[Dave Marx]

What kind of "sick?" Everyone seems to be assuming motion sickness, but the original poster mentioned Pepto, which suggests the possibility of a diffrent kind of upset. If we're talking about gastrointestinal illness, rather than motion sickness, that could be related to stress - over-excitement about the trip, or fear of flying (since it seems to happen when she lands, perhaps it's specifically fear of landing). Or it could be related to irregular diet when traveling. If it's stress, I'd first consider ways to reduce the stress "naturally," rather than use a medication - maybe listening to calming music on headphones, talking about what's making her nervous, reading during the landing process as a form of distraction, etc. If it's food-related, pack something to eat that's consistent with her regular diet.