"Flying crust," aka "flying top," is something which occurs during the baking process when the top crust rises (a lot) faster than the bulk of the loaf underneat. A big bubble forms under the crust and leaves a hole -- often running the length of the loaf -- when the bread is sliced.
If you go to the fresh loaf site, The Fresh Loaf | News & Information for Amateur Bakers and Artisan Bread Enthusiasts
, and search the term, you'll find some discussions.
It happens mostly in breadpan loaves, but happens with handformed as well -- expecially batards. Maybe a little less often with loaves that are shaped by a banneton or the like, or are formed as a boule or miche.
The "predisoposition" usually occurs during the last proofing, when the top part of the bread rises faster than the lower -- because the lower has the weight of the top pressing it down and retarding the rise. One solution is to gently press the center of the dough down (along the long axis of the loaf) near the last part of the final proof. As I said (but misspelled) it forms a characteristic "heart" shaped top -- pretty typical of Euro "sandwich" breads -- and not atypical of sumpermarket loaves, either.
Another solution, more appropriate with free-form loaves, is to let them take part of the proof, then turn them over to finish it. But better, I think, is getting a lot of "surface tension" on the loaf before formation. You control the crust and the crust controls the bread; and, that takes care of that.
I won't try and guess if and how your essentially "no-knead" style of baking performs in terms of flying crust.