Drone and SAR operations terminology.

Automatic Dependent Surveillance-Broadcast. A surveillance system in which crewed aircraft continuously broadcast their position, altitude, and velocity for receipt by ATC and nearby aircraft.

Drones can carry ADS-B IN receivers (not transmitters) to display nearby crewed traffic in the GCS, which is increasingly common as a deconfliction aid for BVLOS and complex operations.

Above Ground Level. Altitude measured from the terrain directly below the aircraft, rather than from sea level. Part 107 caps routine drone operations at 400 feet AGL, though structures may be circled up to 400 ft above the structure’s highest point.

AGL is the altitude reference most relevant to obstacle clearance during low-altitude drone work.

Beyond Visual Line of Sight. Drone operations conducted past the point at which the remote pilot can see the aircraft unaided. BVLOS is restricted under standard Part 107 and currently requires a waiver, though the proposed Part 108 framework is expected to formalize routine BVLOS operations.

BVLOS is the gating capability for serious commercial work like long-range linear inspection, large-area mapping, and SAR over difficult terrain.

Controlled airspace surrounding the busiest US airports, typically extending from the surface up to 10,000 feet MSL in an inverted-wedding-cake shape. Drone flights inside Class B require prior ATC authorization, usually through LAANC for Part 107 operators.

The exact lateral and vertical boundaries vary by airport and are published on sectional charts.

Uncontrolled airspace, generally everything below 1,200 feet AGL outside the lateral boundaries of controlled airspace. Most rural drone work happens in Class G, and Part 107 operations there do not require ATC authorization.

Pilots are still responsible for see-and-avoid, weather minimums, and any local restrictions.

Airspace where ATC provides separation services to participating aircraft. In the United States, this is Class A through E. Drone operations inside controlled airspace require ATC authorization, most commonly issued through LAANC for Part 107 flights.

The complement is uncontrolled (Class G) airspace, which covers most low-altitude rural areas where drone work happens.

A virtual boundary defined in software that constrains where the aircraft is permitted to fly. Geofences can be inclusion (stay inside) or exclusion (stay out), and may be enforced by the autopilot itself, by the GCS, or by both layers in defense.

Well-designed geofencing reduces the risk of inadvertent airspace busts and gives the autopilot a deterministic response when the aircraft approaches the boundary.

Low Altitude Authorization and Notification Capability. The FAA-approved system that gives Part 107 drone pilots near-real-time authorization to operate in controlled airspace below pre-published altitude ceilings.

Authorizations are issued through approved third-party apps. LAANC is the standard mechanism for getting cleared into Class B, C, D, and surface E airspace for routine commercial work.

Mean Sea Level. Altitude measured from the average level of the ocean’s surface. Sectional charts and airspace ceilings (Class B floors, Class E shelves, etc.) are published in MSL.

A drone flying at 200 feet AGL on a 1,000-foot ridge is at 1,200 feet MSL. Mixing the two references is a common cause of airspace busts.

Notice to Air Missions (formerly Notice to Airmen). The official FAA channel for time-critical aeronautical information that affects flight operations: closed runways, navaid outages, TFRs, parachute jumping, and similar.

Pre-flight planning includes a NOTAM check across the full mission area. Modern GCS and briefing tools pull active NOTAMs automatically.

The FAA regulation that governs commercial small UAS operations in the United States, covering aircraft under 55 pounds. Establishes pilot certification, operating limits (400 ft AGL, daylight or twilight, visual line of sight, etc.), and the waiver process for operations outside those limits.

Most US commercial drone work, including mapping, inspection, and public safety, is flown under Part 107.

Temporary Flight Restriction. A short-duration ban or restriction on flight operations in a defined volume of airspace, issued by the FAA in response to events like wildfires, VIP movements, sporting events, or hazardous incidents.

TFRs are published as NOTAMs and apply to drones the same as crewed aircraft. Briefing tools surface active TFRs along the planned mission area before takeoff.

The physical structure of the aircraft: the frame, motors, propellers, and the mechanical assemblies that carry the avionics and payload. Airframe choice drives endurance, payload capacity, weather tolerance, and crash resilience.

Drone airframes range from small folding quadcopters to fixed-wing VTOL platforms with multi-hour endurance. The same autopilot stack runs across most of them.

A mature, open-source autopilot suite that runs on a wide range of flight controller hardware. ArduPilot covers fixed-wing, multirotor, helicopter, rover, submarine, and antenna-tracker vehicle types with a single shared codebase.

Along with PX4, ArduPilot is one of the two dominant open autopilots and the foundation of most independent and commercial drone platforms outside the consumer market. TacLink C2 supports it natively over MAVLink.

The software running on the flight controller that stabilizes the aircraft, executes missions, manages sensors, and communicates with the ground station. The autopilot is the brain of the drone in flight.

The two dominant open autopilots are ArduPilot and PX4. Proprietary autopilots from DJI, Autel, and Skydio fill the consumer and prosumer market.

A secondary computer onboard the aircraft that handles tasks too heavy for the flight controller: computer vision, AI inference, video encoding, mission scripting, or LTE/5G connectivity. It sits alongside the flight controller and communicates with it over MAVLink on a serial link.

Common companion computers include the Raspberry Pi family, NVIDIA Jetson, and various single-board x86 modules.

The physical circuit board onboard the aircraft that runs the autopilot software, reads sensors (IMU, barometer, GPS), and drives the motors and servos. It is the lowest-level hardware in the flight stack.

Pixhawk is the most common open flight controller standard. A typical commercial drone has one flight controller, sometimes paired with a companion computer for higher-level autonomy.

A motorized mount that stabilizes a payload (camera, EO/IR sensor, lidar) against the aircraft’s motion. Two-axis gimbals stabilize pitch and roll; three-axis gimbals also stabilize yaw.

The gimbal is what makes aerial video usable and what lets a sensor stay pointed at a target while the aircraft maneuvers. Quality varies enormously, and gimbal vibration is a frequent root cause of “soft” imagery.

Anything the aircraft carries that is not part of the basic airframe and avionics. The most common drone payloads are RGB cameras, multispectral sensors, thermal (EO/IR) cameras, lidar units, parachutes, and delivery mechanisms.

Payload choice constrains airframe selection (capacity, power, mounting) and drives most of the operational value of the flight.

A family of open-hardware flight controllers originally developed in the PX4 project and now produced by multiple vendors. The Pixhawk standard defines the connector pinout, sensor set, and processor class that the open autopilots target as their reference platform.

When operators say “Pixhawk-class hardware,” they mean any board that follows the standard and can run ArduPilot or PX4 without porting work.

An open-source autopilot stack maintained by the Dronecode Foundation, designed around a modular architecture and a permissive BSD license. PX4 powers research platforms, consumer products, and commercial drones across a broad ecosystem.

PX4 and ArduPilot both run on Pixhawk-class hardware and both speak MAVLink. The choice between them tends to be driven by airframe vendor support, feature parity for a specific use case, and team familiarity.

The radio link that carries MAVLink telemetry and commands between the aircraft and the ground station. Common variants include 915 MHz SiK-firmware radios, RFD900-family long-range modules, and integrated solutions like Herelink that combine telemetry, RC, and HD video.

Range, latency, and link reliability vary widely. Long-range and BVLOS work generally requires either RFD-class hardware, cellular fallback, or both.

Ground Control Station. The software (and sometimes the laptop or tablet running it) that connects to the aircraft, displays telemetry, plans missions, and sends commands. The GCS is the operator’s window into the aircraft.

Open-source GCS options include Mission Planner and QGroundControl. TacLink C2 is a modern GCS built around multi-drone operations and the way teams actually run flights.

A recording of telemetry, commands, sensor data, and events captured by the autopilot during a flight. ArduPilot writes binary .bin dataflash logs; PX4 writes .ulg (ULog) files. Both contain enough information to reconstruct the flight in detail.

Log review is essential after any incident, but also part of a mature workflow even on routine flights: tuning, fault analysis, and proving compliance.

Micro Air Vehicle Link. An open messaging protocol used for communication between ground control stations and unmanned vehicles. MAVLink is the dominant telemetry and command protocol for ArduPilot and PX4, and the foundation layer for most serious open drone platforms.

TacLink C2 is built on MAVLink 2.0 and supports message signing where hardware permits.

The second major version of the MAVLink protocol. Adds extensible payloads, larger message IDs, more efficient packing, and, most importantly, optional cryptographic message signing to authenticate the link between aircraft and ground.

MAVLink 2.0 is backward-compatible with MAVLink 1.0 endpoints and is the version targeted by all current builds of ArduPilot and PX4.

A MAVLink 2.0 feature that adds an HMAC-SHA-256 signature to outbound messages so the receiving end can verify the sender holds the shared key. It defends the command link against spoofing and replay attacks but does not encrypt payload contents.

Message signing requires support on both ends of the link: the autopilot and the GCS. TacLink C2 supports it where the connected hardware does.

The reference GCS for ArduPilot, originally built for Windows. Mission Planner is the long-running, feature-rich incumbent that most ArduPilot pilots have used at some point: it is the tool of record for parameter tuning, log review, and mission planning in the ArduPilot world.

The interface is showing its age and it has historically been Windows-only, which has driven a long search for a modern cross-platform alternative.

A cross-platform open-source GCS built around the Qt framework, supporting both ArduPilot and PX4. QGroundControl runs on Windows, macOS, Linux, iOS, and Android, which has made it the default GCS for many PX4-centric workflows.

Like Mission Planner, QGC reflects its decade-plus of accumulated features in the interface.

A single position in a mission, defined by latitude, longitude, and altitude, plus parameters like loiter time, acceptance radius, and turn behavior. A sequence of waypoints describes an autonomous flight path.

Most mission planning interfaces let the operator drop waypoints visually on a map and then tune their per-point parameters in a side panel.

Pre-configured automatic responses the autopilot executes when something goes wrong: lost RC link, lost GCS link, low battery, GPS loss, geofence breach. Each fail-safe has a configurable action, typically loiter, RTL, or land.

Fail-safe configuration is part of pre-flight, not an afterthought. The few seconds where the autopilot is reacting on its own are exactly when correct settings matter most.

The event in which the aircraft crosses a defined geofence boundary. Modern autopilots can be configured to respond automatically (loiter at the boundary, return to launch, land in place) rather than continuing through.

A breach is always worth investigating after the flight: it usually indicates either a planning error, a wind/drift issue, or a control failure that deserves attention before the next sortie.

An autopilot mode that holds the aircraft at a fixed position and altitude, fighting wind and drift. On multirotors, loiter is essentially a stationary hover; on fixed wings, it is a circling pattern around the loiter point.

Loiter is the standard “pause” for an autonomous flight: drop into loiter, look at the situation, decide what to do next.

A planned flight with a defined objective: a survey grid over a parcel, an inspection of a specific structure, a search segment for a missing person. A mission can be flown manually, semi-autonomously, or fully autonomously, and is usually composed of one or more sorties.

The mission is the unit of work for most operational drone teams: planning, briefing, execution, and debrief all hang off it.

The structured walk-through completed before every flight: airframe condition, propeller torque, battery state, control surface throws, sensor health, GPS lock, RC and telemetry link, fail-safe configuration, weather, NOTAMs, and crew briefing.

Skipping pre-flight is the most common cause of avoidable incidents. A serious team uses a written checklist and works it the same way every time.

Return to Launch. An autopilot flight mode that commands the aircraft to climb to a configured altitude, fly direct to the launch point, and land. RTL is the default response to most fail-safes: lost link, low battery, geofence breach.

Configuring RTL altitude correctly for the local terrain is one of the most important parts of pre-flight setup. A poorly tuned RTL has flown more aircraft into trees and ridgelines than any other failure mode.

A single takeoff-to-landing flight by one aircraft. A mapping mission over a large parcel might be flown across multiple sorties as batteries are swapped; a SAR operation might involve dozens of sorties across multiple aircraft over the course of a day.

The sortie count is one of the most useful operational metrics a team tracks: it captures actual flight activity in a way that hours alone do not.

An autonomous flight defined as a sequence of waypoints that the autopilot executes in order. The aircraft transitions between waypoints under autopilot control, with the operator monitoring rather than flying.

Waypoint missions are the foundation of mapping, survey, inspection, and any other workflow where repeatability matters more than manual finesse.

A systematic, high-thoroughness sweep of a defined search segment using parallel tracks at fixed spacing. Grid search trades speed for coverage and is used after hasty search has not located the subject, or in segments where the probability of detection on a single pass is too low.

Drones flying autonomous parallel-track patterns are well suited to grid search over open terrain. Dense canopy still favors ground teams.

A fast, low-thoroughness sweep of high-probability areas in the early hours of a SAR incident: trails, roads, drainages, last known locations, common destinations. The trade-off is speed over coverage: hasty search aims to find a responsive subject quickly before resources are committed to slower, more systematic methods.

Drones have changed hasty doctrine considerably: an aerial sensor can clear large open areas in minutes that would have taken a hasty team an hour on foot.

The Incident Commander. The single person with overall authority and responsibility for an incident under ICS. All operational direction flows from the IC, either directly or through delegated section chiefs on larger incidents.

A drone team flying on an incident is tasked by the IC (or by Operations on behalf of the IC) and reports back through the same chain.

The Incident Command System. A standardized, scalable framework for managing emergency operations, used across US public safety, fire, and SAR. ICS defines roles (Incident Commander, Operations, Planning, Logistics, Finance), span of control, and a common vocabulary that lets agencies plug into each other on multi-agency incidents.

For a drone team integrating into a public safety response, the answer to “who do I report to?” is always an ICS role.

The most recent confirmed location of the subject, used as the anchor point for initial search planning. LKP comes from a credible source: a sighting, a phone ping, a vehicle location, a trailhead register entry.

Search planners build outward from LKP using statistical models of how subjects of various profiles (lost hiker, dementia patient, child) tend to move, producing a ring of priority segments.

The estimated likelihood that a search effort will find the subject if the subject is in fact present in the searched area. POD is a function of sensor (eye, dog, thermal camera), terrain, vegetation, weather, search speed, and track spacing.

A single hasty pass might be 30 to 50% POD; a thorough grid search at tight spacing on open terrain can exceed 80%. Cumulative POD across multiple search efforts is what eventually drives a segment to “cleared.”

A bounded geographic area assigned to a single search team or aircraft as a unit of work. Segments are typically drawn along terrain features (drainages, ridgelines, roads) so they are easy to brief, easy to bound on the ground, and easy to track on the situation map.

Each segment carries a cumulative POD that climbs as additional resources work it. Once cumulative POD crosses the planning threshold, the segment is marked cleared.