(5) For RNP 1.0, the capability to load from the database into the RNP system the entire segment of the SID, ODP, or STAR to be flown.
Note: Due to variability in systems, this document defines the segment from the first occurrence of a named waypoint, track, or course to the last occurrence of a named waypoint, track, or course. Heading legs prior to the first named waypoint or after the last named waypoint do not have to be loaded from the database.
(6) The means to display the following items, either in the pilot’s primary field of view, or on a readily accessible display page:
(a) The active navigation sensor type;
(b) The identification of the active (To) waypoint;
(c) The ground speed or time to the active (To) waypoint; and
(d) The distance and bearing to the active (To) waypoint.
(7) The capability to execute a “Direct to” function.
(8) The capability for automatic leg sequencing with display to the pilots.
(9) The capability to execute RNP 1.0 terminal procedures extracted from the onboard database including the capability to execute fly-over and fly-by turns.
(10) The system must have the capability to automatically execute leg transitions and maintain tracks consistent with the following ARINC 424 path terminators:
(a) Initial fix (IF) (only for RNP 1.0);
(b) Course to fix (CF);
(c) Direct to fix (DF); and
(d) Track to fix (TF).
Note: Path terminators are defined in ARINC Specification 424, and their application is described in more detail in RTCA documents DO-236C Chg 1, DO-283B (as modified by TSO-C115d) and RTCA/DO-201A.
(11) The system must have either an automatic or a manual capability to fly the aircraft on a heading to intercept a course or to go direct to another fix after reaching a procedure-specified altitude. The system may use heading to altitude (VA), heading to manual 68
(VM) and heading to intercept (VI) path terminators for automatic capability.
(12) The system must have either an automatic leg transition capability or a manual capability to permit the pilot to readily designate a waypoint and select a desired course to or from a designated waypoint. The system may use course to altitude (CA) and fix to manual termination (FM) path terminators for automatic capability.
(13) The capability to load a procedure from the database, by procedure name, into the area navigation system.
(14) The capability to display an indication of the RNP system failure in the pilot’s primary field of view.
(15) The capability to indicate to the crew when the NSE alert limit is exceeded
(i.e., the alert provided by the “onboard performance monitoring and alerting function”).
i. Database Integrity.
The navigation database suppliers must comply with AC 20-153(latest revision). A Type 2 LOA, issued by the appropriate regulatory authority, demonstrates compliance with the criteria. Type 2 LOAs issued prior to this AC are considered compliant.
9-4. System Eligibility and Approval for RNP 2.0 and RNP 1.0 Operations.
Systems meeting the criteria in paragraphs 9-2 and 9-3 are eligible for RNP 2.0 and RNP 1.0 operations.
9-5. Rotorcraft Enroute, Terminal, and Offshore RNP 0.3.
9-5.1 Introduction.
Section 9.5 provides guidance on the performance and functional criteria for rotorcraft enroute RNP 0.3 and the installed GPS/SBAS equipment, at a minimum, must meet the criteria for RNP 2.0, RNP 1.0 and RNP APCH to LNAV minima. The intent is to use rotorcraft enroute RNP 0.3 capability for enroute, terminal, departure, arrival, and offshore rotorcraft operations. Rotorcraft enroute RNP 0.3 is based on GPS/SBAS equipage and the rotorcraft must be approved for IFR operations. The reason is to take advantage of the known functionality, performance and availability GPS/SBAS provides. It is not acceptable to use GPS or DME/DME/IRU for rotorcraft rotorcraft enroute RNP 0.3 operations.
9-5.2 Rotorcraft and System Eligibility for Rotorcraft Enroute RNP 0.3 Operations.
a. The rotorcraft must be approved for IFR operations. Any limitations required for normal IFR operation such as a functioning stability augmentation system, multiple crewmembers, autopilot coupling, etc. will also apply to rotorcraft enroute RNP 0.3.
b. GPS/SBAS stand-alone equipment must be approved in accordance with TSO-C146(AR) Class 1, 2, or 3. These systems must be installed for IFR use in accordance 69
with this AC.
c. GPS/SBAS sensors used in multi-sensor system equipment (e.g., FMS) must be approved in accordance with TSO-C145(AR) Class 1, 2, or 3. These systems must be installed for IFR use in accordance with this AC.
d. Multi-sensor systems must be approved in accordance with TSO-C115b (or later revision), but may also have a TSO-C146(AR) Class Gamma approval (see paragraphs 3-2.g and 3-4). The GPS/SBAS sensors and multi-sensor equipment must comply with the applicable GPS/SBAS equipment chapters and chapters 6, 12-14, 16, 19-20, and 22 of this AC and be installed for IFR use in accordance with this AC.
9-5.3 Performance and Functional Criteria.
a. Accuracy.
(1) During operations on rotorcraft enroute RNP 0.3 routes, the lateral TSE must be within ±0.3 NM for at least 95 percent of the total flight time. The along-track error must also be within ±0.3 NM for at least 95 percent of the total flight time. To satisfy the accuracy requirement, the FTE should not exceed 0.25 NM (see paragraph 9-5.3.i).
(2) Table 9 in chapter 17 indicates allowable “FTE credit” when using an autopilot and/or flight director.
b. Integrity.
Malfunction of the aircraft navigation equipment that causes the TSE to exceed 2 times the RNP value without annunciation is classified as a Major failure condition.
c. Continuity.
(1) Loss of function is classified as a Major failure condition for offshore and remote area operations. The rotorcraft must have dual, independent long-range navigation system equipage for offshore and remote area operations.
(2) Loss of function is classified as a Minor failure condition for domestic rotorcraft enroute RNP 0.3 operations if the operator can revert to a different navigation system and proceed safely to a suitable airport.
d. Performance Monitoring and Alerting.
During rotorcraft enroute RNP 0.3 operations, the RNP system must provide an alert if the accuracy requirement is not met or if the probability that the lateral TSE exceeds 0.6 NM is greater than 10-5 .
e. Path Definition.
RNP equipment should provide lateral guidance so aircraft remain within the lateral boundaries of the defined RNP route (see also paragraph 9-5.3.h.7). Aircraft performance should comply with RTCA/DO-236C, Chg 1.
f. Signal-in-Space.
The aircraft navigation equipment must provide an alert if the probability of signal in-space errors causing a lateral position error greater than 0.6 NM exceeds 10-7 per hour.
g. Functional Criteria for Navigation Displays.
(1) The rotorcraft enroute RNP 0.3 system must have the following navigation displays and functions installed in accordance with this AC.
(2) Navigation data, including a TO/FROM indication and a failure indicator, must be displayed on a lateral deviation display (course deviation indicator (CDI), electronic horizontal situation indicator (EHSI)) and/or a navigation map display. These must be used as primary flight instruments for aircraft navigation, for maneuver anticipation, and for failure/status/integrity indication.
Note: See paragraph 8-3g(2) for guidance on RNP systems
with navigation computers using TO/TO navigation algorithms.
(a) The displays must be visible to the pilot and located in the primary field of view when looking forward along the flight path.
(b) The lateral deviation display scaling must agree with the RNP 0.3 alerting and annunciation limits.
(c) The lateral deviation display must have ±0.3 NM full-scale deflection based on the required total system accuracy.
(d) The display scaling may be set automatically by default logic; automatically to a value obtained from a navigation database; or manually by flight crew procedures. The fullscale deflection value must be known or must be available for display to the pilot commensurate with the required accuracy.
(e) The lateral deviation display must be automatically slaved to the RNP computed path. It is recommended that the course selector of the deviation display be automatically slewed to the RNP computed path.
Note: This does not apply for installations where an electronic map display contains a graphical display of the flight path and path deviation.
(f) As an alternate means, a navigation map display must give equivalent functionality to a lateral deviation display with appropriate map scales (scaling may be set manually by the pilot), and giving equivalent functionality to a lateral deviation display. To be approved as an alternative means, the navigation map display must be shown to meet the TSE criteria and be located in the primary field of view.
h. System Capabilities.
The following system capabilities must be provided, as a minimum, within any rotorcraft enroute RNP 0.3-capable equipment:
(1) The capability to continuously display to the pilot flying, on the primary flight instruments for navigation of the aircraft (primary navigation display), the RNP computed desired path and aircraft position relative to the path. For operations where the required minimum flight crew is two pilots, a means for the pilot not flying must also be provided to verify the desired path and the aircraft position relative to the path.
(2) A navigation database, containing current navigation data officially promulgated for civil aviation, which can be updated in accordance with the AIRAC cycle. The stored resolution of the data must be sufficient to achieve the required track keeping accuracy.
The database must be protected against pilot modification of the stored data.
(3) The means to display the validity period of the navigation data to the pilot.
(4) The means to retrieve and display data stored in the navigation database relating to individual waypoints and navigation aids, so the pilot can verify the route to be flown.
(5) The capability to load from the database into the rotorcraft enroute RNP 0.3 system the entire segments of the procedures or routes to be flown. It is acceptable to manually load route waypoints from the database into a flight plan page and manually set the scaling and alerting.
Note: Due to variability in systems, this document defines the segment from the first occurrence of a named waypoint, track, or course to the last occurrence of a named waypoint, track, or course. Heading legs prior to the first named waypoint or after the last named waypoint do not have to be loaded from the database.
(6) The means to display the following items, either in the pilot’s primary field of view, or on a readily accessible display page:
(a) The active navigation sensor type;
(b) The identification of the active (To) waypoint;
(c) The ground speed or time to the active (To) waypoint; and
(d) The distance and bearing to the active (To) waypoint.
(7) The capability to execute RNP 0.3 routes using waypoints extracted from the onboard database including the capability to execute fly-by turns.
Note: The final waypoint used at the end of RNP 0.3 routes may designate a specific crossing point; that is, a fly over waypoint. There is no intent to use fly-over turns on RNP 0.3 routes
(8) The capability to automatically execute leg transitions and maintain tracks consistent with the following ARINC 424 path terminators:
(a) Initial fix (IF);
(b) Course to fix (CF);
(c) Direct to fix (DF); and
(d) Track to fix (TF).
Note: Path terminators are defined in ARINC Specification 424, and their application is described in more detail in RTCA documents DO-236C Chg 1, DO 283B (as modified by TSO-C115d) and DO-201A.
(9) The capability to automatically or manually fly on a heading to intercept a course or to go direct to another fix after reaching a procedure-specified altitude. The system may use heading to altitude (VA), heading to manual (VM) and heading to intercept (VI) path terminators for automatic capability.
(10) The capability to automatically or manually permit the pilot to readily designate a waypoint and select a desired course to or from a designated waypoint. The system may use course to altitude (CA) and fix to manual termination (FM) path terminators for automatic capability.
(11) The capability to display an indication of the RNP 0.3 system failure in the pilot’s primary field of view.
(12) The capability to indicate to the crew when the NSE alert limit is exceeded (alert provided by the “onboard performance monitoring and alerting function”).
(13) The capability for the flight crew to build an enroute or offshore segment in the equipment flight plan function using individual waypoints from the database. This is similar to existing enroute capability.
Note: It is also acceptable for the navigation system to automatically load all route waypoints from the database by selecting the route name.
i. Flight Director/Autopilot.
For all rotorcraft enroute RNP 0.3 operations, the use of an autopilot and/or FD is an acceptable means of complying with the FTE assumption in paragraph 9-5.3.a(1). Any alternate means of FTE bounding, other than autopilot and/or FD, may require FTE substantiation through an airworthiness demonstration.
Note: Some rotorcraft may need a stability augmentation system to achieve 0.25 NM FTE during manual flight.
j. Database Integrity.
The navigation database suppliers must comply with AC 20-153(latest revision).
The GPS/SBAS TSOA provides sufficient evidence for compliance to AC 20-153(latest revision), but GNSS operational approval for IFR use is based upon a database assurance process through a type 2 LOA (see paragraph 19-8).
9-5.4 Approval for Rotorcraft RNP 0.3 Operations.
a. The GPS/SBAS-enabled navigation system equipment manufacturer should provide an RNP capability statement that the equipment meets the performance and functional criteria in paragraph 9-5.3 for rotorcraft enroute RNP 0.3 operations. If provided, an RNP capability statement must include a description of the equipment procedures for pilots to select the rotorcraft enroute RNP 0.3 capability. The equipment manufacturer may provide the RNP capability statement through a service bulletin or equivalent document and list the GPS/SBAS equipment model(s) that meet the criteria in section 9-5 and are eligible for rotorcraft enroute RNP 0.3 operations.
b. The GPS/SBAS equipment must be installed according to a TC, ATC, or STC and any rotorcraft limitations required for IFR operations also apply to rotorcraft enroute RNP 0.3 capability. As an example to illustrate the point, a single-pilot rotorcraft could have a limitation to use an autopilot when conducting IFR operations. This limitation would also apply to rotorcraft enroute RNP 0.3 capability.
c. Applicants for new GPS/SBAS approvals should consider including rotorcraft enroute RNP 0.3 capability as part of their application and document the capability in the RFM(S). Doing so could benefit customers seeking operational approvals.
Chapter 10. Equipment Performance – RNP Oceanic
10-1. Introduction.
a. This chapter provides guidance for RNP 10 and RNP 4.0 equipment approvals in oceanic areas. RNP 10 supports 50 NM lateral and 50 NM longitudinal separations in oceanic or remote areas without reliance on ground-based navigation aids. Paragraph 10-2 describes the performance and system criteria equipment must meet for RNP 10 and reflects the criteria in the ICAO Performance-based Navigation (PBN) Manual.
b. RNP 4.0 supports 30 NM lateral and 30 NM longitudinal separations in oceanic areas. GNSS is the primary navigation sensor supporting RNP 4.0 operations either as a stand alone system or part of a multi-sensor system. Paragraph 10-3 describes the performance and functional criteria equipment must meet for RNP 4.0 and reflects the criteria in the ICAO PBN Manual.
10-2. Aircraft and System Criteria for RNP 10.
Operational implementation of RNP 10 is an application of RNAV supporting 50 NM lateral and 50 NM longitudinal distance-based aircraft separation minima in oceanic or remote airspace. As an RNAV application, there is no requirement for onboard performance monitoring and alerting. Aircraft operating in RNP 10 oceanic and remote areas must be equipped with at least two independent and serviceable long-range navigation systems using INS/IRU and/or GNSS.
10-2.1 Performance Criteria.
a. Accuracy.
(1) During operations in airspace or on routes designated as RNP 10, the lateral TSE must be within ±10 NM for at least 95 per cent of the total flight time. The along-track error must also be within ±10 NM for at least 95 per cent of the total flight time.
(2) The navigational positioning error is the dominant contributor to cross-track and along-track error for aircraft capable of coupling the navigation system to the flight director or autopilot. A manufacturer or operator may consider FTE, path definition error, and display errors insignificant when obtaining an RNP 10 operations approval.
b. Integrity.
Malfunction of the aircraft’s long-range navigation equipment without annunciation is a major failure condition (i.e., the probability of a malfunction with no annunciation must be less than 10-5 per hour).
c. Continuity.
Loss of function of the long-range navigation equipment is a major failure condition for oceanic and remote operations. Dual independent long- range navigation system equipage 75
may satisfy the continuity criteria (excluding signal-in-space criteria).
d. Signal-In-Space.
If using GNSS, the aircraft long-range navigation equipment must provide an alert if the probability of signal-in-space errors causing a lateral position error greater than 20 NM exceeds 10-7 per hour.
10-2.2 System Criteria.
a. Aircraft Incorporating Two or More GNSSs.
(1) Paragraph 10-2.2.a provides an acceptable means of complying with RNP 10 criteria for aircraft using a GNSS-only installation; that is, no integration with other navigation sensors.
(2) Aircraft approved to use GNSS for oceanic and remote operations without reliance on other long-range navigation systems meet the RNP 10 criteria without the time limitations associated with INS/IRU equipment. However, using GNSS depends upon using an FDE availability prediction (see paragraph 10-2.2.a(3)).
(3) Dual GNSS installations with a TSOA qualify for RNP 10 when the operator uses an approved dispatch GNSS FDE availability prediction. The AFM(S) should also indicate if a particular GNSS installation meets the appropriate FAA criteria for oceanic and remote operations.
(a) When conducting GNSS pre-departure dispatch FDE predictions, the maximum allowable time for a predicted loss of GNSS FDE capability is 34 minutes. The 34 minute time limit must be a condition of the RNP 10 operations approval.
Note 1: If a GNSS FDE prediction indicates a loss of FDE capability exceeding 34 minutes, the performance criteria for the intended RNP 10 operation cannot be met. The operator must reschedule the RNP 10 operation to a period when predicted FDE is available; or, select another route where predicted FDE capability is available.
Note 2: The FAA’s SAPT prediction program does not provide FDE predictions for oceanic operations.
(b) TSO-C145/TSO-C146(AR) and TSO-C196(AR) GNSS equipment supports oceanic and remote operation by virtue of the TSOA when used in conjunction with an approved GNSS FDE prediction program. No further evaluation is needed for TSO-C145/C146/C196 equipment.
(c) TSO-C129(AR) GPS equipment might not support oceanic and remote operations. Appendix 1 describes additional criteria defining an acceptable means of compliance for TSO-C129(AR) GPS equipment to support an operations approval for oceanic 76
and remote operations. The AFM(S) should also indicate if a particular TSO-C129a GNSS installation meets the appendix 1 criteria for oceanic and remote operations.
(4) Multi-sensor navigation systems (i.e., FMSs) meet the RNP 10 criteria when integrating dual GNSS with FDE, and approved using the guidance contained in this AC.
b. Aircraft Incorporating a Single INS/IRU and a Single GNSS.
(1) Aircraft approved to use a single INS/IRU and a single GNSS for oceanic and remote operations meet the RNP 10 criteria without time limitations.
(2) The INS/IRU equipment must meet the standards of paragraph 10-2.1 and 10
2.2.c, but aircraft qualification only requires one INS/IRU.
(3) The GNSS equipment must meet the standards of paragraph 10-2.1 and
10-2.2.a, but aircraft qualification only requires one GNSS.
Note: If a GNSS FDE prediction indicates FDE unavailability exceeding 34 minutes, the performance criteria for the intended RNP 10 operation cannot be met using GNSS. The operator must predicate their RNP 10 operations on an INS/IRU for that portion of the flight.
c. Aircraft Incorporating a Single INS/IRU or a Single GNSS.
(1) Aircraft equipped with a single INS/IRU or a single GNSS are qualified for oceanic and remote navigation in the Houston oceanic control area/flight information region, the Gulf of Mexico portion of the Miami oceanic control area/flight information region, the Monterrey control area, and the Merida High control area within the Mexico flight information region/upper control area. Aircraft equipped with a single GNSS meet the RNP 10 performance criteria in this airspace without time limitations.
Note: Aircraft qualification in these regions is predicated on the air traffic surveillance provided in the Gulf of Mexico. Therefore, RNP 10 authorizations approved solely in accordance with this paragraph must clearly limit the RNP 10 operational approval to the Gulf of Mexico.
(2) The INS/IRU equipment must meet the standards of paragraph 10-2.1 and 10
2.2.c, but only one INS/IRU is required.
(3) The GNSS equipment must meet the standards of paragraph 10-2.1 and
10-2.2.a, but only one GNSS is required.
d. Aircraft Incorporating Two or more INS/IRUs – Standard Time Limit.
(1) Aircraft Equipped with Two or More INSs or IRUs Approved in Accordance with Part 121 Appendix G. Inertial systems approved in accordance with part 121 appendix G 77
meet RNP 10 performance criteria for up to 6.2 hours of flight time. This time starts when the flight crew places the INS/IRU system in the inertial navigation mode.
(a) If the flight crew updates the INS/IRU systems en route (through manual or automatic means), the flight crew must adjust the 6.2 hour RNP 10 time limit to account for the update’s accuracy. The flight crew must base any adjustments to the time limit on the demonstrated capability of the updates stated in the aircraft’s airworthiness approval documentation (i.e. the AFMS(S)).
(b) INS/IRU accuracy, reliability, training, and maintenance issues required by an airworthiness approval in compliance with part 121 appendix G are applicable to an RNP 10 operation, including any associated oceanic/remote navigation procedures. Except as authorized by the FAA Administrator, and in accordance with the applicable section of 14 CFR, RNP 10 operations based solely IRS/IRU requires at least dual equipage (i.e. two or more inertial systems). Refer to 14 CFR § 121.351, § 125.203, and § 135.165.
Note 1: The long-term inertial drift rate of 2.0 NM/hour (a 95 percent radial position error rate (circular error rate)) is the performance basis for the 6.2 hour time limit. This drift rate is statistically equivalent to an individual 95 percent cross-track and an individual 95 percent along-track position error rates (orthogonal error rates) of 1.6015 NM/hour each; and, a 95 percent cross-track and a 95 percent along-track position error limit of 10 NM each
(e.g., 10 NM/1.6015 NM/hour=6.2 hours).
Note 2: The FAA has adopted the ICAO term
“oceanic/remote” instead of Class II.
(2) Aircraft approved for North Atlantic minimum navigation performance specification operations or for RNAV operations in Australia meet RNP 10 criteria for up to 6.2 hours after the flight crew places the long-range navigation system in the inertial navigation mode.
e. Aircraft Incorporating Two or more INS/IRUs – Extended Time Limit.
The 6.2 hour time limit is the baseline for RNP 10 inertial systems performance, and the time limit begins when the flight crew places the long-range navigation system in the inertial navigation mode. However, this time limit may be extended by one of the following methods:
(1) Establishing an extended time limit during a formal RNP 10 airworthiness approval process (e.g., a new TC, ATC, or STC project).
(2) An existing airworthiness approval holder requests an extension for the installed inertial navigation system from the appropriate ACO based on justifying engineering data.
(3) An airworthiness applicant or existing airworthiness approval holder requests an extended time limit by showing how multiple navigation sensors that mix or average navigation position error justifies an extension (e.g., triple-mixed INSs). If the applicant requests an extended time limit based on mixing, then the availability of the mixing capability is a limitation for flight on RNP 10 routes. If the mixing or averaging function is not available, the operator must use a time limit that does not depend on mixing.
10-2.3 System Eligibility and Approval for RNP 10 Operations.
RNP 10 is an RNAV operational application supporting 50 NM lateral and 50 NM longitudinal distance-based aircraft separation minima in oceanic or remote airspace. As an RNAV application, there is no requirement for onboard performance monitoring and alerting.
There are two methods to recognize aircraft and system eligibility for RNP 10 operations: 1) RNP 10 certification; and, 2) prior navigation system certification. In both cases, the aircraft must be equipped with at least two independent and serviceable long-range navigation systems using GNSS and/or INS/IRU.
RNP 10 Aircraft Certification.
a. RNP 10 aircraft qualification is typically documented in the AFM(S) for aircraft with a formal airworthiness approval for RNP operations. RNP operations approval is not typically limited to just RNP 10. The AFM(S) should document the demonstrated RNP accuracy values the aircraft supports along with any limitations (e.g., navigation aid sensor requirements for present position updating). Implementing States may base operational approval on the stated performance in the AFM(S).
Note: Aircraft qualified for RNP 4.0 operations
automatically qualify for RNP 10 operations.
b. An applicant may obtain an airworthiness approval specific to RNP 10 aircraft qualification. The following example AFM(S) wording (or equivalent) is used when RNP 10 is granted for a change in, or new demonstration of, the INS/IRU certified performance:
“The <insert name> navigation system meets the aircraft qualification criteria of AC 20-138 <insert latest revision> as a primary means of navigation for flights up to XXX hours in duration without present position updating. Determining the flight duration starts when the flight crew places the long-range navigation system in the inertial navigation mode.”
Note: The “XXX hours” specified in the AFM(S) for INS/IRU systems do not include credit for present position updating.
(1) For long-range navigation systems capable of updating the aircraft’s present position while airborne, the airworthiness approval must address the impact present position updating has on position accuracy and any impact on time limits for RNP 10 operations. The approval should clarify the role of ground-based navigation facilities in present position 79