Here is a sheet I picked up for a 1939 aviation club meeting (I think):

My
Sanabria (1946) lists the underlying 1938 stamp issued for a club aviation meet, but not the 1939 overprint. Not sure why they would list 1938 and not 1939, as the overprint still pretty clearly seems to relate to aviation.
The sheet of 20 has one intentional inverted stamp, creating the possibility of tete-beche pairs.
Sanabria prices singles and tete-beche pairs.
Here is a detail:

and a look at the pair:

I haven't found much on these on the Interwebz, so if anyone has some specifics, I'd appreciate it. Perhaps a newer
Sanabria lists them...[hint, hint

]
If you have any other colors, or the original 1938 issue, without overprint, please post 'em.
I'll include the language of the overprint for the G@@gle monster:
1er VOL AEROPOSTAL Aller et Retour
LA BAULE ILE D'YEU 5 Aout 1939
2 F.