Military pilots sometimes have to operate into major civilian airports. They do not have to have passed the Air Law exam of the country in which they are flying, and there are some differences between military and civilian flying regulations. Therefore, occasionally carrying a CAA IRE on sorties is a useful standardisation check of the suitability of military regulations and SOPs for safe operation in civilian controlled airspace. This was the basis on which my Group Captain a few years ago accepted liability on behalf of the Crown for a CAA IRE flying on the jump seat during my military IRT.
PAG, why remain silent and be thought of as a fool ...............