I am bringing holy books to Israel by airplane. I want to know whether I can keep them in a carry-on bag that ultimately will be put on the floor, at least the floor of the airport, while I am traveling, or if it would be considered disrespectful of the books, equivalent to putting the books directly on the floor, which I know is not allowed. Does it matter if they are sitting on top of something in the bag like a pillow or sweater, or can the bag itself not be on the floor?
In a long and interesting response on the laws of handling Jewish books R Yirmiyohu Kaganoff specifically writes this appears permitted to him, see here where he writes
Anyone visiting a sefarim store witnesses piles of bagged or boxed sefarim lying on the floor. Are these stores violating the halacha that states "One may not place Sifrei Torah or other sefarim on the ground" (Rama 282:7)?
It seems that this is permitted, for two different reasons:
Most authorities permit placing printed sefarim on the benches where people are sitting in a crowded Beis Medrash. This is because when there is no place to put the sefarim, and people want to learn Torah, it is not a violation of the sefarim’s honor. One could argue, similarly, that it is difficult, if not impossible, for a sefarim store to transport sefarim without placing the boxes or bags of sefarim on the floor, at least temporarily. Similarly, one can contend that while packing and moving, the most secure place to store the boxes of sefarim is on the floor.
One can argue that the Rama prohibited placing sifrei Torah or other sefarim on the ground only when they are not appropriately bagged or boxed. Once the sefarim are packed in a respectful manner, it does not show disdain to place the boxes or bags on the floor.