I don't know specifically about Cathay, but in general, I always bring my son's formula including water, enough for 2 days in case anything should happen to the luggage, same with diapers and clothes. . . this makes for very bulky carry-on I know, but for long-distance travel, I try to plan on what-ifs. If possible, also bring a spare set of clothes for you, in case flying doesn't agree with baby (this I found out the hard way!). I don't believe airlines provide car seats or would allow you to let baby sleep in the stroller. If you travel with baby as a lap child, try to request the bassinet so that your baby can lay down (subject to availability & baby length & weight). I have heard of parents medicating the child, I personally don't believe in it. The rule of thumb to alleviate the ear ache of take off & landing is to allow baby to suck on something, bottle, pacifier, etc. I now allow my son to chew some food, crackers/cheese, to get his jaws & saliva working to relieve any built up pressure. Hope this helps. Good Luck.