Western countries embargoed the Eastern bloc - particularly regarding spare parts, so even if those airlines were able to buy an old western plane, they would lack access to spare parts, rendering any purchases pointless. I strongly believe that the game should reflect that and heavily tax the player who keeps western planes.
Czechoslovakia should become regarded as communist since 1948, which is when Communists took over. They began phasing western planes out almost immediately. Hungary, I believe, should also become communist only in 1948. Becoming communist meant that most western and Middle Eastern routes were cancelled almost overnight. Also, IIRC, there were two types of passport in the eastern bloc - those that allowed entry to capitalist states, and those that only permitted travel within the bloc. The first one was very difficult to obtain so passenger numbers going in that direction should be quite low.
EDIT: I checked online sources and apparently foreign travel was so restricted, that while in 1938 about 90,000 Poles left the country on tourist trips, only 181 did so in 1950. I imagine the situation being similar in other communist countries.
Czechoslovakia should become regarded as communist since 1948, which is when Communists took over. They began phasing western planes out almost immediately. Hungary, I believe, should also become communist only in 1948. Becoming communist meant that most western and Middle Eastern routes were cancelled almost overnight. Also, IIRC, there were two types of passport in the eastern bloc - those that allowed entry to capitalist states, and those that only permitted travel within the bloc. The first one was very difficult to obtain so passenger numbers going in that direction should be quite low.
EDIT: I checked online sources and apparently foreign travel was so restricted, that while in 1938 about 90,000 Poles left the country on tourist trips, only 181 did so in 1950. I imagine the situation being similar in other communist countries.