It doesn't take that much space. Certainly not more space than that you can fit under the seat in front of you.

OK, let's do a thought experiment. You have an infant, and are (for unfathomable reasons, probably related to masochism) taking them from London to Sydney - a 21.5 hour flight - including layover.

How many nappies do you think the average bundle of joy gets through in an almost 24 hour period? You also need their baby food, a changing matt, baby wipes, nappy rash cream, clothing, books and toys to keep them entertained.

Last time I travelled there was hardly room for a small bag under the seat in front, there's no way 24 hours of supplies for a baby would fit easily. Now what if you have twins?

I did a 6 hour flight (which was a 14+ hour day) with my son when he was 8 months. It was pretty easy. Every child is different though. If he was a difficult baby/toddler, there's no way I would have attempted it by myself.

The twins question is easy. You're only allowed one infant per person. So, if you have twins you and the other adult both have a bag for food, changing mat, wipes, diapers, etc.

If you're already thinking it's too much to spend a few extra bucks to improve the experience for everyone, you probably shouldn't be flying anyway.

I'm not sure 6 hours counts as long haul in the context of needing supplies! If you are on a 20+ hour itinerary with multiple layovers and the potential for delays then you will have substantially more carry on items. Throw in needing to bring any medical supplies or bottles/formula for the baby and it's even worse.

Sure, I wasn't trying to imply that it did count as a long-haul; just giving my own point of reference/opinion.

I agree on all of your points. However, if there are other factors involed (as I stated, if my child was more difficult), I simply wouldn't travel. Maybe that's not a decision you can make, but I have.

My response was more for others reading - I agreed with everything you had written.

My experience has always been that most kids travel well especially if the parents have prepared.

hahaha, an infant? ANY DAY. try a 2.5 yo.

When my son was that age he pushed his way into the front window at a toy store and I picked him up, tucked him under my arm, and carried him sideways out of the store.

We sat down and talked about it just a few steps outside. Somebody called the police on us because an officer showed up; the three of us had a good conversation and he left.

a good idea: let's put our 2.5 yos in the overhead!

You also get the space under the seat(s) for the small children too. Give them each a small'ish bag they can carry themselves.