Most pediatricians believe that a 4- to 6-week-old baby can handle airplane flights. But this guidance only refers to babies with no health complications who get the go-ahead from a pediatrician. Premature infants, as well as those with respiratory or other health issues, may fare better on the ground.

Pretty sure a baby can travel from birth but once they are a certain age need their own seat. Check with the airline 🙂

I don’t think there is any age limit – that is, you can fly with them whenever you feel comfortable.

Also; best to organise travel needs well ahead of departure date.

Best to check with each airline for your individual needs.