Y37.47 - Military operations involving unintentional restriction of air and airway Y37.4 - Military operations involving firearm discharge and other forms of conventional warfare Y37.47 - Military operations involving unintentional restriction of air and airway Y37.470 - Military operations involving unintentional restriction of air and airway, military personnel Y37.471 - Military operations involving unintentional restriction of air and airway, civilian