Onex Corp. has signed a friendly deal to buy WestJet Airlines Ltd. in a deal it valued at $5 billion, including assumed debt. Under the agreement, Onex will pay $31 per share for WestJet, which will continue to operate as a privately held company. Onex is controlled by mining billionaire Gerald Schwartz. His wife. Heather Reisman, operates the Indigo chain. The couple are celebrated philanthropists. WestJet shares closed at $18.52 on Friday. The deal comes after Onex approached the airline in March. Completion of the transaction is subject to a number of conditions, including court, regulatory and shareholder approvals.