Reading a book might not sound like an exciting topic for a poem at first, but reading that same book at 30,000 feet? Everything gets more interesting at 30,000 feet, right?
And reading Moby-Dick ups the excitement ante by a thousand. After all, the book takes place on a whaling boat, where the line between life and death is thin at best and non-existent at worst. These high stakes heighten the contrast between the life of these whalers and the life of the speaker.
On the Pequod, these men are risking their lives on the open ocean. At 30,000 feet, we're in a passenger plane, flying smoothly in relative safety. On the whaling boat, the members of the crew have hard, physical work to do. They feel the ocean under them and the salt spray in their faces. At 30,000 feet, we're sitting in a small, cushioned chair, funneling Muzak into our ears from the airplane radio. On the whaling boat, they're hunting huge animals by hurling pointy objects at them; those huge animals also have the power to smash their boat. At 30,000 feet we're… well, you get the idea. There's a huge difference between the two, and the title of "Reading Moby-Dick at 30,000 Feet" clues us in to the fact that the difference is going to be the focal point of the poem.