Qantas Airways Ltd. agreed to buy the rest of Australia’s Alliance Aviation Services Ltd. in a deal valuing the company at A$763 million ($553 million), gaining a fleet of small aircraft operating charter flights for the resources industry.

The deal values Alliance at A$4.75 a share, Qantas said in a statement Thursday. The stock closed Wednesday at A$3.51. Alliance shareholders will be paid in shares in Qantas, which already owns 20% of the company.

Alliance operates about 70 jets—Fokkers and Embraer 190s—that can each seat as many as 100 people. That makes them well suited for charter flights in Western Australia for mining companies including Fortescue Metals Group Ltd. and BHP Group Ltd.

Alliance shares soared 25% to A$4.38 at 10:54 a.m. in Sydney. Qantas fell 1.1% to A$5.61.

Qantas, which also owns Fokker aircraft, said Alliance has a large inventory of spare parts for the planes which will extend the working life of the two companies’ combined fleets.