The child’s ears will be the problem. She/he may have trouble with the change in air pressure. This can be very painful and can damage the ear drums.

no it’s not safe. The rest of the passengers will be dangerous to you and your child after you subject them to a screaming, uncontrollable infant in a closed space.

safe yes
comfortable no

Have the relatives come and visit you and the baby

Yes, it is perfectly safe to travel with a baby that young, even for such a long distance.

Babies often do have difficulty with the pressure in their ears during take-off and again when the plane starts to make its descent to land. If you have the baby nursing or drinking from a bottle during that time, then the baby should be fine. Even sucking on a pacifier can help. It isn’t dangerous to the baby - they just become uncomfortable if they can’t pop their ears. But sucking on something will help.

Bring lots of diapers, changes of clothes, and plenty of formula if necessary for the trip. You should bring more than you think you will need just in case there are delays or in case your baby picks that day to change the routine a little.

Also, many airlines offer basinets for international long-distance flights. They attach to the bulkhead, and provide a place for the baby to lay down and rest during the flight. Policies vary though - some airlines will allow you to reserve this ahead of time, while others assign them at check-in on a first come/first served basis. And there is a limit to the number available on each flight. But that might be something to look into.

Traveling with such a young baby is usually pretty easy - they aren’t yet mobile, they sleep a lot, and they are relatively easy to entertain. I don’t think you’ll have any trouble