One with the plane
Because a human can feel the plane better than data flowing in when it comes to gliding. A human can instantly react to wind currents and scan for the right place to be to help him continue the flight.
After going up in a glider when most were worried about the conditions I'm convinced a human at the controls made the flight possible.
That would be a good question for Fossett; Do you think the flight would have continued if the plane had no pilot?