if he's magically active write down on notecards before the game increasing levels of sensory deprivation, and as you are describing the flight hand them to that player until they land. that way you give the rest of the players a sense of something is going on (which the characters would notice from their companion) without saying the words "hey you notice something odd about fido."
since he can feel the magic around him one of his senses is being removed slowly as he moved further away from the center of the sphere, and when he leaves BAM, <points up to Konsaki's post> do that.
then give him note cards of relie and resubmersion into the sense and magic he's used to.

I think that the rush of panic should be great (like some kind of draconic primal instinct).
The character isnt magical active so he has no magical senses. Since he hasnt been revealed yet, none could see any magical activity or abnormality in his aura.
Since the drakes are dual, they have innate astral senses.
But before "revelation" they are blind to those magical senses.
Do you think that an unawakened drake would have some kind of latent or residual magical sense (some kind of instinct) but that he would never notice it.
Once in orbit, he'd loose this senses and thus notice he is missing something.
(again this is more a technical question : i want some story impact, but not at the cost of innaccuracy regarding dual nature and drakes).
I dont plan on giving insights to other players, anyway they'll all feel some nausea and since he's legendary for still having 2 in constitution, everyone will believe he didnt resist the effects of suborbital travel.

Another possibility i thought about would be an astral projection : his meat body would be still in the plane and he'd have to go to the airport to find it ...
(The character has taken the latent awakening advantage and i said ok, but you get cyberware allergy for free so he's expecting "magical" stuff)

Drakes are only dual in draco form - human form just has astral sight.
If he's entirely unaware of his nature, he won't be astrally perceiving.

Thus, he will just feel somehow weakened and might notice the changing background count as his magic attribute drops.

But astral perception causes dual-naturedness:

So...he should be pretty much boned:

Read your own quote. Astral Perception doesn't cause Dual naturedness, using Astral Perception causes Dual Natureness. The PC doesn't know he has Astral Perception and isn't using it. So, nothing happens.

All but the most powerful adepts will find their abilities gone entirely. Mana voids are very bad news for the awakened. They can kill.

That's why I would go with some sort of descriptive effect, even if the character is not astrally perceiving / aware that they can. I think if you have drake that doesn't know its true nature in the group, this is too good and too atmospheric an opportunity to either trigger the new senses or provide some decent foreshadowing.