1 In a bowl, sift together the cocoa, baking soda, flour and salt. 2  Take a large mixing bowl and stir together the margarine and sugar, until you have a fluffy mixture. 3  Add the eggs one by one, mixing well in between.  Add the vanilla extract and continue mixing.
The airline industry became a systems-oriented world. Actually, the industry is a complex system defined by the interactions among its several sub-systems: aircrafts, airports, passengers and aviation policy. It is also a complex system in the sense that it encompasses several simpler sub-systems.
The history of the airline industry until the 1970s is pretty much related to improving aircrafts and flight conditions. In the first half of the 20th century, this was done with a military focus, because demand for aircrafts came mostly from World War I and World War II.