I would try to change the diaper as close to boarding as possible, then perhaps you could get away without having to change it on the plane. Our flights are short enough that a wet diaper I would just wait until we landed to change. On the longer leg of our last flight DD (then 15mo old) had a major major need for a change. Without going into great detail, it was too messy to do in the seats, so we just took her to the back of the plane, laid her on a blanket I had brought along with changing pad on top. DH was by her head, myself by her feet, so as to bother as little people as possible (including flight attendant who had just sat down to eat) We ended up using 2 ziploc bags, one for the diaper/wipes and another for her clothing she had on at the time. There is no way this one would have waited, be sure to bring ziploc bags!!! It may annoy some people for you to do it this way, but as few as possible. Much less than a cranky dirty diapered baby would anyway.