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i. Restricted Areas. Title 14 CFR part 73 designates restricted areas to contain activities considered hazardous to non-participating aircraft. Aircraft may not operate within 3 nautical miles (NM) of a restricted area unless authorized under the provisions of part 73, § 73.13. There are numerous restricted areas near and along the Gulf of Mexico coastline. Pilots should be aware of these areas and plan flights accordingly.
9-3. NAVIGATION AND COMMUNICATIONS IN THE GULF OF MEXICO.
a. Background. ICAO Annex 6, Part II contains standards and recommended practices adopted as the minimum standards for all airplanes engaged in general aviation international air navigation. It requires those aircraft operated in accordance with IFR, at night, or on a VFR controlled flights (such as in CTA/FIR oceanic airspace) to have installed and approved radio communications equipment capable of conducting two-way communication at any time with the appropriate aeronautical stations on the prescribed frequencies.
b. High Frequency (HF) and VHF Communications. Due to the inherent “line of sight” limitations of VHF radio equipment used for international oceanic airspace communications, aircraft operating on an IFR or controlled VFR flight plan beyond VHF communications capability must maintain a continuous listening watch and communications capability on the assigned HF frequencies. Although ATC assigns these frequencies, actual communication will be with general purpose communication facilities such as an international Flight Service Station (FSS) or Aeronautical Radio, Inc. (ARINC). These facilities will be responsible for the relay of position reports and other information between the aircraft and ATC. Except in an emergency, the use of relay on VHF through aircraft operating at higher altitudes is not an acceptable method of communication with ATC.
c. Communication and Position Reporting.
(1) Non-available Communication. The following describes an area in the Houston CTA/FIR where direct air traffic communication is not available:
• N27°28’ W086°00’ to N27°30’ W087°42’ to;
• N25°50’ W088°15’ to N25°37’ W091°55’ to;
• N24°40’ W093°19’ to N24°28’ W088°01’ to; and
• N24°00’ W086°00’ to beginning point.
(2) Communication Requirements. Pilots planning flights through this area should be aware of the communications and position reporting requirements. HF communications are available for all oceanic flights and limited VHF coverage is also available on 130.7 megahertz (MHz). The communication requirements for IFR flights within the Houston OCA are as follows:
• The aircraft must have functioning two-way radio communications equipment capable of communicating with at least one ground station from any point on the route.
• The crew must maintain a continuous listening watch on the appropriate frequency.
• Make all mandatory position reports.
d. Position Reports. When flying an oceanic route in the Gulf of Mexico, position reports must be made over all designated reporting points. A position report must also be made upon crossing the FIR boundary. Unless otherwise required, reporting points should be located at intervals of 5 or 10° latitude (if flying north/south) or longitude (if flying east/west) either north or south of the equator or east or west of the 180° meridian. Aircraft transversing 10° of latitude or longitude in 1 hour 20 minutes should normally report at 10° intervals. Slower aircraft should report at 5° intervals. In the absence of designated reporting points, make position reports if instructed by ATC. Position reports are vital to air traffic safety and control. Inability to comply is a violation of 14 CFR and ICAO requirements.
e. Navigation Requirements.
(1) Class II Navigation in the Gulf of Mexico. You can conduct Class II navigation on routes in the Gulf of Mexico using Area Navigation (RNAV) with global position system (GPS), inertial reference systems (IRS)/inertial navigation system (INS), or VOR/DME sensors. NDB might also be available. These routes are offshore and shown on en route charts. FAA Order 7110.2, Procedures for Handling Airspace Matters, current edition, establishes the areas which serve aircraft operations between U.S. territorial limits, OCA/FIR boundaries, and/or domestic flights operating over the high seas. These transition CTAs permit ATC to apply domestic procedures and separation minimums. Because there is independent radar surveillance within these CTAs, separation minimums are not as large as for other OCAs. As long as you maintain radar surveillance, you may conduct operations on Gulf routes using RNAV, GPS, IRS/INS, VOR/DME, and NDB. Because of the proximity of these routes to shore-based facilities, using shore-based Navigational Aids (NAVAID) can enhance the accuracy.
(2) Single Long-Range Navigation System (S-LRNS). Approval for use of a S-LRNS on these routes, as well as the navigation techniques, are part of the authorizations (operations specifications (OpSpec), management specifications (MSpec), letters of authorization (LOA)) issued to air carrier operators.
f. Use of NDB for Navigation.
(1) Limitations and Restrictions. The use of NDB as a primary source of navigation on long-range flights presents the operator with numerous limitations and restrictions inherent in low frequency radio equipment and the low frequency signals they receive. NDB NAVAIDs of the highest power (2,000 watts or greater) that are maintained and flight checked as suitable for navigation are limited to a usable service and/or reception range of 75 NM from the facility at any altitude. Although the operator may be able to receive standard AM broadcast stations with NDB equipment, primary dependence on these facilities for navigation is a questionable operating practice. The following are some of the inherent problems associated with reception of these stations:
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• Infrequent station identification.
• Foreign language station identification may be impossible without knowledge of the language.
• Transmitter sites are not always with the studio facilities.
• Termination of service without notice.
• Weather or atmospheric disturbances may cause erratic and unreliable signal reception.
• Flight checks may not have been flown to verify the suitability and reliability of the facility and signal for navigation.
• The “shoreline/mountain” effect may cause signal fluctuations.
• Standard broadcast stations are not approved for navigation purposes.
(2) Evaluate NDB. Considering these limitations, the operator should be able to navigate so as to maintain the course specified in the ATC clearance. Carefully evaluate the inadequacies of NDB as the sole source of navigation as an error of 10° over 2,000 miles can result in a deviation of 350 miles.
9-4. INTERNATIONAL OPERATIONS.
a. Operations to Mexico. Pilots should be aware of the landing restrictions in effect at Mexico City Airport. Operators of aircraft that land or depart from this airport during peak hours will be charged a fee. Operators planning a flight to Mexico should check the NOTAMs for updated information. Part 121 operations to Guadalajara, Mexico must meet § 121.445 special airport qualification requirements.
b. Operations to Cuba. Section 121.445 requirements for special airport qualifications apply to part 121 operations landing or departing from Guantanamo Bay Naval Air Station.
Operators should be aware that the Cuban government has issued a warning that Cuban armed forces will shoot down any aircraft that penetrates Cuban airspace without authorization and refuses to land for inspection.
c. Cuban Legal Considerations. Aircraft that receive orders to land or have landed without proper authorization will be subject to whatever penalties the Cuban authorities may prescribe, without recourse. The pilot and/or aircraft owner will be responsible for any damage, injuries or resulting expense. No aircraft may make an overflight carrying photographic equipment, arms, ammunition, explosives or other articles and substances the Cuban aeronautical authority may specify. The Cuban aeronautical authority will not authorize overflights if the operation constitutes a danger to air navigation or if, in their judgment, the operator does not offer adequate guaranties to cover any liability incurred because of the overflight. These liabilities include damage and loss caused to subjacent persons or property, and payment for any services rendered or obligations that may arise in connection with the overflight. The use of
Cuban radio for flight information, ATC, or other purposes is considered a service and operators should expect to receive billing for its use. Any person or corporation, partnership, organization or association subject to U.S. jurisdiction and considering the operation of aircraft into Cuba must review current Department of Commerce and Department of State regulations relating to trade and other transactions involving Cuba. Within 1 hour of departure, the PIC must file an IFR flight plan and a written statement with the Immigration and Naturalization Service office at the departure airport. This statement must contain all of the information in the flight plan, the name of each occupant of the aircraft, the number of occupants in the aircraft (including the flightcrew), and a description of any cargo. The U.S. Naval airfield/facilities located at Guantanamo Bay, Cuba are unavailable to all civilian air traffic except for valid emergencies.
U.S. authorities will thoroughly investigate all emergency landings to determine their validity and the nature of their business.
9-5. MILITARY AND HELICOPTER OPERATIONS.
a. Military Operations Areas. Military operations represent approximately one-third of the air traffic in the Gulf of Mexico. These operations include a high volume of non-hazardous training flights contained within Military Operation Areas. Military training routes (MTR) are on VFR and sectional maps. However, MTRs are subject to change every 56 days. Because the charts are only issued every 6 months, the FAA strongly advises pilots to contact the nearest FSS for current route dimensions and status.
b. Helicopter Operations. Pilots should be aware of the nature and extent of helicopter operations within the Gulf of Mexico. The density of helicopter traffic is primarily due to the presence of numerous oil rigs and drilling platforms in the Gulf. The majority of these flights are below 2,000 feet mean sea level (MSL) at varying distances from the coastline.
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CHAPTER 10. LONG RANGE NAVIGATION
10-1. GENERAL NAVIGATION CONCEPTS, FAA POLICIES, AND GUIDANCE.
a. General Concepts. In the early days of aviation, few aircraft operated within any given area at the same time. The most demanding navigational requirements were to avoid obstacles and arrive at the intended destination with enough fuel remaining to safely complete a landing.
As aviation evolved, the volume of air traffic grew and a corresponding need to prevent collisions increased. Today, the most significant and demanding navigational requirement in aviation is the need to safely separate aircraft. There are several factors to understand concerning the separation of aircraft by air traffic control (ATC).
b. Separation of Air Traffic. In many situations, ATC does not have an independent means such as radar to separate air traffic and must depend entirely on information relayed from an aircraft to determine its actual geographic position and altitude. A flightcrew’s precision in navigating the aircraft is critical to ATC’s ability to provide safe separation. Even when ATC has an independent means such as radar to verify the aircraft’s position, precise navigation and position reports, when required, are still the primary means of providing safe separation. In most situations, ATC does not have the capability or the responsibility for navigating the aircraft. ATC relies on precise navigation by the flightcrew. Therefore, flight safety in all instrument flight rules (IFR) operations depends directly on the operator’s ability to achieve and maintain certain levels of navigational performance. ATC radar is used to monitor navigational performance, detect navigational errors, and expedite traffic flow. Any aircraft operating in accordance with ATC instructions must navigate to the level of accuracy required to comply with ATC instructions. Navigate aircraft with sufficient precision to avoid airspace where you must obtain prior ATC clearance or ATC instructions. For example, an aircraft flying adjacent to minimum navigation performance specification (MNPS) airspace must fly with a degree of precision that ensures that aircraft will not inadvertently enter MNPS airspace.
c. Visual Flight Rules (VFR) Flight. The control of air traffic requires VFR flights to achieve a certain level of navigational performance to ensure safe separation of aircraft and to expedite the flow of air traffic. During cruising flight, maintain the appropriate VFR flight altitude to ensure the required vertical separation between VFR and IFR aircraft and to assist in collision prevention. Navigate VFR aircraft with sufficient precision to avoid weather conditions that would prevent visual contact with (and avoidance of) other aircraft and to locate a suitable airport and land safely. VFR aircraft that require navigational assistance from ATC adversely affect ATC’s ability to control air traffic and expedite its flow.
d. The Concept of an ATC Clearance. Issuance of an ATC clearance by a controller, and the acceptance of this clearance by a pilot, is a negotiation process that establishes conditions for the prevention of collision hazards (in-flight and terrain). When a controller issues an IFR clearance, it reserves a three-dimensional block of airspace for that aircraft along the defined route. The controller also agrees to issue clearances to all other controlled air traffic to ensure safe separation of all assigned flight routes. When a pilot accepts an ATC IFR clearance, that pilot is agreeing to continuously remain within the assigned three-dimensional block of airspace and to adhere to the flight rules for that operation. This process obligates the pilot to comply with this agreement unless they declare an emergency or receive an amended clearance. Any Par 10-1 Page 111
deviation outside the assigned airspace creates a flight safety hazard. In such cases, the aircraft has failed to navigate to the degree of accuracy required for ATC and has failed to comply with Title 14 of the Code of Federal Regulations (14 CFR) and International Civil Aviation Organization (ICAO) requirements. In a non-radar environment, ATC has no independent knowledge of the aircraft’s actual position or its relationship to other aircraft. Therefore, when a deviation from an agreed upon clearance occurs, it seriously downgrades ATC’s ability to detect a navigational error and resolve collision hazards.
e. Concept of Navigation Performance. Maintain the concept of navigation performance that involves the precision for both the assigned route and altitude by an aircraft operating within a particular area. Navigation performance is measured by the deviation (for any cause) from the exact centerline (CL) of the route and altitude specified in the ATC clearance.
(1) Errors and Flightcrew Competency. This includes errors due to degraded accuracy and reliability of the airborne and ground-based navigational equipment and the flightcrew’s competence in using the equipment. Flightcrew competence involves both Flight Technical Errors (FTE) and navigational errors. FTE is the accuracy with which the pilot controls the aircraft as measured by success in causing the indicated aircraft position to match the desired position.
(2) Impact of Traffic Density on Navigation Performance. Standards of navigational performance vary depending on traffic density and the complexity of the routes flown. Different separation minimums applied by ATC in these two areas reflect the variation in traffic density.
For example, the minimum lateral distance permitted between co-altitude aircraft in Chicago Center’s airspace is 8 nautical miles (NM) (3 NM when using radar), while in North Atlantic (NAT)/MNPS airspace it is 60 NM. The airspace assigned by ATC has lateral dimensions on both sides of the exact CL of the route of flight specified in the ATC clearance equal to one-half of the lateral separation standard (minimum). For example, the overall level of lateral navigation performance necessary for flight safety must be within 4 NM of the airway CL in Chicago Center’s airspace, and within 30 NM in NAT/MNPS airspace. Title 14 CFR part 121, §§ 121.103 and 121.121 require that each aircraft must be navigated to the degree of accuracy required for ATC. Part 91, § 91.123’s requirements related to compliance with ATC clearances and instructions also reflect this fundamental concept.
(3) ICAO Standards and Recommended Practices (SARP). The concept of navigational performance is also inherent in the ICAO SARPs. For example, Annex 2 states that the aircraft “shall adhere to its current flight plan” and “when on an established ATS route, operate along the defined CL of that route.” This is true unless the Strategic Lateral Offset Procedures (SLOP) are approved.
f. Degree of Accuracy Required.
(1) Control of Air Traffic. The fundamental concept for all IFR navigation standards, practices, and procedures is that you must navigate all IFR aircraft to the degree of accuracy required for control of air traffic. When a flight remains within the assigned three-dimensional block of airspace at all times, the IFR navigation standards, practices, and procedures will consider that the operator navigated that aircraft to the degree of accuracy required for the Page 112 Par 10-1
control of air traffic. If an aircraft deviates outside its assigned block of airspace (except during a declared emergency), the operator did not navigate that aircraft to the required degree of accuracy.
(2) Separation Minimums. ATC separation minimums represent the minimum dimensions of a three-dimensional block of airspace that ATC can assign to control flight. These separation minimums have been established for IFR operations in controlled airspace. These standards are usually established through international agreement and implemented through national regulations. These minimums are established for particular categories of navigational operation and specified areas. Examples include navigation on airways in the national airspace of ICAO member states and long-range navigation in oceanic or remote land areas. Separation minimums establish the minimum lateral, vertical, and longitudinal distances that can be used to safely separate aircraft operating within a specified area. Separation minimums also represent the minimum level of overall navigation performance which you can accommodate at any time without jeopardizing flight safety.
(a) Any aircraft deviating greater than one-half the separation minimums established for that operation has failed to meet the required level of navigational performance to the degree of accuracy required for control of air traffic. For example, the vertical separation minimum for airplanes operating above FL 290 in the United States is 1,000 feet. Each aircraft’s actual altitude must remain within +/- 240 feet of the assigned altitude even when considering factors such as atmospheric pressure variations and instrument or pilot errors. This is the Reduced Vertical Separation Minimum (RVSM) requirement. Where the United States provide Air Traffic Services (ATS), 14 CFR and ATC directives establish separation minimums.
Where contracting ICAO member states provide ATSs, those state’s national regulations and ICAO documents establish separation minimums. Operations in uncontrolled airspace do not receive ATS, and separation minimums are not normally established for uncontrolled airspace.
(b) U.S. national airspace separation minimums can be found in the current edition of Federal Aviation Administration (FAA) Order 7110.65, Air Traffic Control. FAA Order 7110.83, Oceanic Air Traffic Control, current edition, prescribes separation minimums in international oceanic airspace delegated to the United States by ICAO. ICAO Document 7030, Regional Supplementary Procedures, current edition, prescribes separation minimums in international airspace.
g. Concept of Operational Service Volume. The concept of operational service volume is critical to understanding and applying the principles of air navigation. Operational service volume is the volume of airspace surrounding an ICAO standard airways navigation facility that is available for operational use. Within that volume of airspace, a signal of usable strength exists as co-channel interference does not operationally limit it. Within this volume of airspace, a Navigational Aid (NAVAID) facility’s signal in space conforms to flight inspection signal strength and course quality standards, including frequency protection. ICAO standard NAVAIDs are VHF Omnidirectional Range (VOR), VOR/distance measuring equipment (DME), and non-directional radio beacon (NDB). Global Navigation Satellite System (GNSS) is also an approved ICAO NAVAID and is applicable in both Class I and Class II navigation areas. The national airspace systems of ICAO contracting member states are based on the operational Par 10-1 Page 113
service volume of these facilities. You can predicate navigational performance within the operational service volume and ATC separation minimums on the use of these facilities.
h. Categories of Navigational Operations. A thorough comprehension of the categories of navigational operations is essential to understanding air navigation concepts and requirements, and in evaluating an operator’s ability to navigate to the required degree of accuracy. In the broad concept of air navigation, the following paragraphs identify two major categories of navigational operations.
i. Class I Navigation. Class I navigation is any en route flight operation conducted in controlled or uncontrolled airspace that is entirely within operational service volumes of ICAO standard NAVAIDs (GNSS, VOR, VOR/DME, and NDB). The operational service volume describes a three-dimensional volume of airspace which categorizes any type of en route navigation as Class I navigation. Within this volume of airspace, IFR navigational performance must be at least as precise as IFR navigation and must use GNSS, VOR, and VOR/DME (or NDB in some countries). The definition of Class I navigation is not dependent upon the equipment installed in the aircraft. En route a VFR flight navigated by pilotage is conducting Class I navigation when operating entirely within the operational service volume. However, the VFR navigational performance in this example must be as precise as VFR pilotage operations are required to be. The operational service volumes of ICAO standard NAVAIDs solely determine the lateral and vertical extent of airspace where you conduct Class I navigation. You cannot conduct Class I navigation outside of this airspace.
(1) VFR or IFR Navigation Operations. Class I navigation also includes VFR or IFR navigation operations on the following:
• Federal airways.
• Published IFR direct routes in the United States.
• Published IFR off-airway routes in the United States.
• Airways, Advisory Routes (ADR), direct routes, and off-airway routes published or approved by a foreign government provided that these routings are continuously within the operational service volume (or foreign equivalent) of ICAO standard NAVAIDs.
(2) Separation Minimums. Class I navigation requirements are directly related to separation minimums used by ATC. IFR separation minimums applied in the U.S. National Airspace System (NAS) and most other countries are based on the use of ICAO standard NAVAIDs. ATC, however, can only apply these separation minimums within areas where the NAVAIDs signal in space meets flight inspection signal strength and course quality standards.
An ICAO standard NAVAID’s signal in space conforms to flight inspection signal strength and course quality standards (including frequency protection) within its designated operational service volume. Therefore, you can predicate air navigation and the safe separation of aircraft within that service volume on the use of these facilities.
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(3) Qualifications for Class I Navigation. Within areas where the safe separation of aircraft is based on the use of ICAO standard NAVAIDs, navigate any IFR operation with at least the same precision specified by the appropriate national separation minimums. Any operation or portion of an operation (VFR or IFR) in controlled or uncontrolled airspace with any navigation system (VOR, VOR/DME, NDB, inertial navigation system (INS) and GNSS) is Class I navigation for that portion of the route that is entirely within the operational service volume of ICAO standard en route NAVAIDs.
j. Class II Navigation. Class II navigation is any en route operation not categorized as Class I navigation and includes any operation, or portion of an operation, that takes place outside the operational service volumes of ICAO standard NAVAIDs. For example, an aircraft equipped with only VOR conducts Class II navigation when the flight operates in an area outside the operational service volumes of federal VORs/DMEs.
(1) Class II Navigation: Operating Outside the Operational Service Volume.
Class II navigation involves operations conducted in areas where the signals in space from ICAO standard NAVAIDs do not meet flight inspection signal strength, course quality, and frequency protection standards. Therefore, ATC cannot predicate aircraft separation on the use of these facilities alone and must apply larger separation criteria. When operating outside the operational service volume of ICAO standard NAVAIDs, you cannot rely upon signals from these stations as the sole means of conducting long-range operations to the degree of accuracy required for the control of air traffic or as the sole means of obstacle avoidance. Therefore, when operating outside the designated operational service volumes of ICAO standard NAVAIDs, operators must use long-range navigation systems (LRNS) (GNSS, LORAN-C, INS/inertial reference system (IRS)) or other approved procedures which may include dead reckoning (DR), pilotage or flight navigator. These systems and/or techniques are necessary to navigate to the degree of accuracy required for the control of air traffic and to avoid obstacles. DR is a contingency procedure that you cannot plan.
(2) Class II Navigation Definition. The definition of Class II navigation is not dependent upon the equipment installed in the aircraft. All airspace outside the operational service volume of ICAO standard NAVAIDs is a three-dimensional volume of airspace within which any type of en route navigation is Class II navigation. For any type of navigation within this volume of airspace, the IFR navigational performance must be as precise as the navigational performance assumed during establishment of the ATC separation minimums for that volume of airspace. The navigational performance for VFR operations in a Class II navigation volume of airspace must be only as precise as VFR navigation operations are required to be.
(3) Class II Requirements. It is possible in turbojet airplanes, with proper procedures and training, to fly many routes between the southeastern United States, Caribbean Islands, and South America with VOR/DME and NDB equipment. In these situations, you can meet Class II navigation requirements even though significant portions of these routes, less than 1 hour, are outside the operational service volumes of ICAO standard NAVAIDs. In the domestic United States, it is not uncommon for low altitude VFR flights in aircraft such as helicopters to conduct Class II navigation while outside the operational service volumes of ICAO standard NAVAIDs when operating over routes of less than 100 NM in length. Class II navigation includes transoceanic operations and operations in desolate/remote land areas such as the Arctic.
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(4) Class II Navigation NAVAIDs. Class II navigation does not automatically require the use of LRNS. In many instances, you can conduct Class II navigation with conventional NAVAIDs if special navigational techniques supplement these NAVAIDs. Any portion of an en route operation in controlled or uncontrolled airspace, with any navigation system or any navigation technique, is Class II navigation for that portion of the route that is outside the operational service volumes of ICAO standard en route NAVAIDs.
10-2. IRS/INS AND LONG-RANGE NAVIGATION PROCEDURES.
a. Background. Recently, an aircraft deviated approximately 60 miles from an assigned NAT track and came within a few feet of colliding with an aircraft assigned to an adjacent track.
Following the near miss, the aircraft that had deviated from its track did not follow established contingency procedures for aircraft experiencing navigational uncertainty, thus creating the potential for further conflict with other aircraft as it returned to its assigned track. The crew’s failure to operate the navigation equipment in a disciplined systematic manner during all phases of flight caused the incident. The crew’s failure to comprehend the relationship between navigation performance, contingency procedure, and collision avoidance further complicated the incident.
(1) Navigation and Human Errors. Although navigation errors are infrequent, human errors account for a majority of the errors attributed to aircraft equipped with automated systems.
Most inadvertent navigation errors have occurred when the equipment was functioning normally, but the operating procedures prescribed were either inadequate or the operator did not follow them. Experience indicates that the increased accuracy and reliability of modern automatic navigation systems can induce a degree of complacency on the part of flightcrews, and may result in failure to routinely cross-check system performance. Under these circumstances, human errors may remain undetected for excessive periods. A common error associated with automated systems is incorrect programming of the oceanic waypoint latitudes by multiples of 1° (60 NM).
In an organized track system (OTS), this can result in the flight maintaining a wrong track with high precision and thereby constituting a serious threat to other aircraft properly occupying that track and FL. Vigilance and diligence in properly applying established procedures are essential to safe oceanic navigation. Although operational procedures may differ among navigation systems, many good practices and procedures are basic to all automated and semi-automated systems.
(2) Practices and Procedures for IFR Long-Range Navigation Operations. IFR long-range navigation operations using pilot-operated electronic long-range navigation equipment should use the practices and procedures recommended in this document. Prior to issuing operations specifications (OpSpecs) authorizing operations requiring long-range navigation equipment, the FAA principal operations inspector (POI) should ensure that the operator’s training program, manuals, and check airman program include and emphasize these practices and procedures. For operations currently authorized by OpSpecs or a letter of authorization (LOA), review the operator’s navigation program to ensure that it follows the guidance contained in this AC. The Flight Technologies and Procedures Division, AFS-400, must approve any deviation from these requirements.
b. Weather. In addition to the normal review of weather information concerning terminals, crews should be alert for hazardous weather that may require a flight plan change or in-flight re-routing. It is important to obtain a copy of the wind flow chart (constant pressure chart or the equivalent) for the FL and the route flown. This information may be valuable when evaluating wind forecasting errors or if DR operations become necessary due to equipment failure. As the flight progresses, give consideration to plotting actual wind information on the plotting chart as a means of evaluating the accuracy of the forecast.
c. Notices to Airmen (NOTAM). Besides checking NOTAMs for departure, destination and alternate airports, check NOTAMs concerning NAVAIDs or special airspace restrictions along the planned route.
d. Waypoint Management. The navigation program should include a standard system for indicating waypoint status as detailed below. The specific procedures recommended are in the list below. Variations in specific symbols may be necessary to accommodate the individual operator’s program.
• The crew stores the waypoint coordinates in the computer. (Enter the waypoint number next to the relevant waypoint coordinates.)
• A second crewmember independently cross-checks the coordinates and zone distances. (Circle the waypoint number.)
• The second crewmember cross-checks the coordinates and zone distances during the approaching waypoint check. (Draw a diagonal line through the waypoint number.)
• Waypoint passage has occurred. (Draw a second diagonal line through the waypoint number.)
• Cross-checking during all phases of flight. (Flight planning, preflight, en route.)
• Official (master) document.
• Plotting.
e. Plotting Procedures. Use of plotting procedures has had a significant impact on the reduction of gross navigation errors (GNE). All flights using long-range navigation equipment as the sole means of navigation require the use of this technique to plot the flight route on a plotting chart and to plot the computer position approximately 10 minutes after waypoint passage. Routes of shorter duration that transit airspace where special conditions exist, such as reduced lateral separation standards, high density traffic, or proximity to potentially hostile border areas may require the use of plotting procedures. All turbojet operations where the route segment between the operational service volume of ICAO standard NAVAIDs, VOR, VOR/DME, and NDB exceed 725 NM and all turboprop operations where the route segment between the operational service volume of ICAO standard NAVAIDs exceeds 450 NM require plotting procedures. The operational service volume is that volume of airspace surrounding a NAVAID which is available Par 10-2 Page 117
for operational use, within which a signal of usable strength exists, and where co-channel interference does not operationally limit that signal. You can determine the operational service volume for a specific NAVAID by contacting the Frequency Management Section within each regional Airway Facilities Division. Operational service volume includes the following:
• The officially-designated standard service volume excluding any portion of restricted standard service volume.
• The extended service volume.
• Within the United States (including offshore control areas (CTA)) by published instrument flight procedures (Victor or jet airways, standard instrument departures (SID), Standard Terminal Arrival Routes (STAR), Standard Instrument Approach Procedures (SIAP) or instrument departure).
• Outside the United States, any designated signal coverage or published instrument flight procedure equivalent to U.S. standards.
f. Flight Planning. Many operators use a computerized navigation flight plan. Take care to verify that all en route waypoints are correct and legibly shown on the flight plan. It is good practice to select a waypoint loading sequence and number each waypoint accordingly. If using more than one copy of the flight plan, designate one copy as the official copy. To eliminate possible confusion, ensure that all necessary information, routing changes, estimated time of arrival (ETA), and waypoint loading sequence is on this flight plan, and use the official copy for all reports to ATC. Additionally, if the flight is within the North Atlantic Organized Track System (NAT OTS), obtain a copy of the current track message and be alert for conflict between the flight plan and the track message. Track messages are issued approximately every 12 hours and describe the NAT routes, gateways, and FLs available for eastbound and westbound flights during the period indicated. While planning an over-water flight, pilots should review NOTAMs for any condition that may affect the operation and accuracy of LRNSs. Approach the use of heading information for cross-checking with caution. In steering a given route segment with a navigation computer, the true heading required to maintain a Great Circle course will change.
For example, the true heading to maintain the Great Circle course from 50°N. 30°W. to 50°N. 40°W. will be 274° at 30°W., 270° at 35°W., and 265° at 40°W. Differences in variation along the route will further change the magnetic heading required to maintain course. The flightcrew must have a thorough understanding of the flight plan heading information and DR technique in order to use this check with any degree of certainty.
g. Navigation Preflight (at Aircraft). Verify navigation system software identification and modification status codes. Cross-check inputs to navigation computers. One crewmember should carry each insertion out in its entirety and another should recall and verify it. Cross-check computer flight plan zone distances with zone distance displayed in navigational computers.
Perform the cross-check of coordinates and zone distances on all computer systems individually when using the remote loading feature. For INS, after placing the systems in the navigation mode, check the groundspeed while the aircraft is stationary. A reading of more than a few knots may indicate an unreliable system.
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