There isn't a cut-and-dry answer to this age-old question. The best answer I can give you is "maybe." It depends entirely on what you actually DO with your MacBook. If you're primarily doing web browsing, emails, social media, writing (documents, spreadsheets, keynote/powerpoints,) and even some more intensive creative pursuits such as film/music/photo editing, you may very well be able to entirely replace your MacBook with your iPad, at least while traveling.
Only you know exactly what your workflow entails, and if using just an iPad will pain points that outweigh the iPad Air's lightweight convenience.