My uneducated guess is that it might be due to its shorter service range. I'd imagine that to fly at a higher cruise height might hurt feul economy and even take longer to finish the trip.Max flight height seems low which would limit the number of flight paths and be less efficient.
This is what I meant but you explained it much better.I might've burned less fuel climbing up to the high FL200s to low FL300s, as compared to using full thrust trying to reach optimum cruise altitude and only briefly enjoying the benefits of climbing that high.
Again, I must stress. C919 as it currently stands is not commercially attractive to airlines. We should look at it as a necessity for Chinese aerospace industry to learn how to complete development and certification of modern airliner. We need to look at it as A300 or A310 for Airbus. Remember, Airbus did not hit it big until A320, which propelled them to a duopoly with Boeing.
Thankfully, China does have a very large domestic market that will purchase C919 in large numbers and help COMAC continue to improve C919. C919 project had only completed 34 out of 276 required CAAC tests by the end of last year. It will take some time for this aircraft to complete certification.
C929 won't be a hit either.
I posted here what COMAC should eventually look to produce.
It’s better for CAAC to be careful then rush through. See what happened to the 737 max, I guess that hurts Boeing badly.CAAC is not playing favorite. They've been giving C919 a hard time, as can be seen in this whole certification ordeal for the last five years. It's just technically C919 does not need FAA approval or renewed regulations to fly in China.