OPERATIONAL CONCEPT AND VALIDATION OF A NEW AIRPORT LOW-LEVEL WIND INFORMATION SYSTEM Tomoko Iijima, Naoki Matayoshi and Shoh Ueda *Japan Aerospace Exploration Agency (JAXA) Keywords: Windshear, Turbulence, Wind Disturbance, Aircraft Operation, ACARS Abstract Pilots are sometimes not provided with sufficient information to avoid go-arounds or other operational disruptions that result from low- level wind disturbances. We identified issues with existing windshear alerting systems, and developed three types of airport low-level wind information systems to enhance pilot situation awareness of wind conditions by providing Figure 1. Causes of go-arounds at Narita landing aircraft with quantitative and visualized International Airport (2008). wind information, ultimately to mitigate air service disruptions due to low-level wind headwind change of more than 20kt is observed (3) disturbances. The three systems, ALWIN (Airport by an airport-based Doppler radar / lidar sensor . Low-level Wind Information) and LOTAS (Low- Although present low-level windshear alert level Turbulence Advisory System) that use systems contribute to the goal of preventing Doppler radar/lidar, and SOLWIN (Sodar-based accidents, they do not always provide sufficient Low-level Wind INformation) that uses Doppler information on wind disturbances to prevent SODAR (SOnic Detection And Ranging), have operational disturbances such as go-arounds. At different costs and capabilities which allow the Narita International Airport (Japan’s largest most cost-effective system to be selected for an international airport), for example, more than airport according to its scale and local weather 90% of go-arounds occur due to wind characteristics. This paper presents the disturbances such as windshear, turbulence, and operational concepts of our newly-developed strong headwinds or crosswinds, as shown in airport low-level wind information systems and Figure 1. describes their validation. On investigating this situation, we found that existing windshear alerting systems provide windshear alerts only when the windshear is 1 Introduction severe enough to pose a high accident risk. In Low-level wind disturbances, such as other words, even if the alerting systems detect windshear and turbulence, near airports can less severe windshear which could nevertheless present hazards to take-offs and landings since still cause a go-around or other air service they disturb aircraft flight paths and attitudes. disruption, this information is not provided to Following several tragic accidents due to strong pilots. We have therefore developed a new windshear (1), the International Civil Aviation airport low-level wind information system to Organization (ICAO) recommended that airport provide landing aircraft with quantitative meteorological services provide windshear (numerical) and visualized (graphical) wind warnings for aircraft flying below 1,600ft above information to enhance pilot situation awareness the runway elevation (2). In Japan, the Japan of wind conditions and ultimately mitigate air Meteorological Agency (JMA) provides service disruption due to low-level wind windshear alerts at major airports when a disturbances. Newly developed graphical and 1 TOMOKO IIJIMA, NAOKI MATAYOSHI and SHOH UEDA textual information provide tactical and strategic such as runway thresholds. Sensor wind data are information on low-level turbulence and processed into graphical / textual representations windshear to flight crews, airline dispatchers and useful for aircraft operations, and may be other ground-based operations staff is intended to transmitted to flight crews in the cockpit via increase operational efficiency (by reducing the ACARS data link text message (e.g., Figure 3) or number of go-arounds) as well as to prevent to ground users (airline dispatcher/operations accidents. Flight crews can obtain the officers) via the Internet to provide a graphical information by ACARS (Aircraft and textual web display, as we have described Communications Addressing and Reporting previously (5), (6), (4). System) datalink text message. This is the first Although there are differences in the wind system in the world that provides quantitative sensors used by the three systems, their wind information to the cockpit. architecture, that is windshear / turbulence Based on this concept, we have developed detection and information provision methods, are three types of airport low-level wind information very similar. Table 1 shows the operational system with different capabilities and costs: concept of each system. Although the three ALWIN (Airport Low-level Wind INformation) systems all aim to provide tactical and strategic (4) and LOTAS (Low-level Turbulence Advisory information on low-level turbulence and System) (5) that use Doppler radar/lidar sensors, windshear, the type and cost of the wind sensor and SOLWIN (Sodar-based Low-level Wind and the information content of the web display INformation) that uses Doppler SODAR (SOnic and ACARS message text differ according to the Detection And Ranging). This allows the system airport’s scale and the characteristics of its local with the best cost benefit for an airport to be weather environment. selected according to the airport’s scale and local The main method for obtaining wind weather characteristics. In this paper, airport information also differs among the three systems. scale refers to traffic volume (the number of daily ALWIN is used mainly in a “pull” (request- scheduled flights) and the number of runways. response) mode of operation, while LOTAS and The ALWIN system has been implemented and SOLWIN are used mainly in a “push” mode. operated officially by the JMA at Tokyo’s two With a “pull” operation (4), flight crews can international airports, Narita and Haneda, since obtain low-level wind information from the 2017. cockpit at any time on request using ACARS. To To verify the effectiveness of our concept, an implement this type of operation, airlines have to operational evaluation was carried out by a modify their ACARS ground systems to respond questionnaire usability survey of flight crews and automatically to flight crew requests by ground-based flight operations support staff. retrieving the latest ALWIN / LOTAS / This paper presents the operational concept SOLWIN text information from the server and of our newly-developed airport low-level wind uplinking it. This automated response to flight information systems and describes their crew requests can improve flight crews’ wind validation. situation awareness and enable them to more effectively conduct approach briefings and plan flight control strategy such as determining the 2 Operational Concepts target approach speed, as shown in Figure 4. The newly-developed system architectures Flight crews typically obtain wind information of the ALWIN, LOTAS and SOLWIN systems via ACARS datalink during cruise as part of their are shown in Figure 2. ALWIN and LOTAS preparations for arrival, and use it to plan the automatically detect wind disturbances on approach and landing. In cases where the low- approach flight paths, including disturbances level wind information indicates turbulent with small-scale spatial structures, using Doppler conditions, flight crews can also obtain the most radar/lidar, while SOLWIN automatically up-to-date information during the approach to detects disturbances directly above Doppler allow them to monitor changes in the wind SODAR sensors to monitor discrete locations situation. 2 OPERATIONAL CONCEPT AND VALIDATION OF A NEW AIRPORT LOW-LEVEL WIND INFORMATION SYSTEM Figure 2-a. System architecture of implemented ALWIN (Airport Low-level Wind INformation). Figure 2-b. System architecture of LOTAS (Low-level Turbulence Advisory System). On the other hand, with a “push” operation ALWIN / LOTAS / SOLWIN text information to (4), ground-based dispatchers or operations staff the aircraft over ACARS, or verbally monitor the wind situation using a web display communicate the wind information indicated in screen, and transmit the information to aircraft in information area of the display over the company flight when notable wind disturbances are radio frequency. To facilitate push mode observed. Operations staff can either uplink the operations, we designed a function to generate an 3 TOMOKO IIJIMA, NAOKI MATAYOSHI and SHOH UEDA Figure 2-c. System architecture of SOLWIN (SOdar-based Wind INformation). (1) FNL (Final) text <- ->: wind speed variance (2) APT (Airport) text Figure 3. Example of ALWIN text display . ACARS text message when the user clicks the Haneda, and on a trial basis with the SOLWIN “ACARS text conversion” button in web system at Oita, a regional airport with about displaye.g. (5). This type of operation does not fourteen daily scheduled flights. At the start of require any modifications to existing airline development, push operation was used with the systems. LOTAS system at Shonai airport, but pull At present, pull operation is used by Japan operation with LOTAS is also possible with Airlines (JAL) with the ALWIN system at modifications to the ACARS ground system. Japan’s largest international airports, Narita and 4 OPERATIONAL CONCEPT AND VALIDATION OF A NEW AIRPORT LOW-LEVEL WIND INFORMATION SYSTEM Table 1. Operational Concepts of ALWIN, LOTAS and SOLWIN. We now describe the main operating volume, such as international airports. Since high characteristics of each system in the following. traffic means that low-level turbulence or windshear could affect many flights,