Sarah Nilsson JD, PhD, MAS
Sarah NilssonJD, PhD, MAS




Aeronautical Information Management (AIM): A portal that allows pilots, airline operators, and other Aeronautical Information Servies (AIS) users to access the latest flight information as well as submit e-flight plans.


Aircraft Crew: The aircraft crew is responsible for the operation and safety of the flight and passenger well-being.

The aircraft crew includes the PIC/SIC and may include other individuals and functions (e.g., aircraft steward to monitor passenger comfort and well- being).

Aircraft crew roles, can be divided into four categories of overall flight management, which progress from strategic to tactical, are used:

(1) mission management (i.e., planning and revising the overall mission, such as setting or changinga destination UAM aerodrome);

(2) flightpath management (i.e., setting and revising the aircraft’s flightpath to achieve the mission in an effective way);

(3) tactical operations (i.e., making modificationsto the aircraft’s flightpath/state to ensure the safety of the aircraft in the short term, typically in response to an unanticipated hazard [e.g., flock of birds], which generally ignores the overall mission objective until a safe state is restored); and

(4) aircraft control (i.e., maintaining the aircraft in a safe state).

Each aircraft crew member receives training and certification at a level deemed appropriate by the FAA for their role in the operation.


Autonomous Aerial Vehicle (AAV): Aircraft designed to operate autonomously, predominantly without a human involved in the mission control.

It is close, by definition, to the UAVs, and not all UAVs are AAVs, since some UAVs require a remote operator or a pilot.


Air Traffic Control (ATC): A service provided by personnel trained and certified by relevant aviation authorities responsible for monitoring and controlling all air traffic within a specific area, such as EASA, FAA, and others.


Air Traffic management (ATM): The necessary toolkit of airborne and ground-based functions (air traffic services, airspace management, and air traffic flow management) required to ensure the safe, secure, and efficient movement of aircraft during all phases of operation.


Battery terminology

specific energy: the amount of energy per unit weight provided by the battery, which ultimately determines the gross weight of the vehicle

charge rate: how quickly the battery can be brought back to a nearly full charge, which determines operational idle time

cycle life: the number of charge/discharge cycles the cell can sustain before its capacity is less than 80% of the original, which determines how often the battery must be replaced

cost per kilowatt-hour: which determines the overall battery cost


Beyond Visual Line of Sight (BVLOS): aka BLOS. This is where the flying of a drone is without a pilot maintaining visual line of sight on the aircraft at all times. 


CNSI: communications, navigation, surveillance, and information.

UAM at UML-4 is enabled by advanced CNSI technologies and services. Information exchange occurs through seamless, secure, and resilient information exchange between producers of data (e.g., aircraft, PSUs, SDSPs, FAA, and fleet operators) and users (e.g., aircraft, PSUs, FAA, SDSPs, and other stakeholders fleet operators).

High numbers of UAM operations along with large quantities of information exchanged exceed the aviation-protected spectrum available in 2020.

UML-4 operations are enabled by the transition to more capable systems and protocols.

Communication: At UML-4, fleet operators maintain communication with PSUs and UAM aircraft in compliance with regulatory requirements to support data exchange required for safe operations.

This occurs through three different communications paths (aircraft to aircraft, aircraft to ground, and ground to ground) during three different stages of operation (surface, departure/arrival, and en route).

To be able to safely operate in the vicinity of or on high-density routes into actively controlled airspace, the PIC is equipped with required ATC communication technologies needed to operate in actively controlled airspace.

The PIC has the capability of communicating with ATC and controlling the aircraft to comply with ATC instructions so that the aircraft can operate in controlled airspace. 

Navigation: Navigation components include systems on the aircraft and navigational aids.

Performance-based navigation (PBN) capabilities enable dynamic precision trajectory-based operations (TBO), even in visibility-restricted conditions.

UAM aircraft navigate using a combination of external data feeds and onboard capabilities (e.g., hardware, software, and transmission mechanisms) to operate with greater route conformance and separation minima.

This greater degree of navigational accuracy allows aircraft to avoid obstacles, execute planned operations, or emergency landings under more restricted conditions than traditionally equipped and capable transport commercial aircraft today (2020).

Surveillance: Surveillance operations for cooperative and non-cooperative operations, are supported by a range of ground, aircraft-borne, and satellite-based infrastructure that augment individual aircraft capabilities, enhance safety, and provide other information (e.g., non-cooperative aircraft or localized weather).

Although surveillance information is utilized and shared by PSUs, in certain cases direct information exchange occurs among multiple aircraft and ground/satellite infrastructure to for tactical hazard identification and reporting.

Information: Information includes data that is not captured as part of CNS and does not utilize aviation protectedspectrum.

It includes passenger internet access while in flight and non-critical information supporting UAM operations (e.g., SDSPs collecting raw data or passenger ticketing apps).

This information may enter the PSU or other UAM networks if it adheres to security, performance and interface standards.

The information may also remain external to the UAM system but provides a key component to arrive at a successful business case.


Concept of Operations (ConOps) in UAM: A definition of operations, operational environments, and applicable legislative and/or regulatory framework documents, in the context of UAM operations.


Control Facility Infrastructure: Economically viable, sufficient, resilient, and secure control facility infrastructure has been developed for PSUs, fleet operators, and other stakeholders.

This infrastructure supports spectrally efficient communication links; navigation services, weather surveillance, functionality in urban canyons, and the ability to account for non-cooperative aircraft. Monitoring of services and infrastructure is required to maintain efficiency and safety.


CTOL: Conventional Takeoff and Landing

Thin Haul: 9-10 pax aircraft


Cybersecurity: Adherence to cybersecurity standards support secure communication between all operational elements.

These requirements include degraded communications and connectivity.


Drone: Aircraft (UAV or UA) or vehicle (e.g. underwater drone) designed to operate autonomously (pre-programmed, without a human in control) or remotely (pilot controls the drone on the ground). Not all dornes are UAVs because drones are not only aerial, they can be aquatic or ground robots too.


DSTs: decision-support tools 


Electromagnetic Interference (EMI): Both cities and electric aircraft can be significant sources of

electromagnetic radiation.

CNSI systems, both on and off the aircraft, incorporate EMI protections against external and internal sources, including other onboard CNSI systems, electric propulsion systems, high-power radio and radar transmitters, power grid components, and lightning strikes.


EVTOL is a type of aircraft that uses electrical (usually lithium-ion batteries) propulsion to takeoff, hover, and land vertically. This alternative power source, in contrast to the conventional combustion engine aircraft, produces less noise and greenhouse gas emissions, being compliant with the environmental protection rules that are gradually adopted worldwide.  

Furthermore, eVTOL aircraft boast high safety standards, but require less space for take-off and landing due to their design.

On top of the above, eVTOL aircraft – due to their advanced engines and sustainable components, as well as mass predicted mass production – are likely to be much cheaper to manufacture and operate than conventional transportation aircraft.


FAA: The FAA is the federal authority over aircraft operations in al lUS airspace and provides the regulatory and operational framework for UML -4 operations.

The FAA provides information on airspace constraints, such as notices to airmen (NOTAMs), airspace restrictions, facility maps, Special Use Airspace (SUA), and Special Activity Airspace (SAA) activity transmitted via FIMS or other FAA provided resources directly to users or via PSUs.

The FAA collaborates with the PSU Network by exchanging data with PSUs and operators to fulfill its obligations, to provide regulatory and operational oversight.

The FAA certifies or qualifies, as appropriate, safety-critical elements in the UOE, including the aircraft crew, PSUs, and aircraft.

Additionally, the FAA is the supplier of the FIMS.


Flight Information Management System (FIMS): The FAA FIMS is an application program interface (API) gateway for data exchange between UOE (and UTM) users and FAA systems.

FIMS delivers relevant NAS information and FAA directives to PSUs and provides access to any information it needs from PSUs.


Fleet Operator: A UAM aircraft fleet operator is responsible for operational control of aircraft and fleet operations.Fleetoperatorsincludeindividualsoperatingtheir ownsingle aircraft(e.g.,owner/operator)or organizations operating a fleet of multiple aircraft for commercial use. The fleet operator is responsible for meeting regulatory requirements and certification, planning flights, and sharing operational intent and current position information of its aircraft with the PSU Network.

Fleet operators manage UAM aircraft that may be piloted, remotely piloted, or highly automated.

The fleet operator holds the operating certificate and is responsible for operational control.



Geofencing: Technology that uses GPS and GLONASS to establish a virtual geographic boundary to prevent drones from flying into specic areas.


Geographic Information System (GIS) Tool: Computer-based tools that allow the use to store and edit spatial and non-spatial data, analyze spatial information output, and visually share the results of these operations by presenting them as maps. 


Ground Services: Ground services to aircraft, including refueling/recharging, aircraft inspection, line maintenance, aircraft servicing (food/beverage/lavatory), deicing, aircraft reconfigurations, and other applicable services similar to today’s commercial airports and FBOs ground services.

These services are provided by licensed and certified personnel employed by UAM aerodrome operators, fleet operators, or third parties contracted by either the UAM aerodrome operators or fleet operators.


In-Time Aviation Safety Management System (IASMS): At UML-4, the system has incorporated an IASMS, which features monitor, assess, and mitigate functions.

The monitor feature is critical as a control to detect adverse events and operations.

The strategic deconfliction of operations plans is a resiliency control to detect when operations could exceed the system’s capacity.

This monitoring function is found throughout the UAM operations, including aircraft health-monitoring information and models, aircraft location data to ensure the aircraft is on its approved flight path, the comparison of forecast to actual weather conditions, and systems to identify and track poten tial non- cooperative traffic.

These and many other features are offered by the PSUs, fleet and UAM aerodrome operators, and SDSPs as safety enhancement features.


Inertial Measurement Unit (IMU): An electronic device that uses accelerometers, gyroscopes, and sometimes magnetometers to measure and report specific force, angular rate, and magnetic field of the drone in flight.


ISSA: In-time System-wide Safety Assurance.

ISSA capabilities contribute to safe airspace operations through services such as constraint management, conformance and system monitoring, and systems-level predictive and prognostic hazard identification.

These capabilities utilize information from the PSU Network and other information sources in the NAS, such as aircraft automated systems, FIMS, and SDSPs, to help provide in-time risk management and safety assurance.

Types of information shared across the SMS and leveraged by ISSA capabilities include geospatial constraints, weather, operations plans, and known locations of air traffic.


Joint European ATM Research Joint Undertaking (SESAR JU): A platform for all initiatives and projects of the EU towards the integration of integrating innovative ATM and UTM solutions, as well as U-Space, towards a large-scale and international PPP in the relevant multidisciplinary thematic field.


MRO: maintenance, repair, and overhaul 


Other Stakeholders: Other stakeholders include the general public, public safety entities (state, local, and federal law enforcement), multimodal partners, and national security entities, such as the Dep artment of Homeland Security (DHS).

SDOs, aviation authorities and safety bodies, SAE International, and the National Fire Protection Association (NFPA) all contribute to elements impacting the design of the UAM system.

These stakeholders have access to information in the PSU Network as law and policy permit.


Pilot in Command (PIC): For this ConOps, the PIC is a human individual who holds “final authority and responsibility for the operation and safety of the flight” of a UAM aircraft.

This individual may be onboard or off-board the aircraft.

A PIC off-board the aircraft is a remote PIC (RPIC).

Additionally, the PIC may be a pilot in the traditional sense of the term or could be part of the aircraft crew (defined below), having a modified role in which automation is responsible for some functions performed by a traditional pilot.

In the remainder of this ConOps, it is assumed that the PIC is a member of an aircraft crew as opposed to a traditional pilot, though traditional pilots are not precludedfrom assuming the roles specified for aircraft crew.

PIC may be responsible for operational control for one or more aircraft at any one time (e.g., via remote oversight have responsibility over multiple aircraft in flight.


PSUs: Providers of Services to UAM 


Provider of Services to UAM (PSU): At UML-4, PSUs provide ATM services that help enable safe and efficient UAM operations within the UOE with minimal FAA involvement.

A PSU provides services within one or multiple UOEs. PSUs may be public (e.g., provided by a local government to manage its public aircraft), or private (e.g., a third-party service provider).

The range of services provided varies from PSU to PSU, but each must meet minimum requirements for qualification by the FAA.

The qualification requirements are based on standards developed and recommended by industry SDOs and accepted by the FAA.

The PSUs communicate airspace restrictions, receive and coordinate operations plans, and approve dynamic route change requests from fleet operators.

PSUs also exchange data and record data as required by regulators (e.g., the FAA) for regulatory and fleet operator accountability purposes.

The FAA determines the process and criteria for qualifying a PSU- provided service.

Not all services provided by PSUs are required to be qualified.

For example, an air traffic separation service is required to be qualified, but an in-flight weather radar service does not require qualification.

Depending on its infrastructure, a PSU may not provide services across the entire UOE.

A fleet operator may act as its own PSU.


PSU Network: The PSU Network describes a fully integrated system of multiple overlapping PSUs servicing the same geographic area/airspace volume.

The PSU Network is a system of systems that provides discovery services (a directory of PSUs in a given area) and other intermediary services.

The PSU Network provides secure information exchange between users of the UOE system including fleet operators, the FAA, UAM aerodrome operators, and others.

Cooperative data exchange between the various PSUs and UOE users (fleet operators, FAA, aircraft, infrastructure, etc.) provides a fully integrated operating picture to support coordination, planning, aircraft deconfliction, conformance monitoring, and emergency information dissemination and response. The requirements governing coordination between the PSUs in the PSU Network are based on standards developedand recommended by industry SDOs and accepted by the FAA.


Public-Private Partnership (PPP): Cooperative arrangement and/or undertaking between two and/or more public and private stakeholder organizations, aiming at long term collaboration for the sake of both public and private interests.


Regional Air Mobility (RAM): Using existing small airports to transport people in small aircraft over distances of up to 300km.


Remotely Piloted Aircraft (RPA): Refers to a high-level UAV operated from a remote pilot station. Its pilot is required to have a significant amount of training compared to pilots of UAV models used mostly for recreational flights, who require minimal or no training at all for their operation.


Remotely Piloted Aircraft System (RPAs): Consists of the RPA and all the necessary components for its operation, including its hardware, software, control links, and the associated remote pilot station(s). 


RFI: radio frequency interference 


SMS: Safety Management Systems

Each SMS is supported by In-time System-wide Safety Assurance (ISSA)


SDOs: standards development organizations


Second in Command (SIC): A human on board the aircraft with secondary and tertiary operational responsibility behind aircraft automated systems and the PIC.

In instances where an onboard SIC exists, it is assumed that the PIC is operating in a remote capacity. The SIC has more responsibility than an aircraft steward and is fully trained and qualified for the assigned roles and responsibilities.

A SIC does not require the same qualifications as a PIC.

The SIC is a necessary role to build the safety case for a single PIC with operational control for more than one aircraft at a time.


State and Local Government: State and local governments have a greater role in UAM at UML-4 than in traditional aviation (i.e., that prior to 2020) because UAM operations occur largely in cities near local communities and businesses.

State and local zoning requirements, noise ordinances, and land-use laws govern approval of the locations of UAM aerodromes and can impact the number and routes of UAM flights.


Supplemental Data Service Providers (SDSPs): SDSPs provide services that support operational decisions.

This information can be provided directly to PSUs, aircraft, fleet operators, or UAM aerodrome operators (e.g., specialized weather data, surveillance, constraint information).

Multiple service providers may provide similar information and be selected at the discretion of the user. The services supplied by an SDSP may be raw data, value added data, one or a suite of decision support tools. SDSPs providing safety-critical services are adheres to data performance and interface standards qualified by FAA (e.g., weather services).

Those providing optional services (fleet management, passenger entertainment, etc.) may not require FAA qualification.


System-Wide Information Management (SWIM): Consists of standards, infrastructure, and governance enabling the management of information related to ATM and its exchange between qualified parties via interoperable services.


Strategic Deconfliction: The implementation of a strategy before flight operations in order to avoid conflicts between different airspace users.


Tactical Deconfliction: The process pf resolving conflicts occurring during flight by giving instructions to change the course, speed, or height of the flight, in order to avoid collisions.


Temporary Flight Restriction (TFR): A temporary notice of restriction on a spcific area of airspace because of the presence of government VIPs, special events, natural disasters, and other unusual occurrences.


TLOA:  touchdown and lift-off area


UAM Aerodrome Operators: UAM aerodrome operators are private or public entities responsible for ensuring the safety of individual takeoff and landing areasand ground services (embarkation, disembarkation, maintenance, etc.) providedat a UAM aerodrome, but do not control airborne traffic.

A UAM aerdrome operator that makes the decision to control airborne traffic must be qualified as a PSU. UAM aerodrome operators share takeoff and landing information with their PSU for dissemination across the PSU Network and can monitor the PSU Network for informational purposes.

UAM aerodrome operators may provide passenger and/or cargo screening and security or may contract out this responsibility.


Unmanned Aerial Vehicle (UAV): aka drone. An aircraft without any human pilot, crew or passengers on board. It could be piloted by an autonomous system (like a robot) or a ground-based human pilot. 


Unmanned Aircraft Systems (UAS): UAV and in addition to it the necessary operation infrastructure and control units on ground and air, such as data transmission infrastructure, and other operation support systems and/or elements.


Unmanned Aerial Vehicle Original Equipment Manufacturer (UAV OEM): Legal and/or physical person, providing overall UAV solutions to the market. An OEM has a close collaboration with suppliers for the successful platform and payload integration demands the easy exchange of successful prediction while mitigating mutual intellectual property and data security concerns. 


Unmanned Aircraft Systems Traffic Management (UTM): An air traffic management ecosystem that controls the flight paths and operations of aerial drones and potentially air taxis. UTM is separate from, but complementary to, the ATM system, which is used for air traffic management aircraft with pilots on board. UTM requires safe airspace integration with traditional airline operations.


UAS Geographical Zone: A portion of airspace that facilitates, restricts, or excludes drone operations in order to address risks pertaining to safety, privacy, protection of personal data, security, or the environment, arising from UAS operations.


UOE: UAM Operating Environment


U-Space: A set of new services relying on a high level of digitalization and automation of functions and specific procedures designed to support safe, efficient, and secure access to airspace for large numbers of drones.


U-Space Service Providers (USSP):  U-Space service providers support the safe and efficient operation of drones and safe access to airspace. These organizations must be certified to provide U-Space services in one or more European member states. 


V2V: vehicle-to-vehicle (V2V) communication


VTOL: vertical takeoff and landing


VTOL UAV: UAV able to take off, hover, and land vertically.


Very-Large Scale Demonstration (VLD): Projects bridging the gap between research and innovation and implementation. VLDs use early versions of end-user systems and integrate these new technology elements into existing systems in order to test it in live conditions. Key stakeholders participation is essential to define the VLDs' goals and secure their commitment to operational rollout.


Very Low Level (VLL): Airspace below 150m (500 feet) AGL used by aircraft such as UAV, medical helicopters, police, and military aircraft. VLL has not yet been integrated into the global airspace classification.

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