I have been trying to use the cold and dark panel to set up the NGX sample flight from EGKK to EHAM. When i type the departure airport, EGKK, on the scratch pad and then line select it in, and then select IRS align. The co-ordinates show up and i place them in the squares that appear. I always get the message in the scratch pad saying that the IRS does not agree with my location. Can anyone tell me how to do this? I have tried other airports , but the result is always the same I have downloaded the latest NavData from Navigraph, so i know the airports i am choosing are in the NGX Nav Data files. EGKK is in the data file, I know this because i can fly the plane using the NGX sample set-up. in this case the IRS is aligned and you dont have to do the alignment. I hope someone can help me with this problem, i have been trying for days to sort this out. Ed McBain

Hi, You must place coordinates from "last position" to the squares that appear, not the airport coordinates. If I understood your question... Hope this help Regards, Richard Portier

not quite right i think you need to align the irs first before you enter the airport dep in the scratch pad

The airport position that appears in the POS INIT page is the aerodrome reference point (ARP), which may be some distance from your actual position. The ARP is basically the middle point of all of the runways. You can... - consult the parking charts for the aerodrome and look up the stand that you are parked at and enter the position listed - use the position under LAST POS (this will be wrong if you reload the aircraft somewhere other than where you last left off) - click on "Next Page" through the POS REF pages until you have a page with your GPS positions and down select those - Ctrl+Z and copy the position displayed in red at the top of the screen Hope this helps!

not quite right i think you need to align the irs first before you enter the airport dep in the scratch pad

This is not necessary.

I really appreciate you trying to help me. I have tried alining the IRS before installing the EGKK Ref Airport and also after installing EGKK. The answer is the same either way. I must be the most dense guy in the world. I can't believe this is so difficult. DavidzI couldn't find any parking charts for EGKK. I did find the following on the general chart, but there is no way this can be typed on the Scratch Pad. No way to enter the degree and seconds marks. 51o 8ii 9N 0o 11ii 4W. I really wish I could do what you have suggested, unfortunately i don't have the faintest idea of how to go about it. I am going to continue to try though. I am presently looking for the page containing the GPS Positions, mentionrd in your e-mail. Best regards Guys and thanks again. Ed McBain

This is what you do: from the page where you're supposed to enter the IRS position, press next page. You should see towards the bottom GPS L and GPS R. Downselect Any one of those two values to the scratchpad (you know... press the key to the left of it), then press previous page. Now upselect the value in the scratchpad to the IRS position prompt. That's all. If you don't see anything at the GPS position prompt, give it some time, as it takes a while to get a GPS fix.

Move the switches to NAV not ALIGN. Or, after align is complete move from ALIGN to NAV.Basically, use only the NAV psoition.For the coordinates, airport is good enaugh if the airport is not too big (IRS position entered will be verified by the system, if it is wrong for more than a value that now I forgot, it will give an error "re-enter position").It is better to use parking coordinates, but last position, airport position or GPS position, are good.Remember that if position is in limits, but not exactly entered, it will be automatically updated on take off.

Move the switches to NAV not ALIGN. Or, after align is complete move from ALIGN to NAV.Basically, use only the NAV psoition.For the coordinates, airport is good enaugh if the airport is not too big (IRS position entered will be verified by the system, if it is wrong for more than a value that now I forgot, it will give an error "re-enter position").It is better to use parking coordinates, but last position, airport position or GPS position, are good.Remember that if position is in limits, but not exactly entered, it will be automatically updated on take off.

The IRS position will never be updated when at take-off or during the flight. The IRS is a stand alone system, the only time you can enter and/or update the IRS position is during alignment. What you are talking about is updating the FMC position when you stand ready for take-off and you pushed the TOGA switch than the FMC position will be updated to the start position on the runway. You see on the ND that airplane symbol line's up with runway symbol. During flight the FMC position is constantly updated with the GPS signal, The ADIRU senses it movemants with 3x accelerometers and three laser gyros. The accelerometer orientation in the ADIRU is on the x, y, and z axes of the airplane. This orientation allows the ADIRU to sense accelerations in each of the three axes. The three laser gyros sense pitch, roll, and yaw rotation around the x, y, and z axes. To show the actual IRS position push the POS button on the EFIS control panel you see two single stars near the airplane symbols They are never at the same position. During flight the IRS position drits

Yes, you're right, but I told to explain that an exact position is not required for navigation as it is updated starting from take off. (if the program pin option is selected as it is almost in all the companies)

It's a not a big deal that the IRS position is not extacly entered for navigation purpose but it should not be more than 1 degree different than the recorded latitude or longitude, if this is not the case these things happens:- ALIGN light flashes,- Status code 4 shows on the ISDU- ENTER IRS POSITION shows on CDU.To avoid these it's best to use the GPS coordinates (on page 2 of FMS POS INIT page), if that is not available than use the last known position. On the FMC POS INIT page 1 there is a GMT time and date showing next to LSK 5L this is the GPS time when the time is zero the GPS coordinates is not jet available wait couple of minutes when the time is correctly showing then the GPS coordinates are also showing.

The problem you are talking about is a problem of stored data, not yet of a detection data.The IRS stores its last position when shut doown. If at the next powerup you enter a position that differs (more than 1°) from the last stored one, Error 4 is shown, just put position again if you are sure about it, it will "overwrite" .If during alignment, the position is still different, but now from the detected one, the IRS continues to align, then time stops to 0 and align flashes and set irs position is shownRe-entering the wrong latitude again (longitude cannot be calculated by ADIRU) code 2 will be shown, this time FAULT come on plus error code 2.In this last case, put the switch of the affected IRS to ALIGN, enter position again, if it is correct FAULT goes out, then put the switch back to NAV, if the problem cannot be corrected, turn to OFF then back to NAV and align the IRS again. But start to think that there is something wrong with the unit if the position entered is good...

I'm searching in manuals as I remember that difference between entered and detected position is lower than 1° (difference from entered and stored)

As we dirft of now from the original problem "Like the IRS does". the FMC position get's it's position from the IRS system when you entered it during alignment if you entered a faulty position and the IRS accept this.The ADRIU calculates the latitude coordinates by earth rotation and it know's the TRUE north heading. So when entered the latitude during alignment the ADIRU checkes it. The ADIRU does not calculate longitude. The ADIRU will not detect an incorrect longitude entry after alignment is complete. When you press TOGA on the active runway with a incorrect IRS and FMC position it will not be correct it. because the difference is to big.

On the classic the maximum difference from detected position and entered one (latitude) is 0.5° while for the longitude uses the stored one (the only value it can use) and this value is the famous 1°. 1° is the same also for the calssic in case of difference from stored latitude.The manual also give sin and cosin error value limts for the latitude difference.On NG manuals I've not found any value for error detection of the IR, but as it is in a different part from the 1° error (that is a big possible error) It could be lower, maybe te same of the classics.

The last position on the FMC (wich is the FMC last calculated position) is always a bit different from the last position stored by the IRS (inside the IRS will be the IR calculated position at shut down).