> Boeing 747's are complex systems; it's not acceptable if one fails occasionally. You're right that 747s should not just fall out of the sky. However, parts o

> Boeing 747's are complex systems; it's not acceptable if one fails occasionally. You're right that 747s should not just fall out of the sky. However, parts of 747s fail constantly. In a machine that complex, they are guaranteed to have some downtime. A well manufactured 747 will fail cleanly and safely and recover smoothly.