It is clear from the section of this amazing text entitled "The Craft" that Guillaumet is such a successful pilot because of an instinctive and incredibly detailed view of Spain rather than merely facts that any pilot could learn or memorise. Guillaumet, when talking through Spain to the author and helping him note down things to watch out for on his map, mentions factors such as orange trees, sheep and a brook. Note what the author writes about this experience:
Little by little, under the lamp, the Spain of my map became a sort of fairyland. The crosses marked to indicate safety zones and traps were so many buoys and beacons. I charted the farmer, the thirty sheep, the brook. And, exactly where she stood, I set a buoy to mark the shepherdess forgotten by the geographers.
Guillaumet therefore is such a successful pilot precisely because of the incredible detail that he goes into when flying. He uses parts of the geography and the terrain to steer by that are far more focused and detailed than any other pilot would use, down to the number of sheep in each field. These various signs are used by Guillaumet, and passed on to the author, to steer him to safety.