Can I use my notebook while in the airplane?

Depends on your notebook model and your traveling class. If you have an economy ticket and your traveling in one of those cheap airlines with very limited seat pitch and you have the luck of a friendly traveler in the next seat who decides to recline his seat during the journey, it get tough to use your notebook. If you are unlucky to travel with ryanair for example, where the pitch is only 30.0" working on a average notebook can be very hard. Last time I tried I could hardly unfold the screen, let alone type properly. I could only work if I would hold the laptop in a v-shape position, which isn't comfortable if you want to write a report.