[Fyron]

Hmm, I would differ with Fyron here, fighters could be launched in space during travels, at least a few of them to keep watch just in case.

Yes, they could. But, this requires you launching them in space yourself. Otherwise, they are in the carrier. If there was no option to launch them into space manually, then alternate methods would be feasible. Also, when combat starts, every single fighter is inside the carrier. If some were in space, they would still be in space at the beginning of combat. As this is not the case (except in cases where you manually launched them into space on the strategic map), it follows that all fighters remain inside the carrier during space travel, except when specifically launched prior to travelling.