The cheapest flight to Sofia you can get by boooking 36 days before departure.
The most popular airlines on the route Pisa - Sofia: Ryanair (FR), Alitalia (AZ), Lufthansa (LH).
The cheapest flights you can book on the route Galileo Galilei (PSA) - Sofia Airport (SOF).
Direct flights last about 1h 55min.
Direct flights available 3 days a week - Tuesday, Thursday, Saturday.
Direct flights: Ryanair (FR).