ADS-B (Automatic Dependent Surveillance – Broadcast)

ADS-B systems broadcast your aircraft’s position to ATC and other appropriately equipped aircraft / vehicles, usually via your transponder. There are two types of ADS-B transmissions: ADS-B Out, which are the transmissions going out from your plane, and ADS-B In, which are transmissions that your aircraft can copy if you have the proper equipment.
Virtually all aircraft are required to be ADS-B Out capable in the United States by 2020 and an LOA is required for many international ADS-B Out operations and all ADS-B In operations.

ADS-C (Automatic Dependent Surveillance – Contract)

This is a Data Link Communications application that allows the aircraft to form an automatic position reporting contract with Air Traffic Control (ATC). When enabled, the aircraft will automatically provide data to ATC without further input from the pilots. Although it has some similarity with ADS-B (Broadcast), the two technologies are different systems and have entirely separate standards, mandates, and requirements.

ATN-B (Aeronautical Telecommunication Network – Baseline)

This is a type of Data Link Communications (DLC) system that provides the aircraft with the capability to perform Controller Pilot Data Link Communications (CPDLC). It is a digital-based system and is primarily used in European continental airspace. (See also “VDL-Mode 2.”)

B-RNAV (Basic Area Navigation)

Also known as “RNAV-5”, it refers to an aircraft’s Area Navigation (RNAV) ability for continental en-route operations. An LOA is not universally required, but is highly recommended. The LOA that authorizes B-RNAV (B034) is the same LOA that authorizes P-RNAV; authorization for P-RNAV is required in Europe and other regions.

CPDLC (Controller-Pilot Data Link Communications)

This is a Data Link Communications (DLC) application that allows pilots to provide text reports to Air Traffic Control (ATC) in lieu of verbal communication to help alleviate radio congestion. In many airspaces where CPDLC is supported, the preference is for pilots to use CPDLC to send reports to ATC and to receive clearances, with high-frequency radio used as a backup. Aircraft operating in the North Atlantic (NAT) Region at or above FL290 will be required to be equipped with CPDLC by January 2020.

CPDLC-DCL (CPDLC Departure Clearances)

CPDLC-DCL provides automated assistance for requesting and delivering initial and revised departure clearances using CPDLC. US Part 91 operators do not currently require a Letter of Authorization (LOA) to use CPDLC-DCL.

LOA D095 / D195

For Part 91 operations, the FAA’s LOA D095 authorizes the operator to use the MMEL as an MEL. LOA D195 requires the operator to create a custom MEL specific to their aircraft.

DLC (Data Link Communications)

This is an umbrella term that covers various technologies, systems, and mandates, including CPDLC, ADS-C, FANS, ATN-B1, LINK 2000+ (SESAR 2020), and more. DLC refers to the aircraft’s ability to communicate with Air Traffic Control (ATC) using Data Link functions – specifically, Controller-Pilot Data Link Communications (CPDLC) and Automatic Dependent Surveillance – Contract (ADS-C).
DLC systems enhance efficiency and safety resulting in lower costs overall for civil and commercial aviation. Some areas of the world are already requiring that aircraft be DLC capable, and a Letter of Authorization (LOA) is required for DLC operations.

ERP (Emergency Response Plan)

Helps anyone of any level of experience respond to emergencies in an organized and responsive manner, adhering to industry best practices and standards.

ERT (Emergency Response Team)

Individuals involved in responding to an emergency as per the Emergency Response Plan (ERP).

FAM (Flight Attendant Manual)

Standard operating procedures for cabin crewmembers, including normal and emergency procedures, passenger service, and catering guidelines.

FANS (Future Air Navigation Systems) 1/A+

This is a worldwide, analog Data Link network that supports Controller-Pilot Data Link Communications (CPDLC).
It is used to refer to a Data Link system that includes both analog (FANS) and digital (ATN-B) components, which is applicable in remote, oceanic or continental airspace. It can be viewed as the broadest-reaching and most capable Data Link system.

Fleet MEL

The operator may elect to have a single MEL for multiple aircraft of the same make and model listed in their Operation Specification/Management Specification (OpSpec/MSpec). This is known as a Fleet MEL.

FOM (Flight Operations Manual)

Describes policies and procedures for the entire Flight Department, including job descriptions and personnel policies, SMS, operating and maintenance procedures, training, and security.

ICAO (Annex 6 Part II)

The International Civil Aviation Organization (ICAO) Standards and Recommended Practices of Annex 6, Part II, apply to International General Aviation operations with airplanes.

Internal Audit Program

Used to evaluate your operations against your documentation. Perform and manage internal audits of facilities, maintenance, dispatch, administration, and operations.

IOM (International Operations or Procedures Manual)

Both a reference for pilots flying oceanic routes and a supporting document for any application to request authorizations from your state Civil Aviation Authority.

LINK-2000+ / SESAR 2020

“LINK-2000+” is the name of a former European program (which is now part of “SESAR 2020”) that requires aircraft to be CPDLC capable and ATN-compliant by 2020 in order to operate above FL285 in Europe. If you receive DLC authorization for ATN CPDLC from your Civil Aviation Authority (e.g., FAA), you will meet the European requirements and do not need to obtain any additional authorizations.
Note: LINK-2000(+) / SESAR 2020 are names of government programs only and do not refer to a specific set of avionics. A “LINK-2000 compliant system” is ultimately a CPDLC system that can interoperate with the ATN network.

LOA / OpSpec/Mspec (Letter of Authorization / Operations Specification / Management Specification)

The formal approval issued by the FAA to operators to authorize specific flight activity.

Master Minimum Equipment List (MMEL)

The MMEL contains a list of equipment and instruments that may be inoperative on a specific type of aircraft. It is also the basis for the development of an individual operator’s MEL. The MMEL is the regulatory authority’s (i.e., FAA’s or EASA’s) document from which the operator’s MEL manuals must be created. Each certified aircraft typically has its own MMEL.


The MEL is the specific inoperative equipment document for a particular make and model aircraft by serial and registration numbers. An MEL generally consists of the MMEL for a particular type aircraft custom tailored to specific aircraft, the MMEL’s preamble, the procedures document, and an LOA. As such, the MEL permits operation of the aircraft under specified conditions with certain equipment inoperative.

NAT HLA (North Atlantic High Level Airspace)

This refers to the standards required to operate in the North Atlantic (NAT) region.
A Letter of Authorization is currently required for NAT HLA / NAT operations, but it is issued primarily on the basis of an aircraft’s oceanic PBN capabilities (e.g., RNP-10/4/2) and long range communication equipment.
Note: Much of this airspace was previously designated as “NAT Minimum Navigation Performance Specifications (MNPS)” airspace. Operators without a NAT HLA authorization but with MNPS authorization may operate in the NAT HLA until December 31, 2019.

NEF (Nonessential Equipment and Furnishings)

Items installed on the aircraft that have no effect on the safe operation of a flight if inoperative, damaged, or missing.

Part-NCC (Non-Commercial operations with Complex motor-powered aircraft)

European mandatory regulations aimed at enhancing safety, training and record-keeping protocols within Europe for companies flying complex corporate aircraft privately.

PBCS (Performance-Based Communication and Surveillance)

PBCS is an umbrella term for communication and surveillance specifications, comparable to the use of “PBN” as an umbrella for navigation specifications. Communication specifications are described in terms of an aircraft’s Required Communication Performance (RCP) ability (e.g., RCP240, RCP400) and surveillance specifications are described in terms of an aircraft’s Required Surveillance Performance (RSP) ability (e.g., RSP180).
In both cases, RCP and RSP, the numerical value refers to the aircraft’s performance in seconds – that is, the maximum time the equipment would take to perform the intended communication / surveillance action. A lower value means that the equipment is faster and therefore capable of more advanced functions. The value does not refer to a static performance time, but instead is an upper window; 99% of all operations must be met within that window to be RCP / RSP certified.
PBCS has been implemented to help ensure that regulators and manufacturers meet and adhere to safe standards when designing advanced communication and surveillance networks, such as CPDLC and ADS-C.

PBN (Performance Based Navigation)

PBN is an umbrella term for Area Navigation (RNAV) / Required Navigation Performance (RNP) specifications and was created to simplify the language used when listing requirements for different airspace. Letters of Authorization (LOAs) may be issued based on the “PBN requirements” of various airspaces.
The PBN concept is primarily intended to structure navigation specifications according to Required Navigation Performance (RNP), and is further subdivided according to phase of flight (e.g., terminal, continental, oceanic, and approach). The number described by an RNP specification is an accuracy threshold for the navigation equipment – that is, the maximum distance (NM) that the sensors could deviate for 99% of the time the aircraft is operating in that portion of flight. Accordingly, the lower the RNP value is, the more accurate the equipment is, and therefore the higher the standard that is being applied.
Most Civil Aviation Authorities, including the FAA, have a separate PBN authorization for each phase of flight. It is recommended that operators obtain an LOA for each phase to clarify their capabilities when operating internationally, as the authorization requirements for each phase of flight vary throughout the world. For example, although no LOA is required for Part 91 operators to conduct terminal PBN operations in the United States, some countries, such as Hong Kong and Australia, do. LOA C063 can be used to demonstrate that the operator is capable of terminal RNP-1 operations in those countries.

P-RNAV (Precision Area Navigation)

Also known as “RNAV-1”, it refers to an aircraft’s Area Navigation (RNAV) ability in the terminal area. A Letter Of Authorization (LOA) is required for P-RNAV operations, especially when operating in Europe.

RCP (Required Communication Performance)

The “communication” component of Performance Based Communication and Surveillance. The amount of time it takes for an instruction to travel from the controller to your aircraft and your acknowledgement back to the controller.

RLatSM (Reduced Lateral Separation Minimum)

Airspace where aircraft are separated laterally by a minimum of 25 nautical miles (1/2 degree). North Atlantic Organized Track System tracks that were previously designated as “RLatSM” are now designated as “PBCS Tracks,” but the designation “RLatSM” could potentially be used elsewhere in the future.

RNP (Required Navigation Performance)

This is the aircraft’s ability to meet navigation requirements, indicated by a number (e.g., RNP-10, RNP-4, etc.). The number refers to the navigation equipment’s accuracy, measured in the maximum distance (NM) that a sensor may deviate for 99% of the phase of flight in which the RNP specification is set.
Aircraft are required to have an oceanic RNP Letter of Authorization (LOA) to operate on most oceanic routes (e.g., RNP-10/4/2). RNP operations in other phases of flight may require an LOA as well, per the International Civil Aviation Organization (ICAO)’s categorization of PBN operations.

RNP APCH (Required Navigation Performance – Approach)

This is the umbrella term for a variety of GNSS-based RNP approaches, both with and without vertical guidance, that would meet a minimum accuracy of RNP-0.3 for the final approach phase. It includes LP, LNAV, LPV, and LNAV/VNAV. It does not refer to advanced approaches that specifically require authorization; such approaches are designated by the term “RNP APCH AR” or “RNP AR,” in which “AR” means “Authorization Required”.
The terms “RNP APCH” versus “RNP AR” can be somewhat misleading. Although the FAA does not specifically require an LOA for RNP APCH for domestic operations, operators should not misinterpret this as saying that only RNP AR requires an LOA – the authorization requirements vary worldwide. Each country’s individual requirements should be reviewed to see not only if RNP APCH is supported, but also if an LOA is required. Some countries, such as Australia and Hong Kong, do require operators to hold LOAs prior to conducting RNP APCH approaches.

RNP-10 / -4 (Oceanic / Remote Required Navigation Performance)

The long-range navigational capability of an aircraft operating in oceanic / remote airspace. RNP-10 means that a navigation system must be able to calculate its position to within a square with a lateral dimension of 10 nautical miles.

RSP (Required Surveillance Performance)

The amount of time it takes for the surveillance system (e.g., ADS-C) to send updated aircraft position in order to ensure a safe separation.

RVSM (Reduced Vertical Separation Minimum)

This is a standard for vertical separation that is usually applied between FL290 (flight level 290) and FL410 (flight level 410). It requires aircraft to meet certain equipment and performance standards, as well as a Letter of Authorization (LOA), to conduct RVSM operations.

SMS (Safety Management System)

The formal, top-down, organization-wide approach to managing safety risk and ensuring the effectiveness of safety risk controls.

SMS Software (Safety Management System Software)

Configurable modular software that serves as a central location to store files, complete risk assessments, post company news, and manage your Read & Initial log.

SPI (Safety Performance Indicators)

A measure to express the level of safety performance achieved, usually presented in terms of the frequency of occurrence of harmful events.

SRP (Safety Risk Profile)

A high-level analysis of the risks inherent to your operations and mitigations to lower risk levels.

VDL (Very High Frequency Data Link) / VDL M0/A / VDL M2

The technical specification for a Data Link Communications (DLC) subnetwork that interacts between the aircraft’s VHF end-systems and corresponding ground-based stations. Although several subnetworks have been defined, only two VDL subnetworks are used: Mode 0/A and Mode 2. Both VDL Mode 0/A and Mode 2 can be used with the FANS network, but VDL Mode 2 is the only available subnetwork to interact with the ATN network.
VDL subnetworks are primarily used for continental CPDLC operations. As aircraft cross the oceanic boundary, it is expected that the equipment will switch to a satellite-based subnetwork instead (e.g., Inmarsat or Iridium).
VDL M2 is the only subnetwork available for US domestic continental CPDLC operations. In addition, the US continental CPDLC system requires that aircraft VDL M2 radio / CMU equipment have tunable multifrequency capability (i.e., compliance with TSO-C160a). Operators who intend to use CPDLC for continental US flights must ensure that their equipment is appropriately compliant, although Part 91 operators do not specifically need to possess an LOA to conduct domestic CPDLC operations. (Note that any international or oceanic operation does still require an LOA.)