Ballistic Slider

Ballistic Slider (バリスティック・スライダー) is a large shuttle system that was designed by Academy City for space travel.

Principles
It was designed for the Academy City Next-Generation Space Travel Competition (学園都市の次期主力宇宙輸送機関のコンペ) but lost to Endymion. It's specifications are unknown, but the mothership alone is very large. The aircraft uses a runway like an airplane while carrying its cargo, the smaller spaceplane.

When the mothership reaches the spaceplane's launch altitude, it is released into the upper atmosphere, and from there the spaceplane uses its own rockets to escape the earth's atmosphere. Presumably, the mothership comes back to earth to perform a conventional runway landing.

The spaceplane can apparently fly on its own, allowing for people like Kamijou Touma and Index who have no experience in piloting a plane to safely ride in it as passengers. It can also apparently dock with Endymion's spaceport on its own. For reasons unknown, there is also hatch on top of it, this was used by Kanzaki Kaori to get out of the spaceplane.