(2) The critical phase of flight is normally from the final approach fix on an approach procedure through missed approach, or from field elevation to 2,500 ft above airport elevation on a departure.
6-4.1 Reasonableness Checks.
a. Many FMSs perform a reasonableness check to verify valid DME measurements.
Reasonableness checks are very effective against database errors or erroneous system acquisition (such as co-channel facilities), and typically fall into two classes:
(1) Those the FMS uses after it acquires a new DME. The FMS compares the aircraft’s position before using the DME to the aircraft’s range to the DME; and
(2) Those the FMS continuously uses, based on redundant information (for example, extra DME signals or IRU data).
b. The reasonableness checks are intended to prevent navigation aids from being used for navigation update in areas where the data can lead to radio position fixing errors due to co-channel interference, multipath, and direct signal screening. In lieu of using radio navigation aid published service volume, the navigation system should provide checks, which preclude use of duplicate frequency navigation aids (NAVAIDs) within range, over-the-horizon NAVAIDs, and use of NAVAIDs with poor geometry.
c. Under certain conditions, reasonableness checks can be invalid.
(1) Do not assume a DME signal remains valid just because it was valid when acquired.
(2) Do not assume extra DME signals are available. The intent of this baseline is to support operations where the infrastructure is minimal (for example, when only two DMEs are available for parts of the procedure).
d. When an FMS manufacturer uses a reasonableness check to satisfy any criteria in this AC, they must test the effectiveness of the check under stressing conditions. An example of this condition is a DME signal that is valid at acquisition and “ramps off” during the test (similar to what a facility under test might do), when there is only one other supporting DME or two signals of equal strength. A “ramp off” rate would be significantly higher or slower than the normal range of groundspeed.
6-4.2 Performance Confirmation.
a. New systems may demonstrate compliance with these criteria as part of the airworthiness approval. For existing systems, the applicant should determine compliance with the equipment and aircraft criteria in this chapter.
b. Aircraft manufacturers (TC holders) incorporating FMS and DME/DME positioning should review the available data for the integrated navigation system, and obtain additional data 45
-- as appropriate, to determine compliance with the criteria in this AC.
c. Equipment manufacturers (typically DME and FMS TSOA/LODA holders) need to consider DME accuracy. DME sensors have been demonstrated to a variety of performance requirements per TSO-C66. TSO-C66 performance standards have evolved as follows:
(1) TSO-C66: (Aug 1960) RTCA/DO-99.
(2) TSO-C66a: (Sep 1965) RTCA/DO- 151, accuracy requirement as total error with 0.1 NM attributed to ground facility, airborne equipment accuracy of 0.5 NM or 3% of distance, whichever is greater, with a maximum of 3 NM.
(3) TSO-C66b: (Nov 1978) RTCA/DO-151a, accuracy requirement as total error with 0.1 NM attributed to ground facility, airborne equipment accuracy of 0.5 NM or 1% of distance, whichever is greater, with a maximum of 3 NM.
(4) TSO-C66c: (Sept 1985) RTCA/DO-189, accuracy requirement as total error for the airborne equipment of 0.17 NM or 0.25% of distance, whichever is greater.
d. The accuracy required by TSO-C66c is adequate to support the criteria in this AC.
DME equipment approved under revision ‘c’ does not require further evaluation for RNAV 1 and RNAV 2 operations. Applicants with equipment built to earlier TSO revisions may use the following process to establish more accurate performance than originally credited to support RNAV 1 and RNAV 2 operations.
(1) Rather than relying on original demonstrated performance, the applicant may elect to review the original TSO or TC/STC test data to determine the demonstrated accuracy and/or make any appropriate changes to qualification tests to determine achieved accuracy.
Note: When conducting accuracy analysis, the DME signal-in-space error can be assumed to be 0.1 NM 95% (both inside and outside the published service volume). If demonstrating accuracy under bench or flight test conditions, the actual accuracy of the bench equipment or ground facility should be considered.
(2) New testing should be performed under the same conditions used to demonstrate compliance with the original TSO-C66 standard.
(3) Applicants who have demonstrated more accurate DME performance should state the demonstrated accuracy in a letter to their customers.
6-4.3 Multi-Sensor System FMS.
a. The FMS or aircraft manufacturer should review the available data for the integrated navigation system, and obtain additional data as appropriate, to determine compliance with the criteria in paragraph 6-4. Applicants who have determined compliance should state such in the operating instructions or AFMS/RFMS, along with any limitations (for example, if the pilot is 46
--- expected to manually inhibit the use of facilities that are listed by NOTAM as unavailable).
The applicant’s certification may limit the compliance to specific DME systems, or may reference any DME qualified to the accuracy requirements of TSO-C66c.
b. FMS accuracy is dependent on a number of factors including: latency effects, the selection of DME facilities, the method of combining information from multiple DMEs, and the effects of other sensors used to determine a position. For FMSs using two (or more) DMEs at the same time and limiting the DME include angle to between 30° and 150°, the accuracy requirement can be met if the DME sensors meet the accuracy requirements of TSO-C66c. For FMSs without these characteristics, the accuracy should be evaluated under poor DME geometry scenarios and should consider the demonstrated DME sensor accuracy. Poor geometry scenarios may include angles at the limits specified earlier, with or without additional DME facilities available outside those conditions.
c. Identify those conditions that would result in failure to meet the accuracy requirement and the means to preclude those identified conditions.
6-5. VOR/DME.
a. Multi-sensor equipment may incorporate VOR/DME updating and must meet the performance for the route to be flown. However, terminal and enroute RNAV implementation in the U.S. does not require using VOR, so any use of VOR must include reasonableness checking and demonstrate that positional accuracy from an erroneous VOR signal-in-space will not exceed 1.75 nm for RNAV 2 and 0.87 nm for RNAV 1 (reference AC 90-100A, appendix 1, paragraph 2.h). This could be accomplished by not using VOR signals when DME/DME will be available or weighting and/or monitoring the VOR signal with DME/DME to ensure it does not mislead position results (for example, through reasonableness checks). See paragraph 6-4.1 for guidance on testing reasonableness checks.
b. For times when the multi-sensor equipment is using data from only a single collocated VOR/DME (such as during an RNAV (VOR/DME) approach), the total maximum position fixing error of the airborne multi-sensor equipment must be equal to or less than that shown in Table 4. To find the cross track (xtk) and along track (atk) error at this point, enter the Table with the tangent distance in nautical miles and distance along track in nautical miles from the tangent point.
- Along-Track Distance (NM) 0 5 10 15 20 25 30 35 40 50 60 70 80 90 100 110 120 130 0 xtk 0.6 0.8 1.1 1.4 1.7 2.0 2.3 2.6 3.2 3.9 4.5 5.2 5.8 6.4 7.1 7.7 8.4 atk 0.6 0.6 0.6 0.6 0.7 0.7 0.8 0.8 0.9 1.0 1.0 1.1 1.2 1.3 1.4 1.5 1.6 5 xtk 0.6 0.6 0.8 1.1 1.4 1.7 2.0 2.3 2.6 3.3 3.9 4.5 5.2 5.8 6.4 7.1 7.7 8.4 atk 0.6 0.6 0.7 0.7 0.7 0.8 0.8 0.8 0.9 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 10 xtk 0.6 0.7 0.9 1.1 1.4 1.7 2.0 2.3 2.6 3.3 3.9 4.5 5.2 5.8 6.5 7.1 7.7 8.4 atk 0.8 0.8 0.8 0.8 0.9 0.9 0.9 1.0 1.0 1.1 1.2 1.2 1.3 1.4 1.5 1.6 1.7 1.8 15 xtk 0.6 0.7 0.9 1.1 1.4 1.7 2.0 2.3 2.6 3.3 3.9 4.5 5.2 5.8 6.5 7.1 7.7 8.4 atk 1.0 1.0 1.0 1.1 1.1 1.1 1.2 1.2 1.2 1.3 1.4 1.4 1.5 1.6 1.7 1.7 1.8 1.9 20 xtk 0.6 0.7 0.9 1.2 1.4 1.7 2.0 2.3 2.7 3.3 3.9 4.6 5.2 5.8 6.5 7.1 7.7 8.4 atk 1.3 1.3 1.3 1.3 1.3 1.4 1.4 1.4 1.4 1.5 1.6 1.6 1.7 1.8 1.9 1.9 2.0 2.1 25 xtk 0.7 0.8 1.0 1.2 1.5 1.8 2.1 2.4 2.7 3.3 3.9 4.6 5.2 5.8 6.5 7.1 7.8 8.4 atk 1.5 1.5 1.6 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.8 1.9 1.9 2.0 2.1 2.1 2.2 2.3 30 xtk 0.7 0.8 1.0 1.2 1.5 1.8 2.1 2.4 2.7 3.3 3.9 4.6 5.2 5.9 6.5 7.1 7.8 8.4 atk 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.1 2.1 2.2 2.2 2.3 2.4 2.4 2.5 35 xtk 0.8 0.8 1.0 1.3 1.5 1.8 2.1 2.4 2.7 3.3 4.0 4.6 5.2 5.9 6.5 7.1 7.8 8.4 atk 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.4 2.4 2.5 2.5 2.6 2.7 2.7 40 xtk 0.8 0.9 1.1 1.3 1.5 1.8 2.1 2.4 2.7 3.3 4.0 4.6 5.2 5.9 6.5 7.1 7.8 8.4 atk 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.7 2.7 2.8 2.9 2.9 3.0 50 xtk 0.9 1.0 1.1 1.3 1.6 1.9 2.2 2.5 2.8 3.4 4.0 4.6 5.3 5.9 6.5 7.2 7.8 8.4 atk 2.9 2.9 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.1 3.1 3.2 3.2 3.3 3.3 3.4 3.4 3.5 60 xtk 1.0 1.0 1.2 1.4 1.7 1.9 2.2 2.5 2.8 3.4 4.0 4.7 5.3 5.9 6.6 7.2 7.8 8.5 atk 3.5 3.5 3.5 3.5 3.5 3.6 3.6 3.6 3.6 3.6 3.7 3.7 3.8 3.8 3.8 3.9 3.9 4.0 70 xtk 1.0 1.1 1.3 1.5 1.7 2.0 2.3 2.6 2.9 3.5 4.1 4.7 5.3 6.0 6.6 7.2 7.9 8.5 atk 4.1 4.1 4.1 4.1 4.1 4.1 4.1 4.2 4.2 4.2 4.2 4.3 4.3 4.4 4.4 4.4 4.5 4.5 80 xtk 1.1 1.2 1.4 1.6 1.8 2.1 2.3 2.6 2.9 3.5 4.1 4.7 5.4 6.0 6.6 7.3 7.9 8.5 atk 4.6 4.7 4.7 4.7 4.7 4.7. 4.7 4.7 4.7 4.8 4.8 4.8 4.9 4.9 5.0 5.0 5.0 5.1 90 xtk 1.2 1.3 1.4 1.6 1.9 2.1 2.4 2.7 3.0 3.5 4.2 4.8 5.4 6.0 6.7 7.3 7.9 8.6 atk 5.2 5.2 5.2 5.2 5.2 5.3 5.3 5.3 5.3 5.3 5.4 5.4 5.4 5.5 5.5 5.5 5.6 5.6 100 xtk 1.3 1.4 1.5 1.7 1.9 2.2 2.4 2.7 3.0 3.6 4.2 4.8 5.4 6.1 6.7 7.3 7.9 8.6 atk 5.8 5.8 5.8 5.8 5.8 5.8 5.9 5.9 5.9 5.9 5.9 6.0 6.0 6.0 6.1 6.1 6.1 6.2 110 xtk 1.4 1.5 1.6 1.8 2.0 2.3 2.5 2.8 3.1 3.6 4.2 4.9 5.5 6.1 6.7 7.3 8.0 8.6 atk 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.5 6.5 6.5 6.5 6.6 6.6 6.6 6.7 6.7 6.7 120 xtk 1.5 1.6 1.7 1.9 2.1 2.3 2.6 2.8 3.1 3.7 4.3 4.9 5.5 6.1 6.8 7.4 8.0 8.6 atk 6.9 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.1 7.1 7.1 7.1 7.2 7.2 7.2 7.3 7.3 130 xtk 1.6 1.7 1.8 2.0 2.2 2.4 2.6 2.9 3.2 3.7 4.3 4.9 5.6 6.2 6.8 7.4 8.0 8.7 atk 7.5 7.5 7.5 7.6 7.6 7.6 7.6 7.6 7.6 7.6 7.7 7.7 7.7 7.7 7.8 7.8 7.8 7.9 Table 4. 2D Accuracy Requirements for Equipment Using a Single Co-located VOR/DME T a n g e n t D i s t a n c e N M Note 1: Equipment error assumes a waypoint input resolution of 0.01 minute, and output resolution of 0.01 minute for approach and 0.1 minute otherwise.
Note 2: Equipment error assumes the maximum allowable difference between the displayed cross-track deviation and the computed cross-track deviation.
Note 3: Multi-sensor equipment accuracy shown in the Table 4 does not necessarily satisfy accuracy requirements for operation in certain airspace. For example, navigation 48
on published J and V routes requires a distance along-track from the tangent point to VOR/DME to be less than approximately 50 NM to meet airway width criteria.
Note 4: Table 4 is a result of the root-sum-square combination of the error elements shown below in Table 5.
Table 4 is computed assuming the waypoint is always at the tangent point and the aircraft is at the along-track distance measured from the same tangent point. This is important in the test procedures because the resulting cross-track error from the course setting is a function of the distance to waypoint.
GROUND EQUIPMENT ERROR AIRBORNE EQUIPMENT ERROR VOR 1.4 degrees VOR 3.0 degrees DME 0.1 nm DME 0.2 nm + 1% Course Setting Error 1.6 degrees Computation Error 0.5 nm Table 5. Error Elements
6-6. INS/IRU.
a. An INS/IRU installation is an acceptable lateral positioning source during a significant portion of the flight provided it meets the requirements described in 14 CFR part 121, appendix G while in inertial mode.
b. Attitude heading reference systems, including an AHRS with inputs from air data computers, do not qualify as instrument navigation devices similar to an INS/IRU. An AHRS is not acceptable as an INS/IRU substitute or replacement for operational use under instrument flight rules on any RNAV or RNP instrument route or procedure. The foundation for the airworthiness approval of a gyro as an AHRS is not equivalent to the foundation for the airworthiness approval of a similar gyro approved as an INS/IRU.
Note 1: Paragraph 6-6 applies to both “stand-alone” and loosely coupled inertial integrations.
Note 2: RTCA Special Committee-159 working group 2C is developing a MOPS for GNSS-aided inertial systems including GNSS-aided inertial systems not meeting 14CFR part 121, appendix G. Paragraphs 6-6 and 6-7 in this AC will be updated when the new MOPS and TSO are published.
--
6-7. INS/IRU – GNSS Integration.
a. The guidance in paragraph 6-7 is applicable for tightly-coupled integrations, and is in addition to the guidance in paragraph 6-6.
b. For GNSS sensors, both RTCA/DO-229D, Change 1 and RTCA/DO-316, appendix R, provides INS/IRU – GNSS integration requirements (appendix R is the same in both documents). The GNSS/inertial hybrid outputs of the INS/IRU must meet the equipment requirements of appendix R. However, appendix R is not invoked by any TSO. It is acceptable for tightly coupled INS/IRU – GNSS hybrid sensors meeting appendix R to be integrated with FMS or multi-mode receivers for operational use under instrument flight rules on RNAV or RNP instrument routes or procedures.
c. The FAA assumes that GPS/inertial position data is limited to enroute through LNAV approach horizontal positioning. Using this position data for operations requiring higher precision would require other integrity and accuracy enhancements such as GPS/SBAS, GPS/GBAS, or other integrity/accuracy monitor function. Since hybrid vertical position and integrity has not been addressed by appendix R, any use should be identified and resolved as part of the appendix R approval process.
(1) No exclusion is intended for previously certified equipment meeting the requirements of RTCA/DO-229C, appendix R. It is acceptable to use previously certified GNSS sensors integrated with INS/IRU systems meeting the requirements specified in RTCA/DO-229C, appendix R. However, RTCA/DO-229C, appendix R assumed selective availability was ‘on’, so it may not adequately describe system performance if the applicant wishes to take credit for selective availability being ‘off.’
(2) Aircraft with GPS/inertial installations approved for LNAV approaches can also include a baro-VNAV installation to provide the vertical guidance deviations acceptable for LNAV/VNAV approaches. Chapters 11, 18, and 23 describe baro-VNAV performance and installation considerations.
d. Tightly coupled INS/IRU systems integrated with GNSS sensors outputting PVT that is the same as GNSS may be demonstrated to be equivalent to either TSO-C145d, or TSO C196b and receive a GNSS TSOA/LODA. Any discrepancies should be identified and resolved as part of the TSO approval, but appendix R will take precedence. It may be necessary to conduct further evaluation during any follow-on approval since the characteristics and performance required for the inertial integration are closely linked to aircraft architecture, integration method, and GNSS failure modes.
(1) TSO-C129a has been cancelled so no new approvals to that standard are possible.
(2) Tightly coupled INS/IRU systems with an existing TSO-C129(AR) TSOA/LODA may still be produced and integrated with GNSS sensors that have an existing TSO-C129(AR) TSOA/LODA.
(3) Applicants requesting a TSO-C196b or TSO-C145d TSOA/LODA for their tightly coupled INS/IRU systems will need to include part number differentiation and installation instructions limiting integration to GNSS sensors approved to the same TSO.
e. When demonstrating RAIM or RAIM equivalency, the GPS signal-in-space failure modes to be used for the demonstration should be proposed and agreed upon as part of the TSO approval. For example, the applicant should address the correlated effects of multiple erroneous pseudoranges due to ionospheric activity. After exclusion of a faulty satellite, show that the position solution is valid and the inertial states/models are not corrupted by the faulty GPS data prior to its detection and exclusion.
f. All attitude and heading data output by the integrated system must comply with the relevant regulations under all foreseeable operating conditions. This includes during GPS signal-in-space failures (including prior to detection and after exclusion).
g. In the absence of any GPS input, the attitude and heading data output by the integrated system must comply with the relevant regulations, including those conditions addressed in the aircraft functional hazard assessment (FHA).
Note: It may be necessary to revise the FHA to address failure conditions unique to the GPS/inertial system.
h. If the system sustains integrity coasting capability, the INS/IRU equipment manufacturer must document the coasting performance and limitations. That is, document the coasting time while sustaining performance at the desired navigation performance level, horizontal alert limit (HAL) or RNP. This documentation must be consistent with the alerting algorithms for the aircraft (e.g., RNP). The coasting performance should consider factors that could influence coasting times (e.g., inertial sensor accuracy, gyro misalignment, inertial parameter calibration accuracy prior to loss of GPS signals, aircraft maneuvers prior to and during the coasting period, and aircraft speed).
6-8. INS/IRU - DME/DME Integration.
a. Paragraph 6-8 defines a minimum DME/DME/IRU (D/D/I) RNAV system baseline performance capable of supporting RNAV 1 and RNAV 2 routes, as well as RNAV 1 DPs and STARs. For routes and procedures designed using this performance standard, the FAA will decide if adequate DME coverage is available using FAA computer modeling and flight inspection assets. This assessment of DME coverage will also determine if an expanded service volume is necessary for select DME facilities.
b. The minimum DME/DME requirements of paragraph 6-4 apply and are not repeated here, except where additional performance is required. The performance confirmat ion process in paragraph 6-4.2 also applies to paragraph 6-8.
c. There is no requirement to use VOR, NDB, LOC, or AHRS during normal operation of the DME/DME/IRU RNAV system.
d. The 95% position estimation error must be better than or equal to the value obtained 51
using the equation referenced in paragraph 6-4.f note 2 given any two DME facilities satisfying the criteria in paragraphs 6-4.b thru 6-4.d, and any combination of other valid DME facilities not meeting that criteria.
Note: Based on an evaluation of IRU performance, the growth in position error after reverting to IRU can be expected to be less than 2 NM per 15 minutes.
e. Inertial system performance must satisfy the criteria in paragraph 6-6.
f. Additional required FMS capabilities are:
(1) Automatic position updating from the DME/DME solution.
Note: Equipment manufacturers or airworthiness applicants should note in the appropriate documentation for the flight crew if any inertial coasting annunciation is suppressed following loss of radio updating.
(2) Accepting a position update immediately prior to takeoff.
(3) Excluding VORs greater than 40 NM from the aircraft.
g. The total system error (TSE) must be less than or equal to 1.0 NM (95%) throughout the route. To maximize the amount of IRU coasting allowed, the flight technical error for D/D/I aircraft on terminal procedures should be limited to 0.5 NM (95%).
Note: The FAA assures that systems meeting the D/D/I RNAV minimum performance standard satisfy this requirement on all identified routes and procedures, and these RNAV systems do not require further evaluation.
Systems seeking approval using different RNAV system characteristics or performance must demonstrate this performance for each published route or procedure.
Chapter 7. Equipment Performance - RNP (General).
7-1. Introduction.
a. The intent of the RNP chapters 7-10 and 17 along with appendix 2 and 3 is to provide the airworthiness guidance manufacturers need for implementing RNP capability when used in conjunction with the performance and installation chapters in this AC applicable to the equipment. The airworthiness information in this AC supersedes the airworthiness guidance in all revisions of ACs 90-101 and 90-105. Applicants should not base their new RNP AR or RNP airworthiness applications on the 90-series ACs because that guidance is not complete for airworthiness purposes. However, previous airworthiness approvals based on those ACs remain valid.
b. RTCA/DO-236C, Chg 1, Minimum Aviation System Performance Standards:
Required Navigation Performance for Area Navigation, dated June 19, 2013, and RTCA/DO 283B are closely linked to provide coherent RNP standards at both the aircraft level and RNP equipment level respectively.
(1) Aircraft manufacturers that use the type certificate process for all design, production and airworthiness approval of RNP capability may use RTCA/DO-236C, Chg 1 as the compliance standard at the aircraft level. While the RNP equipment is included as part of the type certificate, it should comply with RTCA/DO-283B (as modified by TSO-C115d) although requirements trade-offs are possible as long as the aircraft performance meets the requirements of RTCA/DO-236C, Chg 1.
(2) RNP equipment manufacturers building equipment for later installations (i.e., not associated with an aircraft OEM type certificate) cannot anticipate the installed RNP airworthiness capability at the aircraft level. These projects should use the standards in RTCA/DO-283B, as modified by TSO-C115d, for their RNP equipment.
Note: TSO-C115d includes significant modifications to the standards in RTCA/DO-283B. Manufacturers choosing to use the standards in RTCA/DO-283B must incorporate the TSO C115d modifications.
c. A database is an essential component necessary for RNP equipment to perform its intended function. RNP equipment operational approval for IFR use is based upon a database assurance process through a type 2 LOA. A type 2 LOA provides database objective evidence of integrity consistent with the monitoring and alerting requirement for RNP systems.
d. Chapter 8 is specific to the equipment performance considerations for RNP approach (RNP APCH) procedures; chapter 9 is specific to the equipment performance considerations for RNP enroute and terminal operations; and chapter 10 is specific to the equipment performance considerations for oceanic RNP. Chapter 17 describes installation considerations for RNP. Airworthiness guidance for RNP AR, including installation considerations, is addressed in appendix 2 of this AC while appendix 3 of this AC describes advanced RNP functions. Appendix 7 contains templates t o demonstrate RF leg capability.
RNP AR and RNP operational approval guidance can be found in the latest revisions of ACs 53
90-101 and 90-105, respectively.
Note: RNP AR was previously named RNP SAAAR. The name has been changed to RNP AR for international harmonization.
e. A foundation for RNP operations in the U.S. NAS relies on the ability to perform RNP 2.0, RNP 1.0, and RNP APCH operations (excluding RNP AR operations) to the LNAV line of minima. It is important to understand that RNP is an aircraft- level capability comprising the sensor, navigation computer, database, display systems, and flight guidance integration; not just an FMS function or TSO label. In general, aircraft with properly installed GNSS systems qualify for RNP 2.0, RNP 1.0, and RNP APCH to LNAV minima, but there are some additional considerations (see chapters 8 and 9 for specific guidance).
f. Aircraft may have additional RNP capabilities such as RNP APCH to LNAV/VNAV or LPV line of minima, or advanced RNP functions.
(1) GPS/SBAS and FMS equipment manufacturers should provide a statement in the RNP capabilities document for these additional RNP capabilities provided the equipment is installed according to the installation instructions/manual. Reference paragraphs 12-7.b and A5-2 for more information regarding the RNP capabilities document. The statement of RNP capabilities should be part of the installation instructions/manual.
(2) These additional capabilities have aircraft integration dependencies that must be considered during the airworthiness approval before the RNP capability can be approved at the aircraft-level.
g. TSO-C129(AR) equipment may not support all foundational RNP operations due to the minimum requirements in those TSOs. See chapters 8 and 9 for specific guidance on aircraft with TSO-C129(AR) equipment.
h. GPS/SBAS and GPS/GBAS sensors can be approved on aircraft without baro- VNAV to provide vertical path guidance for RNP 0.3 operations and RNP AR operations as low as RNP 0.1. However, all aircraft and FMS requirements for RNP and RNP AR operations still apply. Refer to chapters 15 and 17 of this AC (appendix 2 for RNP AR) for airworthiness guidance, and the latest revisions of AC 90-101, and AC 90-105 for operational guidance.
Note: TSO-C146(AR) invokes either RTCA/DO-229 revision ‘C’ or ‘D’, section 2.2 for Class Gamma GPS/SBAS equipment. The navigation computer requirements in section 2.2 invoked by TSO-C146(AR) are a specific method of complying with the RNP requirements for RNP 2.0, RNP 1.0 and RNP APCH to LNAV minima.
Class 2 and Class 3 equipment provide vertical guidance for RNP approaches when operating within GPS/SBAS coverage.
i. GPS/SBAS and GPS/GBAS used for RNP and RNP AR do not require the baro-VNAV temperature mitigations; however, the aircraft must be within the service provider’s coverage area to use GPS/SBAS or GPS/GBAS for RNP and RNP AR operations.
The following are performance advantages for GPS/SBAS or GPS/GBAS compared to baro-VNAV for RNP and RNP AR:
(1) An accurate and repeatable vertical flight path with consistent alignment of the glide path angle (GPA) with visual landing cues and landing aids (e.g., visual approach slope indicator (VASI) or precision approach path indicator (PAPI)).
(2) No temperature restrictions on using the procedure.
(3) GPS/SBAS and GPS/GBAS can meet the RNP AR 0.1 vertical performance contours without independent system monitoring.
(4) The flight path is not affected by manual or Automated Traffic Information System (ATIS) altimeter setting errors.
7-2. Special Characteristics of RNP Instrument Approaches.
a. GNSS is the primary navigation system to support RNP approach procedures. The missed approach segment may be based upon a conventional NAVAID (e.g., VOR, DME, NDB), but DME/DME-based systems are not acceptable for RNP APCH.
b. Tightly-coupled GPS/IRU or GPS/SBAS/IRU systems can provide a coasting capability in the event GPS positioning is not available.
7-3. Special Characteristics of RNP 1.0 and RNP 2.0 Operations.
a. RNP 1.0 is used on the initial, intermediate and missed approach segments of instrument approaches along with obstacle departure procedures (ODPs), standard instrument departures (SIDs), and STARs. DME/DME/IRU and/or GNSS are the primary navigation systems supporting RNP 1.0 operations.
b. RNP 2.0 routes are intended for operations in oceanic and remote areas. GNSS is the primary navigation system to support RNP 2.0 operations.
Chapter 8. Equipment Performance - RNP Approach.
8-1. Introduction.
This chapter provides guidance on the performance and functional criteria for systems used to conduct RNP approach operations, which are designated under part 97 as RNAV (GPS) or GPS and categorized as RNP APCH in ICAO. The baro-VNAV equipment performance applicable to RNP approaches is specified in chapter 11. B aro-VNAV systems are optional capabilities that are not a minimum requirement to fly RNAV (GPS) or GPS approaches using the LNAV line of minima.
8-2. Aircraft and System Criteria.
a. Aircraft with the following avionics equipment that meet the applicable installation chapters in this AC automatically qualify for RNP APCH to LNAV minima capability without further documentation by virtue of the avionics TSO and airworthiness approval:
• TSO-C115c (or later revision) FMS with a TSO-C129(AR) Class B1 or C1, TSO C145(AR), or TSO-C196(AR) sensor;
Note: See paragraph 8-3.g(2) for “TO/TO” navigation computers.
• TSO-C146 Class Gamma equipment;
• TSO-C129(AR), Class A1 equipment; or,
• Aircraft with an RNP AR approval.
b. A TSO-C115b FMS using a TSO-C129(AR) Class B1/C1, TSO-C145(AR), or TSO C196(AR) sensor with documented compliance to the RNP requirements in RTCA/DO-236 (revision ‘B’ or later) or RTCA/DO-283 (revision ‘A’ or later) as part of the approval basis also provides RNP APCH to LNAV minima capability without further evaluation.
Note: See paragraph 8-3.g(2) for “TO/TO” navigation computers.
c. Avionics or aircraft manufacturers may provide a service bulletin for a pilot or equipment operating handbook entry, or other notification stating aircraft with the equipment in paragraphs 8-2.a and 8-2.b, and an appropriate airworthiness approval, has RNP APCH to LNAV line of minima capability.
Note 1: Aircraft with RNP APCH to LNAV minima capability based on TSO-C129(AR) and TSO-C196(AR) GNSS have limitations requiring operators to perform pre-departure RAIM checks.