2. What is safety?
Safety is the technology devoted to avoid any airplane accident, that is without fatalities (deaths) or severe injuries to passengers and crew or to external people or properties, due to some technical failure or to errors in the procedures (human factor).
Active safety has the goal to avoid accidents. Passive safety (or crashworthiness) has the goal to save people or avoid severe injuries even in the case of an accident, when the airplane is severely damaged.
Safety pays a role in all Air Transportation System and it is involved
- in the design, the manufacture of an aircraft
- in its operational utilization and maintenance
NASA Crash Research
Copyright NASA 2012
The design and manufacture requirements involving safety are fixed by Certification Organizations and compliance to them has to be demonstrated by calculation and/or testing.
The safety technology has gradually improved in aeronautical history, but applied research continues to decrease the number of accident and fatalities or severe injuries in the air transportation.
Parameters to analyse the safety level are :
- the number of accidents for the total number of flights;
- the number of accident for number of km of flight multiplied the global number of passengers (active safety);
- the number of fatalities or severe injuries for number of km of flight multiplied the number of global passengers (active and passive safety);
CIRA Crash simulator
Today the safety measure of air transport is 0,05 deaths per billion passengers * km; 6 times saver thanCar Transportation.
A lot can be the sources of accidents in Air Transportation: structural failures, stability and control problems, navigations and guidance problems, meteorological problems (extreme turbulence, lighting, etc.), and so on.
Just some of them are discussed in this cycle of lessons.