Complex sentence: In 1967, a co-operation contract with SABENA, the Belgian flag carrier airline was signed, which saw BIAS operating scheduled commuter flights out of Brussels Airport, which were branded as "Common Market Commuter", using de Havilland Heron aircraft.
Split into simpler sentences: In 1967, a co-operation contract with SABENA, the Belgian flag carrier airline was signed, which saw BIAS operating scheduled commuter flights out of Brussels Airport. These were branded as "Common Market Commuter", using de Havilland Heron aircraft.