dufflepod 0 Posted October 4, 2015 Share Posted October 4, 2015 I know when you switch the three ADIRUs to NAV they take ten minutes to align. But I thought the "Align IRS" LSK on the Init page of the MCDU was supposed to align the IRS instantly.But when I hit this button, the ND/PFD don't change and I still have the alignment countdown on the ECAM. Is this right? Link to comment Share on other sites More sharing options...
Deputy Sheriffs The Dude 6537 Posted October 4, 2015 Deputy Sheriffs Share Posted October 4, 2015 Yes, this is correct behaviour. There is no instant alignment function. Link to comment Share on other sites More sharing options...
dufflepod 0 Posted October 4, 2015 Author Share Posted October 4, 2015 Thanks for the info. Link to comment Share on other sites More sharing options...
Deputy Sheriffs Tom A320 4915 Posted October 4, 2015 Deputy Sheriffs Share Posted October 4, 2015 You can compare it with your GPS navigation system in your car or even phone. It also needs time to align itself. It's just called a little bit different, something like "waiting or searching for satellites". Link to comment Share on other sites More sharing options...
Milonas 5 Posted November 25, 2015 Share Posted November 25, 2015 On 4-10-2015 15:13:44, Tom A320 said: You can compare it with your GPS navigation system in your car or even phone. It also needs time to align itself. It's just called a little bit different, something like "waiting or searching for satellites". Hi Tom, Your explanation of the GPS navigation is verry clear, but can you tell me why sometimes the aligntime is only 5 minutes and the other time it takes 10 minutes to align? My theory about this is that it depends on the last time where you ended your flight, for example EDDF, and if you start your flightsim the next time outside this region for example KATL, then it takes 10 minutes to align. That's what i've discovered on the behavior of the IRS ADIRS in the Beautiful AirbusA320 Best Regards, Hans Link to comment Share on other sites More sharing options...
pilot_recruit 4 Posted November 25, 2015 Share Posted November 25, 2015 In Airbus, there are 2 ways to align your ADIRS 1/ We called Full Aligned : 3 NAVs you set to OFF position more than 5 seconds, then set them to NAV . Followed the FCOM, we habe to do that for every first flight of the day or crew change . Then it will take >7mins to self-coordinated refer to the last coordinate from the FMGS . 2/ We called Fast Alligned : it's used in case when you check the positions of FM1/2/GPS pos in MCDU DATA page, it shows the deviations are more than 5nm, then you have to re-align the ADIRS by switching 3 NAVs to OFF then NAV postions less than 5 seconds . So the system will be re-aligned to the correct postion, and it take less than 5mins to complete the process . Sometime, due to the incorrect of the a/c position, the alignment cannot be done, you have to manually adjust the position Lat/Lon by insert the referent coordination (parking pos in the chart or sign) into MCDU INIT page -> ALIGN IRS and it takes about 5mins to complete . Regards, Trieu Pham Link to comment Share on other sites More sharing options...
Deputy Sheriffs Tom A320 4915 Posted November 25, 2015 Deputy Sheriffs Share Posted November 25, 2015 Hello Hans, the reason why the alignment takes longer in higher latitudes can be found within the GPS system and the earth itself. Starting with the earth: in higher latitudes you get more and more ionospheric distortions in the communication with the satellites. These distortions have their reason in the earth magnetic field. The second reason is, that there are no GPS satellites orbiting the earth above 55 degrees latitude. That means the higher you get (north or south) the lower the satellites are in the sky, the more atmosphere you have in between giving room for even more distortions. Link to comment Share on other sites More sharing options...
Milonas 5 Posted November 25, 2015 Share Posted November 25, 2015 Thank you all for the explanation how the IRS-ADIRS system works in the wonderful Airbus! Hans Link to comment Share on other sites More sharing options...
Deputy Sheriffs mopperle 4162 Posted November 25, 2015 Deputy Sheriffs Share Posted November 25, 2015 Because we believe this topic has been answered we have closed it. If you have any more questions feel free to open a new topic. Link to comment Share on other sites More sharing options...
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