Md11 - Pressing "b" Changes Qnh

[F.Schmid 0]

Hello!I've noticed each time it is pressed the key "B" over FL180 it changes the value, which should be fixed at 2992 (1013).Of course this problem happens also below FL180 but it can be clearly seen at that altitude.Is it a bug? Is there a fix?RegardsSchmid

[KCA9304 0]

Hello!I've noticed each time it is pressed the key "B" over FL180 it changes the value, which should be fixed at 2992 (1013).Of course this problem happens also below FL180 but it can be clearly seen at that altitude.Is it a bug? Is there a fix?RegardsSchmid

Don't think we can call this a bug. The real aircraft does not have the "B" key to adjust the baro setting.So an easy fix would be to disable this "B" key from the FSX command key menu.What is modelled correctly is when you select 'BAROSET PULL-STD', only ONE click of this rotary knob will return the value to the previous baro setting. This is a handy feature in areas with Transition Levels as low as FL45 for example.Having the ATIS and still descending on FL's it allows you to do a QNH preset, return to STD, and select the QNH by just one click when passing the Transition Level. Just experiment with it.Regards,Harry

[scandinavian13 5,192]

Hello!I've noticed each time it is pressed the key "B" over FL180 it changes the value, which should be fixed at 2992 (1013).Of course this problem happens also below FL180 but it can be clearly seen at that altitude.Is it a bug? Is there a fix?RegardsSchmid

That's not an MD-11 issue, it's a Flight Sim issue. It is modeled at 18,000 because in the US that is the transition level. It is different for other countries, though. MS just modeled it for the US and left the rest out. I have a feeling that it's buried in the weather engine of FS that just over-rides any baro indications above 18,000 but I'm not sure. Basically, the MD-11 does it because FS forces it to, if you press the B key.Cheers,Kyle

[F.Schmid 0]

Hi, Harry

Don't think we can call this a bug. The real aircraft does not have the "B" key to adjust the baro setting.So an easy fix would be to disable this "B" key from the FSX command key menu.

That's why I bought a sim, not a real aircraft. And I have to do all the job that is made also by my FO and FE..... :( Using the "B" key is as easy and practical as "F1/F8" keys. And NONE the other add-ons (and I have plenty of them) changes QNH value at each time I press "B".

What is modelled correctly is when you select 'BAROSET PULL-STD', only ONE click of this rotary knob will return the value to the previous baro setting. This is a handy feature in areas with Transition Levels as low as FL45 for example.Having the ATIS and still descending on FL's it allows you to do a QNH preset, return to STD, and select the QNH by just one click when passing the Transition Level. Just experiment with it.

I really appreciate your suggestion but that's not the point. Of course I can use baro knob as I can use flaps, throttle and all other active controls in the aircraft but I'd like to know why QNH changes.... Best regardsSchmid

[F.Schmid 0]

Hi, Kyle

That's not an MD-11 issue, it's a Flight Sim issue. It is modeled at 18,000 because in the US that is the transition level. It is different for other countries, though. MS just modeled it for the US and left the rest out. I have a feeling that it's buried in the weather engine of FS that just over-rides any baro indications above 18,000 but I'm not sure. Basically, the MD-11 does it because FS forces it to, if you press the B key.

Ooops. I believe I haven't made myself clear.It's certainly a MD-11 issue as all other add-ons (including default FSX aircrafts and PMDG 747) I use don't have this behaviour.Another example: the last flight with MD-11, at FL310, I pressed "B" and QNH assumed 2992 as expected. I pressed "B" again and QNH assumed 2989. Then I pressed again and back to 2992 and so on.What you stated makes sense but if it is 'forced' to 2992, why it changed to 2989? If the real value was 2989 and because of TL it has to be set at 2992, why it changed back to 2992? In other words: If "B" sets correct baro pressure then it shouldn't change each time "B" is pressed, even if the value is not 2992. If this premise is correct, then we could adjust to 2992 using baro knob.My concern is: how reliable is altimeter reading when descending to a non ATC area? Which value to set if you don't have a METAR reading? In these situations, "B" is a great solution.Best regards.Schmid

[scandinavian13 5,192]

My concern is: how reliable is altimeter reading when descending to a non ATC area? Which value to set if you don't have a METAR reading? In these situations, "B" is a great solution.

Schmid,I don't have the MD-11 (yet), so I couldn't tell you what's going on from being able to see it. There's something in there with FS messing with the barometer, guaranteed, even though it may seem to be particular to the MD-11.As for your questions, however, I'll answer them using the system of reality.1 - There are very few places (if any) in the world that you will descend into from Class A Airspace that do not have ATC. That said, in general, you aren't going to descend into any places without ATC to tell you what your altimeter setting should be.2 - Automated weather reports are very frequently found. In the United States there is a good net of automated weather systems. Chances are that, no matter where you are if you watch the local news, the temperatures you see are coming from local airport automated systems (US or elsewhere). That goes to show how many there are. (Here's a worldwide list, if you're interested: http://adds.aviationweather.gov/metars/stations.txt )If you are not able to get a reading from ATC, you should tune to the nearest airport's automated weather reporting system (AWOS/ASOS) and obtain an altimeter reading from it. There is no need to tune all of the airports you pass, however, as altimeter settings do not change rapidly, except in the case of a front. This should never be the case when flying the MD-11, as you'll be on an IFR flight plan (positive ATC coverage at all times, unless the departure/arrival airport does not have ATC) and settings will be provided to you.If you have any more questions, let me know.Cheers,Kyle

[F.Schmid 0]

KyleThank very much for your detailed explanation.Since FS 3.0 I use "B" to set altimeter or, sometimes, I adjust it with baro knob. Depends on how busy I am at that moment. So, as I said before, assigned keys are very useful for me.My question focus not in the technique about baro pressure. It is about the changes on baro pressure reading every time you press the key, which I have never seen in all other add-ons I bought: default FSX, PMDG 747X, LVLD767, ATR72500, Wilco Airbuses series 1 and 2, 737, Legacy, CS C-130.Maybe, as Harry posted before, when on MD-11 I'll have to forget "B" and use only the knob.CheersSchmid

[FlyGuyAlex 0]

Above FL180 in FS if you press B it sets it to 29.92 mercury inches or 1013.25hPa.If you press B below FL180 it sets it to the current altimeter which is set by your weather engine or weather profile you had set up in FS. However not all airspaces and airports have the same TL/TA. So adjust according to the area you are in. So like at Schiphol TL is FL045 so press B there or just change the altimeter in the MD-11