|Object Type:||Control/Data Entry|
|Object Name:||HSI Mode Selector Switch|
|Division:||Inertial Navigation [IND]|
|Year of Manufacture:||circa 1970|
|Location:||Main Object Store|
H.S.I. Mode Switch
Type No. 25-001-01
Ref No. 6JA/111-8588
Ser No. 403
Code No. K0656
Modification Record -
The horizontal situation indicator (commonly called the HSI) is an aircraft flight instrument normally mounted below the artificial horizon in place of a conventional heading indicator. It combines a heading indicator with a VHF omnidirectional range-instrument landing system (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.
A tactical air navigation system, commonly referred to by the acronym TACAN, is a navigation system used by military aircraft. It provides the user with bearing and distance (slant-range or hypotenuse) to a ground or ship-borne station. Aircraft equipped with TACAN avionics can use this system for en route navigation as well as non-precision approaches to landing fields.
The typical TACAN onboard user panel has control switches for setting the channel (corresponding to the desired surface station's assigned frequency), the operation mode for either transmit/receive (T/R, to get both bearing and range) or receive only (REC, to get bearing but not range). Capability was later upgraded to include an air-to-air mode (A/A) where two airborne users can get relative slant-range information. Depending on the installation, Air-to-Air mode may provide range, closure (relative velocity of the other unit), and bearing, though an air-to-air bearing is noticeably less precise than a ground-to-air bearing. This is a Mode Switch to select the TACAN modes for display on the HIS. The NSN given in our database is NSN 6610-99-111-8588 and a Part No.75DSK6210