Talk:Flight level - Knowledge (XXG)

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traffic, as hemispherical rules can easily result in northerly VFR traffic being co-altitude with Southerly VFR traffic with just a few degrees of error in *track* calculation, example, Pilot a thinks he is tracking 175 degrees, but is actually tracking 180 degreees, whilst pilot B correctly thinks he is tracking zero degrees. Hemispherical rule could have them both at, say 7,500 feet on reciprocal courses, whereas Quadrantal rules would have Pilot A at 7,500 and Pilot B at 7,000. Vastly superior separation. The hemispherical rule improves the safety of IFR traffic, which is mostly RPT, by separating it from VFR traffic, whilst confining more numerous VFR aircraft to fewer altitudes, increasing the risk of collision for VFR aircraft. This is to increase the safety of RPT, which is usually flown under the IFR.

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sea-level elevation are used, with a transition level, and that the details differ by jurisdiction. Highlight that it won't prevent lateral collisions, but will greatly reduce the chance of a head-on collision. 2. A subsection highlighting why FL cannot apply everywhere (eg. holding patterns near airports) and that air traffic control can override standard flight levels. 2. Some tables outlining the various schemes in use; hopefully someone can add a world map later; 3. A few paragraphs (being footnotes to the tables) explaining the variations in transition level, the variations in transition bearings; 4. A series of sections explaining the details of schemes in particular places; 5. A few paragraphs on historical practice, such as quadrant bearings, assuming that they're not in current use anywhere.

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least a tropical depression, if not a tropical storm. Lower-grade full hurricanes may develop at pressures at or only a little below this level. Outside the tropics, the famous "Nor'Easter" storms off the coast of New England, or the storms coming out of the Gulf of Alaska that may affect North America's West Coast (including California) are all low-pressure centers. These may be areas of cold, but there is still significant precipitation, liquid or frozen. Same in the rest of the world. (Direction of rotation is reversed in S. Hemisphere.)

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based on whether they are east or west bound, and this somehow makes it a "hemispherical" rule? An explanation would be nice. In fact, I don't really follow any of this. Maybe it is just me, maybe I am just really dense, but I don't feel like i understand flight levels after reading this article, and if the point of an article is to educate those who don't already know, I think this one is not doing a great job at it. If it was, it would make some sense to me.

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the middle of a tornado, and any aircraft flying in that would be torn apart by the storm). In practice, the range of pressures you are likely to encounter will be between 985mb (cold, dry day) and 1045mb (hot and humid) which means your aircraft could be anywhere between 31,100ft and 32,900ft. This works for any FL, e.g. FL200 would be 20,000ft ± 900ft.

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followed by very clear skies and ultra-low humidity. Typical: Storm passes over the Rockies, leaves a ton of snow, then the next day or two, it is totally sunny but much colder. (Humidity typically around 10%.) This is the cold, dry air behind the front, and the pressure is very high. Weather *underneath* high pressure centers tends to be clear and dry.

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The highest sea-level pressure ever recorded was 1085mb. On that day, an aircraft at FL320 would have been flying at 34,100ft. The lowest air pressure ever recorded was 850mb, which would mean an aircraft at FL320 was actually at 27,050ft. However, those were extreme conditions (850mb was measured in

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This article has serious deficiencies in describing Flight Level. Every aircraft above the published transition altitude changes their altimeter setting to 1013 hPa (29.29 inHg) and now refer to their altitude as Flight Level. On the descent when they pass the published transition Level they change

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It may be the case that other countries also retain the Quadrantal rule, this would require consultation of each countries AIP (the non-conformance with ICAO recommendations section is a good place to start). The Quadrantal rule is superior to the hemispherical rule for collision avoidance of *all*

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Many ATCO's, especially from UK, refer to an opposite flight level (for example if the flight is eastbound at FL350 and they instruct a flight to climb to FL360 opposite) as a non-standard flight level. From my personal point of view an even or uneven flight level it is a standard one as long as it

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Hmmm, just hope everybody has accurate pressure meters, and GPSs... if they had to do it all over again maybe they would have used hard tape measure elevations for the FL definition... but wait, if GPS fails one could fall back to the pressure meter which is not dependant on external satellites, so

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Flight levels are used to separate aircraft travelling in opposite directions. Have you got that bit? The "semicircular rule (also known as the hemispheric rule)" is really just a way of defining what are "opposite directions." I agree that the names are a bit arbitrary and possibly confusing. But

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I came here because I was curious what the semicircular rule was and why it was called that, and I have read over the article twice, yet I do not see any explanation of why it is called "semicircular", nor does it appear immediately obvious from the context. So flights are split into flight levels

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As we speak, Tropical Storm Debby, over the Gulf of Mexico, has a central pressure of 991 mb. It is very, very wet, and quite warm. In fact, a pressure of 985 mb will almost always be an area of disturbed weather. (exception noted toward the end) In the tropics or subtropics, it is likely to be at

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Cold air is more dense than warm air; hence, cold air weighs more upon itself and upon the earth. Very high pressure is found in the high-centers *behind* polar or other cold fronts moving south. While the frontal zone (interaction of colder and warmer air) is likely to be high in precip, this is

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There is no theoretical maximum although aerodynamic flight becomes impossible at something in the region of 100,000 feet, FL1000. The highest FL used by civil aircraft these days is somewhere in the 500s. A Gulfstream 550 executive jet has a maximum altitude of FL510 but there may be others with

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The transition layer covers the whole airspace as it is simply the the region between two altitudes. However, outside of controlled airspace it is not obligatory for a pilot to set his altimeter to 1013 (in fact outside controlled airspace it's not even obligatory to carry an altimeter at all!).

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How odd that the US should have a system different from the rest of the world. I fear for visiting pilots! If you want to amend the article to mention this, please do (but add to, rather than replace, the existing info, since it is correct for the UK, Europe, Australia and international airspace.

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The transition level will always be above the transition altitude, and is typically calculated hourly, based on the expected lowest QNH in a certain region. Typically, the transition level is the lowest flight level (according to the semi-circular or quadrantical rule) that is actually above the

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be resolved on the face of a standard aviation altimeter; these figures are used by pilots in actual practice. It would be a rare laboratory-grade instrument that could resolve 0.25 millibar, much less an instrument mounted in an aircraft panel. Since vertical separation of aircraft at Flight

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Or perhaps not, in which case it seems to me odd (non-NPOV) that this article describes almost everything in imperial units, and relegates metric to a minor afterthought. Likewise it seems non-NPOV that it treat any separation scheme except east-west as minor aberrations. This article needs an

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I suggest that an article covering the range of material currently in this article, either as a rewrite of this article or as a new article, should comprise: 1. A section explaining what flight levels are for, that they're based on angular separation of flight tracks, that both barometric and

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your text is wrong: France has since definition from ICAO (in French OACI) accepted and used the Standard rhuleset East/West. There are some heavy trafic routes arround big public aerports, where mandatory routing and FL is fixed. That spacing was made out of ICAO for responds to main traffic

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Trellis, thanks for pointing out my earlier error. Indeed QNH does not give pressure altitude. But nor does it give "true" altitude, except under ISA conditions (temperature 15ºC, density 1.225kg/m3 at sea-level, both decreasing uniformly with altitude). An altimeter cannot be calibrated for

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I would say cold fronts "moving away from the poles" or "moving towards lower latitudes" rather than "moving south". (Also, while the directions of rotation are indeed opposites between the two hemispheres, why mention this when neither clockwise nor anticlockwise is mentioned anywhere?)

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From my experience, it is not that much different in the US and the UK. In both countries you SHOULD apply the quadrantal/semi-circular rule when in VFR and above 3,000ft. In IFR you HAVE TO fly a FL above TA (and the controler tells which one, when you get your departure clearance).

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which means, that those "lowest flight levels" are used for something different - maybe quadrantial / semicircular rules??? - but surely not for the transition levels... i'm not correcting the article because i'm not 100% sure - maybe someone more knowledgeable than me could fix it? -

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Are you saying VFR flight in international airspace uses a quadrantal rule? Or doesn't use thousands plus 500? Or even uses flight levels at all below 10,000 feet rather than altitudes adjusted for local pressure variation? If so, that makes the United States dramatically different.

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says that, as from one minute past midnight, UTC, on the 17 November, 2011, Russia has been using "the standard ICAO Flight Levels in feet, that we are used to in the rest of the world – which is happening everywhere except Mongolia." Is this true? What is the situation in Ukraine?

821:"1013.25" millibars is false precision. Such numbers don't appear on any standard aviation instruments. The figure used in regulations, in the training syllabus, and displayed on altimeters is simply 1013. 1013 millibars converts more closely to 29.91 in Hg, and the error can 1745:

to the local altimeter pressure, the altimeter will now indicate height above sea level. In the North America the transition altitude is 18000 feet and the transition level is FL190. This means every aircraft at Flight Levels will have the same standard altimeter setting.

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The article states that this is now defunct. This is true of much of the world, but in the Kuala Lumpur and Kota Kinabula FIRS (Both Malaysian), this rule remains in effect for uncontrolled airspace above A030 and below FL250. Refer Malaysian AIP ENR 1.7 section 5 :

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Actually, these figures are still approximations because they make assumptions about the rate at which air pressure decreases as you get higher, but this effect is not as great as that caused by the variation in sea-level pressure. Hope that answers your question.

1067:. The dense air is further compressed, which also warms it. So while it eventually finds its escape and lowered pressure toward the ocean, the pressure in mb in the deserts just to the north and east of the Los Angeles basin can be very high -- around 1030 mb, 561:

i have a suspicion that the article is wrong on one thing ... it claims that the lowest FL in Poland is FL 285... which is simply not true, because transition level for Warsaw Okecie airport is FL 060 ... and that is certainly lower than FL 285...

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With regard to the article itself, I would suggest that writers confine themselves to known facts, such as "the Quadrantal rule is defunct in the UK since 2015", instead of making expansive statements that suggests that this applies to the whole

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When flying below the "transition altitude", your altimeter is set to "QNH" (the local or regional pressure at MSL) and your altitude is expressed in "feet". At some airports, your altimeter may also be set to "QFE", the local pressure at field

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The pilot-in-command of a VFR or IFR flight at or above 3000 ft outside controlled airspace and below FL 250 shall select a level corresponding to the appropriate magnetic track as indicated in the following Quandrantal Cruising Levels.

1140:), so the altitude shown will vary from the actual (or true) altitude depending on the conditions at a given time and place. This time I have just removed the word "true", which incorrectly implies an accuracy which is not justified. 865:

Does the transition layer extend and cover the hole FIR (controlled airspace and uncontrolled airspace?), i.e: in uncontrolled airspace is there any limit or altitude at which the pilot has to set his altimiter to standard 1013.25?

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So your track true (T) as on your chart plus/minus (+ for W - for E) variation (for your position on this planet in relation to magnetic north) gives the "track magnetic" (M) that depicts your flight level (odd or even).

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overhaul to separate out the commonalities from the details that differ between jurisdiction, and to restrict the discursive emphasis on any one system to a section or article that clearly identifies it as such.

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The transition altitude differs from country to country, and may actually be different within certain airspace as well. It can be as low as 3000 feet (eg. Netherlands), and as high as 18000 feet (e.g. US and

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Personally I always try to fly a flight level (in VMC), just in case the flight becomes IMC at any stage. So I (and the controller) don't have to worry that much about separation when I do my pop-up filing.

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And then it comes, Graham you are are absolutely right, cloud base has nothing to do with flight levels, but what about terrain clearance (which is always the responsibility of the pilot in command).

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When flying above a certain altitude (generally 3000 ft AGL), you have to fly according to a semi-circular or quadrantical rule. Note that this 3000 ft AGL is NOT the same as the transition altitude!

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orientation, somewhere it could be N/S instead of east-west. But the rhules for half-cirqle according to ICAO are mandatory over the entire french airspace where no special routing is defined.

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When flying above the "transition level", your altimeter is set to the standard atmosphere of 1013.2 mb/hPa, or 29.92 inHg, and your altitude is expressed as a "flight level" (100s of feet).

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I'm not familiar enough with aviation lingo to know whether "flight level" refers to any vertical zoning system, or just the US-centric FL-nnn notation, so I offer two options here.

1059:" region), finds its escape towards sea level in the mountain passes between the high deserts and the coastal basin of Southern California. Winds whip through passes like 1501: 1497: 1483: 1377: 1373: 1359: 697:

Good stuff... the article should stress that FL quadrantal and semi-circular rule are based on "track magnetic" (M) not "track true" (T) as the article might be read.

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https://web.archive.org/web/20130926112255/http://www.eurocontrol.int/sites/default/files/content/documents/nm/airspace/airspace-atmprocedures-cta-atc-perspective.pdf

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Altimeters should not normally be set to the standard setting of 1013.25 (29.92 is the equivalent) below the transition level which is well covered in the article.

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The rules for altitudes and directions are not correct for VFR flight in the United States. I'm not sure what other cases they are incorrect for. See, for example:

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This is the first semi-circular rule. It applies to IFR flights, with some exceptions (see RSVM) (in the UK it only applies to IFR flights above FL 245)

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So for me the FL is depicted by magnetic track (M) and minimum terrain clearance. The latter one differs depending on the rules you apply (VFR or IFR).

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What's with the lazy head comment at the end of the article? It appears on the article Flight_level but not on Flight_Level I'm new and confused :/

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Most countries (except the UK and some Eastern European countries, I have found so far) use the ICAO standard for the semi-circular flight levels

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The transition layer is the layer between the TA and the TL. It's sort of a no-mans-land where you should not be flying for long periods of time.

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over hot deserts, it equals disturbed weather, generally wet, and may be hot or cold, depending on latitude. (An extreme thermal low may induce

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is as well defined in this document. I could say for example that FL420 is a non-standard flight level under RVSM between FL290 and FL410.

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That same cold, heavy air, gravity-driven to seek lower levels than the high deserts of Utah (often, the high center is very near the "

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Perhaps this article needs severe cutting, to describe only “FL _nnn_”, and all the other material should be in a different article.

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Good point, I agree with your change to just remove "true" and make it more accurate on the whole. Thanks for your contributions! —

1024:"In practice, the range of pressures you are likely to encounter will be between 985mb (cold, dry day) and 1045mb (hot and humid)." 280: 262: 227: 104: 20: 1725:

Mention how much the difference between flight level elevation and real elevation could be on some days. 100 ft, a thousand feet?

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conditions.) Very high pressure *never* equals "hot and humid". It may equal "cold and dry", or, as above, hot and dry. Regards,

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Currently studying for my PPL (no instrument rating...) and here's what I have found so far. But IANAPY (I am not a pilot yet)

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https://www.eurocontrol.int/sites/default/files/content/documents/nm/airspace/airspace-atmprocedures-cta-atc-perspective.pdf

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Levels is 1000 ft, minimum, an altimeter setting error of ±0.01 in Hg is negligible and well within the margin of safety. —

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https://web.archive.org/web/20160203091332/http://base.consultant.ru/cons/cgi/online.cgi?req=doc%3Bbase%3DLAW%3Bn%3D119021

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0-179 deg (magnetic track): Odd thousands + 500 below the TA (3500, 5500, 7500), odd FL + 5 above the TL (35, 55, 75, ...)

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Should the page mention the abbreviated way of writing flight levels? (For example, is "flight level 123" = 12300 feet?)

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RVSM (Reduced Vertical Separation Minima) decreases the spacing again, but requires that your airplane is RVSM-certified.

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0-179 deg (magnetic track): Odd thousands below the TA (3000, 5000, 7000, ...), odd FL above the TL (30, 50, 70, ...)

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higher limits. Concorde had a maximum cruise level of FL600. Military aircraft obviously operate higher than this.

267:. If you would like to participate, please visit the project page, where you can join the project and see lists of 1349: 627:

180-359 deg: Even thousands + 500 below the TA (4500, 6500, 8500, ...), even FL + 5 above the TL (45, 65, 85, ...)

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Ah, answers it with pleasure. Thanks. Consider adding something like that into the article if not there already.

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to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the

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to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the

1710: 1311: 1287: 1249: 268: 208: 190: 129: 1694: 1272: 1013:: With all due respect, I must correct the significant misinformation in your post. (Better late than never.) 877: 799: 770: 727: 684: 1575: 1535: 1447: 1411: 1337: 1195: 1116: 1187: 892: 869: 791: 787:

Could we add a snippet about when/why the altimeter would be set to something other than 29.92? --Scott P.

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180-359 deg: Even thousands below the TA (4000, 6000, 8000, ...), even FL above the TL (40, 60, 80, ...)

549:". The cloud base has nothing whatever to do with flight levels. Absolutely none. So stop that already! 1446:. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit 1336:. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit 70: 1224: 1145: 978: 900: 175: 1706: 1646: 1307: 1283: 1245: 524: 492: 454: 161: 1571: 1457: 1112: 940:

Non flyers want to know: e.g., FL320: assume two days with very different pressures. What is the

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Above a certain level, the spacing increases due to inaccuracies of altimeters at high altitutes.

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before doing mass systematic removals. This message is updated dynamically through the template

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Is there an officially recognised upper limit? Does this vary by region? The upper limit for

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https://aip.caam.gov.my/aip%20pdf/ENR/ENR%201/ENR%201.7/Altimeter%20Setting%20Procedures.pdf

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Eastern European countries may or may not use flight levels based on meters instead of feet.

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In short, very low pressure doesn't usually equal "cold and dry". With the exception of a

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This is the quandrantal rule. It applies in the UK to VFR and IFR flights below FL 245:

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000°-089°|090°-179°|180°-269°|270°-359° Cruising (feet) 3 000 | 3 500 | 4 000 | 4 500

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Concluding: an opposite flight level can be described as an non-standard flight level?

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This is the second semi-circular rule. It applies to VFR flights (but not in the UK):

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Eastern European countries may or may not use true track instead of magnetic track.

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http://base.consultant.ru/cons/cgi/online.cgi?req=doc%3Bbase%3DLAW%3Bn%3D119021

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actual, real, non-pressure related, tape measure elevation this could mean?

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An opposite flight level can be defined as a non-standard flight level ???

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0-179 deg (true track): 900m and then every 600m (900, 1500, 2100, ...)

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they are just the names. The concept behind them is very simple.

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I am quite sure they are written as FL45, FL50 etc. instead of FL

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transition altitude, and thus actually usable as a flight level.

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180-259 deg: 1200m and then every 600m (1200, 1800, 2400, ...)

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The page says 'above FL245' but now has examples below FL245!

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for additional information. I made the following changes:

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for additional information. I made the following changes:

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http://www.risingup.com/fars/info/part91-159-FAR.shtml

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The IFR semi-circular rule for Russia as an example:

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0-89 deg (magnetic track): Odd FL (30, 50, 70, ...)

316: 174: 317:This article has not yet been checked against the 992:pressure related FLs are safer. OK over and out. 33:for general discussion of the article's subject. 839:, the unit used worldwide except in the USA is 1482:This message was posted before February 2018. 1358:This message was posted before February 2018. 417:assessing the article against each criterion. 8: 188: 1464:http://www.caa.co.uk/docs/33/CAP410PtA.pdf 1438:I have just modified one external link on 1328:I have just modified one external link on 644:270-359 deg: Even FL + 5 (45, 65, 85, ...) 413:| b5 409:| b4 405:| b3 401:| b2 397:| b1 313: 216: 916:What is the highest used flight level? -- 1636:(DEPARTMENT OF CIVIL AVIATION MALAYSIA) 835:The unit millibars is deprecated by the 638:90-179 deg: Odd FL + 5 (35, 55, 75, ...) 394:the following code to the template call: 261:This article is within the scope of the 1664: 218: 1431:External links modified (January 2018) 641:180-269 deg: Even FL (40, 60, 80, ...) 279:. 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Thanks. 576:Transition altitude / level... 557:Transition altitude / level... 1: 1774:WikiProject Aviation articles 1769:Start-Class aviation articles 1655:15:06, 14 February 2022 (UTC) 1229:22:16, 25 February 2013 (UTC) 831:07:58, 19 November 2009 (UTC) 292:Template:WikiProject Aviation 42:Put new text under old text. 1735:15:00, 31 January 2023 (UTC) 1550:06:34, 22 January 2018 (UTC) 1277:09:51, 1 February 2016 (UTC) 1259:Half-circle rules for France 1219:50 for levels under FL100.-- 1136:temperature or density (see 931:21:38, 28 October 2007 (UTC) 921:14:34, 28 October 2007 (UTC) 882:22:41, 12 October 2007 (UTC) 816:21:42, 28 October 2007 (UTC) 1426:09:12, 2 October 2017 (UTC) 749:13:56, 6 October 2005 (UTC) 1790: 1715:16:45, 13 March 2022 (UTC) 1699:16:40, 13 March 2022 (UTC) 1580:05:18, 26 March 2021 (UTC) 1513:(last update: 5 June 2024) 1435:Hello fellow Wikipedians, 1389:(last update: 5 June 2024) 1325:Hello fellow Wikipedians, 1316:23:26, 16 March 2016 (UTC) 1292:23:32, 16 March 2016 (UTC) 1121:05:34, 26 March 2021 (UTC) 961:02:35, 21 March 2008 (UTC) 648:Variations on this theme: 337:Referencing and citation: 1254:18:19, 29 July 2014 (UTC) 1200:20:01, 15 July 2011 (UTC) 1098:05:23, 25 June 2012 (UTC) 912:Highest used flight level 853:19:04, 10 July 2024 (UTC) 571:12:04, 22 July 2005 (UTC) 233: 215: 80:Be welcoming to newcomers 1755:05:11, 3 July 2024 (UTC) 777:) 06:43, 31 October 2005 553:22:44, 9 Nov 2003 (UTC) 535:) 01:52, 9 November 2003 503:) 00:59, 30 October 2003 476:23:55, 28 Oct 2003 (UTC) 465:) 13:25, 28 October 2003 1597:Magnetic Tracks (feet) 1321:External links modified 1167:23:13, 2 May 2008 (UTC) 1150:22:54, 2 May 2008 (UTC) 1002:02:28, 4 May 2008 (UTC) 983:20:57, 2 May 2008 (UTC) 905:21:07, 2 May 2008 (UTC) 734:) 12:16, 4 October 2005 691:) 14:15, 21 August 2005 439:Different rules in U.S. 348:Coverage and accuracy: 1633:230 | 235 | 240 | 245 1630:210 | 215 | 220 | 225 1627:190 | 195 | 200 | 205 1624:170 | 175 | 180 | 185 1621:150 | 155 | 160 | 165 1618:130 | 135 | 140 | 145 1090:Unimaginative Username 381:Supporting materials: 309: 197:This article is rated 75:avoid personal attacks 1612:11 000| NA | NA | NA 783:Altimeter calibration 512:Inconsistent examples 308: 201:on Knowledge (XXG)'s 100:Neutral point of view 1494:regular verification 1370:regular verification 806:) 03:18, 24 May 2007 264:Aviation WikiProject 105:No original research 1682:Why "semicircular"? 1484:After February 2018 1360:After February 2018 370:Grammar and style: 323:for B-class status: 1538:InternetArchiveBot 1489:InternetArchiveBot 1414:InternetArchiveBot 1365:InternetArchiveBot 754:Errr... Lazy head? 310: 203:content assessment 86:dispute resolution 47: 1514: 1390: 1190:comment added by 1165: 907: 895:comment added by 884: 872:comment added by 808: 794:comment added by 779: 765:comment added by 736: 722:comment added by 693: 679:comment added by 537: 523:comment added by 505: 491:comment added by 467: 453:comment added by 436: 435: 432: 431: 428: 427: 424: 423: 414:= <yes/no: --> 410:= <yes/no: --> 406:= <yes/no: --> 402:= <yes/no: --> 398:= <yes/no: --> 295:aviation articles 281:full instructions 183: 182: 66:Assume good faith 43: 1781: 1674: 1669: 1585:Quadrantal Rule. 1548: 1539: 1512: 1511: 1490: 1461: 1424: 1415: 1388: 1387: 1366: 1202: 1159: 890: 867: 807: 788: 778: 759: 735: 716: 692: 673: 536: 517: 504: 485: 466: 447: 418: 384: 380: 379: 373: 369: 368: 362: 358: 357: 351: 347: 346: 340: 336: 335: 314: 297: 296: 293: 290: 287: 258: 253: 252: 251: 242: 235: 234: 224: 217: 200: 194: 193: 185: 179: 178: 164: 95:Article policies 16: 1789: 1788: 1784: 1783: 1782: 1780: 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level 1327: 1324: 1301: 1266: 1262: 1238: 1216: 1212: 1206:Format of FL 1186:— Preceding 1183: 1180: 1176: 1134: 1057:four corners 1023: 1022: 990: 987: 950: 939: 924: 915: 864: 841:hectopascals 822: 810: 786: 757: 743: 713: 709: 706: 703: 699: 696: 664: 647: 630: 619: 608: 579: 564: 560: 544: 515: 442: 318: 275: 269: 263: 209:WikiProjects 171: 165: 157: 150: 144: 138: 132: 122: 94: 25:Flight level 19:This is the 1306:is 41,000. 1267:cosy-ch -- 1082:thermal low 891:—Preceding 868:—Preceding 828:Quicksilver 790:—Preceding 761:—Preceding 718:—Preceding 675:—Preceding 519:—Preceding 487:—Preceding 449:—Preceding 383:not checked 372:not checked 361:not checked 359:Structure: 350:not checked 339:not checked 276:task forces 199:Start-class 148:free images 31:not a forum 1763:Categories 1660:References 1545:Report bug 1421:Report bug 1221:Abuk SABUK 1142:82.1.57.47 1063:, forming 1061:Cajon Pass 1011:82.1.57.47 975:82.1.57.47 897:82.1.57.47 585:elevation. 547:cloud base 541:Cloud base 270:open tasks 1528:this tool 1521:this tool 1458:dead link 1404:this tool 1397:this tool 1184:Thanks! 1138:Altimeter 928:treesmill 813:treesmill 568:Blueshade 88:if needed 71:Be polite 21:talk page 1647:Psaccani 1534:Cheers.— 1410:Cheers.— 1188:unsigned 893:unsigned 870:unsigned 804:contribs 792:unsigned 775:contribs 763:unsigned 732:contribs 720:unsigned 689:contribs 677:unsigned 592:Canada). 551:GRAHAMUK 533:contribs 525:JoelKatz 521:unsigned 501:contribs 493:JoelKatz 489:unsigned 474:GRAHAMUK 463:contribs 455:JoelKatz 451:unsigned 320:criteria 286:Aviation 228:Aviation 56:get help 29:This is 27:article. 1747:Avi8tor 1727:Jidanni 1462:tag to 1444:my edit 1334:my edit 1298:Ceiling 1235:Ukraine 1157:Krellis 1086:monsoon 994:Jidanni 953:Jidanni 947:highest 845:Avi8tor 154:WP refs 142:scholar 1645:world. 1454:Added 1241:source 1215:45, FL 944:lowest 823:barely 740:Labels 205:scale. 126:Google 1239:This 843:hPa. 169:JSTOR 130:books 84:Seek 1751:talk 1731:talk 1711:talk 1695:talk 1651:talk 1576:talk 1312:talk 1304:RVSM 1288:talk 1273:talk 1250:talk 1225:talk 1196:talk 1162:Talk 1146:talk 1117:talk 1094:talk 1069:IIRC 998:talk 979:talk 957:talk 901:talk 878:talk 849:talk 837:BIPM 800:talk 771:talk 728:talk 685:talk 529:talk 497:talk 459:talk 273:and 162:FENS 136:news 73:and 1502:RfC 1472:to 1378:RfC 1348:to 746:Ojw 392:add 176:TWL 1765:: 1753:) 1733:) 1713:) 1697:) 1653:) 1578:) 1515:. 1510:}} 1506:{{ 1460:}} 1456:{{ 1391:. 1386:}} 1382:{{ 1314:) 1290:) 1275:) 1252:) 1227:) 1198:) 1148:) 1119:) 1096:) 1009:@ 1000:) 981:) 959:) 903:) 880:) 851:) 802:• 773:• 730:• 687:• 531:• 499:• 461:• 156:) 54:; 1749:( 1729:( 1709:( 1693:( 1649:( 1574:( 1547:) 1543:( 1530:. 1523:. 1423:) 1419:( 1406:. 1399:. 1310:( 1286:( 1271:( 1248:( 1223:( 1217:0 1213:0 1194:( 1164:) 1160:( 1144:( 1115:( 1092:( 996:( 977:( 955:( 899:( 876:( 847:( 798:( 769:( 726:( 683:( 527:( 495:( 457:( 283:. 211:: 172:· 166:· 158:· 151:· 145:· 139:· 133:· 128:( 58:.

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