4 Chapter 2. ADS-B In System Installation Guidance.
2-1. System Overview. ADS-B In refers to an appropriately equipped aircraft’s ability to receive and display other aircraft’s ADS-B information and ground station broadcast information, such as TIS-B and ADS-R. The information can be received by an appropriately equipped aircraft on either of two radio frequency (RF) links: 1090 ES or 978 MHz UAT. The received information is processed by onboard avionics and presented to the flight crew on a display. In this AC, guidance is provided for the display of traffic information while on the airport surface and while airborne. This information supports the applications defined in TSO-C195a. This AC will be updated to add appropriate guidance for additional applications as they mature.
2-2. Equipment Classes. TSO-C195a defines minimum performance standards that provide a basis for installation of ADS-B In equipment in aircraft. The TSO defines three avionics equipment classes: (A) cockpit display of traffic information (CDTI) (surface only); (B) CDTI;
and (C) airborne surveillance and separation assurance processing (ASSAP). Class A equipment is intended to support the display of ADS-B traffic while own-ship is on the surface and moving slower than 80 knots. Class A equipment must deactivate the CDTI when airborne or at speeds greater than 80 knots. Class B equipment supports the display of ADS-B traffic when airborne as well as on the ground. Class C equipment processes ADS-B messages to generate traffic data for a CDTI. Table 1 shows which applications are supported by the three equipment classes. An installation requires both the CDTI and ASSAP functions, which are explained in paragraphs 2-4 and 2-5 of this AC, respectively.
Table 1. ADS-B In Equipment Classes
Criticality Equipment Classes Application Loss of Function Hazardous Misleading Information CDTI (Surface Only) (A) CDTI (B) ASSAP (C) 1 Enhanced Visual Acquisition (EVAcq) Minor Major Not Permitted B1 C1 2 Basic Surface (Runways) Minor Major (> 80 Knots) Minor (< 80 Knots) A2 B2 C2 3 Basic Surface (Runways + Taxiways) Minor Major (> 80 Knots) Minor (< 80 Knots) A3 B3 C3 4 Visual Separation on Approach (VSA) Minor Major Not Permitted B4 C4 5 Basic Airborne (AIRB) Minor Major Not Permitted B5 C5 6 In-Trail Procedures (ITP) Minor Major Not Permitted B6 C6
2-3. ADS-B Applications.
a. ADS-B In avionics enable one or more of the following aircraft surveillance applications: enhanced visual acquisition (EVAcq); basic airborne (AIRB); visual separation on approach (VSA), basic surface (SURF) (runways and taxiways, or runways only); and In-Trail Procedures (ITP). Refer to table 1 to see which applications are supported by the three equipment classes.
b. The basic airborne application (AIRB) displays ADS-B traffic on a plan view (bird's eye view) relative to own-ship. This application is the minimum requirement for installations that implement other applications such as VSA or ITP. Each aircraft symbol displayed conveys position, direction, and altitude information. Optionally, additional information, like identity, may be displayed. The traffic information assists the flight crew in visually acquiring traffic while airborne. This application improves both safety and efficiency by providing the flight crew with enhanced traffic awareness. Installations that provide in flight moving map displays in addition to traffic should comply with TSO-C165, Electronic Map Display Equipment for Graphical Depiction of Aircraft Position.
c. The enhanced visual acquisition application (EVAcq), also displays ADS-B traffic on a plan view (bird's eye view) relative to own-ship. This application is designed to support only the display of ADS-B traffic, including ADS-R, TIS-B, and TCAS derived traffic.
Implementations that include other application classes must use the AIRB application instead.
The traffic information assists the flight crew in visually acquiring traffic while airborne.
EVAcq does not relieve the pilot of see and avoid responsibilities found in 14 CFR 91.113b.
This application is expected to improve both safety and efficiency by providing the flight crew enhanced traffic awareness. Installations that provide in-flight moving map displays in addition to traffic should comply with TSO-C165, Electronic Map Display Equipment for Graphical Depiction of Aircraft Position.
d. The visual separation on approach (VSA) application builds upon the basic airborne application (AIRB). It allows the pilot to select an aircraft to follow on approach. Additional information about the selected aircraft, including range and ground speed, is displayed to enhance the pilot’s situational awareness. The CDTI display is used to assist the flight crew in acquiring and maintaining visual contact during a visual approach. The application improves both the safety and the performance of visual approach operations. The VSA application should not be confused with creating a new approach operation. No operational responsibility is changed when using the VSA application.
e. The basic surface application (SURF) with runways and taxiways displays ADS-B traffic on a plan view (bird's eye view) relative to own-ship, superimposed on a map of the airport surface. This map consists of all runways at supported airports and includes taxiways when that data is available. Aircraft on-ground and in-air as well as properly equipped surface vehicles are differentiated by symbols to aid the pilot in visual acquisition. The surface application improves flight crew situational awareness during taxi, takeoff, and landing phases of flight.
This application reduces the possibility of runway incursion and collision. These installations should also comply with TSO-C165 Electronic Map Display Equipment for Graphical Depiction of Aircraft Position for airport moving map displays. The SURF application with
6 runways only does not display taxiways.
f. The In-Trail Procedure (ITP) application enables aircraft that desire flight level changes in procedural airspace to achieve these changes on a more frequent basis, thus improving flight efficiency and safety. The ITP achieves this objective by permitting a climb-through or descend-through maneuver between properly equipped aircraft, using a new distance-based longitudinal separation minimum during the maneuver. The ITP requires the flight crew to use information derived on the aircraft to determine if the initiation criteria (see Table 2, Section 3-3) required for an ITP are met. The initiation criteria are designed such that the spacing between the estimated positions of ownship and surrounding aircraft exceed the separation minima with acceptable probability throughout the maneuver. ITP requires specific application-unique processing and display parameters. In addition, ITP will require an operations approval by the FAA flight standards organization. Guidance for this operations approval will be contained in a future update to AC 90-114, Automatic Dependent Surveillance- Broadcast (ADS-B) Operations.
g. The displayed ADS-B information addressed by this AC is not intended for maneuvering based solely on presence or absence of traffic on the display. As future applications are fielded, we expect that certain maneuvers may be found to be safe and acceptable. The analysis and safety studies to justify such procedures are not yet completed.
When those activities are concluded and the maneuvers are shown to be safe and acceptable in the national airspace system (NAS), appropriate maneuvers are expected to be allowed based in part on the displayed ADS-B In information. We will revise this guidance accordingly at that time. Operational guidance will be published by FAA flight standards organization.
2-4. CDTI.
a. Displays. The ADS-B In system includes at least one flight deck traffic display (i.e., CDTI) depicting the relative position and related information of ADS-B equipped aircraft in a plan view (bird's eye view). The CDTI display may be presented on a dedicated display or integrated into and presented on an existing display (e.g., electronic flight information system (EFIS), multi-function display (MFD)). CDTI equipment should be compliant with the Class A or Class B requirements of TSO-C195a. Class A equipment supports only the Basic Surface application. CDTI equipment should be installed in accordance with manufacturer instructions.
Installation in the forward field of view (14 CFR 23.1321, 25.1321, 27.l321, and 29.1321) will provide the best situational awareness and support subsequent upgrades to other ADS-B applications. Side-mounted displays are acceptable for the basic situational awareness applications and ITP, but have limited potential to support more advanced applications. The display must be installed such that the crew has an unobstructed view of the display when seated in the normal position. For general installation guidance on displays, refer to AC 25-11A and AC 23.1311-1B.
b. ITP Installations. ITP installations must include a CDTI mounted in the forward field of view or as a side mounted display. The traffic display (plan view) must be visible during the ITP vertical maneuver. It is recommended but not required that a graphical vertical/profile view of the traffic be available for flight crews to aid in assessing initiation criteria. This is particularly helpful in situations where there is a significant angle between the track of the own aircraft and the ITP Traffic aircraft (the angle can be any value less than 45
7 degrees and still be a valid ITP situation). In these cases, relative geometry (ahead of and behind) may not be intuitive.
c. Traffic Symbols. The FAA worked closely with the industry to standardize the ADS-B In symbols and features. The resulting symbols are provided in appendix 2. The traffic display should depict the symbols, features, and information defined in the appendix. However, manufacturers may propose alternate symbols in order to integrate ADS-B with existing flight deck symbology. These alternate symbols will need to be justified by human factors analysis as part of the certification process. Alternate symbol sets are not allowed without additional justification. There is one exception to this guidance. It is acceptable to pair a TSO-C195a Class C ASSAP unit with an existing certified traffic display using legacy symbols (e.g. TCAS, TAS) when either the AIRB or EVAcq application are installed. Minor TSO changes or enhancements, may be made to the previously approved traffic display without requiring the equipment to be made fully compliant to TSO-C195a requirements. This exception only applies to previously approved traffic displays. If any other applications beyond EVAcq or AIRB are installed, the display must be fully compliant with TSO-C195a.
(1) Traffic Symbol and Own Ship Symbol Reference Point. The pilot’s guide for the ADS-B equipment must specify the location of the horizontal position reference point on the traffic symbols and the own ship symbol. For example, this position may be the center of the symbol or the tip of the traffic directional arrow. The own ship horizontal position reference point should be consistent with the existing flight deck philosophy. The traffic and own ship symbols are an abstract representation and are not required to reflect the physical extent of the aircraft. This becomes more evident when implementing the surface application with the underlying airport map.
d. Required Controls. The CDTI control panel may be a dedicated control panel or it may be incorporated into another control, such as a multifunction control display unit (MCDU) or Flight Management Computer (FMC) control display unit (CDU). CDTI controls must be readily accessible from the normal seated position. Pilot controls for the ADS-B In equipment must be provided as follows:
(1) A means to adjust the display range between the minimum and maximum values.
(2) A means to adjust the altitude band between the minimum and maximum values.
(3) A means to adjust the brightness of the display.
e. Optional Controls. The following optional controls may be provided:
(1) A means to select between display of relative and actual altitude.
(2) A means to select at least one traffic element.
(3) A means to select alternate display criteria (e.g., filters and vertical views).
(4) A means to declutter, which removes optional traffic information when display of the information is not desired. If decluttering is implemented,
(a) A means must be provided for the flight crew to control the decluttering.
(b) The flight crew must be able to perform the declutter operation by a simple action.
(c) The flight crew should be able to return to the previous state by a simple action.
(d) If automatic decluttering is implemented, a means should be provided for the flight crew to control the automated decluttering function.
(e) An indication that decluttering is active must be provided.
(5) A means to pan the view. If panning is implemented:
(a) There must be a means to control panning.
(b) There must be a means to return to the original view with a simple action.
(6) A means to designate traffic for an application. For example, equipment may allow a selected aircraft to be designated for the visual separation on approach application.
2-5. Airborne Surveillance and Separation Assurance Processing (ASSAP). The ASSAP subsystem accepts ADS-B reports, TIS-B reports, ADS-R reports, and traffic alert and collision avoidance system (TCAS) tracks (if installed). ASSAP correlates sources, generates tracks, and performs application-specific processing. Surveillance tracks and application-specific alerts or guidance are output by ASSAP to the CDTI function. The ASSAP equipment must be compliant with the Class C requirements of TSO-C195a and should be installed in accordance with manufacturer instructions. TCAS processors track transponder-equipped aircraft.
Therefore, TSO-C195a equipment requires installations with TCAS to provide these tracks to the ASSAP equipment to complete the traffic picture. TCAS in this AC is meant to apply to all versions of certified traffic advisory system (TAS) or TCAS compliant with TSO-C147, TSO-C118, or TSO-C119c. Hybrid surveillance TCAS are included. For aircraft installations without TCAS, the TIS-B service provides tracks of transponder-equipped aircraft.
2-6. ADS-B In Receiver and Antenna. The installation must include a UAT (per TSO-C154c) or a 1090 ES (per TSO-C166b) receiver. Ideally, installation of a dual-band receiver would allow for dual-link interoperability where ADS-R coverage is not provided. The ASSAP equipment may interface with the ADS-B receiver equipment or it may be integrated.
If TCAS is installed, the ADS-B In equipment must contain or interface with the TCAS equipment so that the TCAS tracks may be used. Guidance material concerning the installation of the UAT or 1090ES equipment, and associated antenna(s), is provided in AC 20-165.
2-7. Integration Considerations.
a. System Definition. ADS-B In installations include the ADS-B In receiver, antennas, traffic processor, control panels, and display components. All of these component part numbers must be identified as part of the integrated system. Any change to any of the components’ hardware or software requires evaluation of the potential impact to the ADS-B In function.
b. Equipment Compatibility Requirements. A critical component of the ADS-B In system is the positioning sensor. Compatibility between the sensor and the surveillance processor must be established by the equipment manufacturer(s) and detailed in an installation manual or supplement. Position source compatibility should consider the position source requirements in AC 20-165. Compatibility between all other system components should be documented in an installation manual or supplement.
c. Aircraft Integration with ADS-B In System.
(1) Provide electrical power and grounding in accordance with the manufacturer’s installation manual. Conduct an electrical load analysis to verify that there is adequate power capacity for the ADS-B In equipment.
(2) Ensure that the total latency to receive, process, and display traffic data is less than 3.5 seconds. Ensure that traffic time of applicability is within 1 second of the time of display. Ensure the total latency of own-ship position at the display is less than 3.5 seconds.
Ensure that the own-ship time of applicability is within 1 second of the time of display.
Perform a latency analysis in accordance with appendix 1 to demonstrate compliance. The total latency figures here are to be interpreted to mean when an ADS-B message is received. They do not address data age issues while the system is waiting to receive the next position report for an existing track. Data age and timeout requirements are handled separately for each application in TSO-C195a compliant equipment.
(3) The same position source used to provide own ship data for transmission on ADS-B Out should be used to provide position to the ASSAP equipment. Position sources interfaced to the ASSAP equipment must meet the quality metric requirements in DO-317A, section 2.2.4. Further guidance on integration with ADS-B position sources can be found in AC 20-165. Future applications may require that ASSAP and the ADS-B Out equipment use the same position source. Aircraft manufacturers should plan accordingly to prevent extensive redesign. An alternate position source may be used to provide own ship position to the CDTI display, but the accuracy, latency, and display time of applicability requirements still apply (refer to appendix 1). Provide connections in accordance with the manufacturer’s installation manual.
(4) Follow manufacturer’s instructions for strapping and/or programming of configurable aircraft parameters. Manufacturers are highly encouraged to provide instructions to installers for setting the global navigation satellite system (GNSS) antenna offset parameter during installation. The GNSS antenna offset information can be extremely valuable for ADS-B In surface situation awareness and future surface collision alerting applications on large aircraft with GNSS antenna far from the nose.
(5) Verify that the equipments’ environmental qualifications (e.g., RTCA/DO- 160() environmental categories) are suitable for the aircraft type and equipment location.
(6) Any limitations associated with use of the ADS-B In equipment must be recorded in the Aircraft Flight Manual.
(7) ITP requests and clearances can only be granted using Direct Controller Pilot Communication (DCPC). Although it may be possible to perform ITP requests and clearances via voice communications, in most non-radar regions this means requests and clearances must be accomplished using Controller Pilot Datalink Communications (CPDLC). ITP requests can be lengthy and prone to typographical errors. It is recommended that ITP designs integrate the CDTI and data link systems in order to populate ITP requests automatically. An alternative is to provide the request text on the CDTI so that the flight crew can reference the text while entering the information manually. This reduces the possibility of human error while entering the ITP request. Examples of standardized free text CPDLC message formats for an ITP request (downlink message) can be found in Change 1 to RTCA/DO-306.
d. System Safety Analysis. Unannunciated failures and hazardously misleading data must be improbable/remote for Class B and C equipment; but can be probable for Class A equipment. Loss of function can be probable for all Classes. This can be shown using the methods described in AC 25.1309-1(), System Design and Analysis, AC 23-1309-1(), System Safety Analysis and Assessment for Part 23 Airplanes, AC 27-1B, Certification of Transport Category Rotorcraft, Change 3, or in AC 29-2C, Certification of Normal Category Rotorcraft, Change 3 as appropriate.
11 Chapter 3. Test and Evaluation.
3-1. General. Installation of an ADS-B In system should be accomplished on an aircraft with an ADS-B Out system. ADS-R and TIS-B services are only provided to aircraft that indicate, in their ADS-B Out messages, that they are an ADS-B In aircraft. This chapter assumes that the ADS-B Out system complies with AC 20-165, and defines additional tests for the installed system.
3-2. Ground Tests.
a. Ground tests should be conducted on each aircraft installation. Ground tests should include the verification that ADS-B Out, ADS-R, and TIS-B message elements can be accurately received and processed. If ADS-B In equipment is integrated with TCAS, then TIS-B reception is not required for airborne traffic. However if the surface applications are implemented, TIS-B surface targets must be processed even by an installation that includes TCAS. Ground tests should include verification of the integration with a position sensor, since own-ship state data is used to generate the displayed data. In addition, any message elements that are presented on the CDTI display should be verified for accuracy. See AC 20-165 for a list and detailed explanation of each of the message elements. Ground test equipment should be capable of generating all of the different types of messages, including ADS-B Out, ADS-R, and TIS-B messages. If targets of opportunity are available to validate the ADS-B In functionality, they may be used in lieu of dedicated test equipment. Verify that the system receives and displays the following traffic information when stimulated appropriately:
(1) Relative horizontal position.
(2) Ground speed of surface traffic (if implemented).
(3) Directionality (Heading or Track Angle).
(4) Pressure altitude of airborne traffic relative to own-ship.
(5) Vertical trend of airborne traffic.
Note: ASSAP must indicate a climb/descent when traffic vertical velocity exceeds 500 feet per minute (fpm). Indication of vertical trend is allowed to occur at smaller vertical rates.
(6) Air/Ground status of traffic.
(7) Flight ID (if implemented).
(8) TIS-B/ADS-R service status (when not installed with TCAS).
(9) Differential ground speed (if implemented).
b. TCAS-equipped aircraft provide inputs to ASSAP. Verify that the system receives and displays the following information when stimulated appropriately:
(1) Traffic range.
(2) Traffic bearing.
(3) Traffic pressure altitude.
(4) Traffic vertical trend.
(5) Traffic TCAS alert status (i.e., no threat, proximity traffic, traffic advisory, or resolution advisory).
c. If the ADS-B In system supports the surface application, verify that the airport runways are depicted accurately. If taxiway data is available, verify that the airport taxiways are depicted accurately.
d. Evaluate simulated failures of the aircraft sensors integrated with the ADS-B In equipment to determine that the resulting system failure state agrees with the predicted results.
All system failures should be indicated clearly. The effects of system failures should be described in a manual.
e. Observe all of the electronic systems on the flight deck to determine that the ADS-B equipment is not a source of interference (conducted or radiated) to previously installed systems or equipment, and that operation of the ADS-B In equipment is not adversely affected by the previously installed systems and equipment.
f. Evaluate the general arrangement and operation of controls, displays, circuit breakers, indicators, and placards of the ADS-B In and CDTI equipment.
(1) Evaluate the ADS-B In system controls to determine that they are appropriately designed and located to prevent inadvertent actuation. Pay close attention to line select keys, touch screens, or cursor-controlled trackballs, as these can be susceptible to unintended mode selection resulting from their location in the flight deck (for example, proximity to a foot rest or adjacent to a temporary stowage area).
(2) Evaluate the CDTI display to ensure that all information is, at a minimum, legible, unambiguous, and attention-getting (as applicable).
(3) Evaluate the traffic symbols presented on the CDTI display for compliance with the standard recommended symbols from RTCA/DO-317A, which are summarized in appendix 2 of this AC.
g. Evaluate the ADS-B In self-test features.
h. If possible, verify the dynamic performance of displayed traffic by observing any available ADS-B Out, ADS-R, TCAS (if installed), or TIS-B traffic in the area.
i. Evaluate the overall CDTI system installation for satisfactory accessibility and visibility under all lighting conditions.
3-3. Flight Tests.
a. Flight tests must be conducted for each initial installation of a unique configuration of ADS-B In receiver, position sensor, ASSAP, and CDTI equipment. Flight test data from a different aircraft may be used to establish suitability in follow-on installations. Flight testing must be conducted in the range of a cooperative ADS-B Out-equipped aircraft. Flight testing should be conducted within TIS-B and ADS-R coverage. The flight test should verify the following:
(1) The other aircraft flight identification (if implemented).
(2) The ability to select a desired target aircraft (if implemented).
(3) The ability to display ground speed of the selected target aircraft (if implemented).
(4) The bearing from own-ship to the other aircraft.
(5) The distance from own-ship to the other aircraft.
(6) The relative altitude of the other aircraft.
(7) The direction of travel (ground track) of the other aircraft.
(8) The ground speed of the other aircraft (if implemented).
(9) The targets are appropriately displayed during maneuvers throughout the normal flight envelope.
(a) Movement of displayed target information should not result in objectionable jitter, jerkiness, or ratcheting effects.
(b) Movement of displayed target information should not blur, shimmer, or produce unintended dynamic effects such that the information becomes distracting or difficult to interpret.
(c) Filtering or coasting of data intended to smooth the movement of CDTI displayed target information should not introduce significant positioning errors or create system lag that makes it difficult to perform the intended task.
(d) False or redundant tracks should not occur regularly during the flight. This would indicate that the track correlation is not performing properly. This could indicate that the
14 TCAS antenna bearing is performing poorly, as an example.
b. If implemented, verify that the information provided on the CDTI display is suitable for the surface application. Depending upon which surface class has been installed, either runways only will be depicted or both runways and taxiways will be depicted.
c. If ITP is installed, evaluate the ITP functionality. The intent of ITP Flight Testing is to validate that the equipment functions properly when installed on the aircraft. It is not the intent of the ITP flight test to exhaustively test ITP geometries. Individual ITP scenarios to test each ITP geometry may be performed in a conformed ground simulator environment. The scenarios below were chosen to be representative of key operational ranges at which the equipment operates differently. The TCAS validation functionality in particular is difficult to test adequately on ground or in a laboratory environment. This is due to the challenge of creating an RF simulation that accurately reflects the in flight environment and aircraft installation effects. A flight test of ITP should successfully demonstrate the three scenarios below. For each of the scenarios, perform the steps in this paragraph. Verify that the reference traffic is being displayed as a valid reference aircraft for the ITP application. Verify that the reference aircraft is shown on the ADS-B traffic display and any dedicated ITP display. This indicates that the ADS-B surveillance portion of ITP is functioning successfully. Verify that the ITP distance computed agrees with the planned value for the flight profile. The computed value may vary from the planned value due to variations from planned aircraft speeds, range, and position. Differences should be documented and investigated after the flight for correctness. Enter CPDLC commands for an ITP request using either automatically generated messages or manually through free-text input by the pilot. If automatically generated, verify that the CPDLC text accurately represents the ITP reference aircraft information. If the local air traffic facility is equipped and able to receive the CPDLC message successfully, then exercise the CPDLC link and request an acknowledgement from ATC. If the local air traffic facility is not equipped, then the CPDLC link does not need to be exercised. CPDLC installation guidance is covered in AC 20-140() Guidelines for Design Approval of Aircraft Data Link Communication Systems Supporting Air Traffic Services (ATS). During any or all of the scenarios, alter the position, altitude, or ground speed of the aircraft in order to violate the ITP initiation criteria (refer to Table 2 below). Verify that the ITP equipment indicates that an ITP maneuver is not possible. If implemented, verify that the proper reason is indicated for the ITP maneuver not being available.
(1) Scenario 1 ITP Reference aircraft < 30nm: Perform a flight test with two aircraft, one being the Ownship aircraft and the other being the Reference aircraft. Position the aircraft so they are in-trail between 20 and 30 nautical miles and within 15 knots of ground speed. If TCAS validation is implemented, the ITP equipment will use TCAS measurements (range, bearing, and altitude) to validate ADS-B position for version 0 and version 1 targets.
(2) Scenario 2 ITP Reference aircraft > 30nm: Position the aircraft so they are in-trail greater than 30 nautical miles, but within the capability of the manufacturer’s TCAS to get occasional replies, and within 15 knots of ground speed. If TCAS validation is implemented, the ITP equipment will use TCAS measurements of opportunity (range, bearing, and altitude) to validate ADS-B position for version 0 and version 1 targets when able. At this range, TCAS may not be able to sustain a track due to spotty transponder replies. It is the
15 responsibility of the TCAS manufacturer to provide the approximate maximum range at which TCAS measurements are still available.
(3) Scenario 3 ITP Reference aircraft outside of TCAS range: Position the aircraft so they are on similar tracks (within 45 degrees), outside of the manufacturer provided TCAS measurement range, and within 15 knots of ground speed. In this geometry, TCAS validation will be unavailable.
Table 2. ITP Maneuver Criteria
ITP Speed/Distance Criteria ITP Distance >= 15 NM and Closing Ground Speed Differential <= 20 knots or ITP Distance >= 20 NM and Closing Ground Speed Differential <= 30 knots Relative Altitude Criteria Difference in altitude between the ITP and Reference Aircraft is less than or equal to 2000 feet Similar Track Criteria Difference in track angles between ITP and Reference Aircraft less than +/- 45 degrees Position Accuracy for ITP and Reference Aircraft ITP and Reference Aircraft data with horizontal position accuracies of at least 0.5 NM (95%) Position Integrity for ITP and Reference Aircraft ITP and Reference Aircraft data with horizontal position integrity bounds of 1.0 NM @ 1x10E-05 Velocity Accuracy for ITP and Reference Aircraft ITP and Reference Aircraft data with horizontal velocity accuracies of at least 10 m/s (19.4 knots) 95% Closing Mach Differential (ATC Crosscheck) Closing Mach Differential equal or less than 0.06 Mach