CASCADE OPERATIONAL FOCUS GROUP (OFG)

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1 CASCADE OPERATIONAL FOCUS GROUP (OFG) Use of ADS-B for Enhanced Traffic Situational Awareness by Flight Crew During Flight Operations Airborne Surveillance (ATSA-AIRB) 1. INTRODUCTION TO ATSA-AIRB In today s flight operations, flight crews should, to the greatest extent possible, maintain a general awareness of the environment in which they are operating. In particular, flight crews must attempt to maintain surrounding traffic situational awareness. Currently, flight crews build traffic situational awareness by integrating available information from two main sources; out the window observation, and listening to radio communications. Depending on the airspace, relevant radio communications can include traffic information provided to the flight crew (ownship) by a controller, transmissions from a controller to other aircraft, and responses from the other aircraft (the party-line effect ), and air-to-air radio communications in uncontrolled airspace. The Enhanced Traffic Situational Awareness during Flight Operations (ATSA-AIRB) application provides flight crews with a display of surrounding airborne traffic relative to ownship, together with supporting information on that traffic. This information leaflet explains the use of ATSA-AIRB by the flight crew as an aid to visual acquisition of traffic and maintaining situational awareness and own separation in both controlled and uncontrolled airspace. Although there is no change foreseen to controller procedures, it is considered appropriate that controllers are aware of the way flight crews use the ATSA-AIRB application. In an attempt to enhance their traffic situational awareness, some pilots use their TCAS (Traffic alert and Collision Avoidance System) Traffic Display to supplement other available traffic information. In fact, the use of TCAS to support traffic situational awareness has been one of the drivers towards the introduction of Airborne Surveillance Applications. However, the primary objective of the TCAS Traffic Display is to support visual acquisition when TCAS logic generates a Traffic Advisory. While the TCAS Traffic Display can sometimes help to support general traffic situational awareness, in some cases it has confused the flight crew s perception of the traffic situation.

2 2. APPLICATION OVERVIEW ADS-B (Automatic Dependent Surveillance Broadcast) is a technology through which aircraft, aerodrome vehicles and other objects can automatically transmit and/or receive data such as identification, position and additional data, as appropriate, in a broadcast mode via a data link. The ATSA-AIRB application makes use of ADS-B and provides flight crews with a graphical display of surrounding traffic relative to ownship, together with supporting information on that traffic. The ATSA-AIRB application can be used by all suitably equipped aircraft and to achieve the ATSA-AIRB objectives, the flight crew will be provided with appropriate flight deck tools and data (Traffic Display) to support them in the tasks of visual acquisition and maintaining situational awareness. In using the term Traffic Display, the reader should not infer any specific implementation method or format. Information provided by the cockpit traffic display is not a substitute for visual information and flight crews must perform a periodic out the window scan outside the cockpit to detect potential threats, regardless of the flight rules and the class of airspace. Abuse or intentional misuse of information provided to the flight crew or the controller is not considered here. 3. OPERATIONAL ENVIRONMENT The ATSA-AIRB application may be used in any airspace, both controlled and uncontrolled (i.e. class A to G). It is likely to produce more benefits from a safety perspective in airspace where separation is not provided by ATC between all traffic (i.e. class C to G airspace for VFR and class D to G for IFR). The use of ATSA-AIRB does not require any changes to the ATS infrastructure and systems nor ATC procedures. The application can be used in the exact same environments as the current operations from the communication, navigation and surveillance perspectives. 4. OBJECTIVE OF ATSA-AIRB APPLICATION The objective of ATSA-AIRB is to improve flight safety and flight operations by assisting flight crews in building their traffic situational awareness through the provision of an appropriate on-board traffic display.. The traffic density can range from low to very high. The ATSA-AIRB application can be used in both types of flight rules, IFR and VFR (special VFR included). In VMC, a routine out the window scan remains key to safety because there may be aircraft which are not displayed on the Traffic Display (e.g. partial ADS-B equipage environment). In IMC, the display of surrounding traffic will support the party line and ATC communications in building the flight crew situational awareness, bearing in mind

3 that neither of them will provide the complete picture of the surrounding traffic to the flight crew. 5. USE OF ADS-B FOR ATSA-AIRB The ATSA-AIRB application can be used from prior to take-off, through in-flight operations, to landing, in both Instrument Meteorological Conditions (IMC) and Visual Meteorological Conditions (VMC), by aircraft operating under Instrument Flight Rules (IFR) and Visual Flight Rules (VFR) and by all types of aircraft, from large commercial jets to small general aviation aircraft. The application contributes to flight crews enhanced traffic situational awareness, enabling more efficient performance of tasks. The list of tasks and the information currently available depend on the flight rules, airspace and weather environment (e.g. VFR in class G airspace or IFR in class A airspace in IMC conditions). Therefore the application will provide different benefits in the various possible environments. The ATSA-AIRB application requires that the surrounding traffic has ADS-B OUT capability and that the aircraft is equipped with a Traffic Display (which implies ADS-B IN). To achieve maximum benefits (i.e. to have a complete traffic picture), all aircraft need to be equipped with ADS-B OUT and ADS-B-IN. However, this ideal situation will not exist, at least during the transition period to full equipage. Not all aircraft will be equipped with ADS-B OUT capability. This partial ADS-B OUT equipage will result in the display of only some of the surrounding aircraft on board the aircraft appropriately equipped to use the ATSA-AIRB application. 5.1 ADS-B Out and ADS-B In ADS-B Message An ADS-B Message is a packet of information broadcast by an aircraft/vehicle. Each ADS-B message contains a defined set of aircraft/vehicle surveillance

4 parameters. Multiple messages are used to transmit all the required data (i.e. not all the data is transmitted in each individual message but in separate messages to be consolidated by the receiving system into a complete message). Message formats are link-specific (i.e Mhz Extended Squitter, VDL mode 4, UAT etc), as is the number of different messages required to provide a complete set of parameters. Linked to the ADS-B message are 2 functions, ADS-B Out and ADS- B In. ADS-B OUT function: Represents the functional capability of aircraft/vehicles termed the Transmit Aircraft/Vehicle. The ADS-B OUT function consists of the Surveillance Transmit Processing (STP) function and the ADS-B Transmit function. STP receives and processes pertinent ADS-B source information from on-board aircraft sensors and aircraft navigation systems for subsequent transmission by the ADS-B Transmit function (ADS-B Message). ADS-B IN function: Represents the ADS-B functional capability of aircraft/vehicles termed the Receive Aircraft/Vehicles. ADS-B IN includes the ADS-B Receive function, which generates ADS-B information (reports) from received ADS-B messages, the Airborne Surveillance and Separation Assistance Processing (ASSAP) function, which performs surveillance and applicationspecific processing, and the Traffic Display function, which provides the Human Machine Interface (HMI) to the flight crew. 6. AIRBORNE SURVEILLANCE SYSTEM CAPABILITIES 6.1 General ADS-B Capabilities The source of information for the traffic display will be Automatic Dependent Surveillance-Broadcast (ADS-B). ADS-B systems used in the provision of ATSA-AIRB shall have a very high level of reliability, availability and integrity. The possibility of onboard equipment failures or significant system degradations which may cause complete or partial interruptions of service shall be very remote Traffic Display Capabilities The following parameter will be displayed to the flight crew for qualified traffic (Ref 1): Relative horizontal position (i.e. distance and relative bearing); Note: Qualified traffic includes airborne traffic and traffic on the ground. The following list of parameters will be displayed to the flight crew for qualified traffic if they are available: Altitude (relative altitude required. Barometric corrected pressure altitude and absolute pressure altitude optional); Vertical tendency; and When altitude is displayed to the flight crew, vertical tendency will also be displayed. The following list of parameters will be selectable for display to the flight crew for qualified traffic if they are available: Aircraft identification; and Speed information (ground speed).

5 Note: Indicated Air Speed can further enhance the traffic situational awareness of the flight crew in some traffic situations (e.g. in trail) but this parameter is not required. Note: Velocity vector can further enhance the traffic situational awareness of the flight crew, in particular to better assess the evolution of traffic situations, but this parameter is not required. Note: The treatment of unqualified traffic is an implementation issue. Such traffic is not required to be removed from the traffic display as long as the flight crew can clearly distinguish between qualified and unqualified traffic Other Considerations The flight crew will have the capability to determine whether traffic of interest depicted on the Traffic Display is qualified for ATSA-AIRB. The flight crew will: have the capability to determine whether the ownship is qualified for ATSA-AIRB. be presented with clear and uncluttered information on the Traffic Display. be able to adjust the display range and altitude bands of the Traffic Display. When the flight crew detects traffic of interest on the Traffic Display but not qualified for ATSA-AIRB, the flight crew will disregard the Traffic Display for this traffic. If the flight crew detects traffic of interest on the Traffic Display but with ADS-B data not consistent with out the window or radio communication information related to this traffic, the flight crew will disregard the Traffic Display for this traffic. It is assumed that runway centrelines are depicted on the Traffic Display. (Ref 1) (Note: These elements could change as ED164 [Ref 1] is further developed and prior to final approval)

6 Sample of Cockpit Display of Traffic Information (Courtesy AIRBUS) 7. PROCEDURES, PHRASEOLOGY AND WORKING METHODS Controllers may not be aware of whether or not the aircraft is equipped with a traffic display or whether the flight crew is using the application. Consequently, no change is foreseen to ATCOs procedures, phraseology or working methods. Furthermore, from a human factors perspective the introduction of ATSA-AIRB will only affect flight crew and not ATCOs. The ATSA-AIRB application improves current operational procedures by the addition of a Traffic Display that supplements the flight crew s out the window scans and radio communications listening, and supports the flight crew in integrating information from these sources into a comprehensive and accurate picture of surrounding traffic. Correct use of the Traffic Display simplifies the task of correlating information derived from radio communications and out the window scans. The resulting enhanced traffic situational

7 awareness contributes to improving the flight crew s decision-making process for the safe and efficient operation of the flight. The ATSA-AIRB application is an Airborne Traffic Situational Awareness application and does not modify current pilot and controller responsibilities. No manoeuvre that would lead to a non-compliance (i.e. either a deviation or a non-execution) with an ATC clearance or instruction (e.g. heading, speed, flight level, etc.) or for which visual contact or air-to-air radio communication is currently a pre-requisite can be decided based on the Traffic Display alone. Nevertheless, the pilot-in-command is still ultimately responsible for the prevention of collisions. This is especially true in uncontrolled airspace where pilots must be aware that they may not see all surrounding traffic on their Traffic Display (e.g. in a partial ADS-B equipage environment). The ATSA-AIRB application does not require phraseology changes. As ADS-B may not be implemented in the ground system requests from the flight crew for confirmation of another aircraft flight, ID will in this case be refused since it may not be possible to verify from the ground what is being transmitted by the aircraft. In any event, depending on the display of flight ID/Callsign/Aircraft ID, the controller and flight crew may see different IDs. For example, ATC might see Flight ID whilst the flight crew might see aircraft ID. In any event, when reporting visual contact (following traffic information from ATC) and during subsequent voice communications, the flight crew should not use the A/C identification of the preceding aircraft as displayed and should use the elements as provided by the controller for traffic information. 8. References 1. EUROCAE (ED164) Safety, Performance and Interoperability Requirements Document for Enhanced Traffic Situational Awareness During Flight Operations (ATSA- AIRB) Annex A OSED Version 1.7.d 10 April Flight Crew Guidance for Use of ADS-B for Enhanced Traffic Situational Awareness by Flight Crew During Flight Operations (ATSA-AIRB) (EUROCONTROL CASCADE Programme [OFG]) This document is published by EUROCONTROL in the interests of exchange of information. It may be copied in whole or in part, providing that EUROCONTROL is acknowledged as a source. The information contained in this document may not be modified without prior permission from EUROCONTROL. EATMP Infocentre Reference: 09/10/28-29