DALLAS -- In a world where 20/20 vision is required, vision problems can end a pilot's career.
A North Texas doctor says the emotional and psychological stress of failing vision is very real for pilots. What's seemingly unthinkable, a pilot deliberately sabotaging a flight, is also incredibly rare.
But what's more common – and what the New York Times reported pilot Andreas Lubitz may have learned the day he crashed a plane full of people in the French Alps – his vision was declining.
Dr. Albert Pang is an optometrist who's seen a number of North Texas based pilots at his Plano practice.
"You never thought that it's the vision that really changes the person's personality," Pang says. "When you tell them they have a certain eye disease, always the first question they ask is, 'Am I able to fly? How many years do I have to fly?'"
U.S. pilots are required to undergo annual physical exams, but the FAA doesn't require psychological testing.
Denny Kelly is a retired pilot who has investigated over 100 aviation accidents. He says he knows of several pilots who are not forthcoming with medical conditions.
"The concept of the airline pilot is such that there are checks and balances," Kelly says.
Those safety measures include making sure a pilot isn't left alone at the controls. That's a requirement for domestic airlines.
Another option is three pilots in the cockpit, one Kelly says most airlines do not utilize as often anymore.
"You've got to wonder, did cutting corners, saving money, did it cause this accident? I don't know," Kelly says. "I can't say that it did and I can't say that it didn't."
Pang says he knows his diagnosis of a degenerating eye disease can change the life of a pilot, if not in an instant, over a period of a few years.
"What is the responsibility of a doctor? Yes you need to feel the burden of the patients but at the same time I don't want my patient to be on the headline of a newspaper," Pang says. "It's very seldom that we see (a pilot say) 'Can I hide or can I cheat or do I do something to hide it from the airline or the FAA?' They're all pretty honest and put the well-being of the passenger first."
