The US Navy’s E-6B Mercury aircraft is a key component of the United States’ strategic nuclear deterrent. Thoughts are turning to its replacement.
On 19th April, the US Air Force’s (USAF) Global Strike Command test-launched a Boeing LGM-30G Minuteman-III Intercontinental Ballistic Missile (ICBM) from Vandenburg airbase, California. The test had been planned “months in advance,” according to an air force press release. Nonetheless, it followed Russia’s suspension of her cooperation in the bilateral New Strategic Arms Reduction Treaty (New START) on 21st February. The New START treaty was signed by the US and Russia in April 2010.
Alongside the ICBM launch, the Airborne Launch Control System (ALCS) equipping the US Navy’s Boeing E-6B Mercury TACAMO (Take Charge and Move Out) platform was tested. The ALCS can convey commands to launch ICBMs using the aircraft’s communications links. This means that ICBMs can be launched remotely if their own command and control centres, and hardened land communications, are destroyed by a nuclear strike.
Chain of Command
The US President is the only person who can authorise the use of US strategic nuclear weapons. To understand how the TACAMO aircraft work it helps to understand the nuclear decision-making process. Should the President order the use of nuclear weapons, authorisation will be provided using the ‘football’. This is a briefcase containing specialist communications equipment and documents. The latter provide a series of nuclear war plans. Communications are established with the US Department of Defence (DOD) and the US Strategic Command (USSTRATCOM), the military custodian of the US nuclear deterrent. The President then verifies their identity using a series of unique codes. Once this is done, USSSTRATCOM communicates the order to launch nuclear weapons in accordance with the President’s preferred course of action.
Orders are communicated to US nuclear forces in the form of Emergency Action Messages (EAMs) authorising the use of nuclear weapons. EAMs are sent across numerous communications networks. These include the Advanced Extremely High Frequency (AEHF) military communications satellite constellation. The AEHF uses frequencies of 20 gigahertz/GHz and 40GHz. The DOD’s MILSTAR Satellite Communications (SATCOM) carry EAMs although this constellation is being replaced by the AEHF satellites.
Very Low Frequency (VLF) radio transmissions on frequencies of three kilohertz/KHz to 30KHz are also used. VLF is particularly suitable as transmissions can travel for thousands of miles and penetrate several metres underwater. This makes it ideal for sending EAMs to submarines which maybe thousands of miles away from the Continental United States. Low Frequency (LF) radio transmissions on a 14KHz to 60KHz waveband are used primarily to communicate with the ICBM force. Meanwhile, the High Frequency Global Communications System (HFGCS), using a three megahertz/MHz to 30MHz waveband, relays EAMs to USAF strategic bombers. This is in addition to standard military cable telecommunications linking nuclear installations to one another.
US strategic nuclear forces include the LGM-30G ICBMs circa 400 of which are deployed in silos ready for launch across the midwestern United States. The USAF maintains freefall B-61 and B-83 nuclear bombs deployed by Boeing B-52H Stratofortress and Northrop Grumman B-2A Spirit strategic bombers. These aircraft also deploy the Boeing AGM-86B air-to-surface nuclear missile. The US Navy’s element includes ‘Ohio’ class nuclear-powered ballistic missile submarines. The boats carry Lockheed Martin UGM-133A Trident-D5/5LE submarine-launched ballistic missiles.
Having several communications systems available to carry EAMs makes sense from a redundancy perspective. For example, if SATCOM is jammed conventionally or through cyberattack, if satellites or their ground stations are kinetically damaged or destroyed other conduits like VLF, LF or the HFGCS can be used. TACAMO aircraft can relay EAMs across these links to the nuclear forces.
Thoughts are now turning to the E-6B’s replacement. In 2020, the US Navy chose Lockheed Martin’s C-130J turboprop airlifter as the preferred platform for the E-XX TACAMO programme. Ironically, the United States Navy is going back to the fold by choosing the C-130 as the preferred platform. The original TACAMO platform was the EC-130G/Q which entered service in 1968. The current TACAMO platform is Boeing’s E-6B Mercury, based on the 707 series airliner.
“While the E-6B continues to meet mission requirements, it is an aging airframe that has been in service for more than three decades,” the US Navy told Armada in a written statement. The statement continued that the TACAMO mission will be integrated onto a C-130J30 variant. This aircraft will only perform the communications relay segment of the TACAMO task. “The E-6B will continue to execute the airborne command post mission,” the statement articulated. “A separate analysis of alternatives will recommend which aircraft will take on that mission after the E-6B sundown” with a timeline still to be decided. Three test C-130J30s are to be delivered to the navy starting in 2026. While Collins Aerospace has already been selected to provide the VLF system, the navy is in the process “of developing the competitive request for proposals for mission systems integration,” with more details becoming available to this end later this year.
by Dr. Thomas Withington