After getting some badly damaged eggs in a shipment, with damaged air cells, I just had to get to the bottom of the "detached air cell" phenomenon. I didn't see how an air cell could detach, because it's not a separate part of the egg. It's just a gap between the shell and the membrane at the large end of the egg. It's not a separate little bag of air. Study of the membrane in the shell of an egg I ate for breakfast shows that if you poke a hole in the membrane at the large end, into the air cell, you can flatten the menbrane against the shell. This leads me to believe that what happens is this: The membrane ruptures, and flattens against the shell, which allows the air to get out of that space, and into the white portion of the egg. Then you have a free-floating bubble of air, inside the membrane. That's all it is, a bubble. So here's the tricky stuff. I've seen posts where people said the air cell had 're-attached'. How can a bubble attach? That's what appears to happen, but this is what I believe must must be happening: The shells and the membranes are gas-permeable, meaning that gases, such as oxygen, water vapor, and CO2, can pass through. As the moisture in the egg begins to evaporate, (with the egg in an upright position, big end up) the membrane at the top would start to shrink a little. As it does, it will pull away from the shell. This would let the air of that little bubble be drawn back into the space between the shell and the membrane. At this point, if the membrane isn't too badly damaged, it may indeed be possible for the egg to hatch normally, especially if it is kept upright and nearly upright, such as it would be in most auto turners, or carton-hatching. The turning by tilting the carton, (or the 'bator) would not be extreme, so it's possible the air cell could remain re-inflated. If the membrane is badly torn, this may not work. Or the bubble may continue to shift from side to side as the egg tips. Next time you eat an egg, examine the membrane inside the shell. Pull it away from the shell in the big end. You'll see what I mean! You can't peel out an air cell. you can only break and pull out the membrane, which, undamaged, is all one piece.