QNH to STD PRESSURE

[kryten 1]

I use Radar Contact 4 as ATC. On some flights, when I am above the TA I have a problem with ATC telling me that I am not at my assigned altitude when the correct assigned altitude appears on the PFD (and on the MCP). I have previously pushed the STD button on the EFIS and STD appeared on the PFD. It seems to be happening when the initial QNH is low, for example 989. I am starting to think that pressing the STD button does not change the QNH (for example 989) to STD (1013). This would account for the ATC problem. Another thing that makes me think that this is the problem is that when I change from a QNH of 989 to STD I would expect the altimeter tape to "jump" to a new altitude on the PFD altitude tape because of the sudden change to a significantly different pressure setting. There is no "jump". I'd like to know if anyone else has experienced this before. 

[indyrocks 2]

There are a couple of other reasons for RC giving this "helpful reminder" about assigned altitude.

• If you don't maintain a climb/descent rate of +/–500 fpm, RC interprets this as leveling off. If you use VNAV to control the climb, some aircraft begin to struggle above FL300 or so. That's why I've made it a personal procedure to always use the VS mode for the last portion of the climb.
• If you fly a SID that requires leveling off at an intermediate altitude below the ATC-assigned altitude, make sure RC knows about it. Under Dep Procedures, select No Altitude Restr. That means ATC will not issue any intermediate altitude assignments, so it is up to you to climb when necessary.
• Even if you make the selection shown above, the RC controller may complain. I've encountered this mostly when departing London Heathrow. Almost all of EGLL's SIDs require you to maintain an altitude of 6000 ft for quite some time/distance. (The DVR SID requires you to maintain 6000 ft until passing DVR, almost 70 miles from EGLL!) This restriction is shown on the charts as 6000 ft, so you are expected to keep the local barometric pressure setting in the altimeters until you pass the final point in the SID, at which point you switch to the standard 1013 mb as you begin to climb. However, ATC may not like the fact that you're maintaining 6000 ft, even if you've selected the No Altitude Restr option described above. Possibly the confusion is because the Transition Altitude is also 6000 ft, so possibly RC hasn't been programmed to handle this situation properly.
  Note: A friend of mine has come up with an alternative procedure for flights out of EGLL in which he sets an initial cruise altitude of 6000 ft, and then requests climbs until he gets to his intended cruise level. ATC is happy, but it's a royal PITA.

Unfortunately, RC isn't likely to be improved any time soon, since its creator has had some major upheavals in his personal life and has stepped away from RC to enjoy the other things in his life. Despite these problems, I use RC on most of my flights.

[dmwalker 603]

 

 

A friend of mine has come up with an alternative procedure for flights out of EGLL in which he sets an initial cruise altitude of 6000 ft, and then requests climbs until he gets to his intended cruise level.

I wonder if that is the preferred procedure since it was used in the ITT video of Virgin flight EGLL to KSFO and in Craig Read's tutorial from EGLL to KLAX.

[kryten 1]

I have tried identical climbs with a low (989) QNH and a standard (1013) QNH. With a standard QNH there is never a problem but with the low QNH I have found that when I have levelled off at the assigned (by RC ATC) cruise altitude of FL410 RC ATC is not happy until I climb to FL420. The answer seems to be not to fly at a low QNH when using RC (or level off slightly higher than the assigned altitude). I tried your alternative procedure but still had a problem with a low QNH. Thanks for the suggestions.

[scandinavian13 5,192]

Reason number 485 why these ATC programs are complete rubbish...

[FLEX1978 373]

Reason number 485 why these ATC programs are complete rubbish...

 

Hehe, so true!  After reading this topic I wonder how many RC users fly the Dover SID at 6000ft all the way to DVR thinking they are being super realistic  

[Ray Proudfoot 8,947]

I have tried identical climbs with a low (989) QNH and a standard (1013) QNH. With a standard QNH there is never a problem but with the low QNH I have found that when I have levelled off at the assigned (by RC ATC) cruise altitude of FL410 RC ATC is not happy until I climb to FL420. The answer seems to be not to fly at a low QNH when using RC (or level off slightly higher than the assigned altitude). I tried your alternative procedure but still had a problem with a low QNH. Thanks for the suggestions.

Kryten, I see you are continuing to post in this thread but not the one on the RC forum where I have suggested how you can see where the problem is,

 

RC can cope with any QNH pressure and does not require any workaround.

[kryten 1]

Ray,

   I appreciate your help with this matter but feel you are being unfair in saying ;

" I see you are continuing to post in this thread but not the one on the RC forum where I have suggested how you can see where the problem is,"

   I have only made one reply on this thread and that was only yesterday afternoon. I have been away for a couple of days and not done much flying. I want to try several flights before replying to the last RC posts. I intend to fly now and post a reply on the RC forum later this afternoon.

  I would like to thank you again for your suggestions.

[Ray Proudfoot 8,947]

Hi kryten,

 

I've replied to your other post but you will need to ask here why the STD button doesn't appear to be working.

 

Sorry for the misunderstanding.

[iainsmith 9]

Reason number 485 why these ATC programs are complete rubbish...

 

I would respect that opinion if I thought it was informed. So, tell me Kyle - have you used Radar Contact?

I've been using it for eight years and, in spite of its faults (and nothing is perfect) it is a massive improvement on the FSX default ATC.

 

Iain Smith

[max2770 75]

Hehe, so true!  After reading this topic I wonder how many RC users fly the Dover SID at 6000ft all the way to DVR thinking they are being super realistic

 

I've always wondered about the Heathrow SIDs. Are you supposed to maintain 6000 until ATC clearance? The charts don't help...

[kryten 1]

I agree with Iain. RC has one or two faults but it's much better than the default ATC. Using it makes flying seem more realistic to me and I'll continue using it (apart from with a low QNH).

[iainsmith 9]

 

 

I'll continue using it (apart from with a low QNH).

 

Kryten, as Ray has already said to you, low values of QNH should not matter. RC can handle all known values of QNH. Radar Contact support is excellent. Check at the top of the RC forum to see how to log a fault and send it to JD. He will then be able to see exactly what is going wrong in your setup.

 

Iain Smith

[Ray Proudfoot 8,947]

I've always wondered about the Heathrow SIDs. Are you supposed to maintain 6000 until ATC clearance? The charts don't help...

6000ft is your initial clearance altitude in both real life and RC. Once airborne pilots are cleared higher quite quickly - both in r/world and RC.

 

Where real world differs from RC is that pilots are often cleared direct to a waypoint and will not fly the published SID. In RC you always have to fly the SID. "Fly what you file".

 

A real-world flight would never fly all the way to DVR at 6000ft!!

[max2770 75]

6000ft is your initial clearance altitude in both real life and RC. Once airborne pilots are cleared higher quite quickly - both in r/world and RC.

Where real world differs from RC is that pilots are often cleared direct to a waypoint and will not fly the published SID. In RC you always have to fly the SID. "Fly what you file".

A real-world flight would never fly all the way to DVR at 6000ft!!

Thank god, that's what I thought! While I don't own RC, I always figured they didn't follow the chart exactly! Thing is, I didn't know directs were allowed in EU airspace?