Right now the pilots and first officers have to download updates to the printed documents and print them out themselves, if I understand procedure correctly. This isn't an occasional task... but something that takes place on a very regular basis. The documents include everything from standard and emergency procedures to flight plans, airport layouts and so on. Like the blurb above said... it's 35 pounds of paper that they have to carry onto the plane with them... and back off again... everywhere they go. They stick with the pilot... not the plane. But the danger of "hacking" the documentation doesn't go away just because you go with paper. The documents still go through the digital world before they're printed... and still suffer the oh-so-scary danger of "hackers" modifying them. The difference here is that the pilots and officers don't have to lug around a 35+ pound suitcase of books... don't have to waste paper, toner, etc... and can just plug in their iPads to sync all the documentation at once instead of hoping that they got all the documents that had to be updated for their current flight... and got the pages in the right place in the right book. The only disadvantage is that the paper industry will decline faster and the chiropractors won't have as many airline pilots visiting them because their backs were messed up from lugging that stuff around.