I would like to find out why there is a difference between the altimeter on the planes and the actual height. There is a difference between the altimeter and the 'control Z' function that is a part of the FS program. What is the reason there is any difference between the altimeter and the 'control Z' function? In a flight between Zantaa and Heathrow just flown, there was a 500 ft. flight difference. If anyone has an idea please let me know if this is fixable and if not , why not.

first step is understanding that air has weight -http://en.wikipedia.org/wiki/Atmospheric_pressureto allow for pressure differences aircraft altimeters must be adjusted. details on altimeters -http://en.wikipedia.org/wiki/Altimeterto correct the FS altimeter for changes that are simulated if you use real-world weather downloads press the <b> key (unless you have changed the FS default keyboard settings).--

I would like to find out why there is a difference between the altimeter on the planes and the actual height. There is a difference between the altimeter and the 'control Z' function that is a part of the FS program. What is the reason there is any difference between the altimeter and the 'control Z' function? In a flight between Zantaa and Heathrow just flown, there was a 500 ft. flight difference. If anyone has an idea please let me know if this is fixable and if not , why not.

Above 18,000ft (in the US at least and all over the world in FS9) everyone is to set their altimeter to 29.92in. Below 18,000ft you set it to the local barometric pressure, which the ATC will tell you. At any time you can just hit the key for it (default B ) and it will set it appropriately.All this adjusting affects the reading you see on the dial. Mean while, shift-z shows you the actual alt above sea level - the two will not always agree, this is true for real life as well. This is why large planes have Radio Altimeters which use radar to "look" at the terrain and "see" their altitude above it.I'm guessing you had a frustrating experience of the ATC telling you over and over that you were above/below your assigned altitude - if you hit that "B" key, that will stop since THEN you and the ATC will be on the same page about how high up you are.

Where I got the annoying message about being above the assigned altitude is at or above 18,000 ft. The altimeter is not reading correctly and I am getting constant messages from ATC regarding this very thing. I do understand that air has weight, but this is frustrating me because of ATC's messages about this very issue. I cannot understand the difference between the assigned altitude and the real altitude being that different? Is there any way to correct this problem within the FS. I don't know of any but am getting these messages more and more.

Is your altimeter set to 29.92in or 1013hpa above 18000 feet?

When you start on the ground, you would normally have your altimeter set to the local pressure using the dial on the altimeter. This is achieved by tuning into the ATIS (air traffic information service) frequency at the airport and listening to the automatic recorded announcement, which changes every hour and gets a letter of the alphabet assigned to it each time it changes, so at the start of the day you would hear 'information alpha', and hour later you would hear the message change to reflect weather changes and that would then be 'information bravo', then it would change to 'information charlie' an hour after that, etc.Amongst the info you would hear about, is which runway is in use as well as the local barometric pressure setting, which will either be in inches of mercury or Millibars (so you might hear something along the lines of 29.35Hg or 1019.6 Mb), and you then turn the dial on your altimeter so that the figure matches what you heard in the ATIS announcement. Your altimeter should then read exactly how high your airfield is above sea level at that exact time based on the current weather and air pressure.When you contact the control tower to get permission to take off, you will say you have 'information alpha' (or whatever letter the ATIS announcement is currently on), and the tower will then know your altimeter is set correctly, so when you take off and they tell you to climb to a specific altitude, they will also know any other aircraft they also give altitude instructions to will be on the same altimeter setting and so things will be safe because everyone is using the same setting near that airport and so nobody will crash into anyone else (hopefully).But all airports have a 'transition level' in the sky above them and all airspace around the world has a transition level too. At airports in places such as Europe, the transition level can vary and might be a low down as 3,000 feet above the ground, but in the US it is generally set at a standard height of 18,000 feet, which frankly is a better system since it is easier to avoid confusion (note that since Flight Simulator is a program made by a US company, you tend to find it simplifies things and has the transition level at 18,000 feet all around the FS world even though that's not like it is in real life).But whatever the transition level is for wherever you are flying, when you pass through above transition level, you then change your altimeter to a 'standard setting', which would 29.92Hg or 1013.25Mb (depending on which way your altimeter is calibrated), so as you climb up to anywhere past 18,000 feet, you change that dial and you may even hear your virtual copilot say 'altimeter check' when you get near 18,000 feet to remind you to do this. Some altimeters have a 'std' button on them, which will set it automatically to the standard setting when you press that.When all aircraft above 18,000 feet are using the standard setting, this means different countries and ATC zones can pass aircraft along to the next ATC controller without worrying about what setting the pilots have their altimeters on, because they know everyone is on the standard setting. Of course when you descend back down past 18,000 feet, you will be told what the local setting is and you can then go back to using that, which will mean your altimeter should then accurately read 'zero' when you land if the airfield is at roughly sea level (or if not zero, then at least the correct height of the airfield above sea level).Things you need to listen for on ATC therefore include: 'QNH' which is part of the 'Q radio code' for the 'local barometric pressure'. 'QFE' which is sort of similar but adjusted for height so that your altimeter will be on zero when you are actually on the airfield. 'QNE' which is the standard setting you put you altimeter on when above the transition level (i.e. 1013.25Mb or 29.92Hg), and 'QFF', which is a localised reading adjusted to mean sea level based on the pressure at the time.The only ones you'll tend to hear in FS will be QNH and QFE, and it is easy to remember what these are with a simple memory aid: If you imagine QFE is short for 'Query, Field Elevation' then you will easily remember it relates to the altimeter setting at an airfield, and if you imagine QNH is short for 'Query, Nautical Height' then you will remember it is a setting for aircraft above sea level.If you use those settings, ATC will stop bothering you.Some Q code stuff does still get used (such as those ones for altimeter settings), but most of the Q code is somewhat outdated these days, since it was originally designed to make large amounts of info easy to transmit with a morse code key rather than having to tap out a lot of words. For example, when the RMS Titanic was sinking in 1912 after it struck an iceberg, it sent out the then newly-implemented 'SOS' abbreviation for 'send assistance, I am in distress', but it also sent out the older Q Code signal abbreviation 'CQD', which means 'attention all stations, I am in distress'. Unfortunately, many ships which received the signal thought it was a mistake because the Titanic had been widely promoted on newsreels at the time as being 'unsinkable'.You can find out more about the Q code here, if you are curious: http://en.wikipedia.org/wiki/Q_codeAl

Excellent post ChockJust one small correction: You pass transition ALTITUDE on the way up, and transition LEVEL on the way down. Most airfields will have a published transition altitude, and transition level will be given by ATC or ATIS. If flying around in FS with no ATC I just use 1000 above published transition altitude as my transition level but be careful. There should always be a significant buffer between the two for obvious reasons.Real world example: When I fly out of Cape Town International, transition altitude is 7500 feet (published), and most of the time ATIS will report transition level as FL85. This buffer will be increased if conditions warrant it, for example when the atmospheric pressure is very low. Imagine a QNH of 990, which is about as low as I've seen. In these conditions, FL85 equals 7810 feet. That's a big difference, so in such a case transition level might be changed to FL95 for more separation. It can be unnerving changing from flight levels to altitude and find that you've instantly "lost" 700 feet. Change the TL to FL95 and now you have more time to think too.The way FS makes the whole world 18000 feet is immensely irritating and unrealistic. Well it's like this in americaland so it must be like that everywhere *sighRemember also that to get TRUE altitude, you need to correct for temperature too. This is not of much practical use but shows that even with the correct QNH set, the altimeter is still lying. Just not by as much as the pressure changes dictate, but it's still not really TRUE altitude. Even the calibration of different altimeters will cause more of a difference from aircraft to aircraft than correcting for temperature would.http://upload.wikimedia.org/wikipedia/en/6/61/Vertical_distances.svg

Yup, that's true about altitudes and FLs depending on which way you are going, but it was already a long post full of info that might be confusing, so I decided not to get into FLs and altitudes etc LOL That's a legacy of the fact that I normally train people for a living, so I know it's easy to overwhelm people with too much info unless you provide it in easily digestable chunks!Al

Also this .pdf document/tutorial is worth a read. It explains air pressure and working with the altimeter very clearly and includes other useful knowledge.http://anaspides.net/documents/flight_simulator_documents/Basic%20navigation%20concepts.pdf

This topic is well-covered. I would just add two things to help Journeyer. In real flying, you must set your altimeter for the proper conditions and then BELIEVE it. In FS9 this means hit the B key frequently if using Real Weather because the msl barometer setting will change as you move into different weather conditions. When ATC greets you, they specify and altimeter setting. Just tap B. If ATC scolds you for being 500 ft off, just tap B and ignore them. Don't worry about it. There is some logic to all this. When you are parked at an airport, your altimeter should read the elevation of the airport. If you fly to another airport, you should be aware of the elevation of the other airport and expect to see that on your altimeter after you land. The world-wide regulation that you set 29.92in at or above 18,000 ft keeps planes adequately separated by altitude FROM EACH OTHER. At that altitude they seldom need to worry about height above the ground. But with their altimeters all based on 29.92 they are at proper levels relative to each other if they are horizontally close enough to collide.

If ypu want to fly in the sim with correct TA's etc then get PFE or RC4 and do away with the sim ATC which is frankly rubbish and is as far from "As real as it gets" as is possible!vololiberista