11 ( BA11 ) is one of the most important military airbases in Portugal , northwest of Beja , north of the Algarve . 11 ( BA11 ) is one of the most important military airbases in Portugal , northwest of Beja , north of Algarve . 11 ( BA11 ) is one of the most important military airbases in Algarve , northwest of Beja , north of Portugal .