A it should take into account the different amounts of work or the psychological stress undergone by L2 pilots and controllers in their real life environment.
B it does not cover as many language skills and proficiency levels as necessary to validate pilots and controllers’ performance in the L2.
C it does not consider the ICAO’s language proficiency requirements for aviation professionals.
D the number of air traffic controllers and pilots who need to be tested is very large.
E the proficiency levels of the high L2 and low L2 groups are very different.