An airline pilot with poor eyesight had managed to pass his periodic vision exams by memorizing the eye charts beforehand. One year, though, his doctor used a new chart that the pilot had never before seen. The pilot proceeded to recite the old chart and the doctor realized that she'd been hoodwinked.
Well, the pilot proved to be nearly blind as a bat. But the doctor could not contain her curiosity. "How is it that someone with your eyesight can manage to pilot a plane at all? I mean, how for example do you taxi the plane out to the runway?"
"Well," says the pilot, "it's really not very hard. All you have to do is follow the instructions of the ground controller over the radio. And besides, the landmarks have all become quite familiar to me over the years."
"I can understand that," replies the doctor. "But what about the take-off?"
"Again, a simple procedure. I just aim the plane down the runway, go to full throttle, pull back on the stick, and off we go!"
"But once you're aloft?"
"Oh, everything's fully automated these days. The flight computer knows our destination, and all I have to do is hit the autopilot and the plane pretty much flies itself."
"But I still don't see how you land!"
"Oh, that's the easiest part of all. All I do is use the airport's radio beacon to get us on the proper glide path. Then I just throttle down and wait for the co-pilot to yell, 'AIEEEEEEEEEEEEEEEE!!!' pull the nose up, and the plane lands just fine!"