим авиарейсами через Россию из Беларуси и в Беларусь, следует обратить внимание на необходимость наличия транзитной российской визы независимо от времени пребывания в российском аэропорту, если они летят федеральным (внутренним) рейсом из России в Беларусь или обратно.

Passengers who use flights from/to Belarus through Russia should pay attention to the requirement of transit Russian visa disregard of duration of stay in Russian airport, whether they fly by federal (domestic) flight from Russia to Belarus or vice versa.

There is NO mention about carrier of flight or whatever.

Both VMAtm answer and Skott K assumptions are wrong here.

So, you could try to get back to Russia by plane, as there is border check in the airports.

Yes, there is border check in the airport but you won't be allowed to enter Belarus anyway. Russian visa gives no allowance to do that and Belarusian Consular Office in airport don't make visas to foreigners who arrive from Russian flights.
So you won't be able to obtain visa even in airport, you should get it prior to your arrival!

All possible grounds when you are excused from obtaining transit visas are listed in paragraph four of the Resolution of Council of Ministers of Belarus about transit, and RU-BY flights (and vice versa) are not among them.

If you are not eligible to any of this grounds you need Belarussian visa (either transit or entry), no matter of way you arrive Belarus (ground or air).

UPDATE: what concerns Russian or non-Russian planes (as suggested by pnuts), Russian Embassy in Belarus gives zero clarification about this:

Пассажирам, следующим авиарейсами через Россию из Беларуси и в Беларусь, следует обратить внимание на необходимость наличия транзитной российской визы независимо от времени пребывания в российском аэропорту, если они летят федеральным (внутренним) рейсом из России в Беларусь или обратно.

Passengers who use flights from/to Belarus through Russia should pay attention to the requirement of transit Russian visa disregard of duration of stay in Russian airport, whether they fly by federal (domestic) flight from Russia to Belarus or vice versa.

There is NO mention about carrier of flight or whatever.

Both VMAtm answer and Skott K assumptions are wrong here.

So, you could try to get back to Russia by plane, as there is border check in the airports.

Yes, there is border check in the airport but you won't be allowed to enter Belarus anyway. Russian visa gives no allowance to do that and Belarusian Consular Office in airport don't make visas to foreigners who arrive from Russian flights.
So you won't be able to obtain visa even in airport, you should get it prior to your arrival!

All possible grounds when you are excused from obtaining transit visas are listed in paragraph four of the Resolution of Council of Ministers of Belarus about transit, and RU-BY flights (and vice versa) are not among them.

If you are not eligible to any of this grounds you need Belarussian visa (either transit or entry), no matter of way you arrive Belarus (ground or air).

UPDATE: what concerns Russian or non-Russian planes (as suggested by pnuts), Russian Embassy in Belarus gives following clarification about this:

Пассажирам, следующим авиарейсами через Россию из Беларуси и в Беларусь, следует обратить внимание на необходимость наличия транзитной российской визы независимо от времени пребывания в российском аэропорту, если они летят федеральным (внутренним) рейсом из России в Беларусь или обратно.

Passengers which use air flights from and to Belarus across Russia, should pay attention to requirement of transit Russian visa disregard of duration of stay in Russian airport, whether they fly from Russia to Belarus or vice versa.

There is NO mention about carrier of flight or whatever.

Both VMAtm answer and Skott K assumptions are wrong here.

So, you could try to get back to Russia by plane, as there is border check in the airports.

Yes, there is border check in the airport but you won't be allowed to enter Belarus anyway. Russian visa gives no allowance to do that and Belarusian Consular Office in airport don't make visas to foreigners who arrive from Russian flights.
So you won't be able to obtain visa even in airport, you should get it prior to your arrival!

All possible grounds when you are excused from obtaining transit visas are listed in paragraph four of the Resolution of Council of Ministers of Belarus about transit, and RU-BY flights (and vice versa) are not among them.

If you are not eligible to any of this grounds you need Belarussian visa (either transit or entry), no matter of way you arrive Belarus (ground or air).

UPDATE: what concerns Russian or non-Russian planes (as suggested by pnuts), Russian Embassy in Belarus gives zero clarification about this:

Пассажирам, следующим авиарейсами через Россию из Беларуси и в Беларусь, следует обратить внимание на необходимость наличия транзитной российской визы независимо от времени пребывания в российском аэропорту, если они летят федеральным (внутренним) рейсом из России в Беларусь или обратно.

Passengers who use flights from/to Belarus through Russia should pay attention to the requirement of transit Russian visa disregard of duration of stay in Russian airport, whether they fly by federal (domestic) flight from Russia to Belarus or vice versa.

There is NO mention about carrier of flight or whatever.

Both VMAtm answer and Skott K assumptions are wrong here.

So, you could try to get back to Russia by plane, as there is border check in the airports.

Yes, there is border check in the airport but you won't be allowed to enter Belarus anyway. Russian visa gives no allowance to do that and Belarusian Consular Office in airport don't make visas to foreigners who arrive from Russian flights.
So you won't be able to obtain visa even in airport, you should get it prior to your arrival!

All possible grounds when you are excused from obtaining transit visas are listed in paragraph four of the Resolution of Council of Ministers of Belarus about transit, and RU-BY flights (and vice versa) are not among them.

If you are not eligible to any of this grounds you need Belarussian visa (either transit or entry), no matter of way you arrive Belarus (ground or air).

Both VMAtm answer and Skott K assumptions are wrong here.

So, you could try to get back to Russia by plane, as there is border check in the airports.

Yes, there is border check in the airport but you won't be allowed to enter Belarus anyway. Russian visa gives no allowance to do that and Belarusian Consular Office in airport don't make visas to foreigners who arrive from Russian flights.
So you won't be able to obtain visa even in airport, you should get it prior to your arrival!

All possible grounds when you are excused from obtaining transit visas are listed in paragraph four of the Resolution of Council of Ministers of Belarus about transit, and RU-BY flights (and vice versa) are not among them.

If you are not eligible to any of this grounds you need Belarussian visa (either transit or entry), no matter of way you arrive Belarus (ground or air).

UPDATE: what concerns Russian or non-Russian planes (as suggested by pnuts), Russian Embassy in Belarus gives following clarification about this:

Пассажирам, следующим авиарейсами через Россию из Беларуси и в Беларусь, следует обратить внимание на необходимость наличия транзитной российской визы независимо от времени пребывания в российском аэропорту, если они летят федеральным (внутренним) рейсом из России в Беларусь или обратно.

Passengers which use air flights from and to Belarus across Russia, should pay attention to requirement of transit Russian visa disregard of duration of stay in Russian airport, whether they fly from Russia to Belarus or vice versa.

There is NO mention about carrier of flight or whatever.