Military time zone
Themilitary time zonesare a standardized, uniform set oftime zonesfor expressing time across different regions of the world, named after theNATO phonetic Alpha bet.The Zulu time zone (Z) is equivalent toCoordinated Universal Time(UTC) and is often referred to asthemilitary time zone. The military time zone system ensures clear communication in a concise manner, and avoids confusion when coordinating across time zones. The CCEB,representing thearmed forcesof Australia, Canada, New Zealand, the United Kingdom, and the United States, publishes the military time zone system as the ACP 121 standard.[1]The armed forces of Austria and many nations inNATOuse it.[citation needed]
Description
[edit]Going east from theprime meridianat Greenwich, letters "Alfa"[a]to "Mike" (skipping "J", see below) represent the 12 time zones with positiveUTC offsetsuntil reaching theinternational Date Line.Going west from Greenwich, letters "November" to "Yankee" represent zones with negative offsets.
The letters are typically used in conjunction withmilitary time.For example, 6:00 a.m. in zoneUTC−5is written "0600R" and spoken "zero six hundred Romeo".
The numeric zone description or "plus and minus system" indicates the correction which must be applied to the time as expressed in order to convert to UTC. For example, the zone description for the Romeo time zone is +5. Therefore, adding 5 hours to 0600R produces the time in UTC, 1100Z.[1]
Time zone name | Degrees longitude | Designation letter |
Zone description |
Offset |
---|---|---|---|---|
Alfa[a]Time Zone | 7.5 E to 22.5 E | A | −1 | UTC+01:00 |
Bravo Time Zone | 22.5 E to 37.5 E | B | −2 | UTC+02:00 |
Charlie Time Zone | 37.5 E to 52.5 E | C | −3 | UTC+03:00 |
Delta Time Zone | 52.5 E to 67.5 E | D | −4 | UTC+04:00 |
Echo Time Zone | 67.5 E to 82.5 E | E | −5 | UTC+05:00 |
Foxtrot Time Zone | 82.5 E to 97.5 E | F | −6 | UTC+06:00 |
Golf Time Zone | 97.5 E to 112.5 E | G | −7 | UTC+07:00 |
Hotel Time Zone | 112.5 E to 127.5 E | H | −8 | UTC+08:00 |
India Time Zone[b] | 127.5 E to 142.5 E | I | −9 | UTC+09:00 |
Kilo Time Zone | 142.5 E to 157.5 E | K | −10 | UTC+10:00 |
Lima Time Zone | 157.5 E to 172.5 E | L | −11 | UTC+11:00 |
Mike Time Zone | 172.5 E to 180 | M | −12 | UTC+12:00 |
November Time Zone | 7.5 W to 22.5 W | N | +1 or −13 | UTC−01:00UTC+13:00 |
Oscar Time Zone | 22.5 W to 37.5 W | O | +2 | UTC−02:00 |
Papa Time Zone | 37.5 W to 52.5 W | P | +3 | UTC−03:00 |
Quebec Time Zone[c] | 52.5 W to 67.5 W | Q | +4 | UTC−04:00 |
Romeo Time Zone | 67.5 W to 82.5 W | R | +5 | UTC−05:00 |
Sierra Time Zone | 82.5 W to 97.5 W | S | +6 | UTC−06:00 |
Tango Time Zone | 97.5 W to 112.5 W | T | +7 | UTC−07:00 |
Uniform Time Zone | 112.5 W to 127.5 W | U | +8 | UTC−08:00 |
Victor Time Zone | 127.5 W to 142.5 W | V | +9 | UTC−09:00 |
Whiskey Time Zone | 142.5 W to 157.5 W | W | +10 | UTC−10:00 |
X-ray Time Zone | 157.5 W to 172.5 W | X | +11 | UTC−11:00 |
Yankee Time Zone | 172.5 W to 180 | Y | +12 | UTC−12:00 |
Zulu Time Zone | 7.5 W to 7.5 E | Z | 0 | UTC+00:00 |
The letter "J" ( "Juliet" ), originally skipped, may be used to indicate the observer's local time.[2]The letter 'L' was previously misidentified in some editions of U.S. Army publications, such as FM 5-0,[3]as representing 'Local' time, which conflicted with its established use for the Lima time zone (UTC+11). This error has been rectified in the latest edition of FM 5-0, released in May 2022,[4]which no longer includes this incorrect usage. "LT" may also (rarely) be used to denote local time.[5]
The letter "N" is also used to designate zone −13; this is to provide for a ship in zone −12 keeping Daylight Saving Time.[1]
The letter "Z" ( "Zulu" ) indicatesCoordinated Universal Time(UTC).
The ACP 121 standard actually refers toGreenwich Mean Time(GMT) as the base time standard,[1]but UTC has superseded GMT as a more precise time standard,[6]so the time offsets are commonly understood as UTC.[7][8]
History
[edit]Sandford Flemingdevised a system assigning the letters A–Y excluding J to 1-hour time zones, which may have been the inspiration for the system.[9]
The standard was first distributed byNATOas a note in 1950. The note states "This method is based on the systems in use in the Armed Forces of these countries and the United States".[10]The British used a system of lettered zones, which was likely the direct influence.[11][better source needed]
RFC 733 published in 1977 allowed using military time zones in theDate:field ofemails.[12]RFC 1233 in 1989 noted that the signs of the offsets were specified as opposite the common convention (e.g. A=UTC−1 instead of A=UTC+1),[13]and the use of military time zones in emails was deprecated in RFC 2822 in 2001. It is recommended to ignore such designations and treat all such time designations as UTC unless out-of-band information is present.[14]
See also
[edit]Notes
[edit]- ^abThe official spelling is "Alfa", although this is often "corrected" to Alpha - seeNATO phonetic Alpha bet § History.
- ^Not to be confused withIndian Standard Time(UTC+05:30), the time zone used inIndia.
- ^Not to be confused withEastern Time Zone(UTC−5/UTC−4), the time zone used inQuebec.
References
[edit]- ^abcdCombined Communications-Electronics Board(Oct 2010).ACP 121(I), COMMUNICATION INSTRUCTIONS – GENERAL(PDF)(Report). pp. 3A-1–3A-8. Archived fromthe original(PDF)on May 8, 2016.RetrievedAug 8,2011.
- ^"ATP 6-02.70 Techniques for Spectrum Management Operations"(PDF).Retrieved2020-07-21.
- ^"Plans and Orders: Expressing Time",Army Planning and Orders Production, Field Manual 5-0 (FM 101-5)(PDF),Headquarters Department of the Army, United States Army, 20 January 2005, p. G11,
Express all times in a plan or order in terms of one time zone, for example ZULU (Z) or LOCAL (L). I
- ^FM 5-0: Planning and Orders Production.Headquarters, Department of the Army. May 2022. pp. D-6.
- ^"International Code of Signals".Maritime Safety Information.National Geospatial-Intelligence Agency.2020.Retrieved6 July2024.
'LT A120 T1540' = 'Your bearing from me is 120° at (local time) 1540'.
- ^Morris, Doug (May 2008). "Time for the Weather: Translating Zulu".Weatherwise.61(3): 32–35.doi:10.3200/WEWI.61.3.32-35.S2CID194035906.
- ^Leigh, Gabriel (17 November 2020)."Zulu and UTC: the story behind aviation's time zone".Flightradar24 Blog.
- ^"Military Time Zones".Veteran.31 October 2022.
- ^Stromberg, Joseph (November 18, 2011)."Sandford Fleming Sets the World's Clock".Smithsonian Magazine.
To this day, if you look at certain [military] maps that divide the world into time zones, the zones are assigned letters,
- ^Principal Staff Officers Committee (1950-06-15).SG 037: Method of expressing date and time in military messages(Report). NATO Archives Online.
- ^"Time Zones for Earhart Radio Message Database"(PDF).Finding Amelia Resource Library.Retrieved2 June2023.
- ^"Standard for the format of ARPA network text messages".Internet Engineering Task Force. November 1977.
- ^Braden, Robert T. (October 1989)."Requirements for Internet Hosts - Application and Support".Internet Engineering Task Force.
- ^Resnick, Pete (1 April 2001)."Internet Message Format".Internet Engineering Task Force.
External links
[edit]- "Military" time zonesdiscussion on the tz mailing list