"You're crazy," he said. "You can't go that high without oxygen. The
average pilot's limit is around 15,000 to 18,000 feet. You're young and
in good shape. Maybe you got to twenty. But you just imagined you went
higher than that."
"No, I didn't imagine it," I said. "I really went up that high."
"You went ga-ga and imagined it," he said.
He added: "Don't fool around with that sort of business. You're likely
to pass out cold at any moment when you're flying too high without
oxygen. You're likely to pass out cold and fall a long way before
regaining consciousness. You might break your neck."