KARACHI - The Chief of Air Staff, Air Chief Marshal Tahir Rafiq Butt, on Thursday called on Chief Minister Sindh Syed Qaim Ali Shah at the CM House here. He discussed matters of mutual interest with the Chief Minister of Sindh, said a CM House statement.Qaim Ali Shah lauded the role of the Air Force towards the defence of the country. He also discussed matters relating to the selection of youngsters in the Air Force.