Talk:Flight level

message: Someone keeps inserting "See Also cloud base". The cloud base has nothing whatever to do with flight levels. Absolutely none. So stop that already! GRAHAMUK 22:44, 9 Nov 2003 (UTC)
thread_title: Cloud base

message: 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...
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? - Blueshade 12:04, 22 July 2005 (UTC)
thread_title:  Transition altitude / level... 

message: Should the page mention the abbreviated way of writing flight levels? (For example, is "flight level 123" = 12300 feet?) Ojw 13:56, 6 October 2005 (UTC)
thread_title: Labels

message: Could we add a snippet about when/why the altimeter would be set to something other than 29.92? --Scott P. —Preceding unsigned comment added by 204.169.62.46 (talk • contribs) 03:18, 24 May 2007
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. treesmill 21:42, 28 October 2007 (UTC)
replies: text: "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 barely 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 Levels is 1000 ft, minimum, an altimeter setting error of ±0.01 in Hg is negligible and well within the margin of safety. —QuicksilverT @ 07:58, 19 November 2009 (UTC)
thread_title: Altimeter calibration

message: 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?  —Preceding unsigned comment added by 212.72.19.146 (talk) 22:41, 12 October 2007 (UTC)
replies: text: 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!).  —Preceding unsigned comment added by 82.1.57.47 (talk) 21:07, 2 May 2008 (UTC)
thread_title:  Question could arise need an answer 

message: What is the highest used flight level? --88.77.226.109 14:34, 28 October 2007 (UTC)
thread_title:  Highest used flight level 

message: 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 temperature or density (see Altimeter), 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. 82.1.57.47 (talk) 22:54, 2 May 2008 (UTC)
replies: text: Good point, I agree with your change to just remove "true" and make it more accurate on the whole.  Thanks for your contributions! —Krellis (Talk) 23:13, 2 May 2008 (UTC)
thread_title:  True altitude 

message: 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 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.
Concluding: an opposite flight level can be described as an non-standard flight level?
Thanks!  — Preceding unsigned comment added by 86.34.199.124 (talk) 20:01, 15 July 2011 (UTC)
thread_title:  An opposite flight level can be defined as a non-standard flight level ??? 

message: * I am quite sure they are written as FL45, FL50 etc. instead of FL045, FL050 for levels under FL100.--Abuk SABUK (talk) 22:16, 25 February 2013 (UTC)
thread_title:  Format of FL 

message: This source 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? Martinevans123 (talk) 18:19, 29 July 2014 (UTC)
thread_title:  Ukraine 

message: 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 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. 
cosy-ch  --81.13.181.100 (talk) 09:51, 1 February 2016 (UTC)
replies: text: Do you have a source? Thanks. Martinevans123 (talk) 23:32, 16 March 2016 (UTC)
thread_title:  Half-circle rules for France 

message: Is there an officially recognised upper limit? Does this vary by region? The upper limit for RVSM is 41,000. Martinevans123 (talk) 23:26, 16 March 2016 (UTC)
thread_title:  Ceiling 

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thread_title:  External links modified 

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thread_title:  External links modified (January 2018) 

message: 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.
Perhaps this article needs severe cutting, to describe only “FL _nnn_”, and all the other material should be in a different article.
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 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.
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 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.
Martin Kealey (talk) 05:18, 26 March 2021 (UTC)
thread_title:  lacking NPOV re metric vs imperial 

message: 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 https://aip.caam.gov.my/aip%20pdf/ENR/ENR%201/ENR%201.7/Altimeter%20Setting%20Procedures.pdf:
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.
Magnetic Tracks (feet)
000°-089°|090°-179°|180°-269°|270°-359° 
Cruising (feet)
3 000 | 3 500 | 4 000 | 4 500
5 000 | 5 500 | 6 000 | 6 500
7 000 | 7 500 | 8 000 | 8 500
9 000 | 9 500 | 10 000 | 10 500
11 000| NA | NA | NA
Cruising Flight Level (1013.2 HPa)
130 | 135 | 140 | 145
150 | 155 | 160 | 165
170 | 175 | 180 | 185
190 | 195 | 200 | 205
210 | 215 | 220 | 225
230 | 235 | 240 | 245
(DEPARTMENT OF CIVIL AVIATION MALAYSIA)
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* 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. 
 
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 world.Psaccani (talk) 15:06, 14 February 2022 (UTC)
thread_title:  Quadrantal Rule. 

message: 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 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.
64.222.159.22 (talk) 16:40, 13 March 2022 (UTC)
replies: text: 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 they are just the names. The concept behind them is very simple. Martinevans123 (talk) 16:45, 13 March 2022 (UTC)
thread_title:  Why "semicircular"? 

message: Mention how much the difference between flight level elevation and real elevation could be on some days. 100 ft, a thousand feet? Jidanni (talk) 15:00, 31 January 2023 (UTC)
thread_title:  How large could the difference be