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Hectopascals v Inchs of Mercury

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Guest Bayley

I havn't seen this discussed yet so this may not be a big issue to the masses but is fairly significant where Im from. Unless I am doing something seriously wrong in FS9 air pressure is always indicated in inches of mercury, ie 29.92 In New Zealand and many other countries we use QNH and hectopascals. Is there any way that this can be selectable under regional settings in future versions?

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Unless I've got my conversion factors wrong, isn't a hectopascal equal to a millibar?Also, what's QNH got to do with the unit of pressure used?

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Guest Bayley

Yes one hectopascal is equal to one millibar. The reference to QNH is simply that in the USA the atomespheric pressure would be expressed as for example Altimeter 29.92, where as in other countries it would be expressed as QNH 1013 hectopascals (or millibars).

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How many countries actually use the hectopascal for aviation. Although it's an ICAO standard, many countries still use millibars and just identify the fact that they differ from ICAO in their AIPs. I know the UK does.

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Guest Bayley

Thanks for your reply.Whether using hectopascals or millibars is not my point. My point is that in NZ, Australia and other countries altimeters often only have one sub scale (millibars) in which to set the QNH or other such pressure ie QFE that needs to be set. We work in millibars, not inches of mercury like other countries. Trying to set 29.90 for example on an altimiter that has a sub scale reading in millibars requires a conversion every pressure change. Also mental calculations are carried out using the formula of 30 feet for every 1 millibar change in pressure, I would have no idea how to do this using the american system, as it is not taught or used in this part of the world. I am hoping that similar to how you have the option of selecting between feet and metres, and pounds and kilograms there could be in future the option of millibars and inches of mercury.

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Guest Jimbofly

I guess one solution would be to have an option such as "Altimiter Subscale Unit:" in the FS UI. That would allow two types of altimeter to load up with each aircraft. One with an InHG subscale display and another with a millibar subscale display.ACES?James

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The sim already can display atmospheric pressure in either inHg or mb... all that's require is that the gauge be coded to use one or the other... or both!AFAIK though, the sim's ATC will always provide it in inHg...

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Guest

hectopascal == millibar.number is the same, only the term is different. I know Schiphol METARs use it always, and I think Germany does too. Haven't really used my scanner elsewhere (don't get out as much as I did in the past).

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Guest skruer

QNH is used in Denmark and the rest of Western Europe with Greenland and Iceland.I think the US is on of the few which uses inches of mercury.

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Guest Jimbofly

QNH is not a unit of pressure, it is the altimeter setting at a particular location at sea level. IE In Chicago Meigs the airfield is almost 700ft above sea level, so that if the pressure at that location at sea level is 1000 hectopascals, the QNH is 1000 and that's what you set your altimeter to.What you mean to say is that Inches of Mercury is one of the few used in the US whereas HectoPascals or Millibars are used almost univerally everywhere else.James

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The instruments is one thing. It would be nice if local ATC gave you the QNH in the units that are used in the respective country/region.Does "QNH" stand for "Query Normal Height" or "Query Normal Hg" ? And "QFE" perhaps for "Query Field Elevation" ? (All 'measured' in pressure units). I'm just guessing.Cheers,Siggy

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Guest lbb

Hi Siggy,These codes are from the '20s or '30s, when morse was the main way of communicating and an entire series of Q-codes was developed to allow the radio operator to say just about anything in three letters.To give an example, QAN XXX meant: What is the surface wind direction and speed at XXX. So basically they don't mean anything.BTW, I second the request. I think it's rather irritating to have to use inches rather than hectopascal in Europe, and even more irritating is the fact that transition is always at 18,000ft. In Holland the transition height is 3,000ft, which means that if you fly by the RW rules and change to QNE, there is 15,000ft in which most of the time ATC is giving you flak for flying at the wrong height. Especially so, since us poor souls in Europe pay about twice the American retail price (FS9 was 80 euro's, about 100 dollars at the time!!!) for reasons beyond my comprehension (and no, there is no Dutch version, so that can't be it either).Leo Bakker

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Guest

transition altitude here (as in many parts of Europe) is variable.Sometimes it's 3000ft, sometimes 4500.Not sure what it depends upon, probably weather conditions.The reason we pay more is simple: taxes.European copies are produced AFAIK in Ireland, so production cost is higher.Then they're sold through European stores which have far higher overhead because of property and income taxes.Then there's VAT which is several times more than US salestax.

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Guest lbb

FYI, transition altitude is fixed for a certain place. (I suppose FIR boundaries are also transition altitude boundaries).However, transition LEVEL is variable, depending on air pressure, in such a way that there is always 1,000ft in between the TA and TL. This is to make sure that an aircraft that is level at the TA of, say, 3,000ft and one that is level on the TL of FL40 always have 1,000ft of minumum separation.In RW flying in Holland so far I have seen TL at either FL40 or FL45. If I were a little smarter I could predict which, based on the altimeter setting :-)Leo Bakker

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Guest skruer

I mean that QNH is what you are given at an european airport, at the same time you get the transition level - beacuse the two things change all the time. Now I have never flown in the USA but in flight simulator 2004 you get Inches of Mercury instead of QNH when you talk to an ATC. So I then assume that the USA is one of the few countries which uses Inches of Mercury. I might be wrong.

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Hi everyone,There is a way of flying with millibars/hectopascals or inches now :-)Shameless plug begins...Radar Contact v4. Click the link below.Shameless plug ends.Cheers,

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>The reason we pay more is simple: taxes.>European copies are produced AFAIK in Ireland, so production>cost is higher.>Then they're sold through European stores which have far>higher overhead because of property and income taxes.>Then there's VAT which is several times more than US>salestax.There is a thread on this I posted in earlier. We pay around 40% more in the UK for FS (and my copy of FS2004 was produced in Ireland). We do not have 40% higher taxes than America in the UK on goods. We are being ripped off and if you are prepared to sit back and accept that then you are welcome to. I for one will be buying my copy from a tax-haven.

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Guest DreamFleet

Okay.....I just bought a rheostat / dimmer / potentiometer (whatever you want to call it) that controls the overhead red dome light on my Piper Dakota. It's a little "pot" than brightens / dims the dome light, no big deal at all.As much as I hoped the shop could source it at Radio Shack or similar, it turned out to be a "special order" item, and cost $40 without installation and the FedEx charge to ship it in. I figure it cost $100 to replace that little potentiometer.This certainly lends new meaning to the term "rip off". ;-)Always remember, it could be worse, much worse.It could always be the real thing.BTW, yes, we use "IN HG" in the USA. However, when I learned to fly, I did learn that the "standard day" pressure is 29.92 IN HG and 1013.2 MB. We use QNH in the USA.Did you know that there is QNH, QNE, QFE and QFF? ;-) The last one really should not concern pilots (just meteorologists), and you could probably add QFE to that list also.So when I land my plane, the altimeter reads field elevation.Some altimeters show both baro values, some just show one value. The ones we program for DF products always show both. The altimeter in my Dakota only shows IN HG, and these days I have to put put on my reading glasses just to read it! :-lolRegards,http://www.dreamfleet2000.com/gfx/images/F...R_FORUM_LOU.jpg

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Guest

the price is something like 20% higher because of the higher production cost and another 20% because of higher taxes in the UK (which are leveraged over the 20% higher production cost).Yes it's a ripoff, but it's our own socialist "fair division of income" governments that are doing the ripping off, not Microsoft.

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Guest lbb

I doubt many people in Holland would call the current government socialist :-)Anyway, I'm not convinced that this is the answer, because in that case just about everything would have to be double as expensive here as in the States. And to be honest, given the fun I have I don't think 70 euro's is too much as such, it's just that I think it's odd that a product that is in some respects more realistic (ATC, accents, etc.) and thus "worth" more to Americans is in fact more expensive in Europe. However, I doubt my voice in this matter will change much, so I'll leave it at that.Leo Bakker

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