Wikipedia:WikiProject Aviation/Style guide

This is a WikiProject advice page. It contains the advice or opinions of one or more WikiProjects on Wikipedia or its process, as pertaining to topics within the WikiProject(s) area of interest. This page is not one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community.

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The Aviation WikiProject's style guide is intended to apply to all articles within the project's scope—in other words, to all articles related to aviation. While the recommendations presented here are well-suited for the vast majority of such articles, there exist a number of peculiar cases where, for lack of a better solution, alternate approaches have been taken. These exceptions are often the result of protracted negotiation; if something seems unusual or out-of-place, it may be worthwhile to ask before attempting to change it, as there might be reasons for the oddity that are not immediately obvious!

This project should endeavor to remain consistent, firstly by abiding by the guidelines set out in the Manual of Style. Wherever necessary, this page and its subpages will set out more specific guidelines.

Style and formatting should be consistent within a Wikipedia article, though not necessarily throughout Wikipedia as a whole. Being consistent within an article promotes clarity and cohesion. Therefore, even where the Manual of Style permits alternative usages, be consistent within an article.

Wikipedia is written for the general reader, it is not a comprehensive guide to aviation nor a how-to manual. Although aviation fans will find much of interest, writing should not assume they are the target audience. Example: To many readers the term stall used in some associations will evoke the image of an engine stall which refers to a sudden stopping of the engine turning; in actuality a stall is a reduction in the lift generated by an airfoil.

In general, article naming should prefer what the greatest number of English speakers would most easily recognize, with a reasonable minimum of ambiguity, while at the same time making linking to those articles easy and second nature. The names of Wikipedia articles should be optimized for readers over editors, and for a general audience over specialists. In this case WikiProject members would be considered specialists.

Refer also Wikipedia:WikiProject Aviation/Aviation accident task force#Accident article naming conventions

An article should be named as "AIRLINE FLIGHT NUMBER", for example Air Florida Flight 90, or if there is no flight number, then "DATE LOCATION AIRLINE AIRCRAFT TYPE crash", for example 2007 Mogadishu TransAVIAexport Airlines Il-76 crash. The flight number in the article name should not include the IATA airline code or ICAO airline code (eg. "Air France Flight 447", not "Air France Flight AF447" or "Flight AF447"), even if it may be commonly used, although redirects should be created using titles that include those codes and titles using lowercase "flight" when "flight" isn't the first word of the title.

For example, the IATA code for Air France is AF and the ICAO code for Air France is AFR. Therefore, the following redirects were created for Air France Flight 447:

• AF447
• AFR447
• Flight AF447
• Flight AFR447
• Air France Flight AF447
• Air France Flight AFR447
• Air France flight AF447
• Air France flight AFR447

Where an aviation incident article does not use a common name or descriptive name as a title, and instead begins with the opening sentence: Airline Flight XYZ...., it should go on to immediately describe the notability of the incident in as few as words as possible. For this reason, it is not necessary in the opening line to clarify that the flight number may still be in use, or where it is normally scheduled to fly - this is because the normal flight or flight number is not the subject of the article. For example:

• Madeup Airline Flight 123 was a passenger flight from Somewhere to Somewhere Else, that on such and such a day, failed/crashed/blew up/was hijacked. Y
• Madeup Airline Flight 123 is a regularly scheduled passenger flight from Somewhere to Somewhere Else. On such and such a day, the aircraft used on this flight failed/crashed/blew up/was hijacked. N

The flight name using the IATA airline code and ICAO airline code may be added after the article title with a footnote that explains those codes and any flight numbers through codeshare agreements. For example, Malaysia Airlines Flight 370 begins:

• Malaysia Airlines Flight 370 (MH370/MAS370)^[a] was a scheduled international passenger flight operated by Malaysia Airlines that disappeared on 8 March 2014 while flying from Kuala Lumpur International Airport, Malaysia, to Beijing Capital International Airport in China.

In general, aircraft articles are named by their manufacturer, then by name and/or designation number, for example Boeing 747, Supermarine Spitfire.

Articles should always be named as generally as possible, so an article should only be named after a subtype (e.g. Messerschmitt Bf 109G) if writing about that specific version of the aircraft. Usually this will mean that we already have a more general article about the aircraft, relevant to all subtypes. If no general article exists, it may be worthwhile expanding the article slightly so that it encompasses all variants of the aircraft.

For guidelines specific to variants of British military aircraft refer to Wikipedia:Manual of Style/UK military aircraft designations.

Articles are placed under the most common English version of their name, for example Malaysia Airlines, El Al.

Criteria

1. In general use the word airport (or airfield, aerodrome, airbase as appropriate) in the article name.
2. Try to avoid long and unwieldy names like Dakar-Yoff-Léopold Sédar Senghor International Airport, this statement does not preclude the use of such names.
3. Try to use a name that is sourced from a government agency, or the airport operator. If you have multiple choices, use the name that is most commonly used and is precise so that a dab is not needed.

When creating airport articles, redirects should be created from any additional names that the airport may be known as. Check to see if other airports have the same name, which is quite common if you use a common name like Tri-Cities Airport or Tri-City Airport. Likewise only using the city/state/country name can also produce conflicts like San Jose Airport. Be aware that many airport articles do not yet exist so doing a search on Wikipedia for other airports with the same name can produce misleading results.

Generally, article naming should prefer what the greatest number of English speakers would most easily recognize, with a reasonable minimum of ambiguity, while at the same time making linking to those articles easy and second nature.

If that name is with a middle name or an abbreviation, make the Wikipedia article name conform to that format.

Military and award winners are sometimes identified with titles; Heinrich Gontermann is Heinrich Ritter von Gontermann after being awarded the Military Order of Max Joseph. Use the most commonly cited name, and create redirects from the other variations.

The following suggested layouts are intended to help structure a new article or when an existing article requires a substantial rewrite. Changing an established article simply to fit these guidelines should be discussed to gain consensus. The given order of sections is also encouraged but may be varied, particularly if that helps an article progressively develop concepts and avoid repetition. Suggested sections not applicable to the subject should not be included. Articles in a series should use a consistent layout. An "External links" section should be avoided, when possible, by using wikilinks and references in the body of the article.

The opening paragraph (or lead section) should concisely convey:

1. The name of the aircraft
2. Its manufacturer(s)
3. The general category of aircraft it belongs to.

Without going any further, a reader should already have a good basic idea of what kind of aircraft the article is describing.

The article can be structured along these lines:

1. The development and history behind the aircraft, often discussing why a manufacturer, airline, or air force felt there was a need for such an aircraft.
2. The design and major features of the aircraft. This can be combined with above section as "Design and development" if both sections are small, or if the text works better it they are covered together.
3. The Operational history, describing the history of the aircraft in use. This section is something like a "biography" of the aircraft.
4. Major variants and subtypes of the aircraft. These can be arranged in subsections - see Messerschmitt Me 163 for an example of how this can be done.
5. The operators, usually a collection of links to airlines or individual air force squadrons that used this type. May be separated into Military and Civilian sections if applicable and workable.
6. A list of surviving aircraft; examples exhibited in museums. If a large number of aircraft are still preserved, the list should be limited to the most prominent ones.
7. Specifications :
   Main page: Wikipedia:WikiProject_Aircraft/page_content § Aircraft_specifications

The opening paragraph (or lead section) should concisely convey:

1. The airline's name, owner of the airline and some general comments about the airline
2. The IATA and ICAO codes
3. The operational status (cargo/charter/defunct)
4. The country of origin

Without going any further, a reader should already have a good basic idea of what kind of airline the article is describing.

The article can be structured along these lines:

1. The development and history behind the airline- Care should be taken in the structure so that different versions of the airline are clearly marked.
2. A destinations list: following the world based format show in articles like Airline destinations. Once an airline has more than 10 destinations, especially international ones, they could be listed in a stand alone article
3. A list of aircraft flown by the airline and the quantity of each
4. Information about frequent flyer programs and membership clubs.
5. Major incidents and accidents over the airline's history.

When listing airlines and their destinations in airport articles, use {{Airport-dest-list}}.

A master list of destinations can be found at Wikipedia:WikiProject Aviation/Airline destination lists.

This section needs expansion. You can help by adding to it. (August 2009)

This section needs expansion. You can help by adding to it. (August 2009)

• Within this section, using {{Timeline-event}} ((as in this article) will emit metadata, making it possible, for example, to represent a timeline visually

Please see Wikipedia:WikiProject Aviation/Style guide/Layout (Airports) for the most up-to-date formats for airport articles.

This section needs expansion. You can help by adding to it.

Articles on topics that have strong ties to a particular English-speaking nation should use the appropriate variety of English for that nation. In the handful of universal articles such as Aviation the consensus is to continue using the variety of English currently in use.

Avoid lists of trivia by working these bits of information into the main body text. Sections on history, impact or popular culture can help to structure such material.

Sections on popular culture should be avoided unless the subject has had a well-cited and notable impact on popular culture. Any popular culture reference being considered for inclusion must be attributed to a reliable source for the article topic. Items meeting these requirements should typically be worked into the text of the article; a separate section for popular culture items, and in particular the following, should be avoided:

• Compendiums of every trivial appearance of the subject in pop culture (trivia)
• Unsupported speculation about cultural significance or fictional likenesses (original research)

This tends to be a particular problem in articles on aircraft ; for example, the B-17 Flying Fortress and the Spitfire may appear in any World War II film, and their many appearances don't warrant an exhaustive list. On the other hand, the overall idea of the B-17 as a symbol of American power, is certainly notable.

Links included in the See also and External links sections should be integrated into the body of the article whenever possible and used as references. Links that are already used in the body of the article or in an infobox should not be replicated in these sections.

These sections are often used as a quick and easy way to add material to an article. This is not necessarily bad, as a maintaining editor can see the worth of such a link and incorporate it in the body of the article as needed. Links must be examined as to their relationship to the context and scope of the article; if the link does not fit the context and scope, then the link should be redacted or moved to the proper article.

A best practice is to use citation templates to format external links. Web links should include the accessdate field; as these links age, they should be checked to see if they are still live or relevant and the accessdate updated. The proper use of templates also help to prevent titles and descriptions created by editors that may be exhibit POV and makes it easier for another editor to work a link in as a reference.

When there is applicable material on a sister project such as Wikiquote, Wikisource or Wikimedia Commons, then the appropriate project templates should be added to either See also or External links.

{{Portal|Aviation}} can be added to the beginning of the See also section. Other WikiProject portals may also apply.

Units in specification tables and main article text should follow those used by the original manufacturer, e.g., the Supermarine Spitfire being a British aircraft uses Imperial units primarily where the Messerschmitt Bf 109 uses the Metric system. Conversions should be provided where possible using the guidelines at Wikipedia:Manual of Style (dates and numbers).

Use italics, not boldface, for emphasis in article text. Use boldface in the remainder of the article only for a few special uses:

• In aircraft articles, variants if no header is used.

According to MOS:TITLE#Italics and Wikipedia:ITALICS#Italic face, individual named aircraft (but not prefixes, classifications, identifying numbers or other designations for them) should be italicized.

In general, the use of flag icons is not recommended; neither, however, is it prohibited. When deciding whether flag icons are appropriate in a particular context, consider:

• Do the icons convey useful information to the reader, or are they merely decorative? Icons that differentiate among several parties (for example, icons used to indicate commander allegiance in Battle of the Atlantic (1939–1945)) are likely to be useful, while icons that convey irrelevant or redundant information are usually not.
• Can flag icons be used consistently? In other words, do all the groups in a given list have usable flags? If only a few have them, it may be better to omit flags for all the items than to have a different layout for each one.
• Will adding icons disrupt the existing structure or flow of the text?

When flag icons are used, they should be historically accurate ones. In particular:

• When dealing with items related to a particular time period, avoid using anachronistic flags from other time periods. Be especially careful to avoid using the flags of modern countries for ancient ones; in many cases, the proper successor of a country no longer in existence is a matter of considerable controversy.
• Avoid using national flags in inappropriate contexts, such as for groups or individuals not aligned with any country.

When dealing with biographical infobox templates, the most common practice is to use flag icons to indicate allegiance or branch of service, but not place of birth or death. However, there remains considerable disagreement regarding the appropriateness of flags in such cases, so editors should not regard this as a universal rule.

Repeated use of a flag in a table or infobox (usually to save space and avoid repeating the country name) should only be done if the flag has been used previously in the table with the country name.

Infoboxes are used to provide a consistent summary of the subject; navboxes help readers browse through related articles. The various templates maintained by the Aviation WikiProject are all coded to use a common set of styling characteristics, as it is beneficial for providing a consistent appearance to the entire set of articles within our scope. A number of specialized templates are available for use at Wikipedia:WikiProject Aviation/Templates. Non-free images used in infoboxes should be directly related to the subject; the use of generic logos is not recommended and usually constitutes a purely decorative use.

Navigation templates specific to aviation can be found at Wikipedia:WikiProject Aviation/Templates#Footers. Non-free images should not be used in navboxes—this is considered a decorative use.

A few general guidelines apply to all aviation infoboxes:

1. Most of the fields in each infobox can be omitted if desired; the choice of which ones are appropriate for a particular article is left to the discretion of the article's editors.
2. Multiple values given in a single field should be separated by using either {{Flatlist}} or {{Plainlist}}.
3. Any use of flag icons should follow the relevant guidelines.

A primary infobox is intended to provide a summary table for some topic. It should generally be placed at the top of an article, before the lead section; this will cause it to be displayed in the top right corner.

The various navigation templates maintained by the Aviation WikiProject are all intended to be implemented using the standard navigation box format. This is beneficial for providing a consistent appearance to the entire set of articles within our scope.

Wikipedia's general policies and guidelines apply to all aviation-related lists. They are not repeated here but the more important are linked to above.

The requirement described here apply equally to embedded lists (in larger articles) and to stand-alone lists (which have their own page).

This section needs expansion. You can help by adding to it. (August 2009)

Lists should have criteria for inclusion and formatting guidelines clearly defined on the article talk page. Example: Talk:List of accidents and incidents involving commercial aircraft. The use of non-free media in lists usually fails the test for significance.

No images should be included in lists of aircraft, this is not what lists are for.

Images should not be placed before a list such that they push it downwards from its section heading or page title in mobile browsers or shrink it sideways in desktop browsers. Such images should either be placed elsewhere, for example to a gallery (but see WP:GALLERY), or not included.

Use of flags, insignia, badges, etc. should conform to MOS:FLAGS. In general this allows them only where directly relevant to the subject of the list, for example squadron insignia in a list of squadrons.

Lists with multiple columns benefit from layout as tables. The MOS:TABLES default is to avoid the use of in-table CSS markup. Special cases for its use may be agreed by a relevant WikiProject. The Aviation WikiProject has established no special cases where it may be used, therefore it should not be used in aviation-related lists.

The style guide for tables of aircraft in airline fleets is given at WP:ALFC.

Lists are generally of two kinds, simple lists of types and more complex lists including key details of the type.

Simple (e.g. bulleted) lists of aircraft types should follow the general guidelines above.

The rest of this guideline applies to lists which include additional information, do not need to be split up, and consequently benefit from being a sortable table. It comprises some general guidelines applicable to all such lists and some more detailed guidelines applicable to particular kinds of list.

A template providing preformatted table headings for some lists specified below is available as Template:avilisthead.

This guideline is not intended for anything other than tabulated lists of aircraft types.

This guideline is not exhaustive or absolute. It provides a default which should be used unless there is a good reason why it is not suitable for a particular list.

The list should be a sortable table, per WP:WHENTABLE. This allows it to be both sortable and automatically styled. Head the code with the appropriate javascript class:

{| class="wikitable sortable"

Do not use rowspan or colspan markup, as it is difficult for inexperienced editors and assistive technologies to make sense of. For example this requires that you:

• Do not use full-width subheadings: add an extra (sortable) column instead.
• Do not break up any cells into multiple rows for sub-types: either include them all in one generic entry or add a complete row for each sub-type listed.

This detail guideline is suitable for lists of aircraft having a given characteristic, for example the "List of triplanes".

Seven descriptor fields or cells are provided for each entry:

Type	Country	Class	Role	Date	Status	No.	Notes

To help in sorting sensibly, there are constraints on the values to be used in each column. These are given below.

This should be the top-level type designator. Where possible use the same name as the aircraft article, in the format [Manufacturer Type Identifier Name]. In some cases common sense will be needed to modify the type description for a particular entry.

In general, there should be only one entry (row) for each type. Exceptions may be allowable where:

• A production variant evolved from the same basic design has been given a different name.
• A production variant has a different role and is so distinct as to be virtually a different type.
• A production variant incorporates a major airframe redesign such as swept wings.

This is the country of origin for the top-level type designator. A country of local manufacture or modification should only be given if it incorporates a major airframe redesign such as swept wings, and/or a change of name.

National flags or other graphic insignia, however small, should not be used.

The class of an aircraft describes the broadest aspects of its configuration. The classes for general use are:

• Aerostat (includes airships, balloons and hybrids)
• eVTOL (electric personal air vehicles and air taxis intended for autonomous VTOL operation)
• Glider (includes motor-gliders)
• Jet (i.e. jet aeroplanes, by convention this includes direct turbine-driven turbofans)
• Propeller (i.e. propeller-driven aeroplanes, includes turboshafts and ducted fans)
• Rocket powered (i.e. rocket powered aeroplanes, includes hybrid jet + rocket)
• Rotorcraft (includes helicopters, autogyros and hybrids)
• Spaceplane
• UAV (includes drones)

These values can be expanded if need be for a particular topic, by local consensus. Some examples might be:

- A list of WWI airplanes might break down the propeller class into monoplane, biplane, triplane and quadruplane,

- The Military History project might prefer to use "Helicopter" rather than "Rotorcraft".

- A list of aerostats might choose to use Airship (rigid), Airship (semi-rigid), Airship (blimp), Balloon (hot air), balloon (gas) and Hybrid.

A great variety of roles is not helpful when sorting by role. For example Fighter, Scout, Interceptor, Escort fighter, etc. should all be listed simply as "Fighter". Similarly, there is only one description for a Bomber.

Where a type is used in multiple roles but has a primary role, the primary role should be listed. This will typically be either the role for which the type was originally designed, or the role in which it became most notable.

The roles to be used are:

• Attack
• Bomber
• Experimental (includes research)
• Fighter (includes scouts, interceptors, Zeppelin killers, etc.)
• Multi-role (use this only where the roles are of comparable importance)
• Patrol (includes surveillance, reconnaissance and observation)
• Private (includes homebuilds)
• Trainer
• Transport (use this for airliners and executive jets)
• Utility (includes mail, agricultural, firefighter, air-sea rescue, etc)

For an aircraft type which flew, this is the year of first flight.

For a dead or moribund project, this is the year the project was cancelled or became inactive.

For a currently active project this is the year the project was first announced.

Normally the number built, but may vary under local consensus.

A great variety of status descriptors is not helpful when sorting by status. For example if a type has not flown then it remains a "Project", whether or not construction was started or even finished.

The allowed values are:

• Homebuilt
• Operational (for individual craft only, such as one-offs, to which volume "production" is not really applicable)
• Production
• Project
• Prototype

Notes should be kept short and confined to key information, this is not an article lead!

Any citations or footnotes should go at the end of the main text notes.

With care, the sort function can be useful here too. For example the List of multiplane aircraft begins each entry with the number of wings.

This detail guideline applies to lists of types associated with national services and other military organisations that operate many aircraft of different types.

Lists should comprise the following columns:

Type	Origin	Class	Role	Introduced	[Status]	Total	Notes

As per general lists of types.

As per the Country column for general lists of types.

As per general lists of types.

Military roles differ slightly from the general lists of types, mainly because the class of aircraft is split off into a separate column.

The roles to be used are:

• Attack
• Bomber
• Experimental (includes research)
• Fighter (includes scouts, interceptors, Zeppelin killers, etc.)
• Multi-role (use this only where the roles are of comparable importance)
• Patrol (includes surveillance, reconnaissance and observation)
• Private (includes homebuilds)
• Trainer
• Transport (use this for airliners and executive jets)
• Utility (includes mail, agricultural, firefighter, air-sea rescue, etc)

Date on which the first machine was delivered.

A given list may include types currently in service, historical types no longer in service, or both these groups. Heading and usage of this column vary accordingly:

• For lists of types in service, this should be headed In service and include the number currently in service (this includes "hangar queens" and other individual craft which may not currently be airworthy).
• For lists of historical types it should be headed Retired and include the year of last retirement.
• For lists including both, in order for sorting on the column to remain useful, it should be headed Status and should contain entries only of the forms:
  • [No.] in service
  • Retired [Year]

This should be the total number of aircraft taken on over the type's service lifetime. It includes machines which may never have flown.

As per general lists of types.

This detail guideline is suitable for lists of aircraft designed for a given role, for example the "List of torpedo bombers".

The six columns to be used unless agreed otherwise are:

Type	Country	Class	Date	Status	No.	Notes

The Type, Country, Date, Status, No. and Notes values are as for the general list format.

The Class column should also be used as per the general format unless this is inappropriate and a local consensus agreed for a different usage. For example a List of bomber aircraft might use it to distinguish light, medium, heavy and torpedo bombers.

Policy requires that articles reference only reliable sources; however, this is a minimal condition, rather than a final goal. With the exception of certain recent topics that have not yet become the subject of extensive secondary analysis, and for which a lower standard may be temporarily permitted, articles on military history should aim to be based primarily on published secondary works by reputable historians. The use of high-quality primary sources is also appropriate, but care should be taken to use them correctly, without straying into original research. Editors are encouraged to extensively survey the available literature—and, in particular, any available historiographic commentary—regarding an article's topic in order to identify every source considered to be authoritative or significant; these sources should, if possible, be directly consulted when writing the article.

The nature of historical material requires that articles be thoroughly—even exhaustively—cited. At a minimum, the following all require direct citation:

1. Direct quotations of outside material
2. Paraphrase or other borrowing of ideas from an outside source
3. Controversial or disputed statements
4. Subjective or qualitative judgements
5. Numerical quantities or statistics

In general, any statement for which a citation has been explicitly requested by another editor should be provided with one as well.

Beyond this, editors are encouraged to cite any statement that is obscure or difficult to find in the available sources, as well as any significant statement in general. There is no numerical requirement for a particular density of citations or for some predetermined number of citations in an article; editors are expected to use their best judgement as to how much citation is appropriate. When in doubt, cite; additional citations are harmless at worst, and may prove invaluable in the long term.

In general, articles may use one of two citation styles:

• Footnotes

  Footnotes are generally the more appropriate option when the level of citation is very dense, or where the citations include additional commentary. A number of different formatting styles are available; so long as an article is internally consistent, the choice of which to use is left to the discretion of the major editors. For example, discursive notes may either be combined with citations (as here and here), or separated (as here).

  A single footnote may be used to provide citations for any amount of material; while they typically apply to one or a few sentences, they may also cover entire paragraphs or sections of text. In cases where the connection between the citations and the material cited is not obvious, it is helpful to describe it explicitly (for example, "For the details of the operation, see Smith, First Book, 143–188, and Jones, Another Book, chapters 2–7; for the international reaction, see Thomas, Yet Another Book, 122–191").

• Harvard-style references

  Harvard-style references are useful where a limited number of simple citations is needed; they typically should not be used if the article has a significant number of other items in parentheses, or if citations must be accompanied by commentary.

The final choice of which style to follow is left to the discretion of an article's editors.

Editors should attempt to take a reasonable approach when requesting citations. Unless the accuracy of a statement is in significant doubt, it is generally better to start with a request for citations on the article's talk page, rather than by inserting {{fact}} tags—particularly large numbers of such tags—into the article. Over-tagging should be avoided; if a large portion of the article is uncited, adding an {{unreferenced}} or {{citation style}} tag to an entire section is usually more helpful than simply placing {{fact}} tags on every sentence. Note that some articles contain per-paragraph citations, so checking the citations at the end of a paragraph may yield information about facts or figures in the paragraph as a whole.

An alternate to this scheme is currently drafted at Wikipedia:WikiProject Aircraft/Categories/Proposed update.

1. Top-level categories, such as Category:Aviation and Category:Aircraft, should not be populated. (Their category pages can be marked with the {{catdiffuse}} template.) Specific subcategories should be used such as Category:United States airliners 1940–1949.
2. Articles should not generally be in both a category and a subcategory of it. For example, do not put someone in both Category:Canadian airliners 1990–1999 and Category:Canadian aircraft 1990–1999, because the first is a subcategory of the latter. (For exceptions to this rule see SUBCAT.)

The category scheme originates in one root category—Category:Aviation—and can be thought of as a tree structure. A guide to the top-level sub-categories of this category is presented below; for brevity, a number of categories that are rarely used or lie outside the scope of this project have been omitted.

Category:Aviation

Root category for matters related to aviation. This category should be empty of articles,

Category:Aerobatics

Root category for all topics related to aerobatics.

.....

A number of naming conventions exist specifically for category names; most of these are used to ensure consistent naming among all the sub-categories of a particular category.

"X by country"

In most cases, sub-categories of a category named "X by country" take names of the form "X of [the] Y", where Y is the most common name of the country in question. For example:

• Category:Aviation by country → "Aviation in [the] Y" (as in Category:Aviation in Canada)
• Category:Aircraft by country → "Aircraft manufactured by of [the] Y" (as in Category:Aircraft manufactured by Israel)
• Category:Airlines by country → "Airlines of [the] Y" (as in Category:Airlines of the United States)
• Category:Airports by country → "Airports in [the] Y" (as in Category:Airports in Australia)
• Category:Aviation accidents and incidents by country → "Aviation accidents and incidents in [the] Y" (as in Category:Aviation accidents and incidents in Germany)

"X by period"

In most cases, sub-categories of a category named "X by period" take names of the form "X Y", where Y is the name of the period of the subject in question. For example:

• Category:Aircraft by period → "Aircraft Y" (as in Category:Aircraft 1900-1909)
• Category:Airlines by year of establishment → "Airlines established in Y" (as in Category:Airlines established in 1958)

"X by type"

In most cases, sub-categories of a category named "X by type" take names of the form "Y X", where Y describes the type in question. For example:

• Category:Aircraft by type → "Y aircraft" (as in Category:Hypersonic aircraft)
• Category:Airports by type → "Y airport" (as in Category:Defunct airports)

Note that this form of category tree tends to exhibit more varied naming than the others. For example, Category:Aircraft by type also includes the non-standard Category:Airliners (since "Airliner aircraft" would be a cumbersome name).

Intersection categories

The names of intersection categories generally follow the same conventions as above, with the name components of their parent categories placed in normal grammatical order (usually with era given after country). This produces, for example, "Canadian aircraft 1960-1969" (country and era) and "Canadian military trainer aircraft 1930-1939" (country, type, and era).

In general, articles and categories should be placed in the most specific applicable categories, and should not be placed directly in a "parent" category if they are already present in one of its sub-categories. In other words, if an article is placed in Category:United States airliners 1940-1949, there is no need to place it in Category:United States civil aircraft 1940-1949 or Category:Aircraft manufactured by the United States as well.

Note, however, that this applies only to direct placement into a "parent" category; it is normal for a category to have multiple indirect paths up to some other category higher in the tree. For example, Category:United States military transport aircraft 1940-1949 is both a sub-category of Category:Military transport aircraft 1940-1949 (which is a sub-category of Category:Military aircraft 1940-1949) and a sub-category of Category:United States military aircraft 1940-1949 (which is also a sub-category Category:Military aircraft 1940-1949); thus, there are two distinct paths from Category:United States military transport aircraft 1940-1949 up to Category:Military aircraft 1940-1949. This is especially common when dealing with intersection categories.

This section needs expansion. You can help by adding to it. (July 2009)

This section needs expansion. You can help by adding to it. (July 2009)

This section needs expansion. You can help by adding to it. (July 2009)

This section needs expansion. You can help by adding to it. (July 2009)

Airport articles should include the most specific category possible based on location. Each country has its own airport category, which can be found at Category: Airports by country (also available grouped by continent at Category: Airports by continent). For example, Copenhagen Airport in Denmark includes Category: Airports in Denmark.

Some larger countries have sub-categories for first level administrative divisions, such as state or province. These can be found under the country's airport category and should be used where available. For example, Québec City Jean Lesage International Airport in the Canadian province of Quebec includes Category: Airports in Quebec, a sub-category of Category: Airports in Canada (which is not added to the article).

Airport articles often include a location category for an administrative division below that of the airport category. For example, Nice Côte d'Azur Airport in Nice, France, includes both Category: Airports in France and Category: Nice.

Besides the location related categories, some airport articles may include other categories, such as those listed at Category: Airports by type. For example, Independence State Airport in the U.S. state of Oregon includes Category: Residential airparks in addition to Category: Airports in Oregon and Category: Polk County, Oregon.