(photo above is NOT a great example of child restraint!)
A friend of mine is travelling with her nearly 2 year old girl next week and we were having a discussion about flying without a reserved seat for an under (barely) 2-year old. They had already made the decision NOT to buy her a ticket, but I thought I'd first touch base on this topic before moving on to her other questions that prompted more investigation.
First of all, we have had this debate in my household, as we have flown many times with our boys, who are now 2.5 and 5. Most recently, we have travelled from Maine to Oahu, Hawaii and our youngest son, Izaac, turned 2 on the trip. We debated changing the trip to save the over $800 for his ticket, and come home before he turned 2. After about an hour into our first flight, we were SO thankful that we'd spent the money. First of all, it gave us room for him and his travel activities, and it also gave the adults their room. It made Izaac feel like a 'big boy' and it made it easier to get him to settle into the seat belt, for meals etc. By half-way through the flight, we would have paid thousands of dollars for his own seat if we didn't already have one.
My opinion is that once a child is mobile (crawling, standing, walking) it's worth every penny to get that seat for them, but infants and pre-crawlers are mostly going to be held anyway (and they are smaller!), so the seat isn't as essential. Also, if the plane is NOT full, I have been given an extra empty seat (unpaid) for my traveling lap child, but obviously, this is not a fool-proof strategy, as more and more flights are filling up these days!
Another thing to think about however, is that some airlines discount a seat for a child under 2. This was the case when our boys were under 2, but not sure with all of the changes in travel regulations these days. The ticket price (even at full fare) may be worth the extra luggage allowance your small travelling companion now has - we always made good use of it, checking car seats (although, usually these are NOT counted as part of the allowance), kid carrying backpacks or other things we would not PAY to take along.
Our investigation shows that some airlines require any child (even under 2) have a seat for international or similarly long flights.
A link on the FAA you may find useful (in reference to child restraint safety)
SO, now it brings us to the question of what can one bring for the UNticketed passenger?
As far as we can tell, a lap child is considered part of an adult's ticket, and thus is NOT allowed any luggage. Note that airlines will usually check a stroller at the gate, and a diaper bag is usually NOT counted as one of your carry-on bags. It is best, however, to check with your specific airlines. Airline's websites usually have this information in a not-so-hard-to-find place.
One other last tidbit worth mentioning when flying with an 'under 2' child. The bathrooms are equipped with a changing table, but if you've never used one, successful use of one is based on practice, and preparation. The space is tiny, and if you have unexpected turbulence (YIKES) it's a bit scary. Board the plane with your own self contained system you may be able to use on the floor (discretely), and all will be happier!
Make sure you pack proper activities to keep the young traveler busy. One cool activity is a set of hand puppets from Manhattan toy, where one is sized for a 'big' hand, and one for a 'small'.
Enjoy your trip!
The Babykeeper
