I just traveled to Switzerland alone with my seven week old baby. I found it helpful to bjorn her during the trip, although I brought the stroller and carseat which served me well as a smarte cart. It went well--just nursed and pacifier during the takeoff and landing(s--we had four legs), and also used the help of other travelers when I needed to do something like go to the bathroom. I mean, where are they gonna go wtih your kid in an airplane? The best thing so far is taht I brought her a peapod rather than cart the pack n play with us. It's awesome.
http://www.kidco.com/main.taf?p=4,5
Obviously you've gone already but hopefully it was a good trip!