Dude, planes can explode in the air because their windows are the wrong shape. That lesson got learned the hard way. Engines can fall off because of damaged mountings. Engine turbine disks can explode and take all control systems with them. Gears can jam and elevators stuck causing planes to nosedive.

You are talking about a highly pressurized canister of air travelling at the better part of the speed of sound way up in the sky, and it must be made as light as possible. It's a marvel they are as safe as they are.

Remember, you're far, far more likely to be injured or killed driving a car than taking a plane. It's one of - if not the - safest form of transport out there.

Right, and this is an indication of how safe one can make things even given inherent risks in the technology. It's worth remembering how much we devote to this task. And there are plenty of near-misses that are just mind-boggling, like BA-9, for example, where the 747 flew through the ash cloud of a volcano and lost all four engines as well as rendered its windshield more or less opaque. And yet they still landed safely.

Aircraft are amazingly safe as they currently are. However structurally, there isn't a lot of room for redundency.