<Ul> <Li> EASA FFS Level A </Li> <Li> EASA FFS Level B </Li> <Li> EASA FFS Level C </Li> <Li> EASA FFS Level D </Li> </Ul> <Li> EASA FFS Level A </Li> <Li> EASA FFS Level B </Li> <Li> EASA FFS Level C </Li>

When was the first digital computer system used in flight simulation