Navigation And The HUD

[RPRIEVER 52]

Question about the ANP. It appears to be displayed on the CDU, but not the HUD. Is the ANP a fluid value which could change during the approach? If so, and if it became higher than the RNP, where would that alert be displayed?

[michal 44]

I understand pretty much most of the HUD symbology but I was wondering what is this vertical line (actually two lines) slightly to the right of the runway in the above image while 200 ft above runway?Thanks Jane for great images.

[JaneRachel 531]

Question about the ANP. It appears to be displayed on the CDU, but not the HUD. Is the ANP a fluid value which could change during the approach? If so, and if it became higher than the RNP, where would that alert be displayed?

hey Ron, interesting questions there!ANP is indeed fluid as navigational accuracy is constantly updated from all nav sources. It can indeed become larger than the RNP, at which point, you would discontinue the RNAV approach. You will see this on the PFD navigation scale when this situation occurs. You would also be alerted by a message UNABLE REQD NAV PERF-RNP, to really get your attention!It hasn't happened to me in the NGX, but it is feasible considering the navigation systems operate under the exact same criteria as the real aircraft!all the bestJR

[RPRIEVER 52]

hey Ron, interesting questions there!ANP is indeed fluid as navigational accuracy is constantly updated from all nav sources. It can indeed become larger than the RNP, at which point, you would discontinue the RNAV approach. You will see this on the PFD navigation scale when this situation occurs. You would also be alerted by a message UNABLE REQD NAV PERF-RNP, to really get your attention!It hasn't happened to me in the NGX, but it is feasible considering the navigation systems operate under the exact same criteria as the real aircraft!all the bestJR

Thanks, Jane. Perhaps the developers can make this a failures option. <hint>.

[JaneRachel 531]

I understand pretty much most of the HUD symbology but I was wondering what is this vertical line (actually two lines) slightly to the right of the runway in the above image while 200 ft above runway?Thanks Jane for great images.

it is my lateral deviation line as I am crabbing to the right to counter the slight cross wind on the approach. all the bestJR

[michal 44]

it is my lateral deviation line as I am crabbing to the right to counter the slight cross wind on the approach.

thanks, hmmm.. lateral deviation, but the nose is clearly pointed much further to the right so the crabbing part is depicted very well by the wings-like symbol, independently. Your flight path vector is right smack on the runway (presumably this is where you land) so I am still not sure what kind of deviation we are talking about in case of these two vertical lines.

[badderjet 181]

thanks, hmmm.. lateral deviation, but the nose is clearly pointed much further to the right so the crabbing part is depicted very well by the wings-like symbol, independently. Your flight path vector is right smack on the runway so I am still not sure what kind of deviation we are talking about in case of these two vertical lines.

I believe it's the localizer deviation. During localizer operation there is a significant signal gain, a full deflection here will correspond to about 1/5th dot error on a similar HSI display. So I suppose just the slightest deviation will be visible there on the HUGS. Anyone correct me if that's not correct please.

[michal 44]

I believe it's the localizer deviation.

If this was your deviation from the localizer path then you would land off the runway. It doesn't look like ...

[badderjet 181]

If this was your deviation from the localizer path then you would land off the runway. It doesn't look like ...

Did you read any further of what I wrote? :(

[michal 44]

I did, sorry if it doesn't satisfy me ... :( I may later search for some answers... I want to know how pilot is supposed to use this info, procedurally. The above deviation would suggest some corrective action is necessary, but is it really?, flight director says something else. This part is confusing.

[pager94 4]

Great post JR!BB

[badderjet 181]

I did, sorry if it doesn't satisfy me ... :( I may later search for some answers... I want to know how pilot is supposed to use this info, procedurally. The above deviation would suggest some corrective action is necessary, but is it really?, flight director says something else. This part is confusing.

No prob... :( Well yes I understand your confusion. I can only assume the scale is so sensitive that small deviaiton will only be noticeable there, not on the guidance cue. Should be cleared up by someone knowledgable though. Standing by.

[JaneRachel 531]

No prob... :( Well yes I understand your confusion. I can only assume the scale is so sensitive that small deviaiton will only be noticeable there, not on the guidance cue. Should be cleared up by someone knowledgable though. Standing by.

absolutely right, the scale is very sensitive! look at my ground based picture with the 2D HUD. There you can see what looks like a pronounced localiser deviation, yet my nosewheel is pretty close to centreline. It allows for very precise calibration to the localiser pathJR

[theshack440 22]

Great post, thanks for the info Jane!Regards

[andysim 0]

great post and thanks!.I love how all these little stories and pics are becoming more and more common, and that new 1hour+ video that just makes your jaw sit in your lap the whole time!!.This year is going to be a good year!!