Day 16 egg when candled,
(this egg is not a current egg, I am also guessing this is a day 16.)The egg below will show aircell the line should be clean. (the one below is clean,-out of focus though.) It may show a bit lighter near the aircell line and then a dark tip. By day 16 if the tip is not dark, it may still hatch but take a day or so longer.
I have seen people have a clear tip in an egg and an aircell, they thought it had 2 air cells because of the clear tip, but clear tip means unabsorbed fluids.