Page 124 Par 10-3 to fly the normal system and carefully monitor its performance using any additional NAVAIDs available. In the unlikely event that a total navigation failure occurs and other aids are unavailable, the only action may be to fly by contingency DR using the flight plan headings and times. Under these circumstances, flightcrews should continue to use all means available to obtain as much navigational information as possible. Flightcrews should be alert for visual sightings of other aircraft, since a hazard may exist due to an inadvertent deviation from the assigned track. In some cases, it may be possible to establish and maintain visual contact with another aircraft on the same track.
e. Recommended Action Following a Divergence Between Systems. Since a small divergence between systems may be normal, evaluate the significance of the divergence. In general terms, if the divergence is less than 10 NM, the best course may be to closely monitor system performance and continue to steer the system considered most accurate. If the divergence between systems is greater than 10 NM, it may degrade one of the systems. Therefore, make attempts to determine which system may be faulty. If you cannot determine the faulty system using the practices described in this section, and both systems appear normal, the action most likely to limit gross tracking error may be to position the aircraft so that the actual track is midway between the cross-track differences for as long as the position uncertainty exists. Advise ATC that you are experiencing navigation difficulties so that you may adjust separation criteria as necessary. Give consideration to abandoning this “split-the-difference” practice if the divergence exceeds the separation criteria currently in effect on the route of flight. If a divergence of this magnitude occurs and you cannot isolate the faulty system, the best course may be to fly by contingency procedures using the best known wind information. However, in some cases, the best known information may be flight plan headings and times.
10-4. PROVING TESTS AND VALIDATION FLIGHTS. Title 14 CFR parts 121 and 135 require evaluation of an operator’s ability to conduct operations safely and in accordance with the applicable regulations before issuing an operating certificate or authorizing a certificate holder to serve an area or route. The testing method used by the FAA to determine an operator’s capabilities are validation flights. Sections 121.93, 121.113, and 135.145 require an operator to demonstrate the ability to conduct operations over proposed routes or areas in compliance with regulatory requirements before receiving FAA authority to conduct these operations. The FAA requires validation flights for authorization to add any areas of operation beyond the continent of North America and Mexico, and before issuing authorization for special means of navigation.
Though proving tests and validation flights satisfy different requirements, it is common practice for operators to conduct both tests simultaneously. However, validation flights are important to consideration of oceanic operations (14 CFR part 119, § 119.59).
a. Validation Flights. Sections 121.93, 121.113, and 135.145 require operators to show the capability to conduct line operations safely and in compliance with regulatory requirements before receiving authorization to conduct those operations in revenue service. The most common method of validating an operator’s capability is to observe flight operations. The FAA normally requires validation flights before issuing OpSpecs granting authority to conduct operations beyond the populated areas of the North American (NAM) continent. When the FAA conducts a validation flight, they conduct an in-depth review of the applicable portions of the operator’s proposed procedures, including flight following, training programs, manuals, facilities, and maintenance programs. There are four situations that require validation flights in association
with approval of Class II navigation: initial approval; addition of an LRNS or a flight navigator;
operations into new areas; and addition of special or unique navigation procedures. Validation flights are required when an operator proposes to conduct operations that require confirmation of the ability to operate an aircraft type within specified performance limitations. These limitations are based on the character of the terrain, extended over-water, the type of operation, and the performance of the aircraft. Validation flights are also required when an operator proposes to conduct in-flight or ground maneuvers that require special operational authorizations.
b. Carriage of Revenue Passengers on Validation Flights. Title 14 CFR does not forbid the carriage of revenue passengers on validation flights. The operator may receive FAA authorization to carry revenue passengers during the validation flight when the proposed operation is similar to those in the applicant’s previous experience. However, validation flights do not normally permit the carriage of revenue passengers in the following situations:
• When the operator is seeking initial approval to conduct Class II navigation in any airspace designated as a special area of operation;
• When the operator is seeking approval to conduct Class II navigation by an LRNS or by using a flight navigator not previously approved for that means of navigation;
• When the operator is seeking approval to conduct Class II navigation by means of a long-range navigation procedure not previously approved for that operator; and
• When the operator has not previously operated a specific aircraft type in operations requiring special performance authorization.
c. Special Areas of Operation (SAO). Certain areas of Class II airspace are considered special operating airspace for purposes of validation. These areas include the following:
• Northern Canadian areas of magnetic unreliability;
• NAT/MNPS airspace and Canadian MNPS airspace;
• Central Pacific (CENPAC) composite airspace and Northern Pacific (NOPAC) airspace;
• Arctic Ocean and Antarctic airspace; and
• Politically sensitive areas of operation.
d. Special Navigation Procedures. Validation flights are normally required when an applicant proposes to use navigation procedures not previously demonstrated. These procedures include the following:
• Pilotage, including DR;
• Flight navigator procedures;
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• Celestial navigation;
• Pressure pattern and Bellamy drift DR;
• Free gyro or grid procedures; and
• Any combination of the preceding procedures.
e. Other Situations Requiring Validation Flights. Special operational authorizations and special performance authorizations may also require validation flights. The FAA encourages operators who require additional information on validation flights to contact their local FAA Flight Standards District Office (FSDO).
10-5. INS NAVIGATION—SPECIAL PRACTICES AND PROCEDURES.
a. Preflight. Since INS is a self-contained device and not a position fixing device, it will retain and possibly increment any error induced during alignment throughout the flight unless you remove it through updating procedures. Therefore, during preflight, exercise care to ensure that you insert the accurate present position information into the INS. Although most INSs will automatically detect large errors in present position latitude during alignment, large errors in present position longitude may exist without activating a warning indication. When cross-checking present position coordinates, be alert for the correct hemispheric indicator (that is, N., S., E., W.) as well as the correct numerical values. Since you cannot realign most INSs in-flight, it may require special procedures such as ground realignment to correct a significant error in present position. If the INS in use has the capability of “gang-loading” (simultaneous loading) by use of a remote feature, take care so that you cross-check any data entered by this method separately on each individual INS to detect data insertion errors. Verify the INS software identification and modification status codes to ensure installation of the proper equipment and utilization of the appropriate operating checklist. The operating checklists should include a means of ensuring that the INS is ready to navigate and that the operator activated the navigation mode prior to moving the aircraft. Any movement of the aircraft prior to activating the navigation mode may induce very large errors that only ground realignment can correct.
After placing the system in the navigation mode, check the INS groundspeed when the aircraft is stationary. An erroneous reading of more than a few knots may indicate a faulty or less reliable unit. If this occurs, check the malfunction codes.
b. In-Flight Updating. INS is essentially accurate and reliable, but it is possible to introduce errors in an attempt to improve accuracy by in-flight updating. On the other hand, INS errors generally increase with time and are not self-correcting. If large tracking errors occur, they may significantly degrade aircraft safety and separation criteria. Consider these factors in any decision relative to in-flight updating. As a guide to flightcrews, some operators consider that unless the ground facility provides a precise check and unless the error is fairly significant (for example, more than 6 NM or 2 NM/hour), it is preferable to retain the error rather than update.
10-6. FAA APPROVAL OF GLOBAL POSITIONING SYSTEM (GPS) EQUIPMENT AND OPERATIONS.
a. Portable Units. Handle all portable electronic systems and portable GPS units in accordance with § 91.21. The operator of the aircraft must determine that each portable electronic device they use the aircraft they operate will not cause interference with the navigation and communications systems. Mount yoke mounts usually sold with a portable GPS unit to prevent interference with the operation of the aircraft controls. Install permanent mounts and externally mounted antennas for use with a portable GPS unit in a FAA-approved manner. A critical aspect of any GPS installation is the installation of the antenna. Shadowing by the aircraft structure can adversely affect the operation of the GPS equipment. Electrical noise or static in the vicinity of the antenna can adversely affect the performance of the system. Use portable GPS receivers as a supplemental aid to VFR in conjunction with an approved primary means of navigation.
b. GPS Equipment Classes. GPS equipment is categorized into classes A, B, and C (ref. TSO-C129, TSO-C129A, TSO-C145, and TSO-C146).
(1) Class A. Equipment incorporating both the GPS sensor and navigation capability.
This equipment incorporates receiver autonomous integrity monitoring (RAIM).
• Class A1 equipment includes en route, terminal, and non-precision approach navigation capability.
• Class A2 equipment includes only en route and terminal navigation capability.
(2) Class B. Equipment consisting of a GPS sensor that provides data to an integrated navigation system (i.e., flight management system (FMS), multi-sensor navigation system, etc.).
• Class BI equipment includes RAIM and provides en route, terminal, and non-precision approach capability.
• Class B2 equipment includes RAIM and provides only en route and terminal capability.
• Class B3 equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to RAIM and provides en route, terminal, and non-precision approach capability.
• Class B4 equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to RAIM and provides only en route and terminal capability.
(3) Class C. Equipment consisting of a GPS sensor that provides data to an integrated navigation system (i.e., FMS, multi-sensor navigation system, etc.) that provides enhanced guidance to an AP or flight director (FD) in order to reduce FTE.
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• Class C1 equipment includes RAIM and provides en route, terminal, and non-precision approach capability.
• Class C2 equipment includes RAIM and provides only en route and terminal capability.
• Class C3 equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to RAIM and provides en route, terminal, and non-precision approach capability.
• Class C4 equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to RAIM and provides only en route and terminal capability.
c. Avionics Installations and Continued Airworthiness. The operator must ensure that they properly install and maintain the equipment. No special maintenance requirements, other than the standard practices currently applicable to navigation or landing systems, are unique to GPS.
d. Certification of GPS Installations and GPS IFR Operations. Provide documentation that validates approval of the installed GPS airborne receiver in accordance with and the current editions of Advisory Circular (AC) 20-130, Airworthiness Approval of Navigation or Flight Management Systems Integrating Multiple Navigation Sensors, or AC 20-138, Airworthiness Approval of Global Navigation Satellite System (GNSS) Equipment, as appropriate, or other applicable airworthiness criteria established for GPS installations. When it has established that the airborne system receives certification for GPS IFR operations, use the following criteria to determine the operational suitability of airborne systems for GPS IFR use:
FIGURE 10. GPS EQUIPMENT CLASSES TSO-C129
EQUIPMENT CLASS RAIM Integrated Navigation System to Provide RAIM Equivalent.
OCEANIC EN ROUTE
TERMINAL NON-PRECISION
APPROACH
CAPABLE Class A – GPS sensor and navigation capability A1 Yes Yes Yes Yes Yes A2 Yes Yes Yes Yes No Class B – GPS sensor data to an integrated navigation system (i.e., FMS, multi-sensor navigation system, etc.)
B1 Yes Yes Yes Yes Yes B2 Yes Yes Yes Yes No B3 Yes Yes Yes Yes Yes B4 Yes Yes Yes Yes No Class C – GPS sensor data to an integrated navigation system (as in Class B) that provides enhanced guidance to an autopilot (AP) or flight director (FD) to reduce flight technical errors. Limited to part 121 or equivalent criteria.
C1 Yes Yes Yes Yes Yes C2 Yes Yes Yes Yes No C3 Yes Yes Yes Yes Yes C4 Yes Yes Yes Yes No GPS Approval Required For Authorized Use
EQUIPMENT TYPE
INSTALLATION
APPROVAL
REQUIRED
OPERATIONAL
APPROVAL
REQUIRED IFR EN ROUTE IFR
TERMINAL
IFR APPROACH Hand Held X VFR Panel Mount X Par 10-6 Page 129
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X X X X X IFR Oceanic/Remote
X X X X IFR En Route, Terminal, and Approach
X X X X X
e. GPS Equipment Approval and Installation for Class II Navigation and Remote Areas.
• For Class II navigation requiring only the use of a single long-range navigation system (S-LRNS), you may use a GPS IFR installation with a TSO C-129, 129A (or TSO C-145 or TSO C-146, as applicable) authorized navigation system as the only required LRNS.
• For Class II navigation requiring the use of two LRNSs, you may use a single GPS IFR installation with a TSO C-129, 129A (or TSO C-145 or TSO C-146, as applicable) authorized navigation system in conjunction with another approved LRNS, such as an inertial system.
• For Class II navigation requiring the use of two LRNSs, you may use GPS IFR systems for both of the required LRNSs if both GPS units are TSO-C129 or 129A units approved for IFR use and both units also meet the additional requirements specified in FAA Notice 8110.60, GPS as a Primary Means of Navigation for Oceanic/Remote Operations. Specific operational procedures must be accomplished, including performing a fault detection and exclusion (FDE) availability prediction or both GPS units are TSO C-145 or TSO C-146 units approved for IFR use. Accomplish specific operational procedures, including performing a RAIM availability prediction.
f. Aircraft Flight Manual (AFM)/Aircraft Flight Manual Supplement (AFMS) documentation. Aircraft certificated to use GPS as the only LRNSs when two LRNSs are required will have the following statement in the AFM or AFMS: “The ____ GPS equipment as installed has been found to comply with the requirements for GPS primary means of Class II navigation in oceanic and remote airspace, when used in conjunction with the FDE prediction program. This does not constitute operational approval.”
g. FDE Availability Prediction Program. FDE is the capability of GPS to detect a satellite failure that affects navigation and automatically excludes that satellite from the navigation solution. All operators using GPS as the only LRNSs when Class II navigation requires two LRNSs must utilize an FAA-approved FDE prediction program for the installed GPS equipment that is capable of predicting, prior to departure, the maximum outage duration of the loss of fault exclusion, the loss of fault detection, and the loss of navigation function for flight on a specified route. The “specified route of flight” is a series of waypoints to include the route to any required alternates with the time specified by a velocity or series of velocities. Since you may not maintain specific groundspeeds, perform the pre-departure prediction for the range of expected groundspeeds. This FDE prediction program must use the same FDE algorithm (a step-by-step procedure for solving a problem) employed by the installed GPS equipment and you must develop it using an acceptable software development methodology. The FDE prediction program must provide the capability to manually designate satellites that are scheduled to be unavailable in order to perform the prediction accurately. Evaluate the FDE prediction program as part of the navigation system’s installation approval. You can find the requirements for the FDE prediction algorithm in FAA Notice 8110.60, or its successor.
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h. Operational Control Restrictions for Class II Navigation in Oceanic and Remote Areas.
(1) FDE Prediction Program. Prior to departure, the operator must use the FDE prediction program to demonstrate that there are no outages in the capability to navigate the specified route of flight and the FDE prediction program determines whether the GPS constellation is robust enough to provide a navigation solution for the specified route of flight.
Any predicted satellite outages that affect the capability of GPS equipment to provide the navigation function on the specified route of flight requires cancellation, delay, or re-routing of the flight.
(2) Fault Exclusions and Acceptable Durations. Once the navigation function is verified and the equipment can navigate on the specified route of flight, the operator must use the FDE prediction program to demonstrate that the maximum outage of the capability of the equipment to provide fault exclusion for the specified route of flight does not exceed the acceptable duration. Fault exclusion is the ability to exclude a failed satellite from the navigation solution. The acceptable duration is equal to the time it would take to exit the protected airspace, assuming a 35 NM per hour cross-track navigation system error growth rate when starting from the center of the route. For example, a 60 NM lateral separation minimum yields 51 minutes acceptable duration (30 NM divided by 35 NM per hour). If the fault exclusion outage exceeds the acceptable duration, the operator must cancel, delay, or re-route the flight. If the fault exclusion outage exceeds the acceptable duration on the specific route of flight, the operator must cancel, delay, or re-route the flight.
i. En Route Procedures for GPS Class II Navigation in Oceanic and Remote Areas.
(1) Degraded Navigation Capability. If the GPS displays a loss of navigation function alert, the pilot should maintain heading and altitude until they regain GPS navigation. The pilot will report degraded navigation capability to ATC in accordance with § 91.187. Additionally, flightcrew members operating under part 121 will notify the appropriate dispatch or flight following facility of any degraded navigation capability in accordance with the air carrier’s FAA-approved procedures. For at least one hour, the approved long-range GPS units have the ability to automatically provide electronic DR navigation solutions based on last known information. There are strict procedural requirements for dispatch and en route RAIM to ensure satellite coverage along the oceanic routes and that no outages are scheduled to occur during the planned flight. Each operator’s long-range navigation program should require the standardized application of disciplined, systematic cross-checking of navigation information during all phases of flight during Class II navigation.
(2) Satellite Fault Detection Outage. If the GPS displays an indication that a fault detection function outage (e.g., RAIM) is not available, provide navigation integrity by comparing the GPS position with a position computed by extrapolating the last verified position with true airspeed (TAS), heading, and estimated winds. If the positions do not agree to within 10 NM, the pilot should immediately maintain heading and altitude until they regain the exclusion function or navigation integrity and report degraded navigation capability to ATC in accordance with § 91.187.
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(3) Fault Detection Alert. If the GPS displays a fault detection alert (failed satellite), the pilot may choose to continue to operate using the GPS-generated position if they actively monitor the current estimate of position uncertainty displayed on the GPS from the FDE algorithm. If this number exceeds 10 NM or is not available, the pilot should immediately maintain heading and altitude until they exclude the failed satellite and report degraded navigation capability to ATC in accordance with § 91.187.
(4) Validation Tests Are Required. Such tests may consist of a single flight or series of flights. The following are references:
• Sections 121.93 and 121.113.
• Section 135.145.
• FAA Order 8900.1, Volume 3, Chapter 29, Section 8, Validation Test Requirements, current edition.
j. GPS in Lieu of ADF or DME. You may substitute an approved GPS navigation system for an ADF and DME receiver, provided you can call up facility or fix coordinates from the current GPS airborne database. Retrieve waypoints, fixes, intersections, and facility locations used for these operations from the current GPS airborne database. If you cannot retrieve the required positions from the airborne database, the substitution of GPS for ADF and DME will not receive authorization.
• For all operators, using GPS in lieu of DME does not preclude any equipage requirements of the applicable regulations. To provide navigation performance equivalent to ADF or DME avionics, the GPS navigation systems must have proper certification, installation, and authorization for use under IFR, as described above.
• This approval does not alter the conditions and requirements for use of GPS when using it to provide lateral course guidance to fly GPS or GPS Area Navigation (RNAV) standard instrument approach procedures.
• For those operations where the operating rules require installation of DME, the operator’s MEL should include provisions for authorizing continued operations using a certified GPS when the installed “DME” is inoperative. Operators in the NAS may receive authorization to use GPS equipment certified for IFR operations in lieu of ADF and DME equipment for the following operations:
• Determining the aircraft position over a DME fix. GPS satisfies § 91.205(e) requirement for DME at and above 24,000 feet MSL (FL 240).
• Flying a DME arc.
• Navigating to/from an NDB/compass locator.
• Determining the aircraft position over an NDB/compass locator.
• Determining the aircraft position over a fix made up of a crossing NDB/compass locator bearing.
• Holding over an NDB/compass locator.
• The ground-based NDB or DME facility may be temporarily out of service.
• For further information on the use of GPS in lieu of DME, refer to the Aeronautical Information Manual (AIM).
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CHAPTER 11. HELICOPTOR OCEANIC OPERATIONS
11-1. GULF OF MEXICO.
a. Background. Although helicopter operations in the Gulf of Mexico have had an enviable safety record, recent statistics indicate that a significant rise in weather-related accidents has occurred. It is imperative that pilots performing oceanic (offshore) operations do not exceed the minimum weather criteria for visual flight rules (VFR) and instrument flight rules (IFR) flight or the minimum flight altitude parameters for all phases of flight. The operator must comply with all applicable minimum equipment requirements for the operation. Two documents that address issues and requirements for improving rotorcraft operations within the National Airspace System (NAS) are “Rotorcraft Terminal ATC Route Standards” (FAA/RD-90/18) and “Rotorcraft En Route ATC Route Standards” (FAA/RD-90-19). These documents are available to the public through the National Technical Information Service (NTIS), 5285 Port Royal Rd., Springfield, Virginia 22151-2103. All operators should obtain these two documents and ensure that crews are familiar with the operating procedures discussed in these documents.
b. Flight in Environmentally Sensitive Areas. Protection of endangered species and the overflight of environmentally sensitive areas are of increasing concern in the Gulf of Mexico.
Infringements by low-flying airplanes and/or rotorcraft operating en route to airways in the Gulf of Mexico or to helidecks can be disruptive to wildlife while over the shore or near the shore.
The Aeronautical Information Manual (AIM), the current edition of Advisory Circular (AC) 91-36, Visual Flight Rules (VFR) Flight Near Noise-Sensitive Areas, on VFR sectional maps, and on specially designed maps published by Minerals Management Service (MMS) of the Department of the Interior (DOI) contain guidelines for flights in these areas.
11-2. IFR OFFSHORE OPERATIONS. Any operator that desires to conduct IFR operations in uncontrolled airspace will submit a letter describing the proposed operation to the certificate-holding district office (CHDO). This letter should include which specific routes to fly, the exact location of the destination, the type of aircraft used, the navigation equipment on the aircraft, and the specific Navigational Aids (NAVAID) used at the offshore facility, if any.
a. Offshore Operators. Title 14 of the Code of Federal Regulations (14 CFR) part 91 offshore operators are to obtain a letter of authorization (LOA) for IFR operations. They will receive the LOA once they meet all certification requirements.
b. FAA Coordination. After reviewing the request, the CHDO will arrange a coordination meeting with the air traffic elements involved (such as the center, approach control, Flight Service Station (FSS), etc.). If a NAVAID exists at the offshore facility, the regional flight procedures branch will have representation at the coordination meeting. If the operator conducts the proposed operations in a region other than that of the CHDO, the CHDO will coordinate with the FSDO having jurisdiction of the geographic area where they conduct operations. The jurisdictional Flight Standards District Office (FSDO) will perform route checks and other required inspections, and forward reports of these inspections to the CHDO. When the operator meets all of the requirements, the CHDO approves the operation and issues operations specifications (OpSpecs) or an LOA.
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