Talk:Airbus A350/Archive 2

Archive 1

Archive 2

A question.

The title of this article is "Airbus A350 XWB", although when a certain variant is referred to, the "XWB" is gone. This is what I mean:

Aircraft series: Airbus A350 XWB

Variant 1: Airbus A350-900

Variant 2: Airbus A350-1000

Variant 3: Airbus A350-900ULR

Notice that none of the variants have "XWB" in them. Why is that? Is it because "Airbus A350-900 XWB" (for example) would be too long? Or is it due to something else?

Something very similar happens with the Boeing 787 Dreamliner:

Aircraft series: Boeing 787 Dreamliner

Variant 1: Boeing 787-8

Variant 2: Boeing 787-9

Variant 3: Boeing 787-10

...and Boeing 777X series:

Aircraft series: Boeing 777X

Variant 1: Boeing 777-8

Variant 2: Boeing 777-9

EnjoyingMyProblems (talk) 09:11, 1 September 2019 (UTC)

To distinguish with the initial A330-derived A350. Read the history for more. --Marc Lacoste (talk) 14:56, 1 September 2019 (UTC)

Units

[moved from my talk page, more relevant here.--Marc Lacoste (talk) 19:52, 29 October 2019 (UTC)]

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[Context: the discussion is about the units used to measure the distance between NYC and SIN for the -900ULR flight]--Marc Lacoste (talk) 06:08, 30 October 2019 (UTC)

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I don't like miles either, but please remember that the world is bigger than yourself. Most of our UK and US readers probably only know statute miles, while av pros and geeks prefer nautical miles. Wikipedia should be written for those folks as well. As Airbus use nm as their primary unit, see e.g. their technical documentation, page 154, nm should be the primary unit per Wikipedia:WikiProject_Aviation/Style_guide#Units. [unsigned, 19:39, 29 October 2019, ExcitedEngineer]

Airbus is an european airframer, and preferred units are thus the metric system. UK is metric since 1965. The ACAP is not technical documentation but a memento for airport planning. Airbus engineering is done in meters. If an other unit is to be shown, the customary unit in aviation is the nmi. If there is already a mile conversion, an another conversion in land miles would be superfluous. I do not care about units, all are fundamentally abstract. I do care about wikipedia legibility. 2 units are already hard to read. 3 are too much. --Marc Lacoste (talk) 19:52, 29 October 2019 (UTC)

I have no doubt the engineering at Airbus is performed in metric, however their preferred unit in external communication is still nm. In my opinion, it is clear as day that in modern aviation, we use feet for altitude, knots for speed and nm for distance. Also, there is no guideline that states two conversions are too many. As per MOS:CONVERSIONS: "Where an imperial unit is not part of the US customary system, or vice versa – and in particular, where those systems give a single term different definitions – a double conversion may be appropriate.". Many readers unfamiliar with aviation will know only km or only statue miles. It is a minor inconvenience to see a value expressed in three units, it is a major inconvenience to see it expressed in two and understand neither. In all honesty, I tend to stay away from talk page discussions like these and feel we have both spent way too much time on such a trivial issue. However, I do think it lays bare a need for better guidelines in wikiproject aviation. ExcitedEngineer (talk) 20:32, 29 October 2019 (UTC)

WP:Aircraft is the more appropriate Wiki project for aircraft. It is busier and falls under WP:Aviation. Listing two unit conversions here does seem excessive in this case, imo. -Fnlayson (talk) 20:42, 29 October 2019 (UTC)

WP:Aircraft is indeed more specific to this page, but it uses the style guide over at WP:Aviation.ExcitedEngineer (talk) 20:57, 29 October 2019 (UTC)

WP:Air has its own guide, a page content page at WP:Air/PC. And WP:Air is still more active. -Fnlayson (talk) 21:03, 29 October 2019 (UTC)

Conversions are free, and most English speakers are used to using either kilometres or miles, so they should definitely both be included; and as it's related to aviation it seems appropriate to also include nautical miles. So, as I see it, the only decision to make is which is primary: kilometres or nautical miles. -- DeFacto (talk). 21:51, 29 October 2019 (UTC)?

WP:Air specs gives a good guide: use the manufacturer's national system first, eg metric for european/russian aircraft, imperial for US/UK pre metrification.--Marc Lacoste (talk) 06:08, 30 October 2019 (UTC)

@ExcitedEngineer in modern aviation, we use feet for altitude, knots for speed and nm for distance. Not only. Flight levels are not really in hundreds of feet but in equivalents in pressure altitude. The Mach number, not a constant speed, is critical for transsonic airliners. Even the distance is often given in hours as most jetliners have a similar speed. And many parts of aviation are metric first: gliding or within Russian influence... The unit itself is an abstract thing and does not matter so much. We could convert in furlongs or in light years if we want to, but Wikipedia has to stay readable. --Marc Lacoste (talk) 08:53, 30 October 2019 (UTC)

@Marc Lacoste: just a wee correction: the UK may have metricated some things over the years, mainly to do with commerce, manufacture, trading weights and measures, and government administration - but Joe Public still very much use imperial measures, particularly for their pints of beer, their weights (stone and pounds), their heights (feet and inches) and distances are very much still measured in inches, feet, yards and miles and speeds and speed limits are in mph. -- DeFacto (talk). 21:33, 29 October 2019 (UTC)

DeFacto: I know the nuance. On the mainland we still use the pint to order beers (and we lose a bit: it's half a liter not 0.57 L) or the pound at the grocery store (0.5kg, a bit more than 0.45 kg). I measure my surfboards or screens in ftin. When I rent a UK car, mph is used but it does not matter as the dashboard is also in mph. On the other hand, Flight International gives metric units first since a long time (and even metric only in the metrification period). While wikipedia is a general encyclopedia, it still thrives for quality. I think it would be preferable to follow Flight than average Joe.--Marc Lacoste (talk) 06:08, 30 October 2019 (UTC)

My impression, confirmed by a quick straw poll, is that on the vast majority of aviation pages we tend to follow industry practice and use nmi and km only, with statute miles rarely added. This is equally true for pages relating to US manufacturers. It might be useful to clarify this on Wikipedia:WikiProject Aviation/Style guide#Units – or perhaps better still, continue this discussion on the style guide talk page to get wider project consensus. Rosbif73 (talk) 07:51, 30 October 2019 (UTC)

Wikipedia:WikiProject Aviation/Style guide#Units is clear that if Airbus use nm then we should use nm on any Airbus article. Certainly, add km conversion but more than that gets tedious. I see no need for discussion of other options unless we want to revisit the guideline, and the place to do that is Wikipedia talk:WikiProject Aviation/Style guide. — Cheers, Steelpillow (Talk) 11:18, 30 October 2019 (UTC)

In its ACAPs, Airbus use nmi along km (not miles) only in its payload-range diagrams. In most tech specs (weight, dimensions) the preferred units are metric, and the imperial units are between parentheses. That's the way its specs are displayed in Wikipedia, too. I think this present consensus is shared between you, me, Rosbif73 and Fnlayson for 2 units (nmi and km). correct me if I'm wrong.--Marc Lacoste (talk) 12:11, 30 October 2019 (UTC)

Agreed. I have not checked whether Airbus habitually put nm or km first, but I am sure others will soon clarify that. — Cheers, Steelpillow (Talk) 15:22, 30 October 2019 (UTC)

Airbus uses nautical miles exclusively (A350) or primarily (A320) in its payload-range charts and exclusively in its press releases and its section on the A350-900ULR. So can we at least agree that per Wikipedia:WikiProject Aviation/Style guide#Units, nm should be the primary unit? ExcitedEngineer (talk) 21:43, 31 October 2019 (UTC)

@ExcitedEngineer: I agree with nautical miles being primary. -- DeFacto (talk). 21:58, 31 October 2019 (UTC)

The ICAO, while insisting on standardising with the metric system, has put termination of the customary units for specific measurements off indefinitely. See International_Civil_Aviation_Organization#Use_of_the_International_System_of_Units. It's true that statute miles are hardly ever used by manufacturers or in industry literature, but our audience is different. About half of our readers are from the US or the UK. The vast majority of them are either much less familiar or completely unfamiliar with nautical miles and kilometers. ExcitedEngineer (talk) 19:23, 30 October 2019 (UTC)

For those unfamiliar with unit variation but looking at aircraft articles, it's always possible to link the units or add lk=on to convert templates, like 10,000 km (5,400 nmi).--20:40, 30 October 2019 (UTC)

The best way to cater for those who prefer miles - and why make it any more difficult for them than for those who prefer kilometres - is to follow the advice given in MOS:CONVERSIONS. It says Where English-speaking countries use different units for the same quantity, provide a conversion in parentheses. And as double conversions are possible I would propose that we do that now, rather than waste anymore time on this valueless discussion. The syntax is "{{cvt|16,561|km|nmi mi}}" which renders as "16,561 km (8,942 nmi; 10,291 mi)" or "{{cvt|16,561|km|nmi km mi|order=out}}" which renders as "8,942 nmi (16,561 km; 10,291 mi)", depending on which is considered to be the primary unit. -- DeFacto (talk). 22:14, 30 October 2019 (UTC)

So why stop here? Why not going the extra mile (pardon the pun) for 16,561 km (8,942 nmi; 10,291 mi; 82,320 furlongs; 0.00011070 AU; 3,430 leagues; 3,293,000 perches; 9,731,000 sm)? The point is, we have to found an equilibrium between exhaustivity and readability. The current usage in aircraft article is km + nmi. 3 units may be a deterrent, more so because the nmi and mi are close.--Marc Lacoste (talk) 05:42, 31 October 2019 (UTC)

If you can show there is a likely call for those other units too, then you might have a good point. However, there is no recommendation for them mentioned in the MOS. I think, for now, that kilometres and miles cover the vast majority of English speakers, but neither cover enough to justify omitting the other. So let's just stick with the normal three, unless we are happy to drop nautical miles. -- DeFacto (talk). 06:52, 31 October 2019 (UTC)

Maybe you're less familiar with aviation units, even in UK/US, distances are quoted in nmi and airspeed indicators are in knots, not in mi and mph, which are used for ground transportation. nmi should prevail over mi.--Marc Lacoste (talk) 09:23, 31 October 2019 (UTC)

@Marc Lacoste: it is not whether I am familiar with aviation units that matters here, it is whether a significant number of readers are likely to benefit from the addition of the conversion to miles that matters. And as it is so easy to accommodate both nautical and statute miles (it is not an either/or) then it is clear that we would need a very strong argument indeed (which I do not think we have seen yet) to deny those readers that courtesy. -- DeFacto (talk). 13:04, 31 October 2019 (UTC)

As Marc says, in aviation (as in the maritime) when a distance is given in "miles" it means nautical miles.[1] Those in the field are so familiar with nm they do not bother to specify. The uninformed writer or reader will be unaware of this and may falsely assume that "miles" unspecified means statute. Consequently, secondary and tertiary sources are often either unclear or unreliable as to what "miles" they are quoting. Those who are clear about it may well prove to be following industry practice.[2] Confirming the accuracy or otherwise of every number in unclear sources is not really practical, while discovering how many readers actually care that much about exact numbers of statute miles is even more subjective: uninformed editorial opinion is worthless. There is an obvious case here to include statute miles on a case by case basis, as and when both context and reliable source material demand it, but not otherwise. This article is no different from any other in this respect. — Cheers, Steelpillow (Talk) 09:27, 31 October 2019 (UTC)

Units part II

@Marc Lacoste: why, specifically, {{convert}} is "not needed" here? GregorB (talk) 22:59, 15 December 2019 (UTC)

Hello to you too. Because the ref states both units: This gained an additional 22.3m2 (240ft2) of wing area. Convert templates are useful when the ref lacks one.--Marc Lacoste (talk) 07:13, 16 December 2019 (UTC)

• OK, but this is really just two ways to the same destination (except maybe for rounding or an error). -Fnlayson (talk) 15:05, 16 December 2019 (UTC)

• I took issue with Marc over this some time back, as the results should of course be the same in theory. But I have since understood his logic; in practice, when a reference states two units, we often don't know which way round the conversion was done, nor how many digits were intended to be significant, so rounding issues can and do crop up. Rosbif73 (talk) 15:24, 16 December 2019 (UTC)

• Yes, very good points! -Fnlayson (talk) 15:31, 16 December 2019 (UTC)
• But do we need to retain the rather substandard ft², even if the source uses it? GregorB (talk) 21:24, 16 December 2019 (UTC)

Of course not, apply the relevant WP:MOS! (thanks to Rosbif73 for putting in better words than me the reasoning!)--Marc Lacoste (talk) 22:18, 16 December 2019 (UTC)

Revert of formatting edit

@Marc Lacoste: I do not understand why you reverted my edit – the use of {{cvt}} generates exactly the same values while keeping consistent formatting. I see that you want to keep the values from the ref, but the template does not change something as slight as rounding (the numeric representation is identical), and the mathematical conversion certainly does not change. Could you please explain your reasoning, and why I should not reinstate this change when it seems to benefit the article at no cost? ComplexRational (talk) 12:56, 20 January 2020 (UTC)

Hi, @ComplexRational: it's to avoid rounding errors, the source already have made the conversion, but the original number is not known. A future edit may output the result differently (I saw it before in /specs/ sections), so I avoid the template when both are stated by the source. If your goal is to have consistent formatting, you can use a non-breaking space or the {{val}} template: a separation of content and presentation. Cheers, --Marc Lacoste (talk) 14:03, 20 January 2020 (UTC)

OK then, I used {{val}} instead and I think this resolves the problem. I'm not sure exactly what you mean by output, but I'll leave it to this for now (unless/until different values are published). Thank you for your response. ComplexRational (talk) 20:25, 20 January 2020 (UTC)