How can my husband switch from NG to active duty?

My husband is currently a 2Lt in the NG and undergoing flight school training. He has 4 more years left with the NG but he is interested in going to active duty once he graduates flight school. Can anyone explain to me how he could go about doing this? Thank you.How can my husband switch from NG to active duty?
He will have to apply for a conditional release from the Guard. What that means is that the guard will have to give him a release to join active duty. The army actually has 4 components: The active army, the army reserve, the national guard and the inactive ready reserve. Each are actually different branches within the army and when you join one of these branches it does not mean that you are part of all of them. The guard may or may not release him. It depends on their unit manning. If they are short, they may elect to keep him. If they have plenty of soldiers with his mos (military occupational skill) they will probably release him. In all honesty, he should be able to transfer but it will take some time. He may want to contact his unit while he is in training and see if he can start the process now. Good luck.