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Horizontal Situation Indicator

Technical Information

Catalogue No: C0588
Category: Navigation/Inertial
Object Type: Indicator/Instrument
Object Name: Horizontal Situation Indicator
Part No: SF/306/RNA/CPM/2
Serial No: AB278/73
Manufacturer: Smiths
Division: Unknown
Platform(s): Jaguar
Year of Manufacture: 1973
Dimensions: Width (mm): 106
Height (mm): 106
Depth (mm): 235
Weight (g): 2,600
Location: Triple Shelf Unit, RH (indicators) [Main Store]

Horizontal Situation Indicator
Code SF/306/RNA/CPM/2
Ser. No. AB278/73
Supply 6JA/6605-99-111-8586.
Mod. 01 to 04, 06 to 10 & 12 to 13


The Horizontal Situation Indicator is basically the situation indicator for the Smiths SFS.6 Flight System and combines a number of radio and navigational displays in a single 4-inch instrument:
● Glideslope deviation;
● Lateral deviation;
● Range readout;
● "To-From" indication;
● Track Required or TACAN bearing pointer and counter;
● Primary or magnetic heading;
● An index which can be positioned either automatically via the digital computer or manually. This index shows Actual Track or I.L.S. Capture.

Warning indications include:
● Failure flag brought up by power or system failure;
● TRUE/MAG: flag to indicate that the heading displayed is either True or Magnetic;
● LOC: flag to indicate an unacceptable localizer signal;
● CS: flag to indicate an unacceptable glidepath signal;
● "Ignore Range" bar shows when range being displayed is not relevant.

The unit is also marked:

In 1967 Elliotts had been awarded a major contract for the design, development and integration of a Navigation and Weapon Aiming Sub-System (NAVWASS) for the RAF's new Jaguar aircraft.

The Jaguar was designed as a close air support aircraft for supporting ground troops in daylight. The NAVWASS enabled the pilot to navigate and fly at low level and high speed to acquire and accurately attack targets. Trials of the prototype Jaguar system were carried out using a Varsity aircraft at West Malling airfield in Kent


The Jaguar NAV/WASS  sub-system comprises four principal groups of equipment. The sensors, which measure what the aircraft is doing and feed these measurements into the computer; the computer sub-system which processes this measured information into a form which can be used by the pilot; the cockpit controls which control the system's mode of operation and lastly, the cockpit displays which show to the pilot the computer's outputs of converted measurement information and also information, such as target or waypoint position, which is being input into the computer. The system included an E3R inertial platform, Digital Computer, a HUD, Projected Map Display, Horizontal Situation Indicator and various cockpit control panels.

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