Re: How Do CFI\'s Sign Off An Electronic Logbook?
Ditto what everyone else has said, but also think of the required items that a student pilot needs with them in the aircraft during solo flight. Your logbook is one of those items. It's pretty easy to just pull it out and show it to anyone if need be. The proof of pre-solo flight training and all of the endorsements are right there in you logbook.
If you had an electronic logbook on a PDA, what could happen if the batteries went kaput and the FAA wanted to look at your logbook?