View source for Boeing E-6 Mercury

{{short description|Airborne command post aircraft by Boeing based on 707 airframe}}
{{hatnote|"E-6B" redirects here. For the analog flight computer, see [[E6B]]. For the road in Pakistan, see [[E6B expressway (Pakistan)]]}}
{{Use dmy dates|date=March 2023}}
<!--This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout, and guidelines. -->
{{Infobox aircraft
| name = E-6 Mercury
| image = United States Navy Boeing E-6B Mercury of Strategic Communications Wing ONE, Task Group 114.jpg
| caption = Boeing E-6 Mercury
| type = Airborne command and control
| manufacturer = [[Boeing]]
| designer = 
| first_flight = 19 February 1987
| introduction = August 1989
| retired = 
| number_built = 16
| status = In service
| primary_user = [[United States Navy]]
| more_users = 
| developed_from = [[Boeing 707]]
| variants = 
}}

The '''Boeing E-6 Mercury''' (formerly '''E-6 Hermes''') is an airborne command post and communications [[Radio repeater|relay]] based on the [[Boeing 707-300]]. The original E-6A manufactured by [[Boeing Defense, Space & Security|Boeing's defense division]] entered service with the [[United States Navy]] in July 1989, replacing the [[Lockheed EC-130|EC-130Q]]. This platform, now modified to the E-6B standard, conveys instructions from the [[National Command Authority (United States)|National Command Authority]] to [[Fleet submarine|fleet]] [[ballistic missile submarine]]s (see [[communication with submarines]]), a mission known as [[TACAMO]] ("Take Charge And Move Out").

The E-6B model deployed in October 1998 has the ability to remotely control [[LGM-30 Minuteman|Minuteman ICBMs]] using the [[Airborne Launch Control System]]. The E-6B replaced Air Force [[Boeing EC-135|EC-135Cs]] in the ''[[Operation Looking Glass|Looking Glass]]'' role, providing command and control of U.S. nuclear forces should ground-based control become inoperable. With production lasting until 1991, the E-6 was the final new derivative of the Boeing 707 to be built.<ref>Breffort, 2008. p. 235.</ref>

==Design and development==
[[File:Navy-e6-070403-07-16.jpg|thumb|Navy E-6B Mercury at the [[Mojave Air and Space Port]]]]

Like the [[Boeing E-3 Sentry|E-3 Sentry]] [[Airborne early warning and control|Airborne Warning and Control System]] aircraft, the E-6 is adapted from Boeing's [[Boeing 707|707-320]] airliner. Rolled out at Boeing's [[Boeing Renton Factory|Renton Factory]] in December 1986,<ref name=pronjt>{{cite news |url=https://news.google.com/newspapers?id=EotfAAAAIBAJ&pg=4860%2C902676 |work=Lewiston Morning Tribune |location=Idaho |agency=Associated Press |title=Boeing shows prototype of new jet |date=19 December 1986 |page=5B}}</ref> the first E-6 made its [[maiden flight]] in February 1987, when it was flown to nearby [[Boeing Field]] in south [[Seattle]] for fitting of mission avionics. It was delivered to the Navy for testing in July 1988.

The E-6B is an upgrade of the E-6A. It includes a battle staff area and updated mission equipment. The flight deck systems were later replaced with a better, cheaper off-the-shelf [[Boeing 737 Next Generation|737 Next Generation]] cockpit. The first E-6B was accepted in December 1997. All 16 E-6A aircraft were modified to the E-6B standard, with the final delivery taking place in December 2006.<ref>Walsh, Madonna and Brad Mudd. [http://www.boeing.com/news/releases/2006/q4/061201b_nr.html "Boeing Delivers Final Upgraded E6-B to U.S. Navy."] {{webarchive |url=https://web.archive.org/web/20061205110326/http://www.boeing.com/news/releases/2006/q4/061201b_nr.html |date=5 December 2006 }} ''Boeing'', 1 December 2006. Retrieved: 18 June 2011.</ref>

Unlike most Navy aircraft that use the probe-and-drogue in-flight refueling method, the E-6 has a flying boom receptacle on the upper-forward fuselage so it can be refueled by the [[U.S. Air Force]]’s larger tanker fleet of [[KC-135 Stratotanker]]s and [[KC-46 Pegasus]]es.<ref name="GARB">{{cite web |title=Refueling a Shadow |url=https://www.grissom.afrc.af.mil/Home/Photos/igphoto/ |website=Grissom Air Reserve Base |access-date=1 September 2020}}</ref>

==Operational history==
Codenamed [[Looking Glass (airplane)|''Looking Glass'']], the E-6 is [[United States Strategic Command]]'s (USSTRATCOM) Airborne Command Post (ABNCP). It is designed to take over in case the Global Operations Center at [[Offutt Air Force Base]], [[Nebraska]], is destroyed or incapable of communicating with nuclear forces. The term "Looking Glass” reflects the way the ABNCP "mirrors" the GOC’s abilities.<ref>{{Cite web |url=http://www.stratcom.mil/Media/Factsheets/Factsheet-View/Article/960928/e-6b-airborne-command-post-abncp/ |title=USSTRATCOM ABNCP Fact Sheet |access-date=7 May 2017 |archive-url=https://web.archive.org/web/20170420143950/http://www.stratcom.mil/Media/Factsheets/Factsheet-View/Article/960928/e-6b-airborne-command-post-abncp/ |archive-date=20 April 2017 |url-status=live }}</ref>

The E-6A, initially named [[Hermes]], entered service with squadron [[Fleet Air Reconnaissance Squadron 3 (United States Navy)|VQ-3]] in August 1989. A second squadron, [[Fleet Air Reconnaissance Squadron 4 (United States Navy)|VQ-4]], received its first E-6As in January 1991, allowing the EC-130Q to be phased out in June 1991. The&nbsp;E-6A was renamed [[Mercury (mythology)|Mercury]] in autumn 1991 at the Navy’s request.<ref name="AI Jan95p21">Francillon 1995, p. 21.</ref> Sixteen E-6A planes were delivered from 1988 to 1992.<ref>Breffort, 2008. p. 93</ref>

The E-6 fleet is based at [[Tinker Air Force Base]], [[Oklahoma]], and operated by [[Fleet Air Reconnaissance Squadron 3 (United States Navy)|Fleet Air Reconnaissance Squadron 3 (VQ-3)]], [[Fleet Air Reconnaissance Squadron 4 (United States Navy)|VQ-4]], and VQ-7.<ref>{{Cite web|url=https://www.airpac.navy.mil/Organization/Fleet-Air-Reconnaissance-Squadron-VQ-7/About-Us/|title = About Us}}</ref>

In 2021, one of the [[Boeing E-3 Sentry|E-3D Sentry]] aircraft that had been in service with the [[Royal Air Force]] was purchased for conversion into a dedicated E-6 trainer. This was done as a means to extend the life of the operational fleet by reducing the need for E-6s to be used for training missions.<ref>{{cite web |url=https://www.navalnews.com/naval-news/2021/08/pma-271-purchased-a-retired-raf-e-3d-to-be-used-as-an-e-6b-mercury-pilot-training-aircraft/ |title=PMA-271 Purchased A Retired RAF E-3D To Be Used As An E-6B Mercury Pilot Training Aircraft |last= Maranache|first=Martin |date=4 August 2021 |website=Naval News |publisher= |access-date=9 August 2021 |quote=}}</ref> The project was canceled in May 2025, and a new contract was issued to [[Northrop Grumman]] for the salvage of spare parts and eventual scrapping of the airframe.<ref name="z271">{{cite web | last=Langford | first=Craig | title=US scraps TE-6B conversion of ex-British E-3D Sentry | website=UK Defence Journal | date=2025-06-06 | url=https://ukdefencejournal.org.uk/us-scraps-te-6b-conversion-of-ex-british-e-3d-sentry/ | access-date=2025-06-20}}</ref>

=== Replacement ===
In 2015, both the Air Force and Navy realized that they needed new aircraft to serve the missions of both the E-4 and the E-6. At one point, they considered building one plane to replace both aircraft, but by 2020, the Navy decided to go its own way and develop an aircraft specifically for the TACAMO mission, under the [[Lockheed E-XX|E-XX TACAMO]] program. The Air Force independently pursued an E-4 replacement under the [[Survivable Airborne Operations Center]] program.

The Navy selected a variant of the [[Lockheed EC-130|Lockheed EC-130J]], specifically one derived from the lengthened [[Lockheed Martin C-130J Super Hercules|C-130J-30]]. Initial orders were placed in late 2020 with development beginning in earnest in 2022.<ref>{{Cite web |last=Jennings |first=Gareth |date=21 Dec 2020 |title=US Navy to field C-130J-30 in nuclear communications role |url=https://www.janes.com/defence-news/news-detail/us-navy-to-field-c-130j-30-in-nuclear-communications-role |url-status=live |archive-url=https://web.archive.org/web/20231028053806/https://www.janes.com/defence-news/news-detail/us-navy-to-field-c-130j-30-in-nuclear-communications-role |archive-date=28 Oct 2023 |access-date=2023-10-30 |website=Janes.com |language=en}}</ref> Delivery of the first aircraft is expected in FY26.<ref>{{Cite web |last=Newdick |first=Thomas |date=2022-04-05 |title=This Is Our First Look At The Navy's Next 'Doomsday Plane,' The EC-130J TACAMO |url=https://www.twz.com/45086/this-is-our-first-look-at-the-navys-next-doomsday-plane |access-date=2024-10-01 |website=The War Zone |language=en-US}}</ref> The Navy expects the E-6 to fulfill the TACAMO role into the 2030s as the E-XX is transitioned into service.

In October 2024, the replacement aircraft was officially named [[Lockheed Martin E-130J|E-130J]].<ref>{{cite web|title=TACAMO community announces name for new mission aircraft: E-130J|url=https://www.dvidshub.net/news/483549/tacamo-community-announces-name-new-mission-aircraft-e-130j|website=www.dvidshub.net|date=2024-10-21|publisher=Airborne Strategic Command, Control and Communications Program Office|access-date=2024-10-21}}</ref>

==Specifications (E-6B)==
{{stack|
[[File:Navy-e6-070403-03cr-6.jpg|thumb|Detail of the E-6's wingtip]]
[[File:KC-135 refueling E-6B.jpg|thumb|A U.S. Navy E-6B Mercury refuels from a USAF 434th Air Refueling Wing KC-135R Stratotanker (2011)]]
}}
{{Aircraft specs
|ref=Jane's all the world's aircraft, 1992–93<ref name=JAWA92-93>{{cite book |title=Jane's all the world's aircraft, 1992–93 |date=1992 |editor1-last=Lambert |editor1-first=Mark |editor2-last=Munson |editor2-first=Kenneth |editor3-last=Taylor |editor3-first=Michael J.H. |publisher=Jane's Information Group |location=Coulson, Surrey, UK |isbn=0710609876 |edition=83rd |pages=349–350}}</ref>
The US Navy – Fact File: E-6B Mercury Airborne Command Post<ref name=E6_fact_file>{{cite web |title=The US Navy – Fact File: E-6B Mercury airborne command post |url=https://www.navy.mil/navydata/fact_display.asp?cid=1100&tid=800&ct=1 |website=www.navy.mil |access-date=22 February 2024 |date=17 February 2009 |archive-url=https://web.archive.org/web/20190616183057/https://www.navy.mil/navydata/fact_display.asp?cid=1100&tid=800&ct=1 |archive-date=16 June 2019 |url-status=dead }}</ref>
|prime units?=kts
<!--
        General characteristics
-->
|crew=22
|length ft=150
|length in=4
|length note=
|span ft=148
|span in=4
|span note=
|height ft=42
|height in=5
|height note=
|wing area sqft=283.4
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil=<!--'''root:''' [[NACA airfoil|NACA]]; '''tip:''' [[NACA airfoil|NACA]]<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref>-->
|empty weight lb=172795
|empty weight note=
|gross weight lb=
|gross weight note=
|max takeoff weight lb=342000
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=4
|eng1 name=[[CFM International CFM56-2A-2]]
|eng1 type=[[turbofan]] engines
|eng1 kw=<!-- prop engines -->
|eng1 hp=<!-- prop engines -->
|eng1 shp=<!-- prop engines -->
|eng1 kn=<!-- jet/rocket engines -->
|eng1 lbf=<!-- jet/rocket engines -->
|eng1 note=
<!--
        Performance
-->
|max speed kts=522
|max speed note=dash speed
|max speed mach=
|cruise speed kts=455
|cruise speed note=at {{cvt|40000|ft|0}}
|stall speed kts=
|stall speed note=
|never exceed speed kts=
|never exceed speed note=
|minimum control speed kts=
|minimum control speed note=
|range nmi=6600
|range note=
|combat range nmi=6350
|combat range note=
|ferry range nmi=
|ferry range note=
|endurance= on station at {{cvt|1000|nmi|mi km}}
** 10 hours 30 minutes unrefueled
** 28 hours 54 minutes with one refueling
** 72 hours maximum with multiple refuelings
|ceiling ft=40000
|ceiling note=
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|climb rate ftmin=
|climb rate note=
|time to altitude=
|wing loading lb/sqft=112.13
|wing loading note=
|fuel consumption lb/mi=
|thrust/weight=0.281
|more performance=
* '''Critical field length:''' {{cvt|6700|ft|0}}
* '''Max effort take-off run:''' {{cvt|5400|ft|0}}
* '''Landing run at max landing weight:''' {{cvt|2600|ft|0}}
|avionics=
* AN/ARC-182 VHF/UHF TxRx
* AN/ARC-190 HF
* AN/AIC-32 Crew Intercom
* triplex Litton LTN-90
* LTN-211 VLF/Omega
* Smiths SFM 02 digital/analog flight management system
* AN/APS-133 colour weather radar
}}

==See also==
{{aircontent
|see also=
|related=
* [[Boeing 707]]
* [[Airborne Launch Control System]]
|similar aircraft=
* [[Boeing E-4]]
* [[Boeing EC-135]]
* [[Northrop Grumman E-10 MC2A]]
* [[Ilyushin Il-80]]
* [[Tupolev Tu-142#Variants|Tupolev Tu-142MR]]
|lists=
* [[List of active United States military aircraft]]
}}

==References==
{{Reflist}}

==Bibliography==
{{Refbegin}}
* Francillon, René J. (1995). "Messenger of the Gods: The Boeing E-6 Mercury in USN Service." ''[[Air International]]'', Vol. 48, No 1, January 1995, pp.&nbsp;19–24.
* Breffort, Dominique (2008). ''Boeing 707, KC-135 and Civilian and Military Versions''. Paris: Histoire & Collections, 2008. {{ISBN|978-2-35250-075-9}}, pp.&nbsp;93–94
{{Refend}}

==External links==
{{Commons category|Boeing E-6}}
* [https://www.navy.mil/Resources/Fact-Files/Display-FactFiles/Article/2162873/e-6b-mercury-airborne-command-post/ US Navy E-6B Mercury Fact File page]
* [http://www.stratcom.mil/Media/Factsheets/Factsheet-View/Article/960928/e-6b-airborne-command-post-abncp/ USSTRATCOM ABNCP Fact Sheet]
* [http://www.fas.org/nuke/guide/usa/c3i/e-6.htm E-6 Mercury (TACAMO) page at FAS.org]
* [https://web.archive.org/web/20110921004333/http://tech.military.com/equipment/view/89732/e-6-mercury.html E-6 Mercury page on tech.military.com]

{{707 military variants}}
{{US EW aircraft}}

[[Category:Boeing aircraft|E-06 Mercury]]
[[Category:1980s United States command and control aircraft|E-06 Mercury, Boeing]]
[[Category:Quadjets]]
[[Category:United States nuclear command and control]]
[[Category:Boeing 707]]
[[Category:Aircraft first flown in 1987]]
[[Category:Low-wing aircraft]]
[[Category:Aircraft with retractable tricycle landing gear]]