I have had older eggs with large air sacks, but not as much as 1/3rd of the egg and still have them to hatch. The eggs that hatched like that almost always produced a runt or the chick died a few weeks later. I have also had some to survive with a lot of TLC as well. This is something I started doing on eggs that I notice have the larger air sack; I take a spray bottle and spray a fine mist of water on the egg once, sometimes twice a day. Since I started doing this, my hatch & survival ratio has vastly improved. Hope this little trick will work for you as well as it does for me.
I have had that happen with shipped eggs. Are the air cells uneven? I really thought mine were gonners but
I ended up with a very good hatch. Don't give up on them!
Tamera
What about eggs that are on day 18 and have air space on both sides?
Nearly all my Jap eggs are like that, they hatch. But it's just weird. Like 3/5th is chick, rest is air.