Altitude discrepancies

[jsmcwilliam 3]

I run P3D4.5 under Windows 10 and have just started flying the Q400 again after many months on the PMDG NGXu. I have Orbx Global scenery and the 2001 Navgraph Cycle installed. Also Active Sky and VoxATC 7.42. On my two first flights I have been given clearances to descent to a lower flight level (pressure is STD 1013hp) for my approach, however, when I get there Vox continues to pester me with "...descend immediately to FL XX". I tried changing to local pressure as given by Active Sky but this did not help. Then I did a stepwise descent to FL XX - 100, -200, etc and at -600 Vox seemed to be satisfied and stopped its transmissions. This has happenned at both airports in question - in the later case I was asked to climb to the assigned altitude and did a similar stepwise ascent to FL XX +100, +200 etc until Vox was satisfied. Anyone out there with an idea of what is going on here.

John

[vadriver 247]

9 hours ago, jsmcwilliam said:

Also Active Sky

that is ASP4 ??

[jsmcwilliam 3]

Yes. It is - build 7208.

[vadriver 247]

On 3/2/2020 at 10:45 PM, jsmcwilliam said:

after many months on the PMDG NGXu.

so still guessing ...... all was well with vox742 & the ngxu.

i have trouble understanding how there is a difference of 20mb between your Q400 & vox for QNE ..... unless one had a different TL set to the other, but then as you say the vox calls were about FL's (QNE), not altitudes (QNH) ??

as before, where & what phase could help more 

ie hard to guess more

Edited March 7, 2020 by vadriver

[jsmcwilliam 3]

As stated above:

Where: ESSA - ENGM, approaching ESBA I am asked to descent to FL90. Shortly after levelling I am asked repeatedly to "descent immediately to FL90". My solution was to gradually continue descending at 100 ft intervals until ATC was satisfied (8,500 ft) and stopped calling for an immediate descent. The other scenario (ESMQ-ESSA) was after descending to the requested FL I was asked to climb immediately to that FL. In this case I continued to climb at 100 ft intervals until ATC was satisfied (FL+600ft).

[jabloomf1230 2,445]

This may be unrelated to your problem, but I’m wondering whether the ground elevation and approach elevation are creating a conflict in VOXATC. I’ve had a similar issue approaching CYVR from the Vancouver Island side.

[jsmcwilliam 3]

Hi jabloom! Good to hear from you again. We had a long discussion concerning fatal errors on approaching ENGM which I initially hoped you had fixed with an adjusted bgl file. Unfortunately, there were other problems I had not noticed - my EFB was not giving me the ILS frequencies for landing. In the end I decided to bite the bullet and invest in Mega Airports version of ENGM. Some one down the line had suggested that it was the best solution. It fixed everything with the exception of this altutude problem and since I have been having the same problem with ESSA there must be a more global background to the question. I ran the Orbx Global Vector auto configuration and reindexed Vox but this did not help. Your thoughts....

John

[vadriver 247]

picking up on jay's thinking, i wonder if vox is confused by the "settings" for TA / TL at these airports.

the vox default TA (& i believe the TL)  for the EU region is 3500' which is different to what is chartered for TA at 5000' for ESSA & ENGM.

interesting & more so as it may confuse vox about altitudes data in the airac. 

[vadriver 247]

4 hours ago, vadriver said:

& ENGM.

& at 7000' for ENGM

[jsmcwilliam 3]

I ran the Orbx Global Vector auto configuration after installing Mega's ENGM and reindexed Vox but forgot to choose apply. I have done this again and did a flight ESMQ-ESSA. My altitude instructions worked so now I have to test ENGM just to make  sure all is well.

[jsmcwilliam 3]

Did a new flight ESSA-ENGM and was cleared down to FL 70 but had to stop at 7200 in order to satisfy ATC. I was then clears to FL45 - note not altitude 4500 inspite of the TL of 7000. Again I had to stop att 4800 in order to satisfy ATC. I was then cleared to altitude 3500 and using local pressure found that this worked. I need to repeat this flight in order to confirm the above.

[jabloomf1230 2,445]

On 3/9/2020 at 5:41 PM, vadriver said:

picking up on jay's thinking, i wonder if vox is confused by the "settings" for TA / TL at these airports.

the vox default TA (& i believe the TL)  for the EU region is 3500' which is different to what is chartered for TA at 5000' for ESSA & ENGM.

interesting & more so as it may confuse vox about altitudes data in the airac. 

There are a lot of different "moving parts" here and as an aside, the more I look at these types of threads, I really wonder if MSFS 2020 will be able to initially duplicate what VOXATC does. There are three transition altitude regions set in VOXATC, the default (which is North America), UK/EU and Australia/New Zealand. The TA is one potential source of variability, as VADriver has pointed out. Second, the terrain-sensing algorithm in VOXATC attempts to keep the user's aircraft at a safe altitude above terrain. Third, VOXATC gets its weather data via FSUIPC5, which in turn is getting it from the sim, which further is getting it from ASP4. The final source of variability comes in from which version of the airport is active and being used by VOXATC. The active airport should be the one with the highest priority in the scenery library. I don't think that this last issue is the problem, because the altitude discrepancies reported for ENGM by John McWilliam are relatively minor, which leads me to believe its the weather data that is suspect. What I do is to display the QNH variable in the P3d4 menu bar using the facility in FSUIPC5. It can be set up in FSUIPC5 while running the sim, but here's the lines in FSUIPC5.ini:

Quote

[Monitor]
Display=4
Monitor0=0,0EC6,3,0
!1=// Monitor0=0,0EF2,3,0 ;Surface wind direction, *360/65536 gives degrees Magnetic (!).

Note, the QNH is displayed as hPA * 16. For more information consult FSUIPC5 Offsets Status.pdf in the FSUIPC5 documents folder. I also included a comment on how to display surface wind direction at the position of the user's aircraft.

As to the transition altitude, I don't think that it's worthwhile to set up another VOXATC region with a rectangle around ENGM, as I doubt that's the cause of these discrepancies.

[vadriver 247]

6 hours ago, jabloomf1230 said:

I really wonder if MSFS 2020 will be able to initially duplicate what VOXATC does.

jay

for mine, initially probably not, eventually maybe .... i don't feel ATC features that high on the list for MS2020 in the near term.

i still hope TW will "complete" what we have now with Vox so that at least for the next 2-5 years, those like I who will stay with P3D4 will have the most "complete" sim available for the duration.

6 hours ago, jabloomf1230 said:

I don't think that it's worthwhile to set up another VOXATC region with a rectangle around ENGM

it would be an exercise to tweak the regions admittedly.

i do however see the advantages for not only varying TA/TL's but different atis/comms formats at the many airports of Asia (which are not included in the default)

6 hours ago, jabloomf1230 said:

which leads me to believe its the weather data that is suspect

yes i think you are correct ...... but how i wonder. i often hear unusually/obviously different QNH's in descent clearances outside 30nm to destination much as john (OP) did.

20mb is more than i'd expect the difference to be (except in/near a typhoon)

[jsmcwilliam 3]

I repeated my flight ESSA/ENGM today and noted the following. After departing ESSA and passing TL I set my pressure to 1000 hpa instead to 1013. My descent clearance into ENGM to FL70 worked without repeated requests to descend immediately to FL70. I was then cleared to FL45. This was also accepted by ATC. The TL is FL70 so would have expected to be cleared to an altitude and not a FL. I was subsequently cleared to FL35 for the approach but chose to set local pressure Q0981 and this did not cause any problems presumeably because I was close to the localisor and glide path. There are inaccuracies in all this but I understand how to handle it and it is manageable. When I have time I can tinker with FSUIPC but it is really out of my depth to do this!

John