PMDG 777 false terrain alarm

[kevinh 409]

does the term "terrain look ahead warnings" refer to the terrain radar?

 

but when the terrain warning sounds, the radar lights up immediately...

There is no terrain radar.

 

Terrain look ahead refers to the warnings generated by the EGPWS terrain database. These warnings will cause the terrain display to be displayed on the ND. This is the E in EGPWS. GPWS only knows about the terrain directly below you.

[Artur Munteanu 1]

 

What you say is basically correct but EGPWS terrain database updates are not frequent updates like monthly nav data

Never said that is update monthly.

 

The FMC does not contain anything other than spot heights for airports and radio stations. No use for EGPWS

You are totally wrong. The AIRAC Cycle contain much more information, like airport database, numbers of runaways, coordinates of airport, coordinates of runaways, altitude of airport and runaways, nav freq., ILS freq  and much more. The important file wich I talk about is airport.dat wich is in Navdata folder. The altitude and position of the airport is include in that database, and also in the other file. When you go to you're IDENT page of FMC you see this, and it is use also by the other instrument .Landing altitude - tell something to you? -  wich in case of 777 or 747 is automatic like Airbus and is read from the same navdata fmc, on 737 NGX you have to select manual after you read it from FMC. So as you see, the Navdata is not used only by FMC. Why is should not be used also by the EGPWS?

I repeat, not say that this is the solution, but for me it works, the different AIRAC Cycle, make the difference for me, one give me false terrain allarm the other not. And for me is a proof that somehow the EGPWS is related with the Navdata database.

 

If the problem was the AIRAC everybody would see the same problem at these airports. It's highly unlikely that AIRAC elevation data would change from one cycle to another for a long established airport

It seems to me that is a lot of people having this issue with 777. And for AIRAC nobody said that is different elevation data, I say that maybe is missing something, or is a wrong coordinate, or something else. Nobody's perfect on this world. Don't know, I'm not the expert dude.

What you say is basically correct but EGPWS terrain database updates are not frequent updates like monthly nav data

Never said that is update monthly.

 

The FMC does not contain anything other than spot heights for airports and radio stations. No use for EGPWS

You are totally wrong. The AIRAC Cycle contain much more information, like airport database, numbers of runaways, coordinates of airport, coordinates of runaways, altitude of airport and runaways, nav freq., ILS freq  and much more. The important file wich I talk about is airport.dat wich is in Navdata folder. The altitude and position of the airport is include in that database, and also in the other file. When you go to you're IDENT page of FMC you see this, and it is use also by the other instrument .Landing altitude - tell something to you? -  wich in case of 777 or 747 is automatic like Airbus and is read from the same navdata fmc, on 737 NGX you have to select manual after you read it from FMC. So as you see, the Navdata is not used only by FMC. Why is should not be used also by the EGPWS?

I repeat, not say that this is the solution, but for me it works, the different AIRAC Cycle, make the difference for me, one give me false terrain allarm the other not. And for me is a proof that somehow the EGPWS is related with the Navdata database.

 

Don't know, I'm not the expert dude.

Sorry for the double quote, don't know what happend when I try to post it. Hehe... see? as I said, computers and humans: bad thing in our life.

[kevinh 409]

You are totally wrong. The AIRAC Cycle contain much more information, like airport database, numbers of runaways, coordinates of airport, coordinates of runaways, altitude of airport and runaways, nav freq., ILS freq and much more. The important file wich I talk about is airport.dat wich is in Navdata folder. The altitude and position of the airport is include in that database, and also in the other file. When you go to you're IDENT page of FMC you see this, and it is use also by the other instrument .Landing altitude - tell something to you? - wich in case of 777 or 747 is automatic like Airbus and is read from the same navdata fmc, on 737 NGX you have to select manual after you read it from FMC. So as you see, the Navdata is not used only by FMC. Why is should not be used also by the EGPWS?

I repeat, not say that this is the solution, but for me it works, the different AIRAC Cycle, make the difference for me, one give me false terrain allarm the other not. And for me is a proof that somehow the EGPWS is related with the Navdata database.

 

I know the AIRAC contains all that data, but the only terrain height information is as I said. The EGPWS terrain data is from the EGPWS computer only. FMC landing field elevation is used to provide the 1000 ft callout (which is height above runway, not radio altitude), but not for terrain warnings as far as I'm aware.

 

Now it may well be that there are discrepancies between the terrain database PMDG supplied and airfield heights that relate to FSX terrain. Therefore PMDG may be applying an adjustment to EGPWS terrain height to match the FSX airport elevations. That might provide a link between the AIRAC and the terrain warnings. The only way to be sure is to compare the field elevations from the two AIRACs. They are text files so it's easy to do. If there is a problem then it should be reported to Navigraph so it will be corrected in future.

 

 

 

Don't know, I'm not the expert dude.

 

I'm not used to being called "dude" so please don't.

[downscc 1,327]

 

 

It has to read this data from somewhere, and the only airport.dat is in Navdata folder of you're sim, for ex. mine is C:\FSX\PMDG\Navdata.

 

Not quite right.  There is terrain data in the PMDG\DEM folder, lots of it.  It is not updated like navdata.  I initially believed that navdata was involved by reasoning it was logical to use wpNavAPT and Airport.dat files. I was convinced that navdata had nothing to do with GPWS in the PMDG simulation a couple of weeks ago with an exchange with Kevin Hall and looking at online GPWS specifications.  However, just like an exam I changed my response to the wrong answer.  Off-line in the beta channel RSR confirmed that navdata is used by PMDG to determine airport locations and approach channels through the terrain (note terrain data is in the DEM files).

 

Therefore, it is possible that one airac cycle will have false terrain warnings and not another airac cycle.

 

Nice topic.

[Artur Munteanu 1]

The only way to be sure is to compare the field elevations from the two AIRACs. They are text files so it's easy to do. If there is a problem then it should be reported to Navigraph so it will be corrected in future

It's not so easy, because the information of elevation are contained in the "airport.dat" file or "ARPT_RWY.dat" and not in the txt file. The other txt file "wpnavapt.txt" contain only the geographic coordinates (lat. and long.) of the airports. Now, I don't know if you have also the Airbus X, but I have and looking there the Navdata are different from PMDG to Aerosoft. In the folder from Aerosoft NavdataPro, the files are different. For ex: there IS a file "airports.txt" which contain all the information in a text file - lat., long., elevation, and so on. My problem is that I don't know how to read for PMDG the dat file to see the difference. Is more to easy for the Airbus (different way of navdata files, all in txt format).

So I can try to upgrade also the airac cycle for the AirbusX (now I have cycle 1309 wich is sept. 2013) to 1502 and see what happend. There are chance 50% to have false terrein allarm on Airbus also IF there is something wrong with the Airbus navdata cycle, or the EGPWS from Airbus is reading the data from the same location like the 777.

But... I have to be honest, no one pay me to loose my time for hours to make this. As I said I don't have false terrain allarm with 777 on the cycle 1408 so for me again, problem solved.

 

BTW. Sorry for "dude" nothing personal and not try to offend, is just an expresion like "my friend" wich I use.

Now, for the people wich have false terrain alarm in the cockpit of 777 on final approach, there is on the left of FO panel The switch "TERR OVRD" wich you just have to simply push it and this deactivate the annoing alarm. As you presumed that you are Landing, is normal I mean it's not a big deal to perform this action, even Boeing itself tell's you to do it, BUT be sure to do it only in the approach phase!

Have a good fly my friends!

[Jetstream96 20]

Both .dat files are pure text and can be opened via Notepad. ARPT_RWY.dat contains the airport elevation at the end of each line which contains an ICAO code.

[kevinh 409]

Not quite right.  There is terrain data in the PMDG\DEM folder, lots of it.  It is not updated like navdata.  I initially believed that navdata was involved by reasoning it was logical to use wpNavAPT and Airport.dat files. I was convinced that navdata had nothing to do with GPWS in the PMDG simulation a couple of weeks ago with an exchange with Kevin Hall and looking at online GPWS specifications.  However, just like an exam I changed my response to the wrong answer.  Off-line in the beta channel RSR confirmed that navdata is used by PMDG to determine airport locations and approach channels through the terrain (note terrain data is in the DEM files).

 

Therefore, it is possible that one airac cycle will have false terrain warnings and not another airac cycle.

 

Nice topic.

I wondered whether PMDG had done something like that, as I mentioned in my previous post. Clearly the chances that Honeywell's database would align well with FSX runway elevations is low. It's strange though that AIRAC runway elevations would change from one release to another. I don't have AIRAC 1502 to compare with 1501 for the airports mentioned in this thread.

 

Interesting topic indeed.

 

 

BTW. Sorry for "dude" nothing personal and not try to offend, is just an expresion like "my friend" wich I use.

No offence taken.

 

 

 

Now, for the people wich have false terrain alarm in the cockpit of 777 on final approach, there is on the left of FO panel The switch "TERR OVRD" wich you just have to simply push it and this deactivate the annoing alarm. As you presumed that you are Landing, is normal I mean it's not a big deal to perform this action, even Boeing itself tell's you to do it, BUT be sure to do it only in the approach phase!

 

Have a good fly my friends!

 

Good advice.

[cathay747 0]

well of course I do know that there is a terrain override button

 

But I do want to know a long term solution as I know that the problem is existent in many airports

[kevinh 409]

well of course I do know that there is a terrain override button

 

But I do want to know a long term solution as I know that the problem is existent in many airports

Make a list of the airports you know about and submit it in a ticket to PMDG support. They may refer you to Navigraph for a solution but at least they will be aware of the problem.

[art5869 4]

 

I have to log in with reg acvcount, because the facebook login didn't work today.

Anyway, I think PMDG shoul really read THIS:

 

http://www51.honeywell.com/aero/common/documents/egpws-documents/Operation-documents/060-4241-000.pdf

 

 

 

 

[Guest]

Many here have had this issue, one of you was able to fix it downgrading the Airac. So far so good.

 

Is this solution valid for everyone or it has been only a lucky coincidence ? 

 

I still struggle to spot the relationship between an airac cycle and the terrain warning, only in the T7 BTW, not in the 737 NGX.

 

Thanks

[Artur Munteanu 1]

I still struggle to spot the relationship between an airac cycle and the terrain warning, only in the T7 BTW, not in the 737 NGX

Now this is another different thing. The 777 is highly automated even with FBW similar like Airbus, personally I'm not a huge fan of a world where a computer tell to a human what he has to do (especially if the person in question is a pilot!).

 

With 737 NGX everithing has to be done by manual : Landing altitude, cruise alt. for pressurization, Landing elevation and lenght of the runaway, radio freq. for ILS and so on. So the computer was simply reading what YOU tell to read. Here is YOU that read what the computer think that it has to be done! And It's a little bit strange if you think...

[kevinh 409]

 

 

I have to log in with reg acvcount, because the facebook login didn't work today.

Anyway, I think PMDG shoul really read THIS:

 

http://www51.honeywell.com/aero/common/documents/egpws-documents/Operation-documents/060-4241-000.pdf

 

 

 

You can be 99.9999% certain they already have.

 

Now this is another different thing. The 777 is highly automated even with FBW similar like Airbus, personally I'm not a huge fan of a world where a computer tell to a human what he has to do (especially if the person in question is a pilot!).

 

With 737 NGX everithing has to be done by manual : Landing altitude, cruise alt. for pressurization, Landing elevation and lenght of the runaway, radio freq. for ILS and so on. So the computer was simply reading what YOU tell to read. Here is YOU that read what the computer think that it has to be done! And It's a little bit strange if you think...

Landing elevation for the FMC is automatic in the 737NG just as it is in the 777. You don't manually enter the runway elevation, it comes from the AIRAC via the FMC, just like the 777. The runway elevation or length set on the centre pedestal only affects the HGS, if installed. The pressurisation landing altitude does not affect anything else but pressurisation.

 

There seem to be two separate accounts posting as Artur Munteanu here.?????

[Artur Munteanu 1]

There seem to be two separate accounts posting as Artur Munteanu here.?????

Have you read what I said? Of course I have 2 account -  1 is made with registration on AVSIM, the other when I login with FB. As Yesterday didn't work the FB login, I use the other one. It's against some rules of the forum?

[kevinh 409]

Have you read what I said? Of course I have 2 account -  1 is made with registration on AVSIM, the other when I login with FB. As Yesterday didn't work the FB login, I use the other one. It's against some rules of the forum?

I've never noticed anyone else doing it before. That's why I mentioned it. If you already had an AVSIM account why log in with Facebook? I never use my facebook ID to log in to other things since I don't want FB intruding into everything I do, feeding my timeline with stuff it thinks I want to see. However that's your choice of course.

 

If you look here http://forum.avsim.net/page/AVSIM%20Pages/terms_of_use.html you will see that multiple accounts are against AVSIM terms of service. Probably written before the days of logging in with FB or twitter IDs so I don't know if they view that differently now. None of my business, but I think you ought to resolve this with AVSIM before they resolve it for you.