SilkAir (Singapore Changi) has announced it has signed a letter of intent with Boeing (BOE, Washington National) to gradually replace its fleet of 6 A319-100s and 15 A320-200s by B737-800s. It plans to order 23 B737-800s as well as 31 B737 MAX 8s with deliveries of the current generation B737-800s expected to start in 2014 and the final MAX 8s to be in service by 2021.