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propilot83
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Inertial Navigation System

Fri May 01, 2009 6:33 am

On the Boeing 747-100, -200, and -300 models as you can see the cockpits are very outdated and its not the digital glass cockpit like the Boeing 747-400. My question is for anyone who is an expert on this, is in the photo link below you can see the INS or Inertial Navigation System on the bottom console to the left and to the right (also above the spoiler handle). In these types of analog cockpits, how does the pilots find their destination to their airport? In other words, how do they find their waypoints, navigation to their destination without a Flight Management Computer like those on the Boeing 747-400 and Boeing 777, etc.? Does the pilot plug in coordinates of longitude and latitude into the INS? or do they fly from radio beacon to radio beacon to find their destination?

https://www.airliners.net/aviation-ph...os/misc/uf/536876251/phpNO2VTB.bmp

[Edited 2009-04-30 23:38:19]
 
Flighty
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Joined: Thu Apr 05, 2007 3:07 am

RE: Inertial Navigation System

Fri May 01, 2009 6:56 am

This won't answer your question, but it is still very interesting reading:

http://en.wikipedia.org/wiki/Inertial_guidance_system
 
wilco737
Posts: 7275
Joined: Sun Jun 20, 2004 12:21 am

RE: Inertial Navigation System

Fri May 01, 2009 7:05 am



Quoting ProPilot83 (Thread starter):

Every waypoint has coordinates: N53°33'34" E010°34'55" (no clue where that is). You enter these coordinates into the IRS. A max of 10 waypoints only. And you always have to enter them until you are at your destination. If you appraoching the 10th waypoint and haven't entered new ones, then the airplane turns back to waypoint #1 which you have entered  Smile
The coordinates can be found on the charts. Departure, cruise, approach...

wilco737
 
timz
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RE: Inertial Navigation System

Fri May 01, 2009 6:24 pm

I wonder if every named location had its lat-lon on the necessary chart in 1971. Wouldn't 747s sometimes have to track a VOR radial by radio?
 
DescendVia
Posts: 141
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RE: Inertial Navigation System

Fri May 01, 2009 6:54 pm



Quoting ProPilot83 (Thread starter):



Quoting WILCO737 (Reply 2):
The coordinates can be found on the charts. Departure, cruise, approach...

Sorry to go a bit off topic with my post but........
To add to what was said. Even thought these old units do have some enroute RNP and Baisc RNAV (B-RNAV) certifications and even though ICAO built RNAV SID/STARs have the lat/lon printed on the charts, those planes cannot fly them since all procedures have to be line selected from a database. Same goes for the RNAV airways, you cannot use lat/lon to define those waypoints. Not to toot the horn for the FAA but the way they are charting (RNAV stuff without LAT/LON or the VOR/DME radial/distance that define the points) this stuff really lessens the confusion IMO.

Quoting ProPilot83 (Thread starter):
how does the pilots find their destination to their airport?

Not to be mean but I think that is VERY funny. Remember up until 1982 (767 introduction) this type of navigation was really the only way to do it (other then maybe LORAN) and the pilots seemed to get it done just fine. I mean if you literally think about it in its very basic concept, the FMC/CDU is just a very advanced INS unit.

Quoting WILCO737 (Reply 2):
A max of 10 waypoints only.

Actually the later models could accept up to 92 waypoints. IIRC it was called the Delco 92 I think.
 
Tristarsteve
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RE: Inertial Navigation System

Fri May 01, 2009 7:05 pm



Quoting DescendVia (Reply 4):
Remember up until 1982 (767 introduction) this type of navigation was really the only way to do it

Point of order but Tristar FMC started in 1977 on the Saudia aircraft. The GF were fitted a year later as a retrofit.
 
DescendVia
Posts: 141
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RE: Inertial Navigation System

Fri May 01, 2009 8:46 pm



Quoting TristarSteve (Reply 5):

Ok thanks for the correction.

Let me re-phrase......
The first very sophisticated FMC/CDU and the first to have integrated EFIS.
 
744lover
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RE: Inertial Navigation System

Sat May 02, 2009 12:31 pm



Quoting WILCO737 (Reply 2):
A max of 10 waypoints only

Hi Wilco737!!!

To be honest, the litton-72 version depicted in the picture (old D-ABYU, I have a long loving history with that plane)... actualy holds 9 positions. WPT positions goes from 1 to 9 (via the rotating knob). Position 0 (zero) would be your current INS position and could only be used if you wanted to fly directly to a pre-defined WPT. That would mean: pressing WPT CHNG, 0,1, INSERT... That would take you from your current position (0) to waypoint one!!


Best regards!
GHN
 
113312
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RE: Inertial Navigation System

Sat May 02, 2009 1:25 pm

The older Area Navigation (RNAV) systems, including basic INS and VLF/OMEGA used lat/long coordinates for fixed points such as ground based navaids and radial intersections as a basis for navigation in lieu of tracking the navaids themselves. Systems, such as the Delco Carousel IV could only store 9 waypoints just as described for the older Litton systems. Some of the later model OMEGA systems could support more waypoints and ALPHA tags for these waypoints which made it easier by using the charted name along with the lat/long coordinates. The Litton LTN-92 could store a database of fixes as well as routes. However, the use of this information must be verified against charted information and authorization for use enroute and in terminal areas per approved Operations Specifications.

Thus, all "RNAV" is not created equal. FMS is another stepped enhancement which usually includes 3 D and 4 D data (altitude and speed) information along with fix/database information. Terminal procedures, along with airways by name, are contained within a FMS database and approval to use is dependent upon equipage and operational approvals.

While VLF/OMEGA, INS, and FMS all use latitude and longitude for fixes, the accuracy of each type of system and how each determines position is different. All of these systems are generically Area Navigation.
 
wilco737
Posts: 7275
Joined: Sun Jun 20, 2004 12:21 am

RE: Inertial Navigation System

Sun May 03, 2009 8:49 am



Quoting 744lover (Reply 7):
Hi Wilco737!!!

To be honest, the litton-72 version depicted in the picture (old D-ABYU, I have a long loving history with that plane)... actualy holds 9 positions. WPT positions goes from 1 to 9 (via the rotating knob). Position 0 (zero) would be your current INS position and could only be used if you wanted to fly directly to a pre-defined WPT. That would mean: pressing WPT CHNG, 0,1, INSERT... That would take you from your current position (0) to waypoint one!!

Thanks for the detailed info. I have never used that system, it was just from my memory back from the flight school in 2001 where we learnt that, but I grew up on FMS airplanes Big grin

wilco737
 
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Jetlagged
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RE: Inertial Navigation System

Sun May 03, 2009 11:09 am

The Litton 92 INS works much more like an FMS in that waypoints are entered using their names and many more than 10 waypoints can be in memory at any time, not to mention libraries of SIDs, STARs, company routes, etc.

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