Yes, it is. If your Singapore Airlines or SilkAir flight was cancelled and you haven’t flown any sector yet, you can retain your ticket’s value as a Flight Credit and rebook anytime up to December 31, without being charged any rebooking fee. Plus, you’ll likely be eligible for Bonus Flight Credits, depending on your travel class.  If you’re holding a partially utilized ticket, you’re allowed to retain a Flight Credit on the unused portion of your ticket, but you won’t qualify for any Bonus Flight Credits. You also won’t be eligible for Bonus Flight Credits if your flight was cancelled and cancelled the alternative flight offered to you.