- A-PNT — Alternative Position, Navigation and Timing
- A portfolio of non-GNSS navigation technologies — chip-scale atomic clocks, signals of opportunity, vision-inertial, celestial, terrain-relative — used when GPS is denied or degraded.
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- Diagram
- A&D — Aerospace & Defense
- Industry sector covering aircraft, spacecraft, missiles, defence electronics, and their suppliers. Distinct from commercial aerospace alone — A&D explicitly bundles military and dual-use programmes alongside civil aviation.
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- DiagramTry it: Aerospace Defense Industry GuideTry it: Software Testing GuideTry it: Aerodef Standards Guide+1 more
- A2/AD — Anti-Access / Area Denial
- Military strategy and capabilities designed to prevent an adversary from entering or operating freely within a contested operational area. Combines long-range strike, air defense, mines, and cyber capabilities.
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- A2AD — Anti-Access / Area Denial
- Strategy to prevent an adversary entering or operating in a theatre.
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- A2G — Air-to-Ground
- Engagement direction descriptor for weapons, sensors, or communications operating from an airborne platform against a surface target. Distinguishes from A2A (air-to-air) and S2A (surface-to-air) in joint planning notation.
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- 3D modelTry it: Air Ground WtaTry it: Multi Domain Spectrum PlannerTry it: Modern Warfare Guide
- AA — Assembly Area
- An area in which a unit assembles to prepare for further action.
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- AADC — Area Air Defense Commander
- The commander responsible for planning and integrating air and missile defense within a joint operations area.
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- AADL — Architecture Analysis & Design Language
- A modelling language for embedded real-time systems that describes both software and the hardware it runs on, so timing, scheduling and safety properties can be analysed before anything is built.
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- AAM — Air-to-Air Missile
- A guided missile fired from an aircraft to destroy another airborne target.
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- AAP-06 — NATO Glossary of Terms and Definitions
- NATO Allied Administrative Publication 6 — the authoritative bilingual (English/French) dictionary of NATO terminology used across doctrine, planning, and standardisation documents. Updated continuously by the NATO Standardization Office.
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- DiagramTry it: Orbat GuideTry it: Ttps Guide
- AAR — After Action Review
- A structured review process after an operation or training event. Covers what was planned, what happened, why, and what to sustain/improve. Foundational to organizational learning.
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- DiagramTry it: Leop Commissioning GuideTry it: Cultural Transformation SimulatorTry it: Wargaming Methodology Guide+1 more
- AAV — Assault Amphibious Vehicle
- USMC tracked amphibious troop carrier. Mk1 AAV variant mounts a triple-shot MICLIC for mechanised breach.
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- AAW — Anti-Air Warfare
- Defense of a naval force or ground formation against airborne threats including aircraft, cruise missiles, and UAVs. Integrates sensors, weapons, and command systems across multiple platforms.
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- 3D modelTry it: Joint Ops GuideTry it: Orbat Guide
- AAWC — Anti-Air Warfare Commander
- The warfare commander responsible for coordinating air and missile defense of a force.
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- ABCT — Armored Brigade Combat Team
- A brigade combat team built around tanks and mechanized infantry for high-intensity ground combat.
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- ABMS — Advanced Battle Management System
- The US Air Force component of JADC2 — a family of programmes to integrate sensors, decision aids, and shooters across air, space, and cyber. Emphasises open-architecture software-defined networking.
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- DiagramTry it: Tdl GuideTry it: Modern Warfare GuideTry it: Defense Missions Guide+1 more
- AC
- Actual Cost — the money actually spent on the work completed so far.
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- ACA — Airspace Coordination Area
- A designated block of airspace in which friendly aircraft are reasonably safe from friendly surface fires.
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- ACARS — Aircraft Communications Addressing and Reporting System
- A datalink system for exchanging short messages between aircraft and ground stations over radio or satellite.
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- ACAS — Airborne Collision Avoidance System
- The ICAO term for an aircraft system that operates independently of ground equipment to warn of collision risk.
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- ACAT I/II/III — Acquisition Category
- DoD 5000.02 programme classification by dollar value and decision authority. ACAT I (Major Defense Acquisition, MDAP) requires USD(A&S) approval; ACAT II is service-level; ACAT III is program-manager-level. Drives oversight rigour, reporting cadence, and review structure.
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- Diagram
- ACC — Area Control Centre
- An ICAO facility that provides air traffic control service to en-route aircraft within a flight information region.
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- Acceptance Test
- The final test-phase before contract acceptance, executed against the contracted requirements. Successful acceptance triggers payment and assumption of ownership. Typically witnessed by the customer or their authorised QA representative.
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- DiagramTry it: Waterfall Test GuideTry it: Software Testing GuideTry it: Space Standards Guide+1 more
- Acceptance Testing
- The final test phase where the customer verifies a delivered system meets contracted requirements. Success triggers acceptance and payment; failures return the system to the supplier for rework.
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- DiagramTry it: Space Program LifecycleTry it: Digital ProcurementTry it: Aerospace Defense Industry Guide+1 more
- ACE — Agile Combat Employment
- Dispersed, expeditionary basing concept for air forces — operating from multiple austere locations to complicate adversary targeting and increase survivability.
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- ACH — Analysis of Competing Hypotheses
- A structured analytic technique developed by Richards Heuer (CIA). Lists all plausible hypotheses, evaluates each against every piece of evidence, and rejects the one most inconsistent with the evidence.
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- DiagramTry it: Critical Thinking SimTry it: Homeland Security FundamentalsTry it: Defense Fundamentals Guide+1 more
- ACINT — Acoustic Intelligence
- Intelligence derived from the collection and analysis of acoustic (sound) signatures.
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- ACM — Airspace Coordinating Measures
- Measures employed to facilitate the efficient use of airspace and deconflict friendly air and surface activities.
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- ACO — Allied Command Operations
- The NATO strategic command responsible for planning and executing all Alliance operations.
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- ACPR — Adjacent Channel Power Ratio
- The ratio of power leaking into an adjacent channel relative to the main channel power.
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- ACR — Armored Cavalry Regiment
- A self-contained combined-arms regiment historically used for reconnaissance, security, and economy-of-force missions.
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- ACT — Allied Command Transformation
- The NATO strategic command responsible for warfare development, training, and capability transformation.
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- Active Radar Homing
- A missile seeker architecture where the missile carries its own radar transmitter and receiver. Provides fire-and-forget engagement but increases seeker size, cost, and RF vulnerability.
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- DiagramTry it: Defense Fundamentals GuideTry it: Defense Breakthrough Guide
- ACV — Amphibious Combat Vehicle
- A wheeled armored personnel carrier that transports Marines from ship to shore and inland.
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- ADC — Air Data Computer
- A computer that converts pitot-static sensor inputs into airspeed, altitude, and other air data parameters.
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- ADCAP — Advanced Capability (Torpedo)
- The Mk 48 ADCAP upgrade providing improved guidance, speed and target discrimination.
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- ADCON — Administrative Control
- Direction over subordinate forces for administration and support, including personnel, logistics, and readiness.
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- ADCS — Attitude Determination and Control System
- Subsystem responsible for determining and controlling the orientation (attitude) of a spacecraft using sensors (star trackers, sun sensors, gyroscopes) and actuators (reaction wheels, thrusters, magnetorquers).
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- ADF — Automatic Direction Finder
- An onboard radio receiver that indicates the bearing to a tuned non-directional beacon or AM station.
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- ADIRU — Air Data Inertial Reference Unit
- A combined unit providing air data and inertial reference outputs to an aircraft’s avionics systems.
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- ADIZ — Air Defense Identification Zone
- Airspace over land or water within which the identification of aircraft is required in the interest of national security.
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- Adjudication
- The process of resolving the outcomes of wargame moves. Can be rigid (table-driven), semi-rigid (judgement against published rules), or free (expert panel). Choice drives replayability versus credibility trade-off.
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- DiagramTry it: Wargaming Methodology GuideTry it: Ttps GuideTry it: Cbrn Defense Guide
- Adjudication (Wargaming)
- The process of determining outcomes of player actions in a wargame. Methods include deterministic (fixed combat results tables), stochastic (probability-based with dice or Monte Carlo), and expert panel (subject matter expert assessment).
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- ADP — Army Doctrine Publication
- A publication containing the fundamental principles guiding the actions of Army forces.
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- ADR — Active Debris Removal
- Technologies and missions designed to remove existing orbital debris. Approaches include harpoon capture, net capture, robotic arm grapple, and laser ablation.
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- 3D modelTry it: Ssa GuideTry it: Space Environment Effects Guide
- ADS-B — Automatic Dependent Surveillance – Broadcast
- Aircraft broadcasts GNSS position for surveillance without radar.
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- ADS-C — Automatic Dependent Surveillance – Contract
- A datalink surveillance mode where an aircraft reports position on a contract basis, used in oceanic and remote airspace.
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- ADSI — Air Defense Systems Integrator
- A system that correlates and displays air tracks from multiple sensors to support air defense and airspace control.
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- AE9/AP9 — Radiation Belt Models
- NASA's latest trapped radiation environment models. AE9 models trapped electrons; AP9 models trapped protons. Replace legacy AE8/AP8 models with improved statistical treatment and data from CRRES and Van Allen Probes.
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- Diagram
- AED — Automated External Defibrillator
- A portable device that analyzes heart rhythm and delivers a shock to restart a heart in cardiac arrest.
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- AEGIS — Aegis Combat System
- An integrated shipboard combat system centered on the SPY radar for coordinated air/missile defense.
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- AEHF — Advanced Extremely High Frequency
- US protected military SATCOM in GEO providing jam-resistant, low-probability-of-intercept communications for strategic and tactical users. Supports nuclear C2 (NC2).
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- AEP — Acquisition Execution Plan
- DoD programme document describing how the strategy in the Acquisition Strategy will be executed — schedule, resources, risks, dependencies, and decision points. Paired with the Test & Evaluation Master Plan (TEMP) and Systems Engineering Plan (SEP).
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- DiagramTry it: Waterfall Test Guide
- AES — Advanced Encryption Standard
- Symmetric block cipher selected by NIST in 2001 as the replacement for DES. Operates on 128-bit blocks with key sizes of 128, 192, or 256 bits. AES-256 is approved by the NSA for Top Secret classified data.
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- AESA — Active Electronically Scanned Array
- Radar architecture using thousands of individual transmit/receive modules to steer beams electronically with no moving parts. Enables simultaneous multiple modes, rapid beam switching, and LPI waveforms.
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- AEW — Airborne Early Warning
- Aircraft-mounted radar systems (e.g., E-3 AWACS, E-7 Wedgetail) providing extended detection range and over-the-horizon surveillance, compensating for ground radar line-of-sight limitations.
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- AFATDS — Advanced Field Artillery Tactical Data System
- The Army system that automates fire support planning, coordination, and control of field artillery fires.
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- AFDX — Avionics Full-Duplex Switched Ethernet
- Deterministic switched Ethernet for aircraft, standardised as ARINC 664 Part 7. Bandwidth is reserved per virtual link so latency is bounded — ordinary Ethernet gives no such guarantee.
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- AFSC — Air Force Specialty Code
- An alphanumeric code identifying an Air Force member’s occupational specialty and skill level.
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- AFTS — Autonomous Flight Termination System
- An onboard flight-termination system that triggers autonomously without ground range commands.
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- AG — Array Gain
- The improvement in signal-to-noise ratio achieved by coherently combining the elements of a receiving array.
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- AGC — Automatic Gain Control
- A receiver circuit that adjusts gain to keep signal level constant despite fading on the link.
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- AGL — Above Ground Level
- Altitude measured relative to the terrain directly below.
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- AGS — Alliance Ground Surveillance
- A NATO wide-area ground surveillance capability providing radar imagery and moving-target data to member forces.
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- AHRS — Attitude and Heading Reference System
- A system of sensors that provides aircraft attitude and heading information to displays and autopilots.
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- AI — Artificial Intelligence
- Software that performs tasks normally needing human judgement. In this estate it means the inference services in apps/ai and the assistants built on them.
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- AI-Disruption — AI Disruption of Aerospace & Defense
- The accelerating impact of artificial intelligence on aerospace and defence — autonomy, decision aids, generative design, predictive maintenance, software-defined systems. Reshaping job mix, programme economics, and operational concepts.
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- Diagram
- AI-Governance — AI Governance
- The policies, processes, and oversight mechanisms ensuring AI systems are developed and used responsibly. EU AI Act, NIST AI RMF, US DoD AI Ethical Principles, and IEEE 7000-series standards are the leading frameworks.
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- DiagramTry it: Ethics Standards Guide
- AIDC — ATS Interfacility Data Communication
- A datalink protocol used to exchange coordination and transfer messages between adjacent air traffic control units.
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- AIP — Air-Independent Propulsion
- A propulsion technology allowing conventional submarines to operate submerged without atmospheric oxygen.
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- Air Combat
- Combat between aircraft, traditionally close-in (within visual range) but increasingly BVR. Modern air combat blends the BFM (basic fighter manoeuvres), missile geometry (LAR), and sensor fusion across the four-ship.
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- Air Defense
- All measures designed to nullify or reduce the effectiveness of hostile aircraft and missile attacks. Active (interceptors, SAMs, guns) and passive (camouflage, hardening, dispersal). Foundational to any IADS architecture.
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- DiagramTry it: Aerospace Defense Industry GuideTry it: Defense Missions GuideTry it: Defense Fundamentals Guide+1 more
- Air Interdiction
- Air operations against hostile targets outside the immediate range of friendly forces, typically targeting lines of communication, reserves, and logistics to shape the battlespace before contact.
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- Diagram
- Air-to-Ground
- Engagement direction descriptor for weapons or sensors employed by an airborne platform against a surface target. Encompasses CAS (close air support), AI (air interdiction), strategic attack, and SEAD/DEAD.
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- AIRAC — Aeronautical Information Regulation and Control
- A system that coordinates the effective dates of aeronautical information changes on a fixed 28-day cycle.
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- AIRMET — Airmen’s Meteorological Information
- A weather advisory of conditions less severe than SIGMET but potentially hazardous to lighter aircraft.
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- AIS — Automatic Identification System
- Shipboard transponder system broadcasting vessel identity, position, course, and speed. Required by IMO for ships over 300 GT. Military vessels may operate AIS selectively for OPSEC.
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- AIT — Assembly, Integration and Test
- The lifecycle phase where flight or production hardware is assembled, software is integrated, and the combined system is verified against its requirements. AIT facilities include cleanrooms, thermal-vacuum chambers, vibration tables, and EMC ranges. Drives schedule and cost on most space and avionics programmes.
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- Diagram
- AiTR — Aided Target Recognition
- Machine cueing that flags candidate targets in sensor data to assist a human analyst.
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- AKE — Dry Cargo/Ammunition Ship
- A logistics ship delivering ammunition, provisions and stores to deployed naval forces.
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- Albedo
- The fraction of solar energy reflected by a body or surface. Earth's average albedo is approximately 0.3. Important for thermal analysis and optical sensor calibration.
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- ALERTORD — Alert Order
- A planning directive that provides essential guidance and increases readiness for a possible operation.
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- ALOHA — ALOHA random-access protocol
- An early random-access scheme where nodes transmit freely and retransmit after collisions.
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- ALS — Advanced Life Support
- Emergency care extending beyond basic support to include drugs, airway devices, and cardiac monitoring.
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- AM — Amplitude Modulation
- An analog modulation in which the carrier amplitude varies in proportion to the message signal.
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- AMC — Adaptive Modulation and Coding
- Dynamically adjusting modulation and coding rate to match channel conditions.
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- AMC 20-193
- EASA Acceptable Means of Compliance for multicore processor use in airborne systems and software. The harmonised successor to CAST-32A, providing certifiable objectives and verification activities for MCP interference, configuration, and analysis.
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- Diagram
- AMCM — Airborne Mine Countermeasures
- Mine detection and neutralization conducted by helicopters using towed and airborne systems.
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- AMDR — Air and Missile Defense Radar
- The AN/SPY-6(V)1 next-generation naval radar using scalable Radar Modular Assemblies (RMAs) with GaN technology. Provides 30x detection improvement over AN/SPY-1 for the DDG-51 Flight III destroyers.
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- 3D modelTry it: Defense Spectrum MapTry it: Aerospace Defense Industry GuideTry it: Defense Fundamentals Guide
- AMRAAM — Advanced Medium-Range Air-to-Air Missile
- AIM-120 radar-guided BVR missile with active radar terminal homing. Fire-and-forget capability with mid-course datalink update. Standard US/NATO beyond-visual-range weapon. 75-180 km range.
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- AMW — Amphibious Warfare
- Operations launched from the sea by naval and landing forces to project power ashore.
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- Anomaly (True/Mean/Eccentric)
- Angular parameters describing a satellite's position along its orbit. True anomaly is the actual angle from perigee; mean anomaly increases uniformly with time; eccentric anomaly is a geometric intermediate used in Kepler's equation.
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- Anomaly Resolution
- The systematic process of identifying, investigating, and resolving unexpected spacecraft behavior. Involves telemetry analysis, trend review, failure tree analysis, and corrective action.
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- ANSI — American National Standards Institute
- The US body that oversees development of voluntary consensus standards including telecom.
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- Anti-Jam
- Techniques for maintaining communications, navigation, or radar service in the presence of intentional interference. Includes spread-spectrum waveforms, adaptive nulling, beamforming, frequency-hopping, and CRPA antennas for GNSS.
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- Anti-Spoof
- Techniques for detecting and rejecting falsified signals — relevant to GNSS spoofing, AIS spoofing, and authentication of broadcast signals. Methods include signal-quality monitoring, encryption (M-code, Galileo OS-NMA), and inertial cross-checks.
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- 2D animationTry it: Ew GuideTry it: Waterfall Test GuideTry it: Mil Ops Degraded Environments
- Ao — Operational Availability
- The probability that a system is operationally capable at any random point in time. Combines reliability (MTBF), maintainability (MTTR), and logistics support.
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- AOA — Angle of Arrival
- A geolocation technique that determines emitter direction by measuring the angle at which a signal arrives at a sensor, typically using directional antennas or interferometric arrays.
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- AOCS — Attitude and Orbit Control System
- The combined subsystem responsible for both attitude control (orientation) and orbit maintenance (station keeping, collision avoidance). Term used interchangeably with ADCS in some agencies.
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- AOE — Fast Combat Support Ship
- A large replenishment auxiliary supplying fuel, ordnance and stores to combatants underway.
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- AOG — Aircraft on Ground
- A status indicating an aircraft is grounded by a technical problem requiring urgent parts or maintenance.
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- AOI — Area of Interest
- A geographically bounded region designated for collection, monitoring, or analysis.
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- AOP — Argument of Perigee
- Angle within the orbital plane from the ascending node to perigee.
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- AOR — Area of Responsibility
- The geographic area associated with a combatant command within which a commander has authority to plan and conduct operations.
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- AOS — Acquisition of Signal
- Moment when a satellite rises above the minimum elevation mask of a ground station.
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- APD — Avalanche Photodiode
- A photodiode with internal gain from avalanche multiplication, used for low-light and laser-ranging detection.
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- API — Application Programming Interface
- The set of operations one piece of software offers to another, and the contract for calling them. An API is a promise about behaviour, not a description of the code behind it.
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- APOBS — Anti-Personnel Obstacle Breaching System
- Man-portable rocket-projected line charge that clears a footpath roughly 45 m long by 0.6 m wide through anti-personnel obstacles. Two-soldier team, fired from cover.
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- Diagram
- APOD — Aerial Port of Debarkation
- An airfield through which personnel and materiel enter a theater of operations by air.
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- APOE — Aerial Port of Embarkation
- The airfield from which personnel and materiel depart when deploying to a theater.
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- Apogee
- The point in an elliptical orbit farthest from the central body (Earth). At apogee, the satellite travels at its slowest orbital velocity.
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- APP-6 — Allied Procedural Publication 6
- NATO standard for military map symbology providing standardized symbols for units, equipment, installations, and activities. Frame shapes indicate affiliation, fill colors indicate domain, icons identify unit type.
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- Diagram
- APR — Air-Purifying Respirator
- A respirator that filters contaminants from ambient air rather than supplying independent air.
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- APSK — Amplitude and Phase-Shift Keying
- A modulation combining amplitude and phase rings, used in DVB-S2 satellite links.
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- APT — Advanced Persistent Threat
- A sophisticated, well-resourced threat actor (typically nation-state) that gains unauthorized network access and maintains persistent presence for intelligence collection or pre-positioning.
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- DiagramTry it: Multiint Fusion GuideTry it: Cyber Warfare GuideTry it: Homeland Security Fundamentals+1 more
- APU — Auxiliary Power Unit
- Onboard turbine supplying power/air when main engines are off.
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- AQAP — Allied Quality Assurance Publication
- The NATO series of publications defining quality assurance requirements for defense procurement.
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- Architecture Evolution
- The deliberate progression of a system architecture across blocks or generations to incorporate new technology, address obsolescence, and respond to changing threat. Key concept behind GPS Block II→III, AEGIS baselines, and Link 16 increments.
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- DiagramTry it: Space Mission Evolution
- Area of Interest — AI
- A geographic area, typically larger than the AO, that concerns a commander including adjacent and neighbouring areas where activity may affect the unit's mission. The intelligence collection perimeter.
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- Area of Operations — AO
- The geographic area assigned to a unit for the conduct of its mission. The commander has authority to plan and execute all operations within the AO, coordinating with adjacent units through boundary agreements.
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- DiagramTry it: Orbat GuideTry it: Ttps GuideTry it: Ootw Guide Simulator+1 more
- ARFOR — Army Forces
- The Army component headquarters and forces assigned or attached to a joint force.
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- ARFORGEN — Army Force Generation
- The structured progression of Army unit readiness over time to provide trained forces for operations.
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- ARG — Amphibious Ready Group
- A group of amphibious ships and embarked forces prepared for amphibious operations.
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- Argument of Perigee
- The orbital element defining the angle from the ascending node to the perigee point, measured in the orbital plane. Determines the orientation of the orbit's ellipse.
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- 3D modelTry it: Space Fundamentals GuideTry it: Space Environment Effects Guide
- ARINC 429
- Aviation industry-standard one-way, point-to-point digital data bus (12.5 / 100 kbit/s). Transmitter broadcasts to up to 20 receivers on a twisted shielded pair. Workhorse of civil avionics from the 1970s onwards; still ubiquitous in cockpit interfaces.
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- Diagram
- ARINC 653 — Avionics Application Software Standard Interface
- The partitioning standard behind Integrated Modular Avionics: applications of different criticality share one processor with guaranteed separation in time and space, so one partition overrunning cannot affect another.
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- ARINC 664 / AFDX — Avionics Full-Duplex Switched Ethernet
- Deterministic, redundant Ethernet-based avionics network (ARINC 664 part 7). Uses virtual links with bandwidth allocation gaps to bound latency and jitter. Backbone of A380, A350, B787 avionics.
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- Diagram
- ARM — Anti-Radiation Missile
- A missile that homes on the radio frequency emissions of a radar or other electronic emitter. Examples include AGM-88 HARM and AARGM. Used in SEAD/DEAD missions to permanently destroy air defense radars.
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- ARP — Address Resolution Protocol
- A protocol that maps an IP address to its corresponding link-layer MAC address.
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- ARP4754A — Aerospace Recommended Practice 4754A
- SAE standard for development of civil aircraft systems. Defines requirements capture, architecture, safety assessment (FHA, PSSA, SSA), and traceability. Paired with ARP4761 for safety analysis and DO-178C/DO-254 for software/hardware.
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- DiagramTry it: Aerodef Standards Guide
- ARP4761
- SAE Aerospace Recommended Practice for safety assessment of civil airborne systems. Provides methods for FHA, PSSA, SSA, FMEA, and Common Cause Analysis. Paired with ARP4754A for the development side, and DO-178C / DO-254 for software / hardware assurance.
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- Diagram
- ARQ — Automatic Repeat reQuest
- An error-control method that retransmits packets when errors or losses are detected.
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- ARRC — Allied Rapid Reaction Corps
- A high-readiness NATO corps-level headquarters capable of deploying to command land operations.
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- ARS — Auxiliary Rescue and Salvage Ship
- A support vessel providing salvage, towing, diving and firefighting services to the fleet.
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- ARTCC — Air Route Traffic Control Center
- A US facility that controls aircraft flying en route through a large block of airspace between terminal areas.
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- AS (Assault Force) — Assault Force
- Third element of breach organisation under SOSRA. Passes through the lane created by the Breach Force and seizes the far-side objective.
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- Diagram
- AS9100
- The aerospace industry quality management system standard, built on ISO 9001 with additional aerospace-specific requirements. Mandatory for most commercial and military aerospace suppliers.
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- DiagramTry it: Aerodef Standards GuideTry it: Team Leadership Guide
- ASAT — Anti-Satellite Weapon
- Systems designed to disable or destroy orbiting satellites. Types include kinetic hit-to-kill, co-orbital, directed energy (laser), jamming, and cyber attack.
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- Ascending Node
- The point in an orbit where the satellite crosses the equatorial plane from south to north. Combined with RAAN, it defines the orientation of the orbital plane relative to the Earth-centred inertial frame.
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- ASCOPE — Areas, Structures, Capabilities, Organizations, People, Events
- A framework for analyzing civil considerations in the operational environment.
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- ASDA — Accelerate-Stop Distance Available
- The take-off run available plus any stopway, used to determine an aircraft’s ability to stop after a rejected takeoff.
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- AShM — Anti-Ship Missile
- A guided missile designed to attack and destroy surface ships.
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- ASK — Amplitude-Shift Keying
- A digital modulation that encodes data by varying the amplitude of a carrier.
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- ASL — Approved Supplier List
- A registry of vendors pre-qualified to meet quality, reliability, and compliance standards. Accelerates procurement by eliminating re-qualification for each buy.
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- Diagram
- ASM — Air-to-Surface Missile
- Missile launched from aircraft against surface targets.
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- ASN — Assistant Secretary of the Navy
- A senior civilian official overseeing a functional area within the Department of the Navy.
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- ASP — Ammunition Supply Point
- A facility that receives, stores, and issues ammunition to supported units.
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- ASR — Alternate Supply Route
- A secondary route designated for logistics movement when the main supply route is unavailable.
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- ASROC — Anti-Submarine Rocket
- A ship-launched rocket that delivers a homing torpedo or depth charge to a distant submarine.
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- ASTM — American Society for Testing and Materials
- A standards body that develops technical standards for materials, products, systems, and services.
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- Astrodynamics
- The branch of celestial mechanics applied to artificial bodies — orbit determination, manoeuvre planning, rendezvous, perturbation modelling. Combines Kepler/Newton mechanics with the modern numerical methods (DOPRI8, SGP4) needed for operational accuracy.
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- ASuW — Anti-Surface Warfare
- Operations against enemy surface combatants and shipping. Principal weapons: anti-ship cruise missiles (LRASM, Harpoon, NSM), air-launched glide bombs, submarine-launched heavyweight torpedoes. Increasingly contested by long-range hypersonic anti-ship weapons.
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- ASW — Anti-Submarine Warfare
- Operations conducted to deny the enemy effective use of submarines. Encompasses detection (sonar), classification, tracking, and engagement (torpedoes, depth charges).
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- ASWC — Anti-Submarine Warfare Commander
- The warfare commander responsible for coordinating ASW operations within a force.
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- ATC — Air Traffic Control
- Service directing aircraft to maintain safe separation.
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- ATDL — Army Tactical Data Link
- A point-to-point data link used to connect air defense fire units with control systems.
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- ATFM — Air Traffic Flow Management
- The regulation of traffic flow to balance demand against airspace and airport capacity and avoid overload.
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- ATIS — Automatic Terminal Information Service
- A continuous broadcast of recorded aeronautical and weather information at busy airports to reduce controller workload.
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- ATM — Air Traffic Management
- End-to-end management of airspace, flow and air navigation services.
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- Atmospheric Attenuation
- The reduction of RF or optical signals as they pass through the atmosphere — gaseous absorption (H2O at 22/183 GHz, O2 at 60/118 GHz), rain, fog, scintillation. Drives band selection for SATCOM, radar, and free-space optical links.
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- 2D animationTry it: Defense Spectrum MapTry it: Modern Warfare Guide
- ATO — Air Tasking Order
- A 72-hour cycle document that coordinates and allocates air assets across the joint force. Specifies sorties, targets, timing, and support requirements for all air operations.
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- Atomic Oxygen
- Highly reactive single oxygen atoms (O) produced by UV photodissociation of O2 in the upper atmosphere. Erodes spacecraft surfaces in LEO at ~8 km/s relative velocity, particularly polymers and silver coatings.
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- ATP — Advanced Threat Protection
- Security solutions that defend against sophisticated malware and targeted attacks.
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- ATR — Automatic Target Recognition
- Algorithmic detection and classification of targets in sensor data without human intervention.
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- ATS — Air Traffic Services
- The collective term for flight information, alerting, advisory, and air traffic control services provided to aircraft.
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- ATSC — Advanced Television Systems Committee standard
- The North American digital terrestrial television broadcasting standard.
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- ATT&CK — Adversarial Tactics, Techniques, and Common Knowledge
- MITRE knowledge base of adversary tactics and techniques based on real-world observations.
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- Attenuation
- The reduction in signal power as it propagates through a medium — atmospheric absorption, free-space loss, foliage, rain. Quantified in dB/km or dB/path. Sets the practical range and frequency-band selection for any RF link.
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- Attitude Control
- Active control of a spacecraft's orientation in inertial or local frames using actuators (reaction wheels, magnetorquers, thrusters, CMGs) closing the loop on attitude sensors (star trackers, IMUs, sun sensors). Distinguishes from attitude determination (sensing only).
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- AU — Astronomical Unit
- Mean Earth-Sun distance: 149,597,870.7 km.
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- AUV — Autonomous Underwater Vehicle
- A self-guided underwater robot that executes preprogrammed survey and search missions.
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- AV — Antivirus
- Software that detects, prevents, and removes malicious programs from computer systems.
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- AVLB — Armored Vehicle-Launched Bridge
- Armoured chassis (typically tank hull) that launches a scissor-bridge across gaps under fire. Enables mounted manoeuvre across anti-tank ditches, blown bridges, and wet gaps.
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- AWACS — Airborne Warning and Control System
- An airborne radar and command platform that provides surveillance, detection, and air battle management.
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- AWGN — Additive White Gaussian Noise
- The canonical channel noise model in communications theory: noise samples are independent, identically distributed, zero-mean Gaussian. Sets the theoretical performance floor for any modulation/coding scheme via Shannon's capacity formula.
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- AWS — Autonomous Weapons System
- Weapons systems that can select and engage targets without meaningful human control. Subject of significant ethical and legal debate under international humanitarian law (LOAC).
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- DiagramTry it: Career Path SimulatorTry it: Constellation GuideTry it: Smad Orbit Visualizer+1 more
- Azimuth-Elevation
- The two-angle local horizontal coordinate system: azimuth measured clockwise from north, elevation from the horizon. The native format for ground-station antenna pointing, optical telescope mounts, and shipboard radars.
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