[renowner]

Air shafts don't re-apply aerial if your aerial status is ended while you're on one.
(Pictured below, snake mercenary prayer removed the aerial status of the hippogriph on the left there, notice how its no longer flying despite being on an air shaft.)

[Neus]

Hippogriph is a flying monster so it ignores field tile effects that trigger for units standing on them. Air Shafts make the unit airborne when created, which is why it was airborne initially.