The picture depicts a passenger airship as commonly used on Ansgar. It is held afloat by a mixture of ligther-than-air technology and techno-magic. Now as magic isn't science, you can't rely on that input X will always yield you output Y. i.e. you still need a merchant marine magus (colloquially referred to as the "triple M") to keep the magical energies behaving more or less predictable and stable - and therefore your ship afloat (depending on the size of the vessel, you will need a whole bunch of Magi). In case of an unexpected magical breakdown or outburst, the lighter-than-air-technology still ensures that the ship does not crash to the ground, but can be landed in a more or less slow and controlled descent. As long as the magical capacitors are resonably sized and not too many of them are installed, and in conjunction with a competent magus on board, the system has proven to be relatively reliable.