There are four ways to use a Chase Sapphire card to purchase airfare. That's true for all three Sapphire cards: Sapphire Preferred, Sapphire Reserve and the original Sapphire Card (no longer available to new applicants).
1.Redeem Points Through Ultimate Rewards. You can book flights on pretty much any major airline directly through the Ultimate Rewards website. This option allows you to charge part of the flight to your card if you don't have enough points to cover the full fare.
2.Transfer Points to a Travel Partner. A majority of Chase's travel rewards partners are airlines. So if you belong to one of their loyalty programs, you can transfer your Ultimate Rewards points to that program and combine them with the miles/points already in that account for redemption. Transfers are done at a 1:1 ratio.
3.Get Cash Back. You can always redeem your Chase Sapphire points for a statement credit and use the savings to pay for your plane ticket, wherever you book it. Bear in mind that you need at least 2,000 points to redeem for cash, and your points are worth 25% more when redeemed for travel through Chase Ultimate Rewards.
4.Simply Pay with Your Sapphire Card. The most obvious of your options doesn't really involve rewards, but it's nevertheless worth noting that both Chase Sapphire cards can be used to purchase airfare directly from airlines, travel-comparison sites, etc. Besides, paying for a plane ticket could help you reach either of the Sapphire cards' initial spending requirements, thereby earning you a lucrative initial bonus.