meritorious service to a commissioned officer member of the flying personnel, after 30 years of meritorious service for a non-commissioned officer (13 years for non-commissioned officers member of the flying personnel), and after 40 years of service for a private or corporal; Gold Medal: Awarded after 20 years of meritorious service to a non-commissioned officer (9 years for non-commissioned officers member of the flying personnel), and after 25 years of service for a private or corporal; Silver Medal: Awarded after 20 years of meritorious service for a private or corporal. For awards to military personnel, there is no minimum age requirement. For commissioned officers not members of the flying personnel, the Order of Leopold II is only awarded at the time of retirement, even if it is in fact earned before that in line with the rules presented above. Even then, because of the generic rule that one cannot be awarded a National Order at a level below the highest that the recipient has already received, the Order of Leopold II will not be awarded if the recipient has been awarded in the meantime a higher National Order than the Order of Leopold II at the Class he could receive. This apparent anomaly is due to the fact that King Albert I, who was fond of aviation, wanted to provide a special reward to aircraft pilots, and therefore ordered that the Order of Leopold II only be awarded to them. In its early days, the Order of Leopold II awarded to pilots was adorned with a bar for every one hundred hours flown (a practice currently discontinued). The Order of Leopold II is also sometimes awarded to military personnel not meeting the conditions above when they have performed especially meritorious services to the King that do not deserve a special award of the Order of Leopold. This is in particular the case for commissioned officers who have been adjutant to the King or Crown Prince (usually a part-time position for a few especially selected Major), who are usually awarded the Order at the rank of commander. Award conditions for long civilian service The Knight's Cross of the Order of Leopold II is awarded to the presidents, secretaries and members of the board of directors of the largest representative trade organisations such as trade unions on the basis of the number of members of the organisation, of the length of their