Editing MGM-31 Pershing (section)

==Pershing 1a==
{{Infobox weapon
| name               = Pershing 1a
| image              = Launch of Pershing IA (26 Oct 1976).png
| image_size         = 200px
| alt                = missile launching, missile in foreground prepared for launch
| caption            = Pershing 1a launched from the [[Eastern Range]], [[Cape Canaveral Air Force Station]], Launch Complex 16 by C Battery, 3rd Battalion, 84th Field Artillery on 26 October 1976
| origin             = United States
| type               = Surface-to-surface guided missile
| is_missile         = yes
| service            = 1969–1991
| used_by            = {{plainlist|
* [[United States Army]] 108 launchers
* [[German Air Force]] 72 launchers}}
| designer           = [[Martin Marietta]]
| design_date        = 1965–1969
| manufacturer       = Martin Marietta
| unit_cost          = 
| production_date    = 1969
| number             = 754 MGM-31A missiles
| weight             = {{convert|10275|lb|kg|0}}<ref name=OR_3,149 />
| length             = {{convert|34.6|ft|m|1}}
| diameter           = {{convert|40|in|m|0}}
| yield              = {{unbulleted list|[[W50 (nuclear warhead)|W50]] nuclear warhead|{{convert|60|ktonTNT|PJ}}|{{convert|200|ktonTNT|PJ}}|{{convert|400|ktonTNT|PJ}}}}
| engine             = {{unbulleted list|First stage: [[Thiokol]] TX-174|{{convert|25900|lbf|kN}} 38.3 s|Second stage: Thiokol TX-175|{{convert|19100|lbf|kN}} 39 s}}
| vehicle_range      = {{convert|460|mi|km}}
| speed              = Mach 8
| guidance           = [[Pioneer Instrument Company|Eclipse-Pioneer]] ST-120 [[Inertial navigation system|inertial guidance]]
| steering           = Jet vanes, air vanes
| accuracy           = {{convert|1310|ft|m|-1}} [[circular error probable]]
| boost              = 77.3 seconds
| launch_platform    = [[M790]] erector launcher
| transport          = [[M757]] 5-ton tractor
}}

===Development===
In 1964 a series of operational tests and follow-on tests were performed to determine Pershing reliability. The Secretary of Defense then requested that the Army define the modifications required to make Pershing suitable for the Quick Reaction Alert (QRA) role. The Pershing 1a development program was approved in 1965, the original Pershing renamed to Pershing 1 and Martin Marietta received the Pershing 1a production contract in 1967. Project SWAP replaced all the Pershing equipment in Germany by mid-1970 and the first units quickly achieved QRA status. Secretary of Defense [[Robert McNamara]] directed that the U.S. Air Force's [[MGM-13 Mace]] missile would be replaced by the Pershing 1a in 1965.<ref name="parsch"/>

Pershing 1a was a Quick Reaction Alert system and so had faster vehicles, launch times and newer electronics.<ref name="moore"/> The total number of launchers increased from 8 to 36 per battalion. Production of the Pershing 1a missile ended in 1975 and reopened in 1977 to replace missiles expended in training.

Pershing 1a was further improved in 1971 with the Pershing Missile and Power Station Development Program. The analog guidance computer and the control computer in the missile were replaced by a single digital guidance and control computer. The main distributor in the missile that routed power and signals was replaced with a new version. The missile used a rotary inverter to convert DC to AC that was replaced by a solid-state static inverter. The power station was improved for accessibility and maintenance.<ref name="fieldartilleryman1971-8"/> Further improvements in 1976 allowed the firing of a platoon's three missiles in quick succession and from any site without the need for surveying.<ref name="fieldartilleryjournal1976-5"/> The Automatic Reference System (ARS) used an optical laser link and a north-seeking gyro with encode to eliminate the need for pre-selected and surveyed points. The Sequential Launch Adapter connected the PTS to three missiles, eliminating the need to cable and uncable each launcher.

A total of 754 MGM-31A missiles were built.<ref name=OR_3,149/>

===Deployment===
The battalions in Europe reorganized under a new [[table of organization and equipment]] (TOE); an [[infantry]] [[battalion]] was added to provide additional security; and the 56th Artillery Group was reorganized and redesignated the 56th Field Artillery Brigade. Due to the nature of the weapon system, officer positions were increased by one grade: [[Artillery battery|batteries]] were commanded by a [[major (United States)|major]] instead of a [[Captain (United States O-3)|captain]]; battalions were commanded by a [[colonel (United States)|colonel]]; and the [[brigade]] was commanded by a [[Brigadier general (United States)|brigadier general]].{{r|fm611|page1=2-4}}

Pershing 1a was deployed with three U.S. battalions in Europe and two German Air Force wings. Each battalion or wing had 36 mobile launchers. The constitution of West Germany prohibited owning nuclear weapons, thus control of the nuclear warheads remained in the hands of the U.S. Army. During peacetime operations, a portion of the Pershing 1a assets were deployed on the QRA mission. The remainder would be conducting field training or were maintained in [[kaserne]]s awaiting alert. The system was designed to be highly mobile, permitting its dispersal to clandestine sites in times of alert or war and was deployed at distances greater than 100&nbsp;km behind the [[Front line|forward edge of battle area]] or political border. Owing to its mobility and setback, Pershing was considered one of the most survivable theater nuclear weapons ever deployed in Europe.

The primary mission in the [[Supreme Allied Commander|Supreme Allied Commander, Europe]] scheduled plan took one of two forms: peacetime or an increased state of readiness called the period of tension. Different levels or techniques of tasking were used for these mission forms. The peacetime Quick Reaction Alert role required that for each battalion or wing, one firing battery or a portion thereof would be combat alert status (CAS) on a permanent hard site, covering assigned targets.

In peacetime the four batteries of each battalion rotated through four states or conditions of alert readiness, the highest being that of the CAS battery. The purpose of this rotation was to assume the CAS status, to share the burden of CAS responsibility, to provide time for field tactical training and equipment maintenance, and to give ample leave and pass time to personnel without adverse impact on operational requirements.

During periods of increased tension, the firing batteries of each battalion were deployed to previously unused field tactical sites. At these sites, they assumed responsibility for coverage of all assigned targets. During the transition from the peacetime to full combat status, coverage was maintained on the highest priority targets that were assigned to the peacetime CAS batteries.

Once all firing batteries were at their field sites, the firing elements of the battalions were deployed by platoons, which were then separated from each other geographically to reduce vulnerability. The platoons then moved to new firing positions on a random schedule to increase survivability.

===Launcher and support equipment===
The M790 erector launcher (EL) was a modified low-boy flat-bed trailer towed by a [[Ford Motor Company|Ford]] M757 5-ton tractor.<ref name="tm43-001-31_4-286"/> The erection booms used a 3,000&nbsp;psi pneumatic over hydraulic system that could erect the five&nbsp;ton missile from horizontal to vertical in nine seconds. Due to the overall missile length and for security, the warhead was not mated during travel. It was stored in a carrier and mated using a hand-pumped davit after the launcher was emplaced. The EL was pulled by a Ford M757 tractor for U.S. Army units and by a [[Magirus-Deutz]] Jupiter 6×6 for German Air Force units.

The PTS and PS were mounted on a Ford [[M656]] truck for U.S. Army units and a Magirus-Deutz or [[MAN SE]] for German Air Force units.<ref name="tm43-001-31_4-202"/> Launch activation was performed from a remote fire box that could be deployed locally or mounted in the battery control central (BCC). One PTS controlled three launchers— when one launch count was complete, ten large cables were unplugged from the PTS and the PTS was moved up and connected to the next launcher.

===Further improvements===
Missile and power station upgrades in 1974 provided easier access to missile components, reduce maintenance and improved reliability. A new digital guidance and control computer combined the functions of the analog control computer and the analog guidance computer into one package. The [[mean time to repair]] decreased from 8.7 hours to 3.8 hours and the [[mean time between failures]] increased from 32 hours to 65 hours.

More modifications in 1976 greatly reduced the launch time. The sequential launch adapter (SLA) was an automatic switching device mounted in a 10-ton trailer that allowed the PTS to remain connected to all three launchers allowing all three missiles to stay hot. The automatic reference system (ARS) eliminated the theodolites previously used to lay and orient the missile. It included a north-seeking gyro and a laser link to the ST-120 that more quickly oriented the missile.

After the Pershing II explosion in 1985, the Pershing 1a launchers of the German Air Force were retrofitted with ballistic shields.

In 1987 a joint Army/[[United States Department of Energy|Department of Energy]] study concluded that it was technically and financially feasible to replace the W50 warhead carried by Pershing 1a with the W85 warhead developed for Pershing II. However, with the signing of the INF Treaty, development on the conversion was terminated.<ref>{{cite report |date=1987 |title=Nuclear Weapons Surety - Annual Report to the President |url=https://documents.theblackvault.com/documents/nuclear/NuclearSurety1987.pdf |archive-url=https://web.archive.org/web/20141021212001/http://documents.theblackvault.com/documents/nuclear/NuclearSurety1987.pdf |archive-date=2014-10-21 |url-status=live |publisher=US Department of Defense and US Department of Energy |page=21 |docket= |access-date=26 July 2022 |quote=}}</ref>

===Gallery===
<gallery class="center">
Pershing 1a.png|alt=erect missile on launcher|Pershing 1a missile system
PTS PS (Pershing 1a).png|alt=Programmer Test Station and Power station on truck|Programmer Test Station and Power station
BCC (Pershing 1a).png|alt=Battery Control Central on truck|Battery Control Central
AN TRC-80 Radio Terminal Set (Pershing 1a).png|AN/TRC-80 Radio Terminal Set
Pershing Azimuth Reference System.png|alt=soldier aiming Azimuth Reference System|Azimuth Reference System
File:Pershing 1A des FKG 2.jpg|West German Erector Launcher with ballistic shields
</gallery>