The military hat is actually referred to as a "cover," and it is never called a hat. There are specific military cover etiquette that applies to various situations, indoors, outdoors, when being saluted, when at a funeral and when flying in military aircraft. If you are in the military it is crucial that you follow these etiquette procedures regarding your cover. Etiquette in the military is not just a guideline but an act of respect to those around you and to the military in general.
Indoor Cover Etiquette
Covers are not to be worn indoors. There are no exceptions to this etiquette rule. There is some confusion as to what is considered to be "indoors" and what is not. According to the Centers for Disease Control and Prevention (CDC), the following locations are considered to be indoors and therefore a cover must not be worn: offices, hallways, mess halls, lobbies, kitchens, bathrooms, libraries, dwellings, inside airport terminals and subways. According to the CDC, airport terminals and subways can be considered indoors or outdoors and is a matter of preference.
Outdoor Cover Etiquette
Covers must be worn outdoors whenever military personnel are in uniform. There is also some debate and confusion as to what is considered to be “outdoors” and what is not. According to the CDC, you cannot go wrong whenever you wear a cover in an outdoor area. There are some locations that would normally be considered indoors but for military purposes are considered to be outdoors. For example, drill halls are considered to be outdoors when being used for military reasons, even though technically it is an indoor area. Theater marquees and covered walks are also considered to be outdoors. Subways and airport terminals can be considered indoors or outdoors.
Saluting and Cover Etiquette
Whenever you are covered and someone salutes you, or you see an officer of higher rank, it is proper etiquette to salute him. In the military it is considered poor etiquette if you salute someone while you are uncovered. This means that whenever you are in a situation where you are uncovered, such as being indoors, you should not salute someone, even if she is a higher rank than you. Instead you should simply greet the person with a “Good afternoon, ma'am,” or “Good morning, sir.”
Funerals and Cover Etiquette
When attending funerals in uniform, covers should be worn the entire time. Do not take off a cover while at a funeral in uniform. This would be considered poor etiquette. Instead, it is proper to salute while covered during the following procedures: when the casket is moved, when the casket is lowered into the grave and during the firing of the volley. If attending a funeral in civilian attire, covers should not be worn. If wearing a civilian hat or headdress while attending a funeral, it is appropriate to remove the hat or headdress and place it over your heart.
Cover Etiquette While in Military Aircraft
When flying in military aircraft, even though it is considered outdoors, it is usually poor etiquette to wear a cover. This is mainly due to safety concerns. There is a potential safety threat that the cover would blow off and get sucked into the engine which would result in a catastrophe. It really depends upon the flight and the specific scenario. If you are unsure whether or not you should wear a cover, it is best to ask ahead of time.