Flying to the US with a 4 month old

[BabCNesbitt]

We'll be flying to New York with our 4mo DD at the beginning of March. Would a baby of that age get their own separate seat, or would she just be on our laps with a seat belt extender? (And if the latter, would we need to provide that ourselves?) When I've been looking into flight prices, she does seem to get charged for the flight, but I don't know if that means she'll have a separate seat (for a car seat or something like that), or if that's just the charge to have her on the plane on my lap.

(Also, if people fly with babies on their laps, how do they eat the in-flight meal? )

This all depends on which airline you're flying with as they each have their own policies.
However, the most usual is that your baby does not pay full price and does not get her own seat.
Most airlines demand that you pay for a seat for children over the age of 2, but up to that age they can travel on your knee.

For babies, most airlines have cots on the internal walls of the plane. These can be booked in advance and give you somewhere to put her to sleep during the flight. There are usually about 6 of them on each plane.
You can leave her in the cot while you eat your meal.
The cots cannot be used during take off, landing or turbulence. During these times, the baby will be on your knee with a baby/child seat belt which clips on to your own.

I really recommend that you book your seats with a cot.
The way I usually do this personally, is to book my seats over the internet and then call the airline and ask them to book the cot over the phone. I've never had any problem with that.

Alternatively you could travel with a car seat for her to sleep in, but in this case, she will need her own seat which will cost you more.