Film has some advantage over digital for certain kinds of imaging and image storage.

First, a genuinely huge amount of information can be stored in a modestly sized film negative (with my flatbed scanner, I can pull almost a hundred megapixels out of 6x9 cm 120 negatives, and aerographic film is usually used in much larger formats, with better optimized lenses than I can afford, and digital files are needed, scanned at far higher resolution than I can manage). Second, that storage doesn't require constant format/media updates like digital images (what's your oldest hard disk? Can you still read a 3 1/2" floppy?), and a film negative will look like a picture even to the naked eye. Additionally, properly processed and stored silver-image film has a recoverable lifetime many times that of magnetic, optical, or flash RAM media -- measured in lifetimes, rather than years. Even if I still had a working 5 1/4" floppy drive, I wouldn't expect to still be able to read backup disks I made in the late 1980s, but film negatives three times that old are still printable and contain (most of) their original information.

Also worth noting that film negatives are error-tolerant. Ever seen a .jpg file that had all sorts of color stripes, image sections stepped over, and so forth? That can happen when a single byte is changed near the beginning of the file. A small scratch, speck of dust, or even a significant piece missing from a film negative loses only the information in the damaged area, the rest of the negative is just fine and fully usable.

Finally, there's a fairly large installed base of aerial photography equipment -- cameras, comparators, 3D viewers, and so forth -- that runs on film, and it's far cheaper to continue making certain kinds of records the same way they've been made since, in some cases, the end of the Second World War, than it is to replace expensive equipment with newer expensive equipment and convert all the records in a database -- or potentially lose access to them because they weren't converted.