There's some interesting information filtering out from the Air France Airbus crash. Essentially, when the pitot tubes (the device that senses airspeed on aircraft) fails (sometimes due to ice) on the Airbus, the aircraft's automated flight system goes haywire. Airbus aircraft are known for "glass cockpits" (all computer displays) and highly automated flight controls/autopilots (the pilots only indicate intention with inputs to their controls, the computer flies the plane). So, when the airspeed indicator fails, it can trigger the plane's automated flight system to fly differently (which can crash the plane given that the 'flight mode' selected isn't appropriate for the actual conditions) or it can cause the flight system to crash/reboot (there are indications from radio transmissions that this was going on). Regardless, we can learn from this that highly complex systems can be driven into catastrophic failure when the assumptions change (i.e. that sensor inputs are always correct), reactive systems that respond to minor failures can often lead to catastrophic failure (i.e. this is similar to the systems that guard against local power failures on the electricity grid, which can lead to catastrophic system failure as attempts to "save" the system from minor breakdowns overwhelms the entire system), tight coupling (the speed of event onset overwhelms human control), etc. There's lots more.