Appendix A A-10 A.2.34 Global Positioning System (GPS). GPS refers to the worldwide positioning, navigation, and timing determination capability available from the U.S. satellite constellation. The service provided by GPS for civil use is defined in the GPS Standard Positioning Service (SPS) Performance Standard. GPS is composed of space, control, and user elements.
A.2.35 Gross Navigation Error (GNE). A GNE is a lateral deviation of 10 NM or more from the aircraft’s cleared route.
A.2.36 High Frequency (HF) Communications. Radio frequencies between 3 and 30 MHz used for air/ground voice communications in overseas operations. HF communications (or, if supported, SATVOICE) capability is required for all IFR operations in controlled airspace when out of the range of VHF communications. If you are in doubt as to the VHF coverage along your intended route of flight, your aircraft should be equipped with HF communications (or SATVOICE, if supported).
A.2.37 High Seas. The seas beyond the 12 NM from the baseline of a shore. Airspace over the high seas is considered international airspace.
A.2.38 Instrument Meteorological Conditions (IMC) (ICAO). Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling, less than the minima specified for visual meteorological conditions (VMC).
A.2.39 International Civil Aviation Organization (ICAO). ICAO is a specialized agency of the United Nations whose objective is to develop the principles and techniques of international air navigation and to foster planning and development of international civil air transport.
A.2.40 Journey Logbook (ICAO). A record of the flight operation, which should be retained in order to maintain a continuous record of the last 6 months’ operations.
A.2.41 Large Height Deviations (LHD). A deviation from your cleared altitude by 300 feet or more.
A.2.42 Lateral Navigation (LNAV). A function of RNAV equipment that calculates, displays, and provides lateral guidance to a profile or path.
A.2.43 Long-Range Navigation System (LRNS). An electronic navigation unit that is approved for use under IFR as a primary means of navigation. An LRNS must have at least one source of navigational input suitable for oceanic and remote continental navigation, such as an INS or a GPS receiver.
A.2.44 Mach Number Technique. Describes a control technique used by ATC whereby turbojet aircraft operating successively along suitable routes are cleared to maintain appropriate Mach numbers for a relevant portion of the en route phase of flight. The principal objective is to achieve improved utilization of the airspace and to ensure that separation between successive aircraft does not decrease below the established minima.
Appendix A A-11 A.2.45 Master Document. A copy of the operational flight plan, labeled as “Master,” on which the currently effective route clearance is recorded, and which serves as the primary flightcrew reference for updating the progress of the flight. It should list sequentially the waypoints defining the route, the track and distance between each waypoint, and other information relevant to navigation along the cleared track.
A.2.46 Master Minimum Equipment List (MMEL) (ICAO). A list established for a particular aircraft type by the organization responsible for the type design with the approval of the State of Design containing items, one or more of which is permitted to be unserviceable at the commencement of a flight. The MMEL may be associated with special operating conditions, limitations, or procedures.
A.2.47 Minimum Equipment List (MEL) (ICAO). A list that provides for the operation of aircraft, subject to specified conditions, with particular equipment inoperative, prepared by an operator in conformity with, or more restrictive than, the MMEL established for the aircraft type.
A.2.48 Navigation Specification (NavSpec) (ICAO). A set of aircraft and flightcrew requirements needed to support PBN operations within a defined airspace. There are two kinds of NavSpecs:
A.2.48.1 Area Navigation (RNAV) Specification. A NavSpec based on RNAV that does not include the requirement for onboard performance monitoring and alerting, designated by the prefix RNAV (e.g., RNAV 5 or RNAV 1).
A.2.48.2 Required Navigation Performance (RNP) Specification. A NavSpec based on RNAV that includes the requirement for onboard performance monitoring and alerting, designated by the prefix RNP (e.g., RNP 4 or RNP Approach (APCH)).
A.2.49 North Atlantic High Level Airspace (NAT HLA). NAT HLA is that volume of airspace (as defined in ICAO Doc 7030) between FL 285 and FL 420 within the OCAs of Bodo Oceanic, Gander Oceanic, New York Oceanic East, Reykjavik, Santa Maria, and Shanwick, excluding the Shannon and Brest Ocean Transition Areas. Aircraft operators must obtain approval from their State of Registry to operate within NAT HLA.
A.2.50 Notice to Airmen (NOTAM) Domestic/International. A notice containing information concerning the establishment, condition, or change in any aeronautical facility, service, procedure, or hazard, the timely knowledge of which is essential to personnel concerned with flight operations. NOTAMs are distributed via two methods: telecommunications (Class I Distribution) and other than telecommunications (Class II Distribution).
A.2.51 Oceanic Airspace. Airspace over the high seas. Generally, “oceanic” is included in the airspace designation (e.g., OCA), and direct controller-pilot VHF voice communications are not available. ATC is provided using at least some elements of procedural control in accordance with ICAO.
Appendix A A-12 A.2.52 Oceanic Area Control Center (OACC). An ACC with responsibilities for providing ATS in oceanic airspace. Responsibility for the provisions of ATS is delegated by ICAO to various States based primarily upon geographic proximity and the availability of the required resources.
A.2.53 Offshore/Control Airspace Areas. Airspace designated in international airspace, extending outward from 12 NM from the coast of the United States to the CTA/FIR boundary, in accordance with the criteria in 14 CFR part 71, within which the United States applies domestic ATC procedures.
A.2.54 Performance-based Communication (PBC) (ICAO). Communication based on performance specifications applied to the provision of ATS. An RCP specification includes communication performance requirements that are allocated to system components in terms of communication to be provided and associated continuity, availability, integrity, safety, and functionality needed for the proposed operation in the context of a particular airspace concept.
A.2.55 Performance-based Navigation (PBN) (ICAO). RNAV based on performance requirements for aircraft operating along an ATS route, on an IAP, or in a designated airspace. Performance requirements are expressed in NavSpecs (RNAV specification, RNP specification) in terms of accuracy, integrity, continuity, availability, and functionality needed for the proposed operation in the context of a particular airspace concept.
A.2.56 Performance-based Surveillance (PBS) (ICAO). Surveillance based on performance specifications applied to the provision of ATS. An RSP specification includes surveillance performance requirements that are allocated to system components in terms of the surveillance to be provided and associated data delivery time, continuity, availability, integrity, accuracy of the surveillance data, safety, and functionality needed for the proposed operation in the context of a particular airspace concept.
A.2.57 Pilot in Command (PIC) (ICAO). The pilot designated by the operator, or in the case of GA, the owner, as being in command and charged with the safe conduct of a flight.
A.2.58 Procedural Control (ICAO). Term used to indicate that information derived from an ATS surveillance system is not required for the provision of ATC service.
A.2.59 Procedural Separation (ICAO). The separation used when providing procedural control.
A.2.60 Reduced Vertical Separation Minima (RVSM). RVSMs are 1,000 feet vertical separation between FL 290 and FL 410 inclusive. Operators and aircraft must be authorized by the Administrator to operate in RVSM airspace. An operator may be authorized without application to the FAA when meeting the standards of 14 CFR part 91 appendix G, section 9. Alternatively, the B046 authorization is available as a specific approval, when needed for international operations. For additional guidance, refer to AC 91-85, Authorization of Aircraft and Operators for Flight in Reduced Vertical Separation Minimum (RVSM) Airspace.
Appendix A A-13 A.2.61 Remote Continental Airspace. Airspace over land where VHF voice communications, ATC surveillance (via radar or ADS-B), and reliable ground-based NAVAIDs are not available. ATC is provided using procedural control and procedural separation, with LRCS.
A.2.62 Required Communication Performance (RCP) Specification (ICAO). A set of requirements for ATS provision, aircraft capability, and operations needed to support PBC within a defined airspace.
A.2.63 Required Navigation Performance (RNP) Specification (ICAO). A NavSpec based on RNAV that includes the requirement for performance monitoring and alerting, designated by the prefix RNP (e.g., RNP 2, RNP 4, or RNP APCH).
A.2.64 Required Surveillance Performance (RSP) Specification (ICAO). A set of ATS provisions, including communication services and aircraft and operator requirements, needed for surveillance, supporting a performance-based operation within a defined airspace.
A.2.65 Special Use Airspace (SUA). Consists of airspace of defined dimensions where activities must be confined because of their nature, or where limitations are imposed upon aircraft operations that are not a part of those activities, or both.
A.2.65.1 Prohibited Areas. A prohibited area is an SUA designated under 14 CFR part 73, within which no person may operate an aircraft without the permission of the using agency.
A.2.65.2 Restricted Areas. A restricted area is an SUA designated under 14 CFR part 73, within which the flight of aircraft, while not wholly prohibited, is subject to restriction.
A.2.65.3 Warning Areas. A warning area is airspace of defined dimensions, extending from 3 NM outward from the coast of the United States, which contains activity that may be hazardous to nonparticipating aircraft. The purpose of such a warning area is to warn nonparticipating pilots of the potential danger.
A warning area may be located over domestic or international waters or both.
A.2.66 Target Level of Safety (TLS) (ICAO). A generic term representing the level of risk that is considered acceptable in particular circumstances.
A.2.67 Very High Frequency (VHF). The frequency band between 30 and 300 MHz. Portions of this band, 108–118 MHz, are used for certain NAVAIDs, while 118–136 MHz are used for civil air/ground voice communications.
A.2.68 Visual Meteorological Conditions (VMC). Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling, equal to or better than specified minima.
A.2.69 Waypoint. A predetermined geographical position that is defined in terms of latitude/longitude coordinates. Waypoints may be a simple named point in space or
Appendix A A-14 associated with existing NAVAIDs, intersections, or fixes. A waypoint is most often used to indicate a change in direction, speed, or altitude along the desired path. For purposes of RNAV procedures, waypoints are identified as either:
A.2.69.1 Flyby Waypoint. Flyby waypoints are used when an aircraft should begin a turn to the next course prior to reaching the waypoint separating the two route segments. This is known as turn anticipation.
A.2.69.2 Flyover Waypoint. Flyover waypoints are used when the aircraft must fly over the point prior to starting a turn.
Appendix B B-1 APPENDIX B. OPERATIONAL AUTHORIZATIONS: 14 CFR PART 91 LOAs B.1 Authorization for Oceanic and Remote Continental Operations for 14 CFR Part 91.
The FAA requires all operators to obtain the B036 operational authorization to indicate oceanic Required Navigation Performance (RNP) on air traffic control (ATC) flight plans.
Note: Details on oceanic and remote continental authorizations for certificated operators are available from the responsible Flight Standards office.
B.1.1 Oceanic Authorizations. The 14 CFR part 91 Letter of Authorization (LOA) B036 is called “Oceanic Required Navigation Performance (RNP) Operations.” To indicate an oceanic RNP capability (i.e., RNP 2 (oceanic/remote), RNP 4, or RNP 10) on an ATC flight plan, a B036 is required.
B.1.1.1 The FAA recommends 14 CFR part 91 operators obtain LOA B036 for all oceanic operations. While LOA B036 is not required for 14 CFR part 91 to fly in oceanic airspace, it is required to indicate oceanic RNP capability
(i.e., RNP 2 (oceanic/remote), RNP 4, or RNP 10) on ATC flight plans.
Without RNP capability, you may not be cleared on optimal routes and/or altitudes.
B.1.1.2 For some oceanic areas, 14 CFR part 91 operators require LOA B036. Some oceanic areas require a minimum of RNP 10 capability, including, for example, NAT HLA and Central East Pacific (CEP) routes at FL 290 through FL 410. Certain North Pacific (NOPAC) routes require a minimum of RNP 4 capability (as well as RCP 240 and RSP 180) at certain altitudes. You should consult the AIP of the airspace you are planning to fly in to determine if a specific RNP capability is required. For details on required data communications authorizations associated with RCP 240 and RSP 180, refer to AC 90-117, Data Link Communications.
B.1.2 Remote Continental Authorizations. An optional 14 CFR part 91 LOA B030 is available as a means of documenting FAA endorsement of remote continental training and procedures. That LOA is called “IFR Remote Continental Operations and/or IFR Alaska Special Minimum En Route Altitude (MEA) Operations.”
B.1.3 LRNS. Generally, at least two LRNSs are required in oceanic airspace. Operators are encouraged to obtain a B036 for any operations in oceanic flight information regions (FIR). For 14 CFR part 91 subpart F, overwater operations using a single LRNS are permitted, in accordance with 14 CFR § 91.511.
B.1.4 Authorization Process. The FAA uses a five-phase process to approve operator applications. The responsible Flight Standards office can provide you with the details pertinent to each phase and your specific requirements.
B.1.4.1 Phase 1. You determine a need for authorization and contact the FAA.
Appendix B B-2 B.1.4.2 Phase 2. You formally submit a proposal for FAA evaluation.
B.1.4.3 Phase 3. We evaluate the request and determine what level of demonstration is required. We may conduct the demonstration within the responsible Flight Standards office, at your site of operations, or at another suitable location.
B.1.4.4 Phase 4. We observe and evaluate a demonstration of your ability to perform in accordance with your proposal. This is an operational evaluation. If the demonstration is unsuccessful, we will provide feedback on deficient areas and their resolution.
Note: Flight or line observations are not required for General Aviation (GA) LOA applications. For GA operators, we evaluate your application and, if warranted, conduct a knowledge validation (tabletop exercise and/or static airplane demonstration).
B.1.4.5 Phase 5. If your demonstration is successful, we issue the requested operational authorizations.
B.1.5 Web-Based Operations Safety System (WebOPSS).
B.1.5.1 WebOPSS Access. WebOPSS is the FAA’s document management system for issuing operational authorizations to air operators as indicated in 14 CFR.
Authorized aviation industry personnel can apply for access to WebOPSS through their principal inspectors (PI). WebOPSS access allows industry personnel to view and propose changes to their authorizations, which can expedite applications.
B.1.5.2 WebOPSS Training. You will require training prior to receiving WebOPSS access. You can accomplish the training either through an FAA inspector or by taking the WebOPSS formal training course through the FAA’s Mike Monroney Aeronautical Center (MMAC).
Note 1: The Operations Approval Portal System (OAPS) was introduced in 2018 to streamline processing of Next Generation Air Transportation System (NextGen) authorizations. OAPS allows bundling and is integrated with WebOPSS. To register for an account, follow the instructions in OAPS at https://oaps.faa.gov. For support and/or questions, email 9-AWA-AVS-AFS-OAPS@faa.gov.
Note 2: The FAA’s Safety Assurance System (SAS) is programmed to absorb functions that, as of early 2025, were performed by OAPS and WebOPSS. To register for a SAS account, visit the SAS External Portal at https://sas.faa.gov/sas.external.portal/ext/accounts.
B.1.6 Title 14 CFR Part 91 Authorizations. Title 14 CFR part 91 operators can obtain oceanic and/or remote operational authorization per Table B-1 below:
Appendix B B-3 Table B-1. Title 14 CFR Part 91 LOAs for Oceanic and/or Remote Areas LOA Title Remarks A056 Data Link Communications Required to conduct data link communications in oceanic areas.
B036 Oceanic Required Navigation Performance (RNP) Operations Required to indicate oceanic and remote continental RNP capability. See the discussions in paragraph 2.5.1 and in B.1.1.
B039 Operations in North Atlantic High Level Airspace (NAT HLA) Required to operate in NAT HLA.
B046 Operations in Reduced Vertical Separation Minimum (RVSM) Airspace Required to operate outside FAA-controlled RVSM airspace.
D098 Short-Term Operations in Airspace Requiring Specific Approval Available to authorize operations in oceanic/remote airspace, RVSM airspace, and in NAT HLA.
B.2 Map, Authorization for Optional Single Long-Range Navigation System (LRNS).
Figure B-1 shows the area defined in 14 CFR § 91.511(f), where use of a single LRNS is authorized for 14 CFR part 91 subpart F operators.
Figure B-1. Single Long-Range Navigation System (LRNS) Area
Appendix C C-1 APPENDIX C. UNUSUAL WEATHER ACTIVITY C.1 Volcanic Ash.
C.1.1 In 2010, a small volcano in Iceland erupted, spewing volcanic ash into the atmosphere.
Eyjafjallajokull’s eruption stranded 8 million travelers and resulted in the largest airspace shutdown since World War II. As a result, in 2012, ICAO produced the first edition of ICAO Doc 9974, Flight Safety and Volcanic Ash, which provides guidance for aircraft operators when volcanic ash contamination may be a hazard for flight operations.
Whenever your flight planned route approaches the vicinity of a volcanic ash cloud, you should understand the potentially catastrophic effects ingesting volcanic ash could have on your aircraft engines. Currently, nine Volcanic Ash Advisory Centers (VAAC) offer worldwide coverage of volcanic activity and provide valuable information to assist your trip planning efforts. For more information on the VAACs, go to https://www.ospo.noaa.
gov/Products/atmosphere/vaac/other-vaacs.html.
Figure C-1. ICAO Volcanic Ash Advisory Centers C.1.2 Volcanic eruptions emit various gases along with magma, including sulfur dioxide (SO2) and hydrogen sulfide (H2S). When SO2 gas combines with water in the atmosphere, a sulfate aerosol primarily composed of dilute sulfuric acid is formed. Flying through sulfuric acid aerosols has caused crazing of acrylic windows, fading of exterior paint, and
Appendix C C-2 accumulation of sulfate deposits in engines. SO2 gas is colorless, but under certain conditions of reflection and refraction of sunlight, a sulfuric acid aerosol may be a visible atmospheric feature, such as a layer of haze of variable color (brownish, yellowish, bluish, or whitish). Ash particles likely will be present in aerosol haze but possibly in minor or trace amounts.
C.1.3 Volcanoes are the only sources of large quantities of sulfur gases at cruise altitudes, and both types of sulfur gas have a noticeable smell. SO2 is identifiable as the sharp, acrid odor of a freshly struck match. H2S, also known as sewer gas, has the odor of rotten eggs.
“Electrical smoke and fire” and SO2 are two odors described as somewhat similar. Sulfur gases may be detectable only for a short period of time because of “olfactory fatigue” (temporary loss of the ability to smell a particular odor). Inhalation of SO2, even at low concentrations (<5 parts per million (ppm)), can cause respiratory tract irritation, especially in people with asthma and chronic obstructive pulmonary disease.
C.1.4 If you smell sulfur gases in the cockpit, this may indicate volcanic activity that has not yet been detected or reported and/or your possible entry into an ash-bearing cloud. After determining there are no secondary indications that would result from and indicate an electrical fire, you should establish whether the sulfur odor is transient or not.
C.1.5 You can best achieve this by donning your oxygen mask(s) and breathing 100 percent oxygen for the period of time that results in a complete change of air within the cockpit and also allows you to regain your sense of smell. After the appropriate time period, remove your oxygen mask(s) and determine if the odor is still present. If you confirm the continued presence of sulfur gas, you should inform the controlling Air Traffic Service (ATS) unit and dispatch center as soon as practicable to request information about any relevant volcanic activity and the whereabouts of possible volcanic clouds. You do not have the means to determine directly whether or not the cloud is hazardous; therefore, you should seek to exit the cloud.
C.1.6 You might see other indications of volcanic ash, such as fine dust in the aircraft, St. Elmo’s fire visible around your windshield, and/or a visible glow in the intake of your engines. Your airspeed indications may also become unreliable as the ash contaminates your pitot/static system. The Aeronautical Information Manual (AIM), Chapter 7, Safety of Flight, recommends, in the event of encountering an ash cloud, that pilots reverse course and reduce thrust (altitude permitting) to escape from the cloud, and to disengage autothrottles (as applicable), turn on continuous ignition, and turn on all bleed-powered systems so as to provide additional engine stall margin. In addition, the AIM discusses Pilot Weather Reports (PIREP) related to volcanic ash activity and recommends you complete the Volcanic Activity Reporting Form (VAR), found in appendix 2 of the AIM.
You should avoid flying in the vicinity of known volcanic ash. Attempting to overfly an ash plume is also potentially perilous, as an emergency descent could place the aircraft into the plume.
Appendix C C-3 C.2 Space Weather.
C.2.1 The effects of space weather on aviation have generated an increasing amount of interest in recent years. Space weather most commonly impacts radio communications between your aircraft and ground stations. Space weather may also impact navigation signals from space-based and ground-based transmitters as well as onboard avionics components.
Exposure to increased radiation levels during solar events has not been a noticeable issue, but it is a factor that you can plan for in order to protect your frequently flying crewmembers and passengers.
C.2.2 The magnetic field around the Earth converges at the North and South Poles, allowing charged particles to access lower levels of the Earth’s atmosphere. These lower levels are the same levels used to fly international flights around the world. The aviation community has shown increasing interest in this phenomenon at the poles as the expansion of polar routes has seen more and more flights susceptible to space weather.
C.2.3 The solar cycle is an approximately 11-year period that is characterized by solar activity that departs from the sun and has impacts on whatever celestial bodies are in the path of this space weather. The three effects of this weather are known as radio blackouts, geomagnetic storms, and solar radiation storms. These storms can have varying degrees of short- and long-term impact on ground-based navigation signals, aircraft and aircrew in flight, space-based transmitters, spacecraft, and space crew. The Space Weather Prediction Center (SWPC) tracks these storms and issues space weather watches, warnings, and alerts to inform the public of potential impacts.
Figure C-2. Example of a National Oceanic and Atmospheric Administration Scales Activity Report C.2.4 Space weather alerts can be subscribed to through the SWPC Product Subscription Service and the following link: https://pss.swpc.noaa.gov/ProductSubscriptionService/Lo ginWebForm.aspx.
C.2.5 Space Weather Advisory Information. Amendment 78 to ICAO Annex 3, Meteorological Service for International Air Navigation (November 2018), introduced a requirement to issue space weather advisory information when necessitated by space weather events. The space weather advisory message is similar in structure to advisory
Appendix C C-4 messages for tropical cyclones and volcanic ash clouds issued by the Tropical Cyclone Advisory Centers (TCAC) and VAACs concerned.
C.2.6 Space Weather Advisory Centers issue space weather advisory information when there are impacts to high frequency (HF) communications, communications via satellite, Global Navigation Satellite System (GNSS)-based navigation and surveillance systems, or when heightened radiation occurs.
C.2.7 The advisory message informs the user of:
• The type of impact;
• The expected onset, or that the event is already in progress;
• The duration of the event;
• A generalized description of the spatial extent affected for the next 24 hours; and
• A description of the severity of the impact in moderate (MOD) or severe (SEV) categories.
C.2.8 ICAO Annex 3; ICAO Doc 10100, Manual on Space Weather Information in Support of International Air Navigation; and ICAO NAT Doc 006 – Part III, Space Weather Contingency Procedures, published in 2023, are additional references.