


were
instituted by the operating forces without official Navy Department
sanction and as a result, some directives issued on the subject
did little more than to make standard practice official. Some
of the more significant, or possibly more apparent, changes effecting
heavier-than-air aircraft of the operating forces since that date
were directed as follows:
December 1, 1923
June 24, 1924
April 6, 1929
November 6, 1931
November 1942
June 28, 1943
September 14,1943
January 14, 1947
September 18, 1962
April 1, 1980