That's probably the reason why Air China is 3 star and Hainan was 4 star.

Please don't compare Hainan with Air China when Air China is clearly not a 5 star airline suggested by Skytrash. Simply compare Hainan with direct competitors in the region, Asiana, Cathay Pacific, or Singapore, and you will see a clear reason why this rank is a joke.

A reason why most opinions and rank reviews on SQ is low is because they value SQ as a 5 star airline when they write the reviews (so the score of 10 will be valued based on is it a 5 star airline experience, hence high expectations). That was not the case for Hainan.