HSI

HSI may refer to:

Horizontal situation indicator

The horizontal situation indicator (commonly called the HSI) is an aircraft instrument normally mounted below the artificial horizon in place of a conventional heading indicator. It combines a heading indicator with a VOR/ILS display. This reduces pilot workload by lessening the number of elements in the pilot's instrument scan to the six basic flight instruments. Among other advantages, the HSI offers freedom from the confusion of reverse sensing on a Instrument landing system localizer back course approach. As long as the needle is set to the localizer front course, the instrument will indicate whether to fly left or right, in either direction of travel.

HSIs were incorporated into the instrument panels of the Vickers VC10 and Concorde as well as being used on spacecraft like the Space Shuttle.

On the HSI, the aircraft is represented by a schematic figure in the centre of the instrument – the VOR/ILS display is shown in relation to this figure. The heading indicator is usually slaved to a remote compass and the HSI is frequently interconnected with an autopilot capable of following the heading select bug and of executing an ILS approach by following the localizer and glide slope.

Homeland security

Homeland security is an American umbrella term for "the concerted national effort to ensure a homeland that is safe, secure, and resilient against terrorism and other hazards where American interests, aspirations, and ways of life can thrive to the national effort to prevent terrorist attacks within the United States, reduce the vulnerability of the U.S. to terrorism, and minimize the damage from attacks that do occur."

Homeland security is not constrained to terrorist incidents. Terrorism is one of many threats that endanger society. Within the U.S., an all-hazards approach exists regarding homeland security endeavors. In this sense, homeland security encompasses both natural disasters and man-made events. Thus, the domain of homeland security must accommodate a plethora of situations and scenarios, ranging from natural disasters (e.g., Hurricane Katrina) to acts of terrorism (e.g., Boston Marathon bombing).

The term came about following a reorganization of many U.S. government agencies in 2003 to form the United States Department of Homeland Security after the September 11 attacks, and may be used to refer to the actions of that department, the United States Senate Committee on Homeland Security and Governmental Affairs, or the United States House of Representatives Committee on Homeland Security.