The bloated corpse of a decaying gigantic creature is necromatically enhanced and fused with an undercarriage for use as a grisly and terrifying airship. The methane gas from tissue decay keeps it buoyant in atmosphere, but it can be even more flammable than hydrogen if it escapes...
Minor Cultural Modifier: The culture believes, for the soul to leave the body, the corpse' eyes must be open. So any member of that culture takes care any dead body they find has its eyes open. Doubly true for those they kill themselves, for then the corpse will surely rise as an undead hunting him.