By Sea there are actually designs under the tips of its wings and fuselage that allow it to skid across the water if it ever needed to land. They kept this in mind after the XB-0 because building super huge runways was just not feasable
The XB-0 was stationed at Mount Schrim in Belka, however it was moved for the attack on Lumen before Galm attacked the facility. Honestly, I don't know how that behemoth could take off/land from Mount Schrim's runway, seeing as it's only long enough for fighters and not very wide.
No way any of the command cruisers or aerial fortresses could take off from land. The amount of runway space you would need is ridiculous. The Glepnir is one of the only ones where any information on that is provided, and it says something along the lines of it's so big that it needs to take off and land on water. In one of the missions you can also see guiding runway lights over the water. This, along with the very marine-esque design of the aigaion, lead me to believe these huge craft are waterborn.
Take a look at the HK-1 Spruce Goose as an example in the real world.
I don't believe there is any canon material that explains hresvelgr's takeoff or landing capabilities. Or the Aigaion for that matter.
And we have to remember that the scale for aerial objects and the scale for scenery and land-based objects is not very accurate. (e.g. aircraft carriers that you land on are bigger than carriers present in a battle zone). This is for gameplay purposes. In reality, either the hangar for the XB-0 would need to be a whole lot bigger or the XB-0 is a whole lot smaller.
Not only this, but the scale of the player's aircraft is different from other aircraft. The player has fully rendered aircraft, but all other aircraft are at a different scale and not fully detailed, so really there is no way to judge size at all.
Very true. Iremember going past buildings in ace combat 4 and 5 like "Really? Who needs a house that big? How tall are the other residents of strangereal that didn't become figter pilots? What is this, a city for ants?"
I also recall being able to dip your wing in the water and creating a wake in AC4. The hitbox for the water is lower than the skin for the water, creating a gap between the water and death. Also, on take off from carrier, one creates wake.