i use captainslog, check out www.juland.com for the free trial. captainslog is great because it has the airport database which does autonight calculations based on the lat long of the airport, and it also imports times from other formats, not sure if it works with crewtrac or not. this is a huge advantage over keeping a paper logbook because its cleaner and neater (no white-out) and you only need to print it out one time - for your interview. my brother printed his out (over 100 pages) and had it bound with a front and back cover at office depot for about $10 or so to take to his interview

To be on the safe side you should keep both. I use paper logbook for everything and the electric logbook for calculations and backup.