chris
02-17-2005, 07:24 AM
This is an exact copy of my post on the racesimcentral forums in their flight-sim section.
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Since some here are taking up the use of older planes, some equipped with the Inertial Navigation System, I'll explain how one goes about using this sometimes tricky to configure system.
It was based on technology used by the moon landing craft IIRC, and will accurately allow you, or your planes autopilot INS mode to navigate to your destination, while providing you with other useful information.
You can obtain the INS if your plane needs it from:
http://simufly.com/ins
This is how the INS units look:
http://racerplanet.com/forum/attachment.php?attachmentid=5294
If we look at the displays on each INS unit here, you'll see that the numbers indicate:
The 1st INS unit:
1286 - meaning the distance in nautical miles to the next way-point
66.3 - meaning the time in minutes until we reach the next way-point
FROM 45 TO - meaning we are flying from waypoint 4 to waypoint 5
The 2nd INS unit:
214.6 - meaning the track course in degrees.
1165 - meaning the current ground speed of the plane on nautical miles per hour, in this case, 1165, or around Mach 2.03.
Begin using the INS:
==================
1. To start with, they will be switched off. You want to switch them both to the Standby position on the mode select panels. And you also want to have your aircraft parked, with the parking brakes on, and the engines switched OFF. Very important that while aligning the INS, the aircraft must not move, or the alignment will fail.
2. On the mode selector, switch them each to POS
3. Now look at your current position in FS2004 (use Shift+Z to find out the LAT/LONG coordinates. Click on the screw on the top left corner of each INS unit, and you'll activate ability to enter the numbers via your numeric keypad.
4. If your LAT/LONG coordinates are indicated as follows:
N51* 27.67' W0* 26.68'
Then for the INS, you must round them off so that they would be in this case:
N51* 27.7 W0*26.7'
It is the same for all co-ordinates you enter into the INS. To enter those co-ordinates, look on your numeric keypad at the keys with arrows on them, 8, 2, 4, and 6. Imagine them as indicating North (8), South (2), West (4) and East (6).
First you would press 8, to indicate North, then enter 51277, and press once enter on the numeric keypad. Next you would press 4, to indicate West, and then just 26.7, or, if you want to do things the hard way, enter the entire 000267, and press enter once.
The co-ordinates for one INS unit should be now entered. Do the same for the other INS unit, so that they both have indentical co-ordinates.
5. Now switch each INS panel to the DS/TK/STS mode. If the error lights come on, take note of the middle number on the displays, and press the test button.
The middle number at first might be (indicated in bold)
0 06 95
And then when pressing the test button once, it might change to:
0 41 95
That would indicate an INS error code 06-41. Looking in the error code list contained in the Actions and Malfunction Codes manual, this is revealed to mean "Inserted ramp position differs from last computed inertial position by
more than 3 NMs". And you would follow the instructions to rectify the error.
If the error is just 02-63, double click the test button to clear the error and proceed as normal.
6. Now switch the units to the ALIGN mode on the mode select panels. The INS units will begin alignment. You will need to wait for the green Ready NAV light to illuminate. It is important the aircraft does not move AT ALL during this process, or alignment will not be successful. The alignment could take 15 minutes. You note it is aligning, because the accuracy index (indicated in bold below)...
0 0 95
... will start counting down, from 95, to 85, then 75, then 65 and so on. The NAV READY light should illuminate sometime after the accuracy index shows 55. During this alignment procedure, you might wish to review your flight plan, or go over your checklists and procedures.
When the Ready NAV light illuminates, it means you can switch the INS units to the NAV mode. I however prefer to wait until the accuracy index (indicated below in bold)...
0 0 55
... reads 05, as indicated below:
0 0 05
This means it is aligned very accurately. Now I switch to Nav mode on both INS units. If it NAV READY light does not illuminate, it may be accompanied by the error light, in which case you should note the error, in the manner described earlier and take appropriate actions to resolve the error. If it still doesn't illuminate, you may have mistakenly entered incorrect initial locations into the INS.
7. Now you can switch each INS unit to the WAY PT mode. Also press the RE-MOTE button on each of them, so it is illuminated. Pressing this will link them together for fast insertion of navigation waypoints.
8. See the little black rocker switch with the number on it. This indicates your waypoint number that you are programming in. If it shows 0, then on the display, it will already be showing your present position, as you entered it. Switch to position 1. Now, as you did earlier to enter the intial position in the POS mode, enter the LAT/LONG waypoints for your first waypoint.
9. When done, move the rocker switch to position 2, then enter the 2nd waypoint. Repeat for all 9 waypoint positions. Now, what happens when there are more waypoints that you can add into the INS? What you do is enter just the first 9, and then later on in the flight once you are nearing waypoint 8, move the position selector to position 1, and start entering in the next batch of waypoints, up to position 7 for instance, being careful not to overwrite the waypoints that your are currently flying between.
Once the INS hits waypoint 9, it will wrap to waypoint 1. On the FROM TO indicator, it will show 91, indicating your are flying from the waypoint in position 9, to the waypoint in position 1. And then it would go 12, 23, 34, 45, 56, 67, 78, and so on.
Once you are done, you are almost ready to set off. Now be sure to check on the INS units, that the AUTO/MAN switch is set to AUTO. This will make the INS units automatically switch waypoints at the appropriate time without you needing to do it manually.
10. Now depending on your aircraft, you will look in various locations to find the INS NAV MODE rocker switches. These determine which INS will be used for your navigation. Switch on the 1st one. You can always turn on the second one if the 1st INS should have some form of failure during your flight.
11. Now you are ready to begin your taxi to the runway, and to take-off. Once you have lifted off from the runway, and established yourself on a steady climb, enabled your autopilot, if it is not on already, and then activate the heading hold mode (HDG). The aircraft will start to turn onto the appropriate course.
12. Continue normally. As you fly along, and get within 2 minutes of the next waypoint, the yellow alert light will illuminate. This is warning you that your next waypoint is near, and to be ready to change the waypoints over, if you are controlling that manually.
13. As you fly, you may wish to switch one INS to DIS/TIME, and the other to TK/GS. The DIS/TIME will show distance and estimated time until next waypoint, while the TK/GS will show the track heading, and ground speed.
14. For some reason, like for instance if you are flying Concorde and will be performing a moderately sharp turn at Mach 2, you might wish to fly the turn manually. At which point you would switch the INS units to HDG/DA & XTK/TKE, and follow the headings suggested by the INS yourself manually, until the turn is complete. Once turn is completed simply activate HDG mode again on the autopilot and resume normally.
15. When on landing approach, you can disengage the INS by switching off the INS NAV MODE selector switches. The INS will still be operational, but it won't fly your plane for you. You may find the WIND mode on the INS useful to display the wind speed and heading.
If you had specific co-ordinates for a particular landing approach, you could also enter them into the INS shortly before beginning the approach and have it fly the approach for you, while you maintained the correct vertical speeds, or just follow its suggested headings.
After landing and arrival at the terminal or parking, you can follow the shut-down procedures in the INS manual. And that concludes this basic introduction to using the Inertial Navigation System. I hope you've found it helpful.
-------------------------------------------------------------
Since some here are taking up the use of older planes, some equipped with the Inertial Navigation System, I'll explain how one goes about using this sometimes tricky to configure system.
It was based on technology used by the moon landing craft IIRC, and will accurately allow you, or your planes autopilot INS mode to navigate to your destination, while providing you with other useful information.
You can obtain the INS if your plane needs it from:
http://simufly.com/ins
This is how the INS units look:
http://racerplanet.com/forum/attachment.php?attachmentid=5294
If we look at the displays on each INS unit here, you'll see that the numbers indicate:
The 1st INS unit:
1286 - meaning the distance in nautical miles to the next way-point
66.3 - meaning the time in minutes until we reach the next way-point
FROM 45 TO - meaning we are flying from waypoint 4 to waypoint 5
The 2nd INS unit:
214.6 - meaning the track course in degrees.
1165 - meaning the current ground speed of the plane on nautical miles per hour, in this case, 1165, or around Mach 2.03.
Begin using the INS:
==================
1. To start with, they will be switched off. You want to switch them both to the Standby position on the mode select panels. And you also want to have your aircraft parked, with the parking brakes on, and the engines switched OFF. Very important that while aligning the INS, the aircraft must not move, or the alignment will fail.
2. On the mode selector, switch them each to POS
3. Now look at your current position in FS2004 (use Shift+Z to find out the LAT/LONG coordinates. Click on the screw on the top left corner of each INS unit, and you'll activate ability to enter the numbers via your numeric keypad.
4. If your LAT/LONG coordinates are indicated as follows:
N51* 27.67' W0* 26.68'
Then for the INS, you must round them off so that they would be in this case:
N51* 27.7 W0*26.7'
It is the same for all co-ordinates you enter into the INS. To enter those co-ordinates, look on your numeric keypad at the keys with arrows on them, 8, 2, 4, and 6. Imagine them as indicating North (8), South (2), West (4) and East (6).
First you would press 8, to indicate North, then enter 51277, and press once enter on the numeric keypad. Next you would press 4, to indicate West, and then just 26.7, or, if you want to do things the hard way, enter the entire 000267, and press enter once.
The co-ordinates for one INS unit should be now entered. Do the same for the other INS unit, so that they both have indentical co-ordinates.
5. Now switch each INS panel to the DS/TK/STS mode. If the error lights come on, take note of the middle number on the displays, and press the test button.
The middle number at first might be (indicated in bold)
0 06 95
And then when pressing the test button once, it might change to:
0 41 95
That would indicate an INS error code 06-41. Looking in the error code list contained in the Actions and Malfunction Codes manual, this is revealed to mean "Inserted ramp position differs from last computed inertial position by
more than 3 NMs". And you would follow the instructions to rectify the error.
If the error is just 02-63, double click the test button to clear the error and proceed as normal.
6. Now switch the units to the ALIGN mode on the mode select panels. The INS units will begin alignment. You will need to wait for the green Ready NAV light to illuminate. It is important the aircraft does not move AT ALL during this process, or alignment will not be successful. The alignment could take 15 minutes. You note it is aligning, because the accuracy index (indicated in bold below)...
0 0 95
... will start counting down, from 95, to 85, then 75, then 65 and so on. The NAV READY light should illuminate sometime after the accuracy index shows 55. During this alignment procedure, you might wish to review your flight plan, or go over your checklists and procedures.
When the Ready NAV light illuminates, it means you can switch the INS units to the NAV mode. I however prefer to wait until the accuracy index (indicated below in bold)...
0 0 55
... reads 05, as indicated below:
0 0 05
This means it is aligned very accurately. Now I switch to Nav mode on both INS units. If it NAV READY light does not illuminate, it may be accompanied by the error light, in which case you should note the error, in the manner described earlier and take appropriate actions to resolve the error. If it still doesn't illuminate, you may have mistakenly entered incorrect initial locations into the INS.
7. Now you can switch each INS unit to the WAY PT mode. Also press the RE-MOTE button on each of them, so it is illuminated. Pressing this will link them together for fast insertion of navigation waypoints.
8. See the little black rocker switch with the number on it. This indicates your waypoint number that you are programming in. If it shows 0, then on the display, it will already be showing your present position, as you entered it. Switch to position 1. Now, as you did earlier to enter the intial position in the POS mode, enter the LAT/LONG waypoints for your first waypoint.
9. When done, move the rocker switch to position 2, then enter the 2nd waypoint. Repeat for all 9 waypoint positions. Now, what happens when there are more waypoints that you can add into the INS? What you do is enter just the first 9, and then later on in the flight once you are nearing waypoint 8, move the position selector to position 1, and start entering in the next batch of waypoints, up to position 7 for instance, being careful not to overwrite the waypoints that your are currently flying between.
Once the INS hits waypoint 9, it will wrap to waypoint 1. On the FROM TO indicator, it will show 91, indicating your are flying from the waypoint in position 9, to the waypoint in position 1. And then it would go 12, 23, 34, 45, 56, 67, 78, and so on.
Once you are done, you are almost ready to set off. Now be sure to check on the INS units, that the AUTO/MAN switch is set to AUTO. This will make the INS units automatically switch waypoints at the appropriate time without you needing to do it manually.
10. Now depending on your aircraft, you will look in various locations to find the INS NAV MODE rocker switches. These determine which INS will be used for your navigation. Switch on the 1st one. You can always turn on the second one if the 1st INS should have some form of failure during your flight.
11. Now you are ready to begin your taxi to the runway, and to take-off. Once you have lifted off from the runway, and established yourself on a steady climb, enabled your autopilot, if it is not on already, and then activate the heading hold mode (HDG). The aircraft will start to turn onto the appropriate course.
12. Continue normally. As you fly along, and get within 2 minutes of the next waypoint, the yellow alert light will illuminate. This is warning you that your next waypoint is near, and to be ready to change the waypoints over, if you are controlling that manually.
13. As you fly, you may wish to switch one INS to DIS/TIME, and the other to TK/GS. The DIS/TIME will show distance and estimated time until next waypoint, while the TK/GS will show the track heading, and ground speed.
14. For some reason, like for instance if you are flying Concorde and will be performing a moderately sharp turn at Mach 2, you might wish to fly the turn manually. At which point you would switch the INS units to HDG/DA & XTK/TKE, and follow the headings suggested by the INS yourself manually, until the turn is complete. Once turn is completed simply activate HDG mode again on the autopilot and resume normally.
15. When on landing approach, you can disengage the INS by switching off the INS NAV MODE selector switches. The INS will still be operational, but it won't fly your plane for you. You may find the WIND mode on the INS useful to display the wind speed and heading.
If you had specific co-ordinates for a particular landing approach, you could also enter them into the INS shortly before beginning the approach and have it fly the approach for you, while you maintained the correct vertical speeds, or just follow its suggested headings.
After landing and arrival at the terminal or parking, you can follow the shut-down procedures in the INS manual. And that concludes this basic introduction to using the Inertial Navigation System. I hope you've found it helpful.