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The horizontal situation indicator (commonly called the HSI) is an
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
HSI is part of a remote indicating compass system, which was developed to compensate for the errors and limitations of the older type of heading indicators. The two panel-mounted components of a typical system include the HSI and a slaving control and compensator unit, which pilots can set to auto-correct the gyro error using readings from a remotely mounted magnetic slaving transmitter when the system is set to "slave gyro" mode. In a "free gyro" mode, pilots have to manually adjust their HSI.
aircraft
An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...
flight instrument
Flight instruments are the instruments in the cockpit of an aircraft that provide the pilot with data about the flight situation of that aircraft, such as altitude, airspeed, Variometer, vertical speed, heading and much more other crucial inform ...
normally mounted below the artificial horizon in place of a conventional heading indicator
Heading can refer to:
* Heading (metalworking), a process which incorporates the extruding and upsetting processes
* Heading (navigation), the direction a person or vehicle is facing, usually similar to its course
** Aircraft heading, the dire ...
. It combines a heading indicator with a VHF omnidirectional range
Very High Frequency Omnidirectional Range Station (VOR) is a type of short-range VHF radio navigation system for aircraft, enabling aircraft with a VOR receiver to determine the azimuth (also radial), referenced to magnetic north, between the a ...
- instrument landing system (VOR-ILS) display.
Advantage
The HSI can reduce 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 aninstrument landing system localizer
Instrument may refer to:
Science and technology
* Flight instruments, the devices used to measure the speed, altitude, and pertinent flight angles of various kinds of aircraft
* Laboratory equipment, the measuring tools used in a scientific l ...
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.
Display
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
An autopilot is a system used to control the path of a vehicle without requiring constant manual control by a human operator. Autopilots do not replace human operators. Instead, the autopilot assists the operator's control of the vehicle, allow ...
capable of following the heading select bug and of executing an ILS approach by following the localizer and glide slope.
On a conventional VOR indicator, left–right and to–from must be interpreted in the context of the selected course. When an HSI is tuned to a VOR station, left and right always mean left and right and TO/FROM is indicated by a simple triangular arrowhead pointing to the VOR. If the arrowhead points to the same side as the course selector arrow, it means TO, and if it points behind to the side opposite the course selector, it means FROM. The HSI illustrated here is a type designed for smaller airplanes and is the size of a standard 3 ¼-inch instrument. Airline and jet aircraft HSIs are larger and may include more display elements.
The most modern HSI displays are electronic and often integrated with electronic flight instrument systems into so-called "glass cockpit
A glass cockpit is an aircraft cockpit that features an array of electronic (digital) flight instrument display device, displays, typically large liquid-crystal display, LCD screens, rather than traditional Analog device, analog dials and gauges ...
" systems.
Remote indicating compass
HSI is part of a remote indicating compass system, which was developed to compensate for the errors and limitations of the older type of heading indicators. The two panel-mounted components of a typical system include the HSI and a slaving control and compensator unit, which pilots can set to auto-correct the gyro error using readings from a remotely mounted magnetic slaving transmitter when the system is set to "slave gyro" mode. In a "free gyro" mode, pilots have to manually adjust their HSI.
See also
*Acronyms and abbreviations in avionics
Below are abbreviations used in aviation, avionics, aerospace, and aeronautics.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
N numbers (turbines)
O
P
Q
R
S
T
U
V
V speeds
W
X
Y
Z
See also
* List of avia ...
* Flight instruments
Flight instruments are the instruments in the cockpit of an aircraft that provide the pilot with data about the flight situation of that aircraft, such as altitude, airspeed, vertical speed, heading and much more other crucial information in f ...
* Radio magnetic indicator
Notes
{{Aircraft components Avionics Navigational flight instruments Radio navigation