Just about anything by Mark Twain. Though if you want just one choice to start, here's a hint:
"All modern American literature comes from one book by Mark Twain called Huckleberry Finn." -- Ernest Hemmingway.
I just finished reading "Three Men in a Boat" published in 1889 by Jerome K. Jerome. Wry British humor of the day. I read it to satisfy an itch delivered 50 years ago when I read Robert Heinlein's "Have Space Suit, Will Travel" (a classic book of another sort worth reading) that began:
You see, I had this space suit. How it happened was this way:
“Dad,” I said, “I want to go to the Moon.”
“Certainly,” he answered and looked back at his book. It was Jerome K. Jerome’s Three Men in a Boat, which he must know by heart.Later in Heinlein's story, the father character says:
"Reminds me of this passage I'm reading. They're trying to open a tin of pineapple and Harris has left the can opener back in London. They try several ways." He started to read aloud and I sneaked out-I had heard that passage five hundred times. Well, three hundred.I just had to read the book to find out how they eventually opened the tin of pineapples.
Anyway, there are the classic classics: the Iliad and the Odyssey. No need to read them in the original Greek.
Naturally, as a pilot, some Jules Verne would be appropriate (hard to avoid Hollywood taint when reading his original books) but "Robur the Conqueror" could be added as a topical classic. Don't let it give you any ideas!