The US government flag flying flags at half-staff on April 15, 2014 is in honor of Sergeant Timothy Wayne Owens who died during the Fort Hood shootings.
Only the President or a state Governor can order when and for how long the American flag is to be flown at half-staff on government property.
For State Government buildings the Governor can and in Michigan every time a Michigan citizen loses their life in the Iraq or Afghanistan Military conflict the flags are ordered Half Staff . It depends on whether you are talking Federal buildings
Traditionally this is when someone dies
To mourn the death of a public official.
What are the rules about flying the American Flag
Chicago Bears fly flags at half staff to honour the anyone that died during the service to their city or country, most recently this was done to honour the death of 19 fire fighters that died.
Since the Kennedy assassination, this practice has been in effect. Half-staff or half-mast started out with the Kennedy funerals and then stayed on long after the events.
technical staff
Formerly half mast (Navy) and half staff (Army) were to honor deceased VIPs (Very Important People-US Military & Government Personnel). Today, that tradition has been expanded to many (civilian) people and many events.
The medical staff are simply known as the "Flying doctors". However, other staff besides medical doctors are included, as specialists such as dentists are also needed to service the remote areas of the outback.
October 15, 1969 was the date of the Vietnam Moratorium Day, a day of demonstration held to protest the United States' involvement in Vietnam. Then New York City Mayor John Lindsay ordered all flags at city buildings be flown at half staff as part of the Moratorium. Since Shea Stadium was owned by the city, Lindsay wanted the flag at the game also flown at half staff. MLB Comissioner Bowie Kuhn said no.
April 17, 1996