Author Topic: CIVA INS navigation  (Read 2890 times)

0 Members and 1 Guest are viewing this topic.

Offline Adrian Chitan

  • Pilots
  • Full Member
  • **
  • Posts: 153
  • Popularity: +17/-1
    • View Profile
CIVA INS navigation
« on: May 31, 2014, 08:16:12 AM »
Hello, hello

For this post I want to talk about the Delco Carousel IV-An Inertial Navigation System (CIVA - read as "SIVA"). I believe this post will be useful for controllers because they'll know what to expect from a plane that is navigating on CIVA and not the usual GPS or VOR-to-VOR navigation. I'll try to keep it as short as possible.

As you all know, before the introduction of GPS navigation into aviation (early '80s) planes were using either radio navigation or inertial navigation systems. The problem with radio navigation is that radio beacons (VORs, NDBs, etc.) are limited in range. So unless you wanted to put a bloaty shack with a 20 meter high antenna every 50 miles of your landscape, you had to use INS navigation. The US is a better candidate for radio navigation because their country is filled with VORs and NDBs but in Europe you can find yourself in dead spots quite often and pray that the wind correction you calculated is good enough to reach the area of the next NDB/VOR.

What is INS? It is a dead reckoning method of knowing where you are all the time by knowing how much have you moved from a well known initial position. This is possible by the use of gyroscopes and accelerometers which can give you motion in all three axes and thus, pinpoint your position. Nowadays it is highly used in submarine navigation and military aircraft (though both have GPS realignment posibilities). Now let's get into the CIVA INS.

The CIVA INS system uses a computer (archaic) to get all the necessary info from the gyroscopes and calculate a position for you. The CIVA INS system was used in the 707, 727, 737-100 and -200, DC-10, L-1011 Tristar and 747-100 -200 and -300. Below is an extract of the CIVA computer panel (offline).



The first thing to do when you want to use an INS system is to align it to your current static position. This may be the most important thing in INS. If your first position is flawed, than your whole navigation will be. In the pictures below, the first one shows the CIVA with an initial position (POS) inserted, the second depicts the align mode (ALIGN) in the desired track/system (DSRTK/STS - the first digit in the second number has to go to 0 for a full alignment) and the third shows a fully aligned CIVA.

          

After the alignment, you switch the CIVA to NAV and Bob's your uncle. As navigation procedures the CIVA takes you from point A to point B by using a series of waypoints for witch you have to insert the coordinates, of course. Unfortunately, the computer is limited to saving only 9 waypoints and one initial position, so while in flight you have to insert the next waypoints in the spots that you have already passed.

The thing that concerns the controllers is that CIVA can only go in successive waypoint segments. This means that CIVA will only go from 1 to 2, 2 to 3 and so on. It can never go from 3 to 9.  Until now, all is fine and dandy, but the problems arise when the pilot gets a "direct to ..." call. Let's take an example. Let's say you have 5 WPs in your CIVA as in the picture below.



As the CIVA is following the FP (the triangle on the red line), the pilot gets a direct to 5 call. He then proceeds to the CIVA panel and presses the waypoint change button (WY PT CHG) and then the 5 button. This makes CIVA change the next waypoint from 3 to 5. But the segment that CIVA will proceed to follow is the 4 to 5 segment and not current position to 5 (!!!). This will make the plane turn almost north, because the CIVA wants to first intercept the 4-5 segment (which in this case will be the green line) and then turn right towards 5. This may make the controller ask "DBX9050, where are you going?" but, from the CIVA point of view, you are going "direct to 5" :D.

Hope this helps the controllers better understand what the pilot is doing while "fighting" a CIVA INS :).

Cheers,
Adrian
« Last Edit: May 31, 2014, 02:22:19 PM by Adrian Chitan »

Offline Sorin Baciu

  • Pilots
  • Newbie
  • **
  • Posts: 16
  • Popularity: +5/-0
    • View Profile
Re: CIVA INS navigation
« Reply #1 on: June 01, 2014, 03:20:00 PM »
super super super...mersi adrian... foarte utila explicatia si din punct de vedere al controlorului facand si eu parte din acea categorie dar si din punct de vedere al pilotului...as incerca si eu ca pilot un astfel de sistem dar in FS9 nu stiu ce avion gasesc cu asa ceva...poate vechiul concorde...
in final esti UTIL ca intodeauna si tin sa multumesc pentru aceasta. O zii buna in continuare

Offline Adrian Chitan

  • Pilots
  • Full Member
  • **
  • Posts: 153
  • Popularity: +17/-1
    • View Profile
Re: CIVA INS navigation
« Reply #2 on: June 01, 2014, 05:46:46 PM »
Multumesc pentru incurajari, Sorin!

Da...CIVA asta pentru X-Plane este de sine statator, adica teoretic ai putea sa-l pui pe orice avion. Dar nu are rost.

Din ce tutoriale am mai vazut si eu pe net, cred ca pentru FSX/9 ai ghicit-o cu Concorde-ul.

Am uitat sa mentionez ca CIVA are si procedura de realigment in flight cand faci zboruri lungi. Dar iti trebuie 2 (cel putin) VOR-uri si/sau NDB-uri prin preajma, normal. Dar e superb ca ai atatea de facut in zbor :D.

Stiu ca Concorde-ul mergea pe INS sigur, dar nu stiu cum l-au implementat in FS.

Salutare.
« Last Edit: June 02, 2014, 07:26:16 AM by Adrian Chitan »

 

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27