What is the correct altimeter setting for this airport?

[bushp04]

The local airport for me is KTUP (Tupelo, MS), and I've noticed that my Cessna 182's altimeter shows about 372 ft. MSL.

Do I have to make a mental adjustment to account for this every time I land?

[JSkorna]

The map says 346 ft. Keep your altimeter adjusted by hitting the "B" key.

Hope this helps,
Jim
ActiveSky Support
http://www.hifisim.com/images/as2004proudsupporter.jpg

[dmountford]

The alimtiter is calibrated based on barometric pressure, i.e. pressure of the air in either millibars or hectopascals...

If you're flying out of an airfield at 300+ feet, you need to make a mental note of the altitude the airport is at... Then fly at 1000 AGL (Above Ground Level) for your circuits which equals around 1300+ feet...

[TornadoWilkes]

When flying real world, the ATC can radio you a different setting for your altimter that will force it to read zero when at ground level. If you have ever scanned the airwaves in Europe at least, you will hear ATC/pilots refer to this altimeter setting as QFE.

Unfortunately, FS does not do this.

[zfehr]

QFH is basically only used in Russia and China, the FH referring to field elevation. IMHO this would be a rather dangerous setting since it is only useful for the particular field you are at. QNH is the standard which relates to mean air pressure and is much more common, will correlate to all given object altitudes on your charts, also correlates to the altitudes given in the airfield manual and for maintaining proper pattern altitude. While sitting on the ground you can tune your altimeter to read "0" and get the QFH yourself, wouldn't find it very useful in real world flying though.

Zane

[Nige]

There are three ways to set your altimeter. QFE (Field Elevation), QNH (Nautical Horizon) and Flight Levels.

If you go to your local airport and set the altimeter to zero that is using QFE. It is nice for practicing circuits because your altimeter is showing your height above the airstrip and no mental arithmatic is required. However, unless your airfield is at sea level QFE is no use if you fly to another airfield because your map will show all altitudes as height above sea level and you will not know your true height above ground or what altitude your target airfields is. QFE is rarely used and is actually illegal in many countries.

QNH involves getting into your aircraft and setting the altimeter to reflect the home airfield's height above sea level. So if your home airfield has an altitude of 1,150' ASL you set your altimeter to 1'150'. This will mean that you need a little mental arithmatic if you just want to practice circuits but it also means that if you fly off somewhere else your map will now make sense. If the map shows a mountain at 8,750' and your altimeter reads 8'750' you will just scrape the top of it. When you reach your target airfield your map will tell you the altitude ASL of it and you will need to make a mental calculation to find your correct circuit height. Because the altimeter is a sensitive barometer it will change its reading during a flight as you fly through different weather areas which is why ATC and ATIS reports will tell you the 'area QNH". FS will tell you 'altimeter 29.92' which is the actual air pressure read on the little window on the altimeter. Pressing B in the sim will set your local QNH. The main purpose of the QNH system is TERRAIN AVOIDANCE.

Once you are above an altitude where terrain could be a problem the main concern is COLLISION AVOIDANCE. So above a certain altitude, 18,000' in the US, 10,000' in Australia, the Flight Level system starts. This involves everyone setting their altimeters to a standard setting of 29.92" as if everyone was flying in the International Standard Atmosphere. Thus if two aircraft are near each other and they both have the same altimeter reading they know that they are actually at the same altitude even if they have flown through different weather systems. This does not happen with the QNH system unless both aircraft have been constantly resetting to the 'area QNH' and it virtually never applies in the QFE system. The altitude where the Flight Level system takes over from the QNH system is called the 'transition altitude' and Flight Levels are expressed as multiples of 100'. Therefore 25,400' is 'Flight Level 254'. Once you have set your altimeter for flight Levels you do not need to bother with altering it until you descend below the transition altitude.

Hope this all makes sense.

[flyinggriffin]

When flying in the states, you set your altimeter to the barometeric pressure setting that is reported by either ATC,FSS, or the AWOS/ASOS. What this will do is set the altimeter relative to sea level or MSL (mean sea level). So, sitting on the ground at my home airport of Schenectady County it reads aroun 377 feet depending on where on the aiport you are. When at KLAS you will see the altimeter read around 2200 feet. Looking at a sectional, those obstructions or mountains will have the elevations in MSL which is what it's set for. Once you go over 18,000ft you reset your altimeter to 29.92. Now, if you set your altimeter to zero at KLAS then when you flew to KSCH assuming you didn't reset it, guess what it would read? A negative number, (kinda like the bankroll most people come away from Las Vegas with). This is simplified but the reason why we do what we do in the U.S.

Pattern Altitude is published in guides that you can buy either from the goverment or private sources. This will usually be field elevation plus 1000ft but in some cases it may only be 800ft. The local airport can say what it wants pattern altitude. Schenectady is 1200ft. not 1400 like it would be if you just rounded up and added a thouands feet. Yes, it requires a mental adjustment to think this way, but in real life you learn how things should look at pattern altitude. I have had situations where things got really busy, usually due to lots of traffic and I forgot to reset my altimeter and realized it when looking out the window, that something doesn't look right.

So, what does our intrepid aviator do if he is at east nowhere strip and it doesn't have an outhouse let alone weather reporting. Trying to get flight service on the radio only gets you dead air. How do you set your altimeter? Easy! Even the worst, out of the way strip usually has the field elevation listed somewhere. You can also look it up on the sectional. You set your altimeter to read the field elevation in MSL. That will get serve you until you can get an accurate barometer reading.

[lnuss]

When flying real world, the ATC can radio you a different setting for your altimter that will force it to read zero when at ground level.
ATC in the U.S. doesn't do this. There are places where this setting is used, but I don't think altimeters CAN be set to zero at my home field (5276 MSL), and in any case, I'd hate to have to try to mentally convert the 14,000+ foot MSL altitudes on mountain peaks (and other stuff, too) into the difference from my field elevation and the peak. Let's see, Pikes Peak is 14,110 MSL, minus 5276 means that Pikes Peak should then top out at 8834 on my altimeter. Hmmm... seems dangerous to me.

[TornadoWilkes]

QFH? I've never heard of this one, I wonder what the difference is to QFE?

Just for the record, QFE is used extensively in the UK and is passed by ATC on joining the circuit. As you'll understand, our airports are hundreds of feet above MSL so turning the knob a few millibars is no big deal here. I don't think I have ever done a circuit with QNH set on the altimeter.

I guess you guys in the states would get wrist ache. :-lol

Oh and we also drive on the correct side of the road ;-)

Edit: Found it [link:www.zerobeat.net/qrp/qsignals.html|QFH]

[flyinggriffin]

Hummmm...as I understand it, with the weather you normally have in the U.K. unless you are instrument rated you are not going to be flying more than a few hundred feet above the airport most days :)

Oh, and if you have ever driven in some parts of New England, they use BOTH sides of the road.!!!!!