To train an inspector at the department, it can take six to eight months. They need to learn the rules. Someone from the industry, on the other hand, is already aware of the regulations and should be familiar with them.
As for the check pilots, we will be able to give you the details of the training, and the time it takes to train someone as a check pilot. However, if you look at different modes of transportation, whether it's rail, marine, or air, the periods may vary, but there is mandatory training, be it in regulations, investigations, and so on.