When we came to Argentina in December 2010, we flew from Chicago, via Washington to Argentina with United. We had both our cats with us in the cabin, of course in seperate carriers. The carriers had to be small of course because they had to fit 'under the seat in front of you'. At that time they had a policy of max. two small animals in cabin per flight and they had to travel with two different passengers so I had one cat and my husband the other. Don't know what United policy is now or whether this was only for flights exit-USA?