Source: The Great Interpretation of Dreams (Ibn Sirin)
Walking on air in a dream indicates arrogance and falsehood if the dreamer is not righteous. If righteous, it indicates exaltation and a blessed journey.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
Walking in the air indicates travel, fame, or righteousness in religion.
Source: Signs in the Science of Expressions (Ibn Shaheen)
Walking in the air is interpreted as travel or exaltation.