Not at assigned altitude

[kryten 1]

I have had this problem on several occasions. As an example, I was flying from LFPG to EDDM with an assigned cruise altitude of FL410. ATC cleared me to FL410, I climbed and levelled off at FL410. The MCP was showing FL410, the PFD altimeter was showing FL410. the pressure was set as STD and yet ATC kept telling me that I was not at my assigned altitude.  I'm flying FSX in the PMDG 747. Any suggestions as to why this is happening?

[IanHarrison 522]

Silly question, but are you sure that RC has imported the correct Flight plan\ Flight level?

It is very easy to mis-type the figures : e.g. 419 not 410 in the planner.

[Ray Proudfoot 8,950]

How did you change to STD Pressure? Not the B key I hope. That only works for the US with a TA of 18000ft.

 

Use the button on the panel. See if that helps.

[ronzie 21]

You can check the assigned altitude received from the plan near the bottom of the controller page, just as an after thought. Note that there two 00s are appended to that altitude for display.

 

Now if a change in altitude is involved here, any minor transient dip or climb upsets RC's controllers and some aircraft dip or overshoot.

 

On the controller page, FYI, are shown the transition altitudes for each airport although at FL410 that should not be an issue.

 

What altitude variance are you allowing in the RC in the RC general tab. I up it a bit to 300 just to take of thermals and convective drafts, etc, that I get from my weather app even that high up when crossing high mountains. It takes a while for the aircraft to respond to those corrections.

[kryten 1]

Thanks to those who took the time to reply.

Ian : I use FSBuild to create the FP, print it out and then import it into RC4. The FP is the correct one and the FL was checked.

Ray : I have built a cockpit which includes a cpflight EFIS. When I pass the TA I press the STD button on the cpflight EFIS. STD appears on the PFD.  

Ronzie : I checked the assigned altitude on the RC4 controller page. I get a call out of "altitude check" when passing the TA. I set the altitude variance to 500 ft.

 

I flew from EDDM back to LFPG at a cruise altitude of FL390 and had the same problem. One thing I noticed was that on the problem flights the initial QNH was low. It was 989 last time. I'm wondering if pressing the STD button does actually set a standard pressure. If it does not actually change the QNH to 1013 it could be the cause of the problem. Perhaps I should contact PMDG about this.

[Ray Proudfoot 8,950]

 

 

Ray : I have built a cockpit which includes a cpflight EFIS. When I pass the TA I press the STD button on the cpflight EFIS. STD appears on the PFD.... I set the altitude variance to 500 ft.

 

The default is 300ft. Suggest you set it back to that and try again. Also, if the altimeter has a readout of the pressure check it's set to STD (29.92 / 1013.2). It has to be to do with the altimeter and /or the variation you have used.

[kryten 1]

Ray, I've reset the altitude variance to 300. I don't know how to check the STD pressure. The QNH setting is displayed at the bottom of the altimeter tape and the reading changes to STD when the STD button is pressedand so I've no way of knowing that the pressure setting is actually 1013. Two things I've noticed. If the QNH is 989 and i'm climbing after passing  the AT with the pressure set to STD when I change to a new ATC and call out my altitude it is lower than the reading on the altimeter tape. Also at an assigned cruise altitude of FL410 ATC says I am not at assigned altitude but if I climb to FL420 ATC is happy. Presumably it thinks I am at FL410 even though the 747 altimeter shows FL420. Do you know how RC4 determines the altitude it thinks I am at? 

[Ray Proudfoot 8,950]

kryten,

 

I don't know exactly how RC determines your altitude. But this problem has to be to do with how STD pressure is set. Can you turn on tooltips in FSX and hover over the altimeter when you;re at your cruise altitude and RC is berating you? It should give the reading.

 

If STD is displayed then theoretically pressure should be 29.92 / 1013.2. If you can't see the altitude using tooltips it may require a log to JD.

 

But first see how you get on with tooltips.

[ronzie 21]

Try this:

 

In the backup altimeter set 1013 mb (when in the flight levels) and turn off STD. See if the aircraft changes altitude or you get any instrument discrepancy reading. To get the aircraft to act for this test you may have to activate FLCHG.

[Ray Proudfoot 8,950]

kryten,

 

Try this. It will show what the actual pressure setting is.

 

Open FSUIPC interface and choose Logging tab.

 

On the right hand side enter:-

 

Base=IPC

Offset=0330

Type=U16

 

Display to FS Title bar.

 

Hit OK.

 

In Windowed mode you will see a number in the title bar. Divide that number by 16 and that is the current pressure on the altimeter. If it says 16212 then that is standard pressure. Any other number means the altimeter isn't set to STD.

[kryten 1]

I have flown several flights and the following is typical of what I get. I'm not too sure how to show quotes from other people but I'll try using "selective quotes". If it is not righr I'll have to do this again.

 

 

Try this. It will show what the actual pressure setting is.
 
Open FSUIPC interface and choose Logging tab.
 
On the right hand side enter:-
 
Base=IPC
Offset=0330
Type=U16
 
Display to FS Title bar.
 
Hit OK.
 
In Windowed mode you will see a number in the title bar. Divide that number by 16 and that is the current pressure on the altimeter. If it says 16212 then that is standard pressure. Any other number means the altimeter isn't set to STD.

 

At a QNH of 1013 the title bar number was 16208 (1013) and when set to a QNH of 989 was 15824 (989). Pressing the STD button after TA had no effect on this number.

 

 

 

 

 

In the backup altimeter set 1013 mb (when in the flight levels) and turn off STD. See if the aircraft changes altitude or you get any instrument discrepancy reading. To get the aircraft to act for this test you may have to activate FLCHG.

 

With a QNH of 989 I turned off STD as you said and both PFD altitude and backup altitude changed and, using FLCH, the aircraft changed altitude.

 

 

 

I don't know exactly how RC determines your altitude. But this problem has to be to do with how STD pressure is set. Can you turn on tooltips in FSX and hover over the altimeter when you;re at your cruise altitude and RC is berating you? It should give the reading.
 
If STD is displayed then theoretically pressure should be 29.92 / 1013.2. If you can't see the altitude using tooltips it may require a log to JD.

 

i have tooltips turned on in order to change the trim but with STD selected the pressure is not displayed.

 

Today I noticed that, when descending and being handed over to a new controller, the RC pilot called out altitudes of about 1000ft above what was on the PFD altimeter. Also, I was cleared down to FL24 and then before reaching it down to FL15. I attained and levelled off at FL15 and then was handed over to a new controller. The RC pilot called out to the new controller that I was at FL24. I was then berated by ATC for not being at FL15 even though I was at FL15 on the PFD altimeter.

I'm sorry but my last post went slightly wrong. In answer to Rays post of ;

 

Try this. It will show what the actual pressure setting is.

 

Open FSUIPC interface and choose Logging tab.

 

On the right hand side enter:-

 

Base=IPC

Offset=0330

Type=U16

 

Display to FS Title bar.

 

Hit OK.

 

In Windowed mode you will see a number in the title bar. Divide that number by 16 and that is the current pressure on the altimeter. If it says 16212 then that is standard pressure. Any other number means the altimeter isn't set to STD.

 

My reply should have been :

 

At a QNH of 1013 the title bar number was 16208 (1013) and when set to a QNH of 989 was 15824 (989). Pressing the STD button after TA had no effect on this number. The number on the title bar only reflected what was entered manually. Pressing STD had no effect.

[Ray Proudfoot 8,950]

Kryten,

 

"Pressing the STD button had no effect".

 

That confirms my suspicion that you were not at the correct altitude. RC is working correctly. You will need to ask on the PMDG forum why that button is not setting standard pressure.

[kryten 1]

Ray,

 

As I said, pressing the STD button had no effect on the number displayed on the title bar but it did have an effect on the altitude displayed on the PFD. To me this suggests that pressing STD was causing the PDF altimeter to display an altitude based on a standard pressure but that the number on the title bar represented what was manually set on the QNH. This number is not affected by pressing STD as when pressing STD a second time the original QNH is displayed, not 1013.

  I think the easiest thing for me to do is not to fly with a low pressure.

[Ray Proudfoot 8,950]

Kryten,

 

Avoiding low (or high) pressure is not the answer. You need to find a way of manually tuning the altimeter pressure to either 1013.2 or QNH if the STD button isn't working.

 

Isn't there someone on the PMDG forum who can help you with this? You can't be the first person to fly the 747-400 with RC.

[kryten 1]

Ray,

 

As you know, I have started a topic on the PMDG 747 forum about this problem but nobody has replied that they have tried using RC with their 747. Perhaps the best thing to do would be to start a new topic on the forum called "Anyone using Radar Contact?" and ask people to try flying with a low QNH. It would be very informative. What do you think?