There are several types of "flight law" modes (see http://en.wikipedia.org/wiki/Flight_control_modes_%28electronic%29 http://en.wikipedia.org/wiki/Flight_contro

There are several types of "flight law" modes (see http://en.wikipedia.org/wiki/Flight_control_modes_%28electronic%29 http://en.wikipedia.org/wiki/Flight_control_modes_%28electro... ) that define the set of protections enforce-able by the software. For example, in the case of Airbus airplanes, flying in normal law's flare mode provides protection against high angle of attack and bank angle protection. However, when something bad happens, the plane is usually switched in alternate or direct law, based on the philosophy that the software can fail and the pilot is the only one able to see the big picture and compensate for possible faulty sensor data. It's all a question of who to trust in highly-tensed situations: is the pilot suffering from vertigo or it's just a matter of faulty sensor readings due to external ice build-up? And if the software were to override pilot decisions, just think about liabilities in case something goes wrong, which is a Pandora's box for aircraft manufacturers.