I'd be surprised if you find anything that comes out and says this product is as safe as or safer than a car seat. It doesn't have any side protection and no crotch strap. A car seat would hold your child in better.

But air travel itself is safe and this stops, as you pointed out, the major concern which is the top half of the body from lurching forward. Now if airlines had shoulder straps for us adults... Your dd in a CARES harness will probably be safer than you are in just the lap belt!

Everything, including the articles linked on their site, skirt the actual question of which is safer. Here's the FAA's press release;
http://www.faa.gov/news/press_releas...fm?newsId=7381

For me, the fact that it's approved by other governments is a big plus. How many times my car seats were taken away by foreign airlines for this reason!! A car seat isn't very effective if the child can't use it... Bring something that states this, off the CARES harness site or the airlines', if mentioned there, just to put under the nose of any uninformed Flight Attendant.

You know that CARES harnesses can be rented. I wonder if they're doing that in Oz. I would ask how they clean them and make sure it doesn't involve soaking the harness (which compromises the strength of the fabric).

The only issue to consider is the question of car seats at your destinations. There is a device you might want to look into if your dd is 35lbs.

http://www.safetrafficsystem.com/

Here's another product but the cars in the U.S. would have to have a tether. Have them check but unless it's a very old car, it should have them.

http://www.safeguardseat.com/go/index.htm

Cosco Sceneras can often be found for as little as $40 and my dd was in hers' until age 3 1/2 (average size).

If you borrow one, be aware that most U.S. car seats "expire" after 6 years. A few go further but it's usually printed on the seat itself. Please have your families check if unsure. You can also do what I did and order one on line, having it delivered to their address. You may want to look at the owner's manual on line so you aren't all tired and trying to figure it out at the airport for the first time...

Australia has fewer options for higher harnessed seats so you might want to take advantage of your trip to pick one up and take it back with you.

http://www.kyledavidmiller.org/pages..._is_Safest.htm
http://www.kyledavidmiller.org/pages...aland_Only.htm

Have a good trip!