I flew UA SFO-SYD mid-2002 with my then 7 month old. We bought her a seat and used her car seat on the plane. The only problem is that a rear facing carrier can block the full recline of the seat in front in economy, so you have to have the carseat more upright than normal. We flew Qantas from SYD-CNS using the bassinet seating in the bulkhead (economy), which I found very nice. A nice wool blanket was even provided. An extension seatbelt is provided for the baby, to be used at takeoff/landing/turbulance. Qantas would not allow us to use our rear facing carseat on their plane- we had to use the extension belt only- on our BNE-SYD flight, even though we'd bought her a seat. Basically a liability issue, but I was told on the flight that Qantas will provide and install their own seat if you buy an infant a ticket, just give plenty of notice.