(a) Applicability.

(1) Minimum Performance Standard. This technical standard order (TSO) prescribes the minimum performance standard that airborne supplemental area navigation equipment using the global positioning system (GPS) must meet in order to be identified with the applicable TSO marking. Airborne supplemental area navigation equipment using GPS that are to be so identified and that are manufactured on or after the date of this TSO must meet the minimum performance standard of Section 2, RTCA, Inc. Document No. RTCA/DO-208, "Minimum Operational Performance Standards for Airborne Supplemental Navigation Equipment Using Global Positioning System (GPS)," dated July 1991.

(2) Equipment Classes. Equipment approved under this TSO shall be identified with the applicable equipment class as follows:

(i) Class A( ). Equipment incorporating both the GPS sensor and navigation capability. This equipment shall incorporate Receiver Autonomous Integrity Monitoring (RAIM) as defined by paragraph (a)(3)(xv) of this TSO.

1. Class A1. En route, terminal, and non-precision approach (except localizer, localizer directional aid (LDA), and simplified directional facility (SDF)) navigation capability.

2. Class A2. En route and terminal navigation capability only.

(ii) Class B( ). Equipment consisting of a GPS sensor that provides data to an integrated navigation system (i.e., flight management system, multi-sensor navigation system, etc.). The equipment consisting of a GPS sensor must meet all of the Class B( ) requirements specified in this TSO in order to be identified with a Class B( ) marking.

1. Class B1. En route, terminal, and non-precision approach (except localizer, LDA, and SDF) capability. This equipment provides RAIM capability as specified in paragraph (a)(4)(vii) of this TSO.

2. Class B2. En route and terminal capability only. This equipment provides RAIM capability as specified in paragraph (a)(4)(vii) of this TSO.

3. Class B3. En route, terminal, and non-precision approach (except localizer, LDA, and SDF) capability. This equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to that provided by RAIM as specified in paragraph (a)(4)(vii) of this TSO.

4. Class B4. En route and terminal capability only. This equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to that provided by RAIM as specified in paragraph (a)(4)(vii) of this TSO.

(iii) Class C( ). Equipment consisting of a GPS sensor that provides data to an integrated navigation system (i.e., flight management system, multi-sensor navigation system, etc.) which provides enhanced guidance to an autopilot or flight director in order to reduce flight technical error. Class C equipment is limited to installations in aircraft approved under 14 CFR Part 121 or equivalent criteria. (It is intended that this class of equipment need not meet the display requirements applicable to the other equipment classes of this TSO.) The equipment consisting of a GPS sensor must meet all of the Class C( ) requirements specified in this TSO in order to be identified with a Class C( ) marking.

1. Class C1. En route, terminal, and non-precision approach (except localizer, LDA, and SDF) capability. This equipment provides RAIM capability as specified in paragraph (a)(5)(vii) of this TSO.

2. Class C2. En route and terminal capability only. This equipment provides RAIM capability as specified in paragraph (a)(5)(vii) of this TSO.

3. Class C3. En route, terminal, and non-precision approach (except localizer, LDA, and SDF) capability. This equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to that provided by RAIM as specified in paragraph (a)(5)(vii) of this TSO.

4. Class C4. En route and terminal capability only. This equipment requires the integrated navigation system to provide a level of GPS integrity equivalent to that provided by RAIM as specified in paragraph (a)(5)(vii) of this TSO.

(3) Exceptions to RTCA/DO-208 for Class A( ) Equipment:

(i) Operation of Controls. Add the following requirement to paragraph 2.1.4. of RTCA/DO-208: Controls shall be designed to maximize operational suitability and minimize pilot workload. Reliance on pilot memory for operational procedures shall be minimized.

(ii) Accessibility of Controls. Add the following requirement to paragraph 2.1.5 of RTCA/DO-208: Controls that are normally adjusted in flight shall be readily accessible and properly labeled as to their function.

(iii) Sensor Interfaces. In lieu of paragraph 2.1.6 of RTCA/DO-208, substitute the following requirement: The interfaces with other aircraft equipment must be designed such that normal or abnormal RNAV equipment operation shall not adversely affect the operation of other equipment nor shall normal or abnormal operation of other equipment adversely affect the RNAV equipment operation.

(iv) Control/Display Readability. In lieu of paragraph 2.1.8 of RTCA/DO-208, substitute the following requirement: The equipment shall be designed so that all displays and controls shall be readable under all normal cockpit conditions and expected ambient light conditions (total darkness to bright reflected sunlight). All displays and controls shall be arranged to facilitate equipment usage.

(v) Maneuver Anticipation. Add the following requirement to paragraph 2.1.10 of RTCA/DO-208: For systems approved for non precision approaches (class A1 equipment), maneuver anticipation (turning prior to the "to" waypoint) shall not be implemented at the missed approach fix or the missed approach holding fix.

(vi) Update Rate. In lieu of paragraph 2.1.11 of RTCA/DO-208, substitute the following requirement: Navigation information used for display shall be updated at an interval of 1.0 second or less.

(vii) Numeric Display Information. In lieu of paragraph 2.2.1.1.1 of RTCA/DO-208, substitute the following requirement:

1. Equipment certified to class A2 shall continuously provide either a display or electrical output with the following requirements:

a. The display shall be as accurate as the resolution required for the displayed full scale range, referenced to a centered CDI display (see table in paragraph (a)(3)(viii)).

b. The equipment shall provide a numeric display or electrical output of cross-track deviation to at least + 20 nm (left and right). A minimum resolution of 0.1 nm up to 9.9 nm and 1.0 nm beyond shall be provided. The display may be pilot selectable.

2. Equipment certified to class A1, shall, in addition to the requirements for class A2:

a. Provide a numeric (digital) display or electrical output of cross-track deviation to a resolution of 0.01 nm for deviations less than 1.0 nm.

b. Compute and display track angle error (TAE) to the nearest one degree. Track angle error is the difference between desired track and actual track (magnetic or true). In lieu of providing a numeric display of track angle error, non-numeric TAE may be displayed in conjunction with the non-numeric cross-track deviation, provided the display provides equivalent situational awareness.

2. The applicable non-numeric display information shall be automatically presented upon activation of the appropriate operating mode and the conditions outlined in paragraph (a)(3)(xii).

3. A means shall be provided for manual selection of the applicable display sensitivities in paragraph (a)(3)(viii)1. Additionally, the equipment shall display the non-numeric scale sensitivity, or provide an electrical output to display this information on an external display.

4. For Class A1 equipment, manual selection of a different scale sensitivity shall result in deselection of the approach mode. A proper indication must be provided.

5. In lieu of a linear lateral deviation scale for the final approach segment (final approach fix to missed approach point), an angular deviation display that emulates the nominal ILS localizer/MLS azimuth display resolution may be used, beginning with a full scale cross-track deflection of +0.3 nm at the final approach fix decreasing to +0.0576 nm (plus or minus 350 feet) at the runway threshold.

(ix) Waypoint Entry. In lieu of paragraphs 2.2.1.5 and 2.2.1.9 of RTCA/DO-208, substitute the following requirements:

1. Equipment certified to class A2 shall at least provide the capability to manually enter and display (prior to its utilization in the flight plan) the coordinates of a waypoint in terms of latitude and longitude with a resolution of 0.1 minute or better. If the equipment provides the ability to enter a waypoint as a range and bearing from another waypoint, the waypoint input resolution shall be 0.1 nm and 1 degree or better.

2. Equipment certified to class A1 shall at least provide the capability to manually enter and display (prior to its utilization in the flight plan) the coordinates of a waypoint in terms of latitude and longitude with a resolution of 0.01 minute or better. If the equipment provides the ability to enter a waypoint as a range and bearing from another waypoint, the waypoint input resolution shall be 0.1 nm and 0.1 degree or better.

(x) Waypoint Storage. In lieu of paragraph 2.2.1.6 of RTCA/DO-208, substitute the following requirements:

1. The equipment shall provide an appropriately updatable navigation data base containing at least the following location information in terms of latitude and longitude with a resolution of 0.01 minute or better for the area(s) in which IFR operations are to be approved: all airports, VORs (and VORTACs), NDBs, and all named waypoints and intersections shown on en route and terminal area charts, Standard Instrument Departures (SIDs) and Standard Terminal Arrival Routes (STARs).

2. Equipment certified to class A1, in addition to the requirements of paragraph (a)(3)(x)1, shall provide the following:

a. The equipment navigation data base shall also include all waypoints and intersections included in published non-precision instrument approach (except localizer, LDA, and SDF) procedures.

b. The equipment shall store all waypoints, intersections, and/or navigation aids and present them in the correct order for a selected approach as depicted on published non-precision instrument approach procedure charts. The sequence of waypoints shall consist of at least the following: selected initial approach fix (IAF), intermediate approach fix(es) (when applicable), final approach fix, missed approach point, and missed approach holding point. For procedures with multiple IAFs, the system shall present all IAFs and provide the capability for pilot selection of the desired IAF. Selection of the desired IAF shall automatically insert the remaining waypoints in the approach procedure in the proper sequence.

c. Waypoints utilized as a final approach fix or missed approach point in a non-precision approach procedure shall be uniquely identified as such to provide proper approach mode operation.

d. Modification of data associated with published instrument approach procedures by the user shall not be possible.

GPS RNAV 2D Accuracy Requirements

(95% Confidence)

(xvii) Sensitivity and Dynamic Range. Add the following requirements to paragraph 2.2.3.1 of RTCA/DO-208: Antenna elevation mask angles below 7.5 degrees may be utilized provided the applicant develops acceptable test conditions and supporting analysis to substantiate use of the desired mask angle.

(xviii) Dynamic Tracking. Add the following requirement to paragraph 2.2.3.4 of RTCA/DO-208: The equipment shall meet the applicable GPS position integrity performance requirements of Table 2-1 within the specified times stated in paragraphs a. and b.

(xix) (VNAV) Functional and Accuracy Requirements-Standard Conditions. Add the following requirement to paragraph 2.3 of RTCA/DO-208: If the vertical navigation (VNAV) option is provided by the equipment, the equipment must meet the requirements of paragraphs 2.3 and 2.5.3 of RTCA/DO-208.

(xx) Altitude Measurement Tests. In addition to RTCA/DO 208, the following requirements and tests apply to equipment which uses altitude-aiding. If alternative algorithms or test procedures are to be used, the manufacturer shall establish a set of tests acceptable to and approved by the cognizant Aircraft Certification Office and demonstrate equivalent performance with those tests.

1. " 2.5.2.5.3.8. Tests to Verify that Altitude Measurement is Properly Incorporated."

a. As stated in paragraph 2.5.2.5.1, all tests described in paragraph 2.5.2.5 apply to GPS equipment that employs a snapshot-type RAIM integrity algorithm that uses pseudorange measurements from GPS satellites either singly or in conjunction with an altitude input. The following on-line tests shall be performed to verify that the altitude measurement is properly incorporated. Tests should start early enough for the receiver to settle before each of the specified test periods begins.

b. All tests shall be conducted using the Optimal 21 constellation as described in Appendix I of RTCA/DO-208 for July 1, 1990. Test times are with respect to the GPS epoch time described in the same appendix. Note that the angle from the vernal equinox to the Greenwich meridian at GPS time 0:00 on July 1, 1990 is 278.8° , which must be taken into account when determining the position of satellites in an earth-centered, earth-fixed coordinate system.

ii. For these tests, the receiver is fixed at the geometric location and altitude specified and the SVs change their orbital positions. The "Failed SV" for each test must not provide any signals to the receiver for the duration of the test. If an initial error is not specified for a space vehicle (SV) pseudorange measurement, the error for the test for those SVs should be set to zero.

iii. Data should be recorded for each test during the specified "Period of Test" to determine the time at which the RAIM integrity limit alarm is activated. For a successful test, this alarm must not occur during the time from the start of the test to the time identified as the "Earliest Alarm Time", but must occur between the time identified as "Earliest Alarm Time" and the "Latest Alarm Time". As shown below, a

positive error rate in meters per minute is induced in either the identified SV pseudorange value or the barometric altimeter input beginning at the "Start Time of Ramp Error" and continuing throughout the test. The magnitude of the error rate is specified by the "Error Rate".

a. For these tests the SVs change their orbital positions and the identified "Failed SV" must not provide any signals to the receiver for the duration of the tests. If an initial error is not specified for a space vehicle(SV) pseudorange measurement, the error for the test for those SVs should be set to zero. Data should be recorded for each test during the specified "Period of Test" to determine the time at which the RAIM integrity limit alarm is activated. For a successful test, this alarm must not occur during the time from the start of the test to the time identified as the "Earliest Alarm Time", but must occur between the time identified as the "Earliest Alarm Time" and the "Latest Alarm Time". As shown below, a positive error rate in meters per minute is induced in either the identified SV pseudorange value or the pressure altitude input beginning at the "Start Time of Ramp Error" and continuing until the end of the test. The magnitude of the error rate is specified by the "Error Rate."

b. A positive SV error causes a pseudorange which is smaller than the actual distance from the receiver to the SV.

c. A positive altitude error causes a barometric altitude which is higher than the geometric altitude.

3. For Class A1, A2, B1, B2, C1, and C2 equipment conduct the following tests with pressure altitude used as an input for GPS navigation and RAIM. For these tests, the GPS receiver should be simulated in motion from the "Initial Location" at the beginning of the test and should then move along a great circle route with the specified "Ground Speed" toward the "Final Location". The receiver should be positioned at the appropriate geometric altitude with the specified pressure altitude input at the beginning of the test. These altitudes are either maintained or reduced as specified by the "Altitude Profile". The geometric altitude and the pressure altitude input should begin to be reduced at the "Time of Top of Descent" and should be reduced to the specified altitude at the "Time of Bottom of Descent". The initial conditions for these tests are as follows:

(xxi) Pressure Altitude Input Requirements. If the equipment incorporates altitude aiding, the following requirements apply. An alternate acceptable algorithm for incorporating barometric altitude is specified in appendix G of RTCA/DO-229, "MOPS for GPS/Wide Area Augmentation System Airborne Equipment", January 16, 1996.

2. An alternate methodology for incorporation of pressure altitude data may be utilized, provided it yields at least equivalent performance. Use of alternate methods will require the manufacturer to conduct a statistical demonstration of its validity acceptable to and approved by the FAA. The ACO will review the test procedures and results prior to issuing a TSOA.

3. Additionally, Class A1 equipment, when operating in approach mode, shall provide the capability for manual input of barometric pressure setting (unless the automatic altitude input utilizes barometric corrected altitude data). Concurrent with the approach enable alert, a suitable means to alert the pilot of the need to manually insert the barometric pressure setting shall be provided if the setting is input manually. If the automatic altitude input utilizes barometric corrected altitude data, a means shall be provided for the pilot to confirm the automatic entry.

4. Two different ways of augmenting the GPS solution equation with altitude aiding are used. One is to use pressure altitude data calibrated with GPS derived altitude data. The other method is to use pressure altitude data corrected for the local barometric pressure setting and the difference between the WGS-84 ellipsoid altitude and mean sea level altitude at the present position.

6. In a similar manner, the vector Z in equation 1 is modified by the addition of an n+1 element equal to B/(sbaro/ssv).

c. This function shall display, upon request, RAIM availability at the ETA and over an interval of at least +15 minutes computed in intervals of 5 minutes or less about the ETA.

6. The GPS equipment shall detect a pseudorange step error greater than 1000 meters, including steps which cause loss of lock for less than 10 seconds. A pseudorange step is defined to be a sudden change in the measured distance to a satellite. If a pseudorange step is detected for a satellite, that satellite shall be excluded from use in the

navigation algorithm until its integrity can be verified through fault detection (RAIM). The manufacturer is free to choose any method to calculate the predicted pseudorange or to detect a step. However, any method used should properly take into account satellite movement and aircraft dynamics up to a groundspeed of 750 knots and accelerations up to 14.7 meters/second/second.

(viii) 2D Accuracy Requirements (95 percent probability). In lieu of paragraph 2.2.2 of RTCA/DO-208, substitute the following requirement: The total of error contributions of the airborne equipment shall not exceed the error value listed in this paragraph. The reference spheroid shall use latitude/longitude values corresponding to the WGS-84 ellipsoid (see Appendix B of RTCA/DO-208). Since FTE factors are beyond the control of the equipment manufacturer or installer, these error sources are not included in this paragraph.

GPS RNAV 2D Accuracy Requirements

(95% Confidence)

(ix) Sensitivity and Dynamic Range. Add the following requirements to paragraph 2.2.3.1 of RTCA/DO-208: Antenna elevation mask angles below 7.5 degrees may be utilized provided the applicant develops acceptable test conditions and supporting analysis to substantiate use of the desired mask angle.

(x) Dynamic Tracking. Add the following requirement to paragraph 2.2.3.4 of RTCA/DO-208: The equipment shall meet the applicable GPS position integrity performance requirements of Table 2-1 within the specified times stated in paragraphs a. and b.

(xi) Pressure Altitude Input Requirements. If the equipment incorporates altitude aiding, the following requirements apply:

1. Pressure altitude data shall not be utilized in GPS sensors certified to class B3 and B4 for RAIM or position determination functions. This requirement does not preclude the use of altitude data for smoothing.

2. Equipment certified to class B1 and B2 shall utilize pressure altitude data in the same manner as described in paragraphs (a)(3)(xx) and (xxi) of this TSO.

(xii) Equipment Test Procedures. Add the following requirement to paragraph 2.5.2 of RTCA/DO-208: For equipment certified to class B3 and B4, paragraphs 2.5.2.5.1 through 2.5.2.5.3.7 do not apply.

(xiii) 2D Functional Performance. In lieu of paragraph 2.5.2.1 of RTCA/DO-208, substitute the following requirement: Each of the functional capabilities identified in subparagraph 2.2.1.11 shall be demonstrated. These capabilities shall be evaluated either by inspection or in conjunction with the tests described in paragraph 2.5.2.

(xiv) 2D Failure Indication. In lieu of paragraph 2.5.2.7 of RTCA/DO-208, substitute the following requirements:

1. Connect the equipment as shown in RTCA/DO-208, Figure 2-2. Remove the electrical power input to the equipment. There shall be a warning indication by the equipment.

2. The tests for the integrity of the navigation signals are specified in subparagraph 2.5.2.5 of RTCA/DO-208. For equipment certified to class B3 and B4, the requirements of this paragraph do not apply.

(5) Exceptions to RTCA/DO-208 for Class C( ) Equipment:

(i) The following paragraphs of RTCA/DO-208 do not apply to GPS sensors certified to class C( ) requirements: 2.1.8, 2.1.10, 2.1.11, 2.2.1.1 through 2.2.1.10, 2.2.1.12, 2.3, 2.5.2.1 through 2.5.2.4, 2.5.2.10, and 2.5.3. The following paragraphs of RTCA/DO-208 do not apply to GPS sensors certified to class C(3) and C(4) requirements: 2.5.2.5 and 2.5.2.7. The integrated navigation system with which the GPS sensor is installed shall provide the following. GPS sensors certified to Class C( ) must demonstrate that the GPS sensor, when incorporated into an integrated navigation system (flight management system, multi-sensor navigation system, etc.) meets all of the requirements of this TSO, including the requirements listed below. The GPS installation procedures shall specify for reference which integrated navigation system was used for this demonstration.

1. Maneuver anticipation capability equivalent to that required by paragraph (a)(3)(v) of this TSO for equipment certified to class C1/C3.

2. Waypoint distance display capability equivalent to that required by RTCA/DO-208 paragraph 2.2.1.2 for the appropriate equipment class (C1/C3 or C2/C4).

3. TO-FROM Indication capability equivalent to that required by RTCA/DO-208 paragraph 2.2.1.3 for the appropriate equipment class (C1/C3 or C2/C4).

4. Flight path selection capability equivalent to that required by RTCA/DO-208 paragraph 2.2.1.4 for the appropriate equipment class (C1/C3 or C3/C4).

5. Waypoint entry and storage capability equivalent to that required by paragraph (a)(3)(ix) and (a)(3)(x) of this TSO for the appropriate equipment class (C1/C3 or C2/C4).

6. Waypoint or leg sequencing capability equivalent to that required by paragraph (a)(3)(xi) of this TSO for the appropriate equipment class (C1/C3 or C2/C4).

7. Position display capability equivalent to that required by RTCA/DO-208 paragraph 2.2.1.8 for the appropriate equipment class (C1/C3 or C2/C4).

8. Failure/status indication capability equivalent to that required by paragraphs (a)(3)(xiii) 1., 2., and 3. of this TSO for the appropriate equipment class (C1/C3 or C2/C4).

9. Flight plan capability equivalent to that required by paragraph (a)(3)(xxii) of this TSO for the appropriate equipment class (C1/C3 or C2/C4).

10. Approach Mode Sequencing capability equivalent to that required by paragraph (a)(3)(xii) of this TSO for the appropriate equipment class (C1/C3), with the exception of paragraphs (a)(3)(xii)1c, (a)(3)(xii)1d, (a)(3)(xii)1e.ii, and (a)(3)(xii)2b, and (a)(3)(xii)3b.

(ii) Operation of Controls. Add the following requirement to paragraph 2.1.4. of RTCA/DO-208: Controls shall be designed to maximize operational suitability and minimize pilot workload. Reliance on pilot memory for operational procedures shall be minimized.

(iii) Accessibility of Controls. Add the following requirement to paragraph 2.1.5 of RTCA/DO-208: Controls that are normally adjusted in flight shall be readily accessible and properly labeled as to their function.

(iv) Sensor Interfaces. In lieu of paragraph 2.1.6 of RTCA/DO-208, substitute the following requirement: The interfaces with other aircraft equipment must be designed such that normal or abnormal RNAV equipment operation shall not adversely affect the operation of other equipment nor shall normal or abnormal operation of other equipment adversely affect the RNAV equipment operation.

(v) Update Rate. In lieu of paragraph 2.1.11 of RTCA/DO-208, substitute the following requirement: Data output shall be updated at an interval of 1.0 second or less.

(vi) Integrity Alarm for GPS Receivers. Add the following requirements to paragraph 2.2.1.13 of RTCA/DO-208:

1. The requirements of this paragraph do not apply to equipment certified to class C3 and C4.

2. Delete the second sentence of the opening paragraph 2.2.1.13.2 and replace with: "A separate and distinctive indication shall be raised in each of the following two circumstances."

3. Add the following requirement to paragraph 2.2.1.13.2 of RTCA/DO-208: In order to minimize nuisance integrity alarms when system navigation accuracy is otherwise not in doubt, properly substantiated compensating features (such as clock coasting, pressure altitude, inertial data, other sensors etc.) may be incorporated into the system. The alarm under these conditions may be delayed for a period of time consistent with the worst cases of undetected clock drift or other failures that would cause the position error to exceed the accuracy required for that phase of flight. The applicant must develop appropriate test procedures to demonstrate the proposed compensating features provide the required level of navigation accuracy and integrity.

(vii) RAIM Implementation. Any algorithm which verifies the integrity of the position output using GPS measurements and barometric aiding is considered a RAIM algorithm. An algorithm which uses additional information (e.g., multi-sensor system) to verify the integrity of the position output may be acceptable as a RAIM-equivalent. Note that if RAIM is not incorporated in the GPS sensor, the sensor is only eligible for Class B3, B4, C3, and C4 certification. For sensors that provide RAIM, add the following requirements to paragraph 2.2.1.13.3 of RTCA/DO-208:

1. The requirements of this paragraph do not apply to equipment certified to class C3 and C4.

2. The RAIM function shall provide a worldwide availability of at least 95% given the optimal 21 GPS constellation (evaluated at a maximum resolution of 3 degrees in latitude, 180 nm in longitude, every 5 minutes). Barometric altitude aiding may be necessary to achieve this availability. RAIM-equivalent functions must also demonstrate an availability of at least 95%. If the equipment incorporates altitude aiding, appropriate requirements can be found in paragraph (a)(5)(xi) of this TSO.

3. The integrated navigation system with which the GPS sensor is interfaced must provide the RAIM function with terminal integrity performance as specified in Table 2-1 of RTCA/DO-208 within 30 nm of the departure and destination points. In addition, approach mode (class C1 equipment) integrity performance shall be provided from 2 nm prior to the final approach fix to the missed approach point. En route integrity performance shall be provided during other conditions.

4. The equipment shall automatically select the RAIM integrity performance requirements applicable to the phase of flight.

5. Equipment certified to class C1 shall provide a RAIM prediction function:

a. This function must automatically predict the availability of RAIM at the final approach fix and missed approach point of an active approach when 2 nm inbound to the final approach fix.

c. This function shall display, upon request, RAIM availability at the ETA and over an interval of at least +15 minutes computed in intervals of 5 minutes or less about the ETA.

6. The GPS equipment shall detect a pseudorange step error greater than 1000 meters, including steps which cause loss of lock for less than 10 seconds. A pseudorange step is defined to be a sudden change in the measured distance to a satellite. If a pseudorange step is detected for a satellite, that satellite shall be excluded from use in the navigation algorithm until its integrity can be verified through fault detection (RAIM). The manufacturer is free to choose any method to calculate the predicted pseudorange or to detect a step. However, any method used should properly take into account satellite movement and aircraft dynamics up to a groundspeed of 750 knots and accelerations up to 14.7 meters/second/second.

(viii) 2D Accuracy Requirements (95 percent probability). In lieu of paragraph 2.2.2 of RTCA/DO-208, substitute the following requirement: The total of error contributions of the airborne equipment shall not exceed the error value listed in this paragraph. The reference spheroid shall use latitude/longitude values corresponding to the WGS-84 ellipsoid (see Appendix B of RTCA/DO-208). Since FTE factors are beyond the control of the equipment manufacturer or installer, these error sources are not included in this paragraph.

GPS RNAV 2D Accuracy Requirements

(95% Confidence)

(ix) Sensitivity and Dynamic Range. Add the following requirements to paragraph 2.2.3.1 of RTCA/DO-208: Antenna elevation mask angles below 7.5 degrees may be utilized provided the applicant develops acceptable test conditions and supporting analysis to substantiate use of the desired mask angle.

(x) Dynamic Tracking. Add the following requirement to paragraph 2.2.3.4 of RTCA/DO-208: The equipment shall meet the applicable GPS position integrity performance requirements of Table 2-1 within the specified times stated in paragraphs a. and b.

(xi) Pressure Altitude Input Requirements. If the equipment incorporates altitude aiding, the following requirements apply:

1. Pressure altitude data shall not be utilized in GPS sensor certified to class C3 and C4 for RAIM or position determination functions. This requirement does not preclude the use of altitude data for smoothing.

2. Equipment certified to class C1 and C2 shall utilize pressure altitude data in the same manner as described in paragraphs (a)(3)(xx) and (xxi) of this TSO.

(xii) Equipment Test Procedures. Add the following requirement to paragraph 2.5.2 of RTCA/DO-208: For equipment certified to class C3 and C4, paragraphs 2.5.2.5.1 through 2.5.2.5.3.7 do not apply.

(xiii) 2D Functional Performance. In lieu of paragraph 2.5.2.1 of RTCA/DO-208, substitute the following requirement: Each of the functional capabilities identified in subparagraph 2.2.1.11 shall be demonstrated. These capabilities shall be evaluated either by inspection or in conjunction with the tests described in paragraph 2.5.2.

(xiv) 2D Failure Indication. In lieu of paragraph 2.5.2.7 of RTCA/DO-208, substitute the following requirements:

1. Connect the equipment as shown in RTCA/DO-208, Figure 2-2. Remove the electrical power input to the equipment. There shall be a warning indication by the equipment.

2. The tests for the integrity of the navigation signals are specified in subparagraph 2.5.2.5 of RTCA/DO-208. For equipment certified to class C3 and C4, the requirements of this paragraph do not apply.

(6) Satellite Selection. The requirements in paragraph 2.5.2.11 of RTCA/DO-208 apply to satellite selection (for acquisition) as well as during operation (after acquisition). All parameters used for satellite selection shall be re-evaluated at least once every five minutes for each satellite used for positioning. In addition, the following paragraphs clarify minimum parameters to be used during the selection process in paragraph 2.5.2.11 of RTCA/DO-208. The equipment must reject a satellite if:

(i) The health word indicates that the satellite is unhealthy.

(ii) The parity check fails repeatedly, i.e., on more than 5 consecutive words.

(iii) The navigation data contains all 1’s, or all 0s.

(iv) The alert flag (bit 18 of the Handover Word is set to ‘1’.

(v) The URA field described in paragraph 2.5.3 of the GPS SPS Signal Specification indicates the absence of an accuracy prediction (value N=15). Note that paragraph 2.5.2.11 of RTCA/DO-208 contains guidance on the use of the URA field and explains that the satellite must also be rejected if the URA > 64 unless additional integrity monitoring validation is performed.

(9) Emission of Radio Frequency Energy Test. Delete the words "(When Required)" from paragraph 2.4.18 of RTCA/DO-208. This test is required.

(b) Marking. In addition to the marking specified in 14 CFR Part 21.607(d), the following information shall be legibly and permanently marked on the major equipment components:

(1) Each separate component of equipment that is manufactured under this TSO must be permanently and legibly marked with at least the name of the manufacturer and the TSO number.

(2) With regard to 14 CFR Part 21.607(d)(2), the part number is to include hardware and software identification, or a separate part number may be utilized for hardware and software. Either approach must include a means for showing the modification status.

(3) The software level or levels in accordance with RTCA/DO-178B.

(4) The equipment class.

(c) Data Requirements.

(1) In addition to meeting the requirements of 14 CFR Part 21.605, the manufacturer must furnish the Manager, Aircraft Certification Office (ACO), Federal Aviation Administration, having purview of the manufacturer's facilities, one copy each of the following technical data:

(i) Operating instruction.

(ii) Equipment limitations.

(iii) Installation procedures and limitations (including any necessary sensor interface restrictions for Class B( ) and Class C( ) equipment).

(iv) Schematic drawings as applicable to the installation procedures.

(v) Wiring diagrams as applicable to the installation procedures.

(vi) Specifications.

(vii) List of the major components (by part number) that make up the equipment system complying with the standards prescribed in this TSO.

(viii) An environmental qualifications form as described in RTCA Document DO-160C for each component of the system.

(ix) Manufacturer's TSO qualification test report.

(x) Nameplate drawing.

(2) In addition to those data requirements that are to be furnished directly to the FAA, each manufacturer must have available for review by the manager of the ACO having purview of the manufacturer's facilities, the following technical data:

(i) A drawing list, enumerating all of the drawings and processes that are necessary to define the article's design.

(ii) The functional test specification to be used to test each production article to ensure compliance with this TSO.

(iii) Equipment calibration procedures.

(iv) Corrective maintenance procedures (within 12 months after TSO authorization).

(v) Schematic drawings.

(vi) Wiring diagrams.

(viii) The results of the environmental qualification tests conducted in accordance with RTCA Document DO-160C.

(d) Data to be Furnished with Manufactured Units. One copy of the data and information specified in paragraphs (c)(1)(i) through (viii) of this TSO, and instructions for periodic maintenance and calibration which are necessary for continued airworthiness must go to each person receiving for use one or more articles manufactured under this TSO. In addition, a note with the following statement must be included:

(e) Availability of Reference Documents.

(1) Copies of RTCA Document Nos. DO-160C, DO-178B, DO-200, DO-201, DO-208 and DO-229 may be purchased from the RTCA Inc., 1140 Connecticut Avenue, N.W., Suite 1020, Washington, D.C. 20036.

(2) Federal Aviation Regulations Part 21, Subpart O, may be purchased form the Superintendent of Documents, Government Printing Office, Washington, DC 20402-9325. Advisory Circular 20-110 (current revision), "Index of Aviation Technical Standard Orders," may be obtained from the U.S. Department of Transportation, Utilization and Storage Section, M-443.2, Washington, DC 20590.

John K. McGrath

Manager, Aircraft Engineering Division

Aircraft Certification Service