Which country's airforce sometimes uses the logo "BBC" together with the national insignia on its aircraft?
The logo "BBC" in this case are the Cyrillic characters for "VVS" the letters that identify the Russian air force. VVS stands for Voenno-Vozdushnye Sily (Russian: Военно-воздушные силы "military-air forces").
Here's a nice example of the "BBC" logo on one of their warplanes:
More Info:
en.wikipedia.org