He won't really form a bond if he never sees Dad in person...he will know who he is, but since he is so young, he won't have the understanding of dad as a real person if he never sees him! I think older kids who already had the bond would be okay maintaining the bond through Skype and phone for a while if necessary, but not if the bond was never there to begin with and not for 5 years.
That said, I would not be okay with a very young child going so far for an extended period of time either, which creates a pretty big problem! Do you think he is going to file for custody? He will probably be granted a week over holidays plus a few weeks over the summer, starting from a pretty young age, so it would more than likely be to your benefit to work something else with him first. Also just an FYI, but you might be ordered to pay for all of that travel since you were the one to move away...not necessarily, but there is a chance.
Are you willing/able to take the child there a few times a year? Is dad willing/able to travel to you to see the child a few times a year? That's really my only idea that doesn't involve the child going for a long time alone ,but obviously you'll have to get along enough to spend time together during those visits, plus have the $$ for a lot of travelling.
Regarding sending a 5-year-old alone cross country...I personally wouldn't. I'm not sure that airlines allow this at that age either, but you'd have to ask the policy and ask how supervised they would be during lay overs etc.
I think it is more common for the parents to fly with the kids until they are older-i.e. dad would fly to you, pick up son, fly back to Alaska, then at end of visit you would fly to Alaska then fly home with son. Again, very pricey.
Skype and phone is a nice supplement for a long distance parent, but I don't at all think it is a substitute for in person parenting, so I hope you guys find a solution!