We recently traveled to China and Hong Kong with our 5-1/2 mth old this past Sept. The flight was 12 hours with a 12 hour time difference. Our daughter did great going there, and adjusted pretty quickly to the time change since we arrived in the evening and were able to go to sleep for the night. We also had the bulkhead seats on the plane, with the bassinett. The bassinett wasn't that helpful because you have to take the baby out everytime there is turbulence, but it's nice to have the extra space on the floor in front and you could probably make a little bed for the baby to sleep there on the plane. Our baby slept well on the plane, and the times she was fussy, myhusband walked her to the back of the plane- for about an hour and she clamed down.
For travel there, I chose to forgo the carseat and stroller, and we just used the Ergo and B. Bjorn the whole time, but your 9 mth old may be too big to carry around all the time in a baby carrier. Our friends that came with us brought the stroller for their 10-mth old, but keep in mind that other countries arent always as stroller friendly as the US. In China, we got a ton of attention with the baby and everyone wanted to touch and hold her. We tried to be relaxed about it, but not all parents would be comfortable with strangers touching their child. In the Ergo baby, I could cover her head, so that avoided a lot of unwanted attention since they couldn't see the baby. Hope that helps... Have fun!!