Jump to content

RNAV GPS approach - does not descend as expect passing FAF


Recommended Posts

Hi,

 

Can someone confirm that a fully Managed RNAV (GPS) approach can be flown in the A320 Professional?

 

I tried one today at Frankfurt and the aircraft did not descend on the computed glideslope after reaching the FAF.

Was attempting a full managed RNAV GPS approach at EDDF.

 

Had entered 25L RNAV (GPS) Z approach in the MCDU coming off of the UNOKO 2S arrival.

A/P and A/THR set to ON.

DA was set to 673 ft on MCDU Approach page along with other Approach data.

ND was set to 10nm range

 

Approach p/b was armed but LS was kept off. ND was in Arc mode.

FCU was programmed for Alt 4000ft for FAF at LEDKI

FINAL  and APP NAV came alive on the FMA. Flaps set to Full and fully configured for landing.

V/DEV brick was also alive on PFD.

 

Aircraft continued to approach 25L at 4000ft with no descent after FAF and proceeded to overfly 25L.

 

Question; Did I miss anything in the setup of the RNAV GPS approach?

 

Note: My understanding is that the aircraft should descend below 4000ft after reaching the FAF and that you can continue to fly this approach fully managed before the MDA is reached at which point the AP can be disengaged for a hand-flown landing.

Note2: Have already referred to the Step-by -Step manual (Vol 6) but this only covers a NPA approach where a VOR approach is used in the example.

 

Will fly the same approach tomorrow and take a few screenshots but am wondering if this specific type of NPA GPS approach is fully supported in the current Airbus?

 

Thanks
Mark

 

Link to comment
Share on other sites

Hi,

 

More info here as I repeated this flight twice more today with the same approach and the same results. Not sure what is happening here. Any insights welcome.

 

 

With reference to the images attached below I added some captions.

If anyone can shed some light on how this should RNAV GPS approach should be flown, I would be grateful.

 

Cheers
Mark

 

-637.jpg shows FMC with the RNAV 25L Z approach programmed. Note the GPS signal being PRIMARY and accuracy being HIGH.

Please login to display this image.

 

 

-421.jpg shows Approach mode activated. FMA displays Descent mode and APP NAV active on FMA. ALT FINAL armed. 4000ft is the FAF at LEDKI. LS is OFF.

Please login to display this image.

 

-819.jpg shows FINAL still armed but not active 0.4nm prior to FAF. Note aircraft is now fully configured at this stage in fully MANAGED mode.Note the green V/DEV brick is dead on the correct approach line. Everything as expected at this point.

Please login to display this image.

 

-359.jpg shows altitude remaining at 4000ft just after the FAF has been reached. Aircraft does not descend on glide slope to 25L. Note VDEV green brick has moved down the Alt scale indicating aircraft is now above the expected glide slope.

Please login to display this image.

 

-284.jpg shows AP now set to off and configured for manual landing to 25L. Note blue FINAL message on the FMA is still in armed mode and never transitions to FINAL APP mode on the FMA.

Please login to display this image.

 

 

Link to comment
Share on other sites

Some things looks wrong here, for example: too early configuration for landing, but , back to RNAV APP apparently looks like a database error. Pay attention at "white numbers" below LEDIK waypoint, you can read your GP shows 0.0° and that it's exactly what your aircraft does NO descent. A correct reading should be -3.0°.

My advice is : Try another RNAV approach, maybe a different airport or runway and pay attention on this.

Link to comment
Share on other sites

14 hours ago, Polo said:

Some things looks wrong here, for example: too early configuration for landing,.

Its fairly common to be configured for landing early though. In my place folks are flaps and gears down at speed restricted 10-15nm from the runway during the busy days. But i know elsewhere especially in europe atc pushes for pilots to only be configured before 1000feet, so you were expecting this level of configuration?

Link to comment
Share on other sites

Thanks for the info and advice.

 

Yes, for the approach I was definitely configured early by intent as I had read that prior to FAF, the aircraft had to be fully configured, slow and stabilized although there is not so much detail on what "stabilized" really means, Hence I configured early just to be safe.

 

As regards the FMC, let me try Rwy 25C at EDDF and see if that provides a glide angle for that runway. I will look at some other airports as well.

 

Regards
Mark

Link to comment
Share on other sites

Hi,

 

Well it looks like the chart data is not correct for the Airbus, at least for Navigraph.

 

I am using Navigraph and the latest cycle (2005)  installed and have compared a few airports and RNAV approaches and it looks like the glide angle to the runway for RNAV approaches are missing.

Question: Can someone confirm this please? Could this be a Navigraph issue ? Would be worth knowing if Navdata Pro exhibits the same symptom or not?

 

The following screenshots from EDDK and EDDM RNAV approaches all show 0 degrees.

 

EDDM 26L RNAV

Please login to display this image.

 

EDDK 14R RNAV

Please login to display this image.

 

EDDM 8L RNAV

Please login to display this image.

 

I also compared this to an RNAV approach to EDDM 8L video I found on the web (albeit with a different vendors A320) but the chart data should match. Here I do see a -3.0 glide angle at the FAF in the FMC.

EDDM 8L RNAV showing the -3.0 glide angle.

Please login to display this image.

 

Cheers
Mark

Link to comment
Share on other sites

In all your screenshots regarding EDDF Approach I see you have not activated the LS-Button. 

Try it next time and RNAV will work 🙂

You will see in the left down corner of the MFD the regarding data for the Rwy.

 

Wolfgang

 

Please login to display this image.

Link to comment
Share on other sites

11 minutes ago, Hoffie3000 said:

In all your screenshots regarding EDDF Approach I see you have not activated the LS-Button. 

Try it next time and RNAV will work 🙂

You will see in the left down corner of the MFD the regarding data for the Rwy.

 

Wolfgang

 

Please login to display this image.

 

The LS button is only for Precision approaches, for NPA's please DO NOT push it as it will block the NPA indications from the PFD and overwrite them with an empty ILS scale.

Link to comment
Share on other sites

Can confirm navdatapro (LIDO) has coded the descent angle of -3.00 in the navdata while navigraph does not. Maybe that's the issue but the VDEV brick appears to be moving down correctly in the guys screenshots shouldn't the aircraft still follow the VDEV down anyway?

Please login to display this image.

Link to comment
Share on other sites

Thanks,  that info helps.

I think I will contact Navigraph support and  ask them about the observations  made wit the RNAV approach.

 

Cheers
Mark

 

 

Link to comment
Share on other sites

vor 2 Stunden , supera380 sagte:

Thanks,  that info helps.

I think I will contact Navigraph support and  ask them about the observations  made wit the RNAV approach.

 

Cheers
Mark

 

 


Hi Mark

 

thank you for your investigation. Would you mind to inform here about the answer of Navigraph support?
 

I noticed this issue on other airports as well but initially thought about a bug of the A330. I think it happened to me in HTDA. 
 

Kind regards,

 

Remo

Link to comment
Share on other sites

Hi,

 

I placed my observations for this behaviour over at the Navigraph support forum based on info available to date:

https://forum.navigraph.com/viewtopic.php?f=20&t=9267

 

Cheers
Mark

3 minutes ago, Remolus said:


Hi Mark

 

thank you for your investigation. Would you mind to inform here about the answer of Navigraph support?
 

I noticed this issue on other airports as well but initially thought about a bug of the A330. I think it happened to me in HTDA. 
 

Kind regards,

 

Remo

 

Hi Remo,

Sure. I provided a link to the Navigraph forum where I raised the observation in this thread above.

 

 

Link to comment
Share on other sites

1 hour ago, AAC47 said:

I noticed that You was in Alitude Capture Mode and You was about to reach 4000 ft AFTER LEDKI and that could be reason

that FINAL APP wasn't activated....

 

If You made several approaches stabilized at 4000 ft before LEDKI without success this is not the reason for this missed approach

 

I used AIRAC 2003 for info and had no problem with my RNAV (GPS) Z Rwy 25L so it could be a AIRAC issue

 

 

Please login to display this image.

Which navdata provider are you using navigraph or navdatapro?

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Privacy Policy & Terms of Use