I just came across an interesting image, the only color picture in the January 1910 issue of Scribner's Magazine at the Modernist Journals Project, and wanted to document it here for a later expansion. It seems relevant to the passages having to do with airplanes, angels, and of course churches. It depicts an early biplane and monoplane with the profile of Rheims cathedral in the background. Rheims of course became a focal point for Allied propaganda after it was shelled by the Germans.
The poster refers to an aviation event at Rheims in September 1909. Perhaps Proust attended it. Some biographical searching about his experiences with early flight and where they took place could be very useful. Also the caption centers on the idea of point of view, a crucial focus of the Recherche. Will have to read the story to which the image corresponds, "The Point of View" on p. 124.