Technical Proposal Low Level Windshear Alert System

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TELVENT Almos LLWAS Low Level Windshear Alert System Technical Proposal Low Level Windshear Alert System Title Low Level Windshear Alert System Version 1 Date 30 November 2006 Ref TELVENT Low Level Windshear Alert System Almos 1 LLWAS Low Level Windshear Alert System Table of Contents Technical Proposal ................................................................................0 1. Introduction…………………………………………………………………4 1.1 Company Background & LLWAS Experience...................................................4 1.2 LLWAS System Summary................................................................................5 2. System Description..............................................................................6 2.1 System Performance.......................................................................................6 2.1.1 System Performance Overview ..............................................................6 2.1.1 LLWAS Top Level Description ................................................................7 2.1.1.1 System Overview...............................................................................7 2.1.1.2 System Diagram..............................................................................10 2.1.2 Master Station (MS) ............................................................................10 2.1.2.1 Controller Hardware .......................................................................10 2.1.2.2 Master Station Computer Configuration.........................................12 2.1.2.3 Multi-port RS232 ............................................................................12 2.1.2.4 Rack Configuration.........................................................................13 2.1.2.5 LLWAS Software.............................................................................15 2.1.2.6 Master Station LLWAS Displays .......................................................16 2.1.3 Remote Station (RS) ............................................................................18 2.1.3.1 System Description .........................................................................19 2.1.3.2 Wind Sensor Simulator ...................................................................20 2.1.3.3 Reliability Issues ..............................................................................21 2.1.3.4 Remote Station Electrical Power Requirements ...............................21 2.1.3.5 Environmental Conditions...............................................................21 2.1.3.6 Remote Station Obstruction Lights..................................................22 2.1.4 LLWAS Wind Sensors ..........................................................................22 2.1.5 Wind Masts………………………………………………………...……..23 2.1.6 RF and Land Line Data Links................................................................23 2.1.6.1 Detailed Communication Specification............................................23 2.1.7 Display Equipment ..............................................................................24 2.1.7.1 Overview ........................................................................................24 2.1.7.2 Alphanumeric Alarm Display (AAD).................................................25 TELVENT Low Level Windshear Alert System Almos 2 LLWAS Low Level Windshear Alert System 2.1.7.3 Graphical Alarm Display Screens (GAD)...........................................31 2.1.8 Interfaces...........................................................................................33 2.1.8.1 External Data Interface....................................................................33 2.1.9 Algorithm Implementation ..................................................................33 2.1.9.1 LLWAS Algorithm Functions............................................................35 2.1.10 Archiving/Playback..........................................................................36 2.1.11 Maintenance………...…………………………………………………38 2.1.11.1 Master Station Maintenance Screens ..............................................39 2.1.11.2 Built–In Test Equipment - BITE ........................................................42 2.1.11.3 Site Performance Evaluation System (SPES) .....................................44 2.1.11.4 Installation and Maintenance Tools.................................................49 2.1.12 System Modes (States) .......................................................................50 2.1.12.1 Real Time Normal ...........................................................................50 2.1.12.2 Real Time Degraded........................................................................50 2.1.12.3 System Support...............................................................................50 2.1.12.4 Initialization ....................................................................................51 2.1.12.5 Off..................................................................................................51 2.2 Configuration File ........................................................................................51 2.2.1 ACF……………………………………………………………………......53 2.2.2 DCF…………………………………………………………………...…...53 2.2.3 MCF, SCF……………………………………………………………….....53 3. Realibility, Maintability, Availability (RMA), and Supportability.............53 3.1 RMA Characteristics .....................................................................................53 3.1.1 Mean Time Between Failure (MTBF) / Mean Time Between Critical Failures (MTBCF) .................................................................................53 3.1.2 Mean Time Between Corrective Maintenance Action (MTBCMA)........54 3.1.3 Built in Test and Fault Isolation capability ............................................54 3.1.4 Mean Time To Repair (MTTR) ..............................................................55 3.1.5 MTBF Evaluation .................................................................................56 3.1.5.1 Purpose ..........................................................................................56 3.1.5.2 References ......................................................................................56 3.1.5.3 Definitions ......................................................................................56 3.1.5.4 Approach........................................................................................56 3.1.5.5 Reliability Data................................................................................56 TELVENT Low Level Windshear Alert System Almos 3 LLWAS Low Level Windshear Alert System 3.1.5.6 Reliability Calculations ....................................................................57 3.1.5.7 Results ............................................................................................58 3.2 Supportability...............................................................................................58 TELVENT Low Level Windshear Alert System Almos 4 LLWAS Low Level Windshear Alert System 1. Introduction 1.1 Company Background & LLWAS Experience Almos Systems is an ISO9001 quality endorsed company with extensive experience in meteorological system design, development and production. Almos products and services utilize extensive knowledge and experience in the application of World Meteorological Organization (WMO) and ICAO codes and rules. Almos manufactures Automatic Weather Stations, communication equipment and specialised computer equipment for control towers. Almos also specialises in meteorological processing and display software. Almos offers system design, integration, installation, and training and maintenance services of meteorological systems. The software package offered is based on the Almos “MetConsole”, which is a commercial off-the-shelf product that was developed in partnership with the Australian Bureau of Meteorology and Air services Australia (formally Civil Aviation Authority) and has been in operational use in airports in Australia and internationally for several years. A program to adopt the Almos MetConsole at approximately 300 Australian sites has recently commenced after two years of development and operational testing. Almos Systems received a Federal Government grant to develop a graphics based Phase III LLWAS software solution, as an extension of the field tested Almos MetConsole package. This programme culminated in the installation of the latest MetConsole version 2.3, including a complete LLWAS III NE master station and display system at Darwin International Airport, which was the first Phase III system outside USA. The system is owned and operated by the Bureau of Meteorology but was manufactured, supplied and installed by Almos Systems. Systems using Almos MetConsole are in operational use at a number of international airports around the world. Almos was among the first companies to standardise on Windows NT technology. Operational MetConsole systems are still running on the first version of NT and on the latest versions of NT. The Remote Stations offered are based on the Almos Automatic Weather Stations, which have been exclusively adopted by the Australian Bureau of Meteorology. A modernisation program to replace all weather stations at Australian civil and military airports is almost complete. Hundreds of Almos TELVENT Low Level Windshear Alert System Almos 5 LLWAS Low Level Windshear Alert System weather stations have been providing aviation and synoptic information for several years. These systems operate in harsh and remote locations; yet have a field proven MTBF of more than 35 years. In 1996, Almos Systems was selected to supply Remote Stations for the FAA Phase III LLWAS (NE) program. These units were designed and developed to the point where the FAA project staff witnessed the type and factory testing and 40 units were delivered. Ongoing support and maintenance is available from our factories in Australia and The Netherlands and from technology centres across the world in North and South America, Spain and China. Almos is a developer and manufacturer of LLWAS equipment, and has been manufacturing LLWAS equipment since 1996 as a logical extension of our commitment to the aviation weather industry. Our experience in both developing products for aviation weather systems, and managing installations of these systems ensures that we can provide the most qualified installation support and services to all of our customers. 1.2 LLWAS System Summary The Almos LLWAS-III system is a component of Almos’ advanced MetConsole Aviation/Meteorology display and processing system. The modularity of Almos’ design ensures that the provided LLWAS will meet and exceed lifetime requirements while providing a maximum of future expandability options if required. The main MetConsole system is a completely configurable software package designed to operate under Windows environments (95, 98, NT, 2000, 2003,…). A wide variety of communications, display and processing modules may be included with a MetConsole system to provide the required functionality. In addition, dual server operation of the MetConsole package ensures that system configuration and servicing may take place without interruption of the LLWAS detection algorithm. Additional modules may be ordered initially or added later, including ATIS (computer generated voice, data output, or operator-recorded message), METAR/SPECI, AFTN integration and a variety of standard WMO messages, data input/output and observer screens. MetConsole is designed to allow you TELVENT Low Level Windshear Alert System Almos 6 LLWAS Low Level Windshear Alert System to completely integrate your Aviation computer systems, either now or in the future. The MetConsole LLWAS component uses a communications and processing design that has been installed and tested in a number of different environments, including Darwin International Airport (Australia), Sungshan and Chiang Kai Shek Airports (Taiwan), Bilbao and Tenerife Airports (Spain) and Kuwait International Airport (Kuwait). Key points in the selection of an Almos MetConsole solution include: • Cost effective • User friendly • Extensive, well written user help & manuals • High speed Processing • Extremely Reliable Communications • Robust Equipment • Commitment to Quality and Reliability • Committed to Customer Satisfaction • COTS processor - No customisation required. • Experience in design and manufacture of LLWAS equipment • Worldwide coverage • UCAR Licensee since 1996 • Easy maintenance makes better use of manpower. • Expandable software configurable to each customer’s unique requirements. • Easy connection to DWR LLWAS Radar. 2. System Description 2.1 System Performance 2.1.1 System Performance Overview Almos’ LLWAS is implemented using Almos’ MetConsole software system to provide both a proven, reliable design as well as a system that is easy to use TELVENT Low Level Windshear Alert System Almos 7 LLWAS Low Level Windshear Alert System and maintain. (MetConsole is the same system software used for AWOS, ATIS, ASOS and other system products.) This document describes the proposed implementation of this system to ensure that the LLWAS detection system meets or exceeds all internationally recognised requirements. Almos’ LLWAS system uses the UCAR Phase-III LLWAS algorithm. Coupled with a fault tolerant communications system that well exceeds the standard 1.05e7 bit error rates, Almos’ probability of detection meets that promised by the UCAR Phase-III LLWAS algorithm for any given airport configuration. The Almos LLWAS system provides the detection performance for a standard airport configuration as included in the following table: POD 94% The probability that some alert (WSA or MBA) is issued whenever microburst intensity exceeds 15 knots POD:MB 97% The probability that some alert (WSA or MBA) is issued whenever microburst intensity exceeds 30 knots. PID:MB 92% The probability that an MBA is issued whenever microburst intensity exceeds 30 knots PFA:MB 3% The probability that an issued MBA is false; it is not related to any part of a microburst life cycle. POW 7% The probability that an issued WSA is an over warning; the event is a microburst with strength less than 30 knots. PUW 8% The probability that an issued WSA is an underwarning; the event is a microburst with strength greater than 30 knots. Determining an exact POD at each airport is possible only through operational use with the installed configuration, as localised meteorological, topographic and geographic features will affect the resulting performance. 2.1.1 LLWAS Top Level Description 2.1.1.1 System Overview Remote Station Network: The system to be installed at the airport consists of a network of eight WAWS (Wind-only Automatic Weather Station) units. The number of WAWS TELVENT Low Level Windshear Alert System Almos 8 LLWAS Low Level Windshear Alert System required at a site is dependent on the results of a site survey, which takes into account the configuration of the runways, the topography of the desired area of coverage. Depending on the form of communication used, this network may consist of a combination of radio (Model 2100-Z-RAD) or landline (Model 2100-Z-LDL) WAWS units. To provide master station communications to the landline and radio networks, two Master Station Communication Set units are to be installed. A landline MSCS (2100-Z-MSLL) provides a communications hub for the landline WAWS units, and a radio MSCS (2100-Z-MSRD) provides a communications hub for all radio WAWS units. Because the LLWAS Algorithm is configured only to operate on fixed station addresses, spare WAWS units can be tested by setting them outside of the range of the ‘operationally in use’ WAWS network. The stations being tested can then be queried and run as normal but without any data being used by the LLWAS calculation or displayed on windshear display workstations. Master Station: The master station consists of a dual redundant server configuration (primary server with hot backup). Serial and Parallel Multiplexers provide communications channels to whichever server is designated the ‘hot’ server through a failover process. This redundant system ensures that the system remains operational even in the case of a server failure. RS232 threshold wind interfaces and MSCS communications are connected to the Serial multiplexer. A keyboard/video/mouse extender allows the monitor keyboard and mouse that form the system console to access both servers and to be located outside of the rack if desirable. The Server computers operate Almos LLWAS MetConsole, and provide a TCP/IP socket for external interface. A multi-port RS232 controller greatly extends the I/O communications capabilities of each server PC without providing any significant extra workload on the PC. LAN All computers are connected to a central UTP hub. This hub configuration ensures that any loss of communication or cable damage on any single system TELVENT Low Level Windshear Alert System Almos 9 LLWAS Low Level Windshear Alert System does not affect any other system. The hub is mounted close to the server pair for easy maintenance and inspection of the server connection. A description of the server and hub hardware is provided in the section describing Rack Configuration. A third PC, either installed in the equipment room or a more remote location, processes data archiving and provides an archive replay facility. Operator Workstations Meteorological Workstations shall be located in the Meteorological office and Meteorological observation room. LLWAS alert displays shall be installed in the Air Traffic Control Tower. The number of these workstations may be increased without practical limit. Using a standard PC running a MetConsole client, these systems provide display and processing functionality. Because of the network hub configuration, disconnection (or software/hardware/cable fault) on any PC is isolated from the remainder of the network and ensures that the tower process carries on using the remaining systems. TELVENT Low Level Windshear Alert System Almos 10 LLWAS Low Level Windshear Alert System 2.1.1.2 System Diagram 2.1.2 Master Station (MS) The Almos Master Station consists of two main components: A Master Station Communications Set (MSCS) providing communications to all remote stations, and a dual-redundant MetConsole Server Pair providing data processing and storage. 2.1.2.1 Controller Hardware 2.1.2.1.1 Master Station Communications Set Two models of MSCS unit are used. 2100-Z-MSRD provides radio communications with up to 16 Radio WAWS units (2100-Z-RAD) on a single channel. A single RS-232 communications port provides data TELVENT Low Level Windshear Alert System Almos 11 LLWAS Low Level Windshear Alert System communications to a MetConsole server PC. Lightning and surge protection are built in. Mean Time between Failure (MTBF) for the MSCS electronics is 40,000 hours. 2100-Z-MSLL is a landline version providing landline communications with up to 20 Landline WAWS units (2100-Z-LDL) on a single telephone cable. Interface to the PC is the same as MSRD, using a single RS-232 communications port. Lightning and surge protection (transformer isolation) are built in. 2.1.2.1.2 Data Multiplexer / Switch Almos RS-232 Multiplexer provides automated server data changeover in the event of a server failover. This device and the MetConsole interface software ensure that server failover is performed in the minimum amount of time and without requiring operator intervention. Multiplexer Overview MASTER STATION COMMUNICATION SET (LANDLINE) MASTER STATION COMMUNICATION SET (RADIO) WIND REMOTE STATION LDL WIND REMOTE STATION LDL LANDLINE REMOTE STATION O WIND REMOTE STATION RAD WIND REMOTE STATION RAD RADIO REMOTE STATION NETWORK ... TO MASTER STATION PC TO MASTER STATION PC ADDITIONAL STATIONS ALMOS MULTIPLEXER MCS-RADIO MCS-LANDLINE EXTERNAL INTERFACE EXTERNAL INTERFACE EXTERNAL INTERFACE REMOTE SITE SUPPORT EXTERNAL INTERFACE PRIMARY SERVER SECONDARY SERVER TELVENT Low Level Windshear Alert System Almos 12 LLWAS Low Level Windshear Alert System 2.1.2.2 Master Station Computer Configuration The Master Station computers, like all computers used in the Almos LLWAS MetConsole network, are Intel Pentium architecture PCs operating Windows Server version of Operating System. A DVD-ROM is provided standard on all PCs, allowing simple software installation from an Almos LLWAS MetConsole install DVD. The Almos DVD installation process is an extremely simple process designed to require a minimum of operator supervision, making better use of valuable maintenance engineers’ time. Soundcards are installed on all PCs for the purpose of providing audible alarms. LCD displays are offered for all display PCs and include integrated brightness controls for use in a tower environment. Displays include integrated speakers for simplified alert volume control and muting. A high capacity Hard Disk is installed on both server PCs for the purpose of storing data online. The choice of the Windows Server operating system follows Almos’ commitment to quality by integrating with high quality, proven operating systems in the critical aviation environment. 2.1.2.3 Multi-port RS232 Standard Personal Computer architecture limits the PC system to 4 RS-232 ports. Standard Airport systems often require many more ports in order to cope with the large variety of incoming and outgoing data. The Moxa Multi-port RS232 controller attaches to the expansion bus of a Master Station PC (two are supplied; one for each Master Station) and extends the number of ports available on the PC significantly. These TELVENT Low Level Windshear Alert System Almos 13 LLWAS Low Level Windshear Alert System controllers are commonly used in high-end airport and meteorological processing systems. Each module installed supplies 16 additional high-speed ports; an onboard RISC processor reduces PC workload allowing more efficient CPU utilization. The Moxa controllers to be installed will interface to Master Station Controllers, a modem provided for remote support and other RS232 data input/outputs. 2.1.2.4 Rack Configuration Proposed Rack Configuration for the ATC equipment room is as shown below. Incoming network cables (through the floor) are connected to the UTP network hub via a patch panel. The patch panel allows easy access to network cabling. The hub is connected to both server PCs, arranged side by side and clearly marked “Primary” and “Secondary”. Both Multi-port Moxa controllers are mounted above the PCs, and ports from the Moxa controllers and PC Printer ports are connected directly to adjacent Serial Multiplexer / Parallel Multiplexer units. These cables are then run down through the floor to their various devices. An intelligent Keyboard, Video & Mouse (KVM) switch allows the user to switch the system console screen to display either server’s data. While the keyboard and mouse are being used on one server, the KVM switch maintains communications with the other unit, preventing loss of signal common to simple switching devices. A modem provides dial-up support access and is software secured (modem hangs up on receipt of a call and automatically dials a dedicated support number, allowing only access through the support office). PRINTER PAPER TRAY POWER SUPPLY MODEM PC SWITCH M/S SRV-A KVM EXTENDER LAN HUB PATCH PANEL M/S SRV-A MOXA-A-1 MOXA-A-2 MOXA-B-1 MOXA-B-2 TELVENT Low Level Windshear Alert System Almos 14 LLWAS Low Level Windshear Alert System A 19” CRT monitor, keyboard and mouse are provided external to the rack for use as a System Console. Controller Software The Master Station Communications Set (MSCS) communicates with remote stations using a selective-retry, multi-drop binary communication protocol. The efficient design of this system was demonstrated during testing and trials with the FAA during the commissioning phase of the Almos LLWAS MSCS design in 1997. For a very detailed discussion on the communication protocol, please see below the section under RF and Land Line Data Links entitled Detailed Communication Specification. The system is designed to provide reliable communications in line with FAA LLWAS specifications. This reliability has been proven to representatives of the FAA Phase III LLWAS program. All communications between the Remote Stations and the Master Station is performed at 2400 baud. Due to the extremely high efficiency of the protocol it is not necessary to use a higher baud rate in order to satisfy the data transfer rate requirements of the system. Low baud rates like 2400 are considerably more noise immune than high baud rates like 19,200 baud and therefore are a much better option in noisy environments, such as radio communications surrounding an airport. Bit error rate: <10-5 Communications Reliability: > 99.9% (48Hr MER < 10-4, 1Hr MER < 10-3) The remote station communication system uses a highly advanced binary communication protocol. This was developed specifically for the FAA Phase III LLWAS programme and has been proven to exceed the strict communication efficiency requirements that were defined for that specification. The MSCS polls all the remote stations at the beginning of the system cycle, which is typically 10 seconds, and then waits sufficient time for all the units to respond. REPOLL SAMPLE 4 STATION POLL CYCLE RS3 REPLY MISSING REPLY RS2 REPLY RS1 REPLY POLL REPOLL RS4 REPLY MISSING REPLY TIME TELVENT Low Level Windshear Alert System Almos 15 LLWAS Low Level Windshear Alert System All units for which a response was not received are then selectively repolled until the end of the data acquisition time. This period is calculated to leave sufficient time for the data processing, display and archiving functions of the system. RC and Linear averaging is performed on board the Remote Station WAWS unit. This reduces the transmitted packet size and greatly enhances the reliability of the communications system. This approach was witnessed and approved by FAA personnel during type testing. For Centrefield wind gust, the WAWS unit reports ten-second gust information. This data is then processed by the MetConsole Server and displayed on Operator Workstations. 2.1.2.5 LLWAS Software Almos systems’ implementation of the UCAR Phase III Algorithm uses an efficient implementation based on and tested against the Version 1990.02 Algorithm Specification. The system is designed to allow easy expansion to accommodate FAA approved enhancements to this algorithm. 2.1.2.5.1 LLWAS Configuration All MetConsole stations are configured through a single shared configuration database. This database file contains configuration information pertaining to the role of each station on the network (primary server, secondary server, archiving PC, SPES workstation, operator workstations, displays etc). In addition, the configuration database contains LLWAS parameters contained in the ACF, SPES thresholds & parameters, DCF configurations and other configuration data. Figure 1 - LLWAS System Configuration (Typical) SYSTEM CONFIGURATION (SCF) and MAINTENANCE CONFIGURATION (MCF) (Averaging constants, Displays, Parameters, etc) AIRPORT CONFIGURATION FILE (ACF) DISPLAY CONFIGURATION FILE CONFIGURATIO DATABAS (METCFG.MDB AAD DISPLAY SYSTEM INPUT DEVICE ARCHIVE STATION KEYBOAR D & MOUSE AAD DISPLAY SYSTEM INPUT DEVICE AAD DISPLAY SYSTEM INPUT DEVICE RAW CONFIGURATION FIL ES & PARAMETER S SHARED (BOTH LLWAS MetConsole Overvie TELVENT Low Level Windshear Alert System Almos 16 LLWAS Low Level Windshear Alert System The advantage of this shared configuration database approach is that systemwide configuration can be achieved through reconfiguration of a single central source file. The configuration database is centrally stored and changes to this file are automatically integrated by MetConsole instances operating across the network. 2.1.2.6 Master Station LLWAS Displays All MetConsole screens are constructed using a configuration database. This configuration database defines the names of each ‘screen’, the ‘screen objects’ to be displayed on each screen, and the data item(s) to be displayed by each ‘screen object’. This design is extremely flexible and allows a maintenance engineer to easily change the LLWAS screens to reflect new additional sensors and other equipment. A number of screen objects are non-LLWAS specific, and will be used on Maintenance and server displays to display the current status of various variables such as sensor status, detected wind speed & direction etc. (LLWAS display objects are described under the section titled Display Equipment. 2.1.2.6.1 System Overview Window A ‘System Overview’ window provides a tree control containing all configured remote stations, configuration parameters and statistics, and communications information (also available in comprehensive form through a separate ‘Ports’ window). Figure 2 - The system overview window provides comprehensive data views. CONFIGURATION DATABASE (METCFG.MDB) RAW CONFIGURATION FILES & PARAMETERS SHARED DATABASE (BOTH SERVERS) LLWAS MetConsole Display Configuration Overview SCREENS SCREEN OBJECTS OBJECT TYPES TELVENT Low Level Windshear Alert System Almos 17 LLWAS Low Level Windshear Alert System The ‘System Overview’ window will only be accessible by the Maintenance user and is not required for ATC users. This window provides information about each LLWAS data variable, overall communications status, and specific Remote Station diagnostic information. Variable information may also be queried from all user screens, if the user has sufficient security access. Figure 3 - Query data from a user screen. Variable information includes comprehensive data query options, with all variables displayed in logical category divisions. Figure 4 - Remote Station data views – LLWAS remote station statistics TELVENT Low Level Windshear Alert System Almos 18 LLWAS Low Level Windshear Alert System A System Overview tree display is also provided in the System Overview window, and displays the current connection status of all remote components of the LLWAS system in a graphical and easy to read manner. Figure 5 - System overview (Sungshan airport example) Having well organized graphical tools to aid in diagnosing faults and troubleshooting ensures simple system maintenance. 2.1.3 Remote Station (RS) The Almos Systems Remote Stations (RS) are also called Wind Automatic Weather Station (WAWS). The function of these devices is to collect and transmit wind speed and direction information back to a central monitoring site. The acquired data is transmitted to a Master Station Communications Set (MSCS) at the central monitoring facility via a radio network (radio option) or optional landline network (landline option). Up to 16 radio or 20 landline WAWS can be connected to one MSCS. With multiple MSCS, one Low Level Wind Alert System (LLWAS) may have up to 256 WAWS units. The WAWS may be powered from 120VAC / 60Hz, 220VAC / 60Hz or 240VAC / 50Hz or from a Solar Power Set. TELVENT Low Level Windshear Alert System Almos 19 LLWAS Low Level Windshear Alert System 2.1.3.1 System Description The WAWS includes the following electrical subassemblies: • ALMOS 2100-Z CPU Board • Power Supply System • Radio Interface and Radio Heater (Radio Option) • Radio & RF Surge Suppressor (Radio Option) • Line Isolation Board (Optional Landline Option) • Solar Power Set (Solar Power Option) • Stainless enclosure • Designed for extreme environmental conditions: • Altitude: 10,000 feet operating, 50,000 feet non-operating. • Operating temperature: -40C to +70C • Blowing Rain: Present • EM interference: FCC class A compliant • Humidity: <15% to 100% operating. • MTBF: 272,945 hours (31.2 years) For the location of the items inside the WAWS, refer to drawing AS842-01-2 in appendix II of the WAWS Installation and Maintenance Manual. TELVENT Low Level Windshear Alert System Almos 20 LLWAS Low Level Windshear Alert System Figure 6 - WAWS Block Diagram 2.1.3.2 Wind Sensor Simulator Each remote station will include a wind sensor simulator, providing selectable values for wind speed and direction. The simulator can be remotely operated TELVENT Low Level Windshear Alert System Almos 21 LLWAS Low Level Windshear Alert System over the radio or cable link or locally operated using the built-in maintenance port. 2.1.3.3 Reliability Issues Mean Time Between Failure (MTBF) for the remote station electronics is 40,000 hours. Preventative maintenance requirements for the remote station (not including sensor) do not require more than one visit per year to each remote site. No LRU failure can cause damage or interfere with the operation of any other LRU. In addition, high voltage suppression is provided using gas discharge tubes and transorb devices. This is considered superior to the optical isolation used by many manufacturers. As a result, no Almos weather station has ever caused damage to other network elements, even during a direct lightning strike. Protective devices are provided on all power, sensor and communications connections in the remote stations. All connections (except RF) utilise gas discharge tubes and transorb devices, providing two-stage protection. A coaxial surge protector is provided on the incoming RF connection. 2.1.3.4 Remote Station Electrical Power Requirements Power may be supplied using a solar panel with a maintenance-free sealed lead-acid battery set and a built in solar regulator, or commercial mains power. Average power requirements for LRUs (including wind sensor and radio) are approximately 160mA at 12 V. All remote stations are battery backed with a maintenance free sealed leadacid battery, providing at least 32 hours of operation. 2.1.3.5 Environmental Conditions The remote stations offered fully satisfy the military temperature range requirements. Extremely high temperatures of over 55°C may be endured without adversely affecting the operating of the system. The design of the equipment shelter also helps to keep the temperature of the electronics as low as possible in high ambient temperature conditions. The enclosure’s protective category corresponds to NEMA-4X. TELVENT Low Level Windshear Alert System Almos 22 LLWAS Low Level Windshear Alert System • Altitude: 10,000 feet operating, 50,000 feet non-operating. • Operating temperature: -40C to +70C • Blowing Rain: Present • EM interference: FCC class A compliant • Humidity: <15% to 100% operating. • MTBF: 272,945 hours (31.2 years) 2.1.3.6 Remote Station Obstruction Lights Obstruction lights are fitted to all masts supplied. The type of obstruction light offered is the Obelux 32-12-HTS. This FAA and ICAO compliant obstruction light offers the following benefits: • Long maintenance intervals • Low energy cost (less than 10W) • Supply power voltage variations do not affect light output. • Very low total lifetime costs. • Low wind load • ICAO & FAA compliance • Exceeds temperature requirements – –55C to +80C operating 2.1.4 LLWAS Wind Sensors There are several options available for the wind sensor, both cup-and-vane and ultrasonic types. Sensors are supplied by selected third party suppliers. Almos do not manufacture sensors and therefore sensor selection is solely based on independent, unbiased evaluation of technical performance and sale price. Several types of wind sensors are supported by the Almos WAWS aleady however any type can be interfaced should the customer’s preference fall outside of the sensors for which drivers already exist namely: Vaisala WAA/WAV151 - Cup and Vane Vaisala WS425 - Ultrasonic METEK USA1 - Ultrasonic Met-One - Ultrasonic TELVENT Low Level Windshear Alert System Almos 23 LLWAS Low Level Windshear Alert System All ultrasonic sensors are virtually maintenance free. Only annual checks are required to ensure that the sensing elements are free of debris. Each sensor is directly connected to the Almos WAWS (Remote Station) unit using either a serial (RS232 or RS422) link or a digital interface. This allows the Almos WAWS to perform all data averaging, logging, error correction and communications functions directly on the measured data. This architecture allows provision of any range of measurement averages, from instantaneous to very long average periods. In an LLWAS environment, the standard measurement period is the 10 second RC average (the System Cycle). 2.1.5 Wind Masts Most LLWAS systems are implemented with 10m, 15m or 20m poles. In most case 10m is sufficient. Higher poles are sometimes installed to avoid obstructions. While it is best that all poles are the same height, this is rarely achieved in practice. Poles need to be strong enough to withstand high winds and also to provide easy access to equipment for maintenance. Almos offers both frangible and non-frangible tilting masts. 2.1.6 RF and Land Line Data Links 2.1.6.1 Detailed Communication Specification The remote station is supplied with facilities for both radio (RF) and landline (non RF) communications. 2.1.6.1.1 RF communications RF communications utilises a multi-drop radio protocol that allows up to 16 remote stations to communicate on the same radio channel. RF communications uses digitally tuned Data Radios. The radio frequency and other parameters are fully programmable. Assuming that there are no obstructions and line-of-sight problems, reliable communications is assured between the master station and any remote station up to a distance of 7 nautical miles. Under ideal conditions, transmission paths of up to 25 nautical miles are possible. TELVENT Low Level Windshear Alert System Almos 24 LLWAS Low Level Windshear Alert System 9 element 9dB directional yagi antennas are used at the remote stations and 3dB omni-directional antennas are used at the master stations. The yagi antenna is stainless steel. The omni-directional antenna has a stainless steel mounting tube with a fibreglass radome. 2.1.6.1.2 Landline communications Landline communications utilises a multi-drop modem configuration that allows a number of remote stations to be connected together on a single landline channel. The recommended maximum number of units on a landline link is 20. To prevent faulty remote stations from saturating the communication channel the remote stations are fitted with a watchdog circuit that disables transmission in case a remote station is not operating correctly. The master station configuration may include several Master Station Communication Sets (MSCS), enabling communications via any combination of RF and landline links. Multiple RS232 communications ports are required on the master station PC for communications to the remote stations. 2.1.7 Display Equipment 2.1.7.1 Overview The Low Level Windshear Alert System (LLWAS) provides two methods of displaying windshear and microburst alarm data on user workstations. These are: • AAD (Alphanumeric Alarm Display) – Text Only • GAD (Graphical Alarm Display) – Text and Graphics All display devices use a high resolution, high brightness LCD colour monitor and may display either display format (graphics or text). The AAD provides the user with data in a textual display. This screen shows the current windshear status of the airport in textual form. It gives the status of a selected number of runway thresholds and a centerfield location. In order to use the AAD most effectively, the user can select a “runway threshold configuration” that matches their current frame of reference. The user can choose to view windshear information for a selected group of available runway thresholds. This allows Air Traffic Controllers to concentrate on areas that are within their specific sphere of control. TELVENT Low Level Windshear Alert System Almos 25 LLWAS Low Level Windshear Alert System The GAD is used to show a map of the airport and the location of wind sensors. If a windshear or microburst is detected, then the map will show, using coloured highlights, those areas of the airport affected. 2.1.7.2 Alphanumeric Alarm Display (AAD) AAD display screens are an integrated screen object displaying a number of runway threshold winds & windshear reports, status variables and centrefield information. While the AAD simply reports the status of single data elements, these elements can be configured to use backup sensors for centrefield and threshold winds, providing ATC with constant data. All parameters on the Almos AAD are completely configurable, including number of lines per display (8 message + 2 status), colours & highlighting rules, audible alarms and line formats. Audible alarms are sounded through the PC sound card when a hazardous wind shear is detected. The duration, in seconds of this audible alarm is configurable and default duration is 30 seconds. 2.1.7.2.1 General Description The AAD is a multi-line read-only display having the following features: • Threshold wind data can be selected and displayed for each runway • Displays LLWAS messages in a syntax that is configurable. (This • allows easy changes to be made to the system's output without changing the software). • Displays a database-configurable number of rows and columns per • display. • Status information is displayed on the AAD. • Centrefield & alarm information is displayed on the AAD. • Audible alarm, which sounds at full volume. (Users can adjust the • volume using a volume control). • A configurable flashing/hi-lighting method can be selected for new messages. • Can be configured to indicate alarm updates for particular thresholds for a specified period of time. TELVENT Low Level Windshear Alert System Almos 26 LLWAS Low Level Windshear Alert System • The system time is displayed on the AAD. • Auto-scales character size to the selected AAD object size. (The font is configurable). • Displays a configurable Communication Failure message if the server is not found after a timeout period. • Displays missing wind data as a configurable value. • Does not display any persisted data. (No LLWAS messages or wind information is persisted). • All configurable parameters have a default setting. While the AAD reports the status of single data elements, these elements can be configured to use backup sensors for centrefield and threshold winds, providing ATC with constant data. 2.1.7.2.2 The Screen All parameters on the AAD are configurable, including the ten available display lines (8 message + 2 status), colours & highlighting rules, audible alarm and line formats. Each message line provides 6 possible items of information: 1. Runway identifier 2. Alert type 3. Wind speed gain or loss 4. Location of windshear or microburst 5. Threshold wind direction and speed 6. Possible alarm outside the network zone When the system is operating normally, line 9 (second-last line from the bottom) is blank. If a problem occurs, the text DEGRADED, SUPPORT, INITIALIZATION or OFF is displayed, to indicate the state of the system. Line 10 is reserved for LLWAS system messages. When there is active communication between the server (master station) and AAD, the following information is displayed: • Centrefield wind direction and speed • Centrefield gust speed • System time (in UTC) TELVENT Low Level Windshear Alert System Almos 27 LLWAS Low Level Windshear Alert System • Audible alarm state (On or Off) If no information is received from the server within a configurable time period, the AAD will blank and display “COMMUNICATION FAILURE” on line 10. The following identifiers are used in the AAD: A Approach D Departure LA Left approach LD Left departure RA Right approach RD Right departure CA Centre arrival CD Centre departure ALM Alarm MBA Microburst alarm WSA Windshear alarm G Gust K Knots (wind speed) +/- Gain or loss (change in windspeed) CF Centrefield MF Nautical “Miles Final” (final approach) MD Nautical “Miles Departure” (departure corridor) RWY Location (runway) * Possible alarm outside the network zone TELVENT Low Level Windshear Alert System Almos 28 LLWAS Low Level Windshear Alert System Figure 2-7 is a typical example of an AAD. Figure 2-7 Typical AAD Referring to the example display above, line 1 provides the following information: 10A Operational runway “10 Arrival” WSA Windshear alarm 46K+ Estimated wind speed gain “46 knots” 2MF Location “2 nautical miles from final” 090 Threshold wind direction “90 degrees” 12 Threshold wind speed “12 knots” No * is shown, therefore a windshear alarm outside the network area is not indicated. In the example, line 2 provides the following information: 10D Operational runway “10 Departure” WSA Windshear alarm 20K- Estimated wind speed loss “20 knots” RWY Location “Runway 10D” TELVENT Low Level Windshear Alert System Almos 29 LLWAS Low Level Windshear Alert System 090 Threshold wind direction “90 degrees” 12 Threshold wind speed “12 knots” Since no * is displayed, no windshear alarm outside the network area is indicated. Lines 5, 6, 7 and 8 are unused in this example. As the system is operating normally, line 9 remains blank. Line 10 displays the following information: CF Centrefield location 090 Wind direction “90 degrees” 16 Centerfield wind speed “16 knots” G22 Centerfield wind gusting to “22 knots” 1046 System time 1046 UTC ALM OFF Audible alarm is switched Off 2.1.7.2.3 Operation During normal operation (no windshear alarms) the AAD displays Runway Identification, Wind Direction and Wind Speed for each selected runway. The bottom line of the display (line 10) shows Centerfield Wind Direction & Speed, Gust Wind Speed, System Time (UTC) and Audible Alarm Status. Figure 2-8 An AAD in normal operation, showing no alarms. TELVENT Low Level Windshear Alert System Almos 30 LLWAS Low Level Windshear Alert System When a wind threshold is reached, the information line associated with the affected runway(s) will flash red for a predetermined period of time. The information displayed will now include data relating to the alarm condition, as described in section 2.1.7.2.2. Figure 2-9 An AAD highlighting a “Microburst Alert” for runways 10A and 28D, by flashing red for a predetermined period of time. When the “highlighting” period has expired, the AAD will stop flashing and display steady text information relating to the alarm condition. Figure 2-10 An AAD displaying “Microburst alarm” information after the highlighting period has expired. TELVENT Low Level Windshear Alert System Almos 31 LLWAS Low Level Windshear Alert System 2.1.7.2.4 Runway Threshold Configuration Display The Runway Threshold Configuration Display is an object that can be placed on a screen containing an AAD. A drop-down list allows the user to select and view any available display configuration. Figure 2-11 AAD Configuration Drop-down List Each configuration determines which runway windshear threshold information is to be displayed on the AAD. For example, if the user selects a configuration that shows the windshear information for “Runway 10 Approach and Runway 28 Departure”, then the AAD will only display windshear information relating to those two zones. The other display lines will be left blank. This saves the ATC from having to distinguish between their runway windshear thresholds and the rest of the airport. If “All Runways” is selected, then windshear information relating to all the runways is displayed. Once a configuration has been selected, this is shown on the Runway Threshold Configuration Display as illustrated below. Figure 2-12 Display Configuration Selection 2.1.7.3 Graphical Alarm Display Screens (GAD) The GAD display consists of two separate screen objects, an AAD screen object (described above) and a separate map display. Buttons at the bottom of the screen allow selection of different background bitmaps as appropriate. Because the map is a screen object, the GAD can be displayed with other data as well, such as the Supervisor’s AAD Selector (described below). The Almos Map display (GAD Object) consists of a background bitmap and numerous graphical objects overlaid upon this background. TELVENT Low Level Windshear Alert System Almos 32 LLWAS Low Level Windshear Alert System Arrows Arrows point where the wind is blowing ‘to’ by default. Sensors that are marked out of scan or in a fault condition appear as a red circle. Wind Speed Box Next to each arrow, a floating wind speed box shows the current wind speed. The box moves with the arrow in such a way so as to not obscure the arrow itself. Edge/Triangle Alarm displays During divergence/convergence detection, a red line (shaded based on strength) depicts the area in which the wind shear is being detected. Combined with the AAD object already on screen, this provides an excellent windshear warning system and situation display. Figure 2-13 LLWAS Map (Normal Operation) Triangles are displayed as shaded red areas. The degree of shading reflects the intensity of windshear within that area. A typical LLWAS Map showing areas affected by windshear is shown below. Figure 2-14 LLWAS Map (Showing Windshear) TELVENT Low Level Windshear Alert System Almos 33 LLWAS Low Level Windshear Alert System 2.1.8 Interfaces The Almos LLWAS system offered supports interfaces of up to 256 remote stations using the communications methods (radio and landline) described herein. Due to the client/server network nature of the Almos LLWAS system, the number of supported display terminals, system consoles and printers is practically unlimited. The provided network hub is may be linked to any number of additional hubs, increasing the supported number of workstations significantly. A dedicated port can be set up to send data to an external network such as the Official Airport System network. Using TCP/IP, the external connection can access real-time data from the MetConsole server. This may be used for connection to third party software of for remote diagnostics and data display. This interface is called the External Data Interface and the default format is described in detail below. 2.1.8.1 External Data Interface The Almos LLWAS system gets data in from the wind sensor stations, from threshold sensor stations and, in some cases, from other sensors around the airport. This data is distributed to many modules in the system and various calculations are performed on it. MetConsole also makes the data from the LLWAS system available to external users. 2.1.9 Algorithm Implementation Almos LLWAS MetConsole uses an efficient LLWAS algorithm implementation designed to perform all required calculations in a minimum amount of time. TELVENT Low Level Windshear Alert System Almos 34 LLWAS Low Level Windshear Alert System F i g u r e 1 5 - LLWAS Data Input Averaging (RC/Linear) is performed on the remote stations. RC and Linear averaging constants are transmitted to the remote stations based on values configured on the server. These configuration constants then can be updated at any point without visiting the remote sites. Processing averaging on the remote sites also means that only the final averaged values need be transmitted to the master station, reducing transmission time and increasing reliability. Wind Gust computation is also partially computed on the remote stations. Remote stations report 10 second average information to the master station, which in turn computes a 10 minute gust using the UAL Wind Gust Algorithm attached to this document. On the master station server, a timer calls various components of the software every second. As each component has an associated time period, it can determine if the current ‘tick’ is appropriate for executing its associated process. For example, LLWAS has an associated ten second time period. Even though LLWAS is called every second it will only execute on the tenth second – thus keeping in time with the LLWAS system cycle. Timer TICK Threshold Sensor Interface Master Station Controller(s) Process MODULES Arithmetic (Wind Gust etc) UCAR LLWAS ALGORITHM 1. Data Preparation 2. Network Statistical Analysis 3. Divergence Analysis 4. Alert Analysis 5. Format Messages SPES DQA 1. Bin Data per cycle 2. Process Periodic SPES Reports DATABASE LOGGING SERVER REPLICATION DISPLAY WIND REMOTE STATION LDL MASTER STATION SERVER KEYBOARD & MOUSE TELVENT Low Level Windshear Alert System Almos 35 LLWAS Low Level Windshear Alert System Each process is designed to operate extremely efficiently, taking only a number of milliseconds to complete. Therefore, all items executed by the timer are completed well in advance of the next timer ‘tick’. 2.1.9.1 LLWAS Algorithm Functions 2.1.9.1.1 FAA Gust Parameters 1. Time (seconds) of first variable average 2. Variable name 3. Gust calculation time period (seconds) 4. Gust variable name 5. Calculation intervals (seconds) 6. Peak_Wind_Threshold 7. CF_Threshold 8. Gust_Threshold 9. Calm_Threshold The gust algorithm uses wind measurements from an LLWAS centrefield station to determine gust wind speed. The algorithm determines peak wind speeds over a 10-minute period and compares these with a 2-minute average wind speed. This is accomplished in two stages: 1. Wind speeds during the last minute that exceed the 2-minute centerfield average by 5 knots are recorded, in order to determine a peak wind speed. 2. Recorded peak winds measured over the past 10 minute period are compared with the centerfield average wind speed, to determine a maximum peak wind speed (gust). The calculated gust wind speed is displayed for 10 minutes, unless the maximum peak wind measurements fall to within 3 knots of the centerfield average wind speed. TELVENT Low Level Windshear Alert System Almos 36 LLWAS Low Level Windshear Alert System 2.1.9.1.2 LLWASAAD Parameters Units 1. Wind direction “D” degrees 2. Wind speed “S” knots 3. Gust knots This function calculates a gust string that displays centerfield wind data at the bottom of the AAD. The string format input determines the order and content of the gust string output e.g. a string format of the form CF<DIR><SPD><G><GUST> would produce the following centerfield wind display (<G> adds the character “G” if a gust is currently valid): Wind direction – Average wind speed – Wind gust speed The gust threshold is a value set above the average wind speed. When the calculated “peak” wind exceeds the average by more than the threshold, then a gust value is displayed on the AAD. 2.1.10 Archiving / Playback The Archiver application is used to independently store data from the remote MetConsole servers. Two optional features are often installed with the Archiver to provide a full archive & replay system: • Media backup • Data replay One of a number of media backup options is available (i.e. Tape, optical disk, removable disk drive). The archiver application normally runs in the Windows task bar, and as such is usually available from the bottom right of the screen (depending on any personalised settings that may have been set up). The displayed icon may change depending on the state of the archiver: The archiver is connected to the hot server, and idle. TELVENT Low Level Windshear Alert System Almos 37 LLWAS Low Level Windshear Alert System The archiver is currently receiving data from the hot server. The archiver is unable to connect to the hot server, and is retrying. To access the archiver application, right-click on the icon (whichever icon is displayed) to display a menu. Click on Open Main Window to open the archiver application screen. Click on Close to close the archiver, or click on About to view the archiver copyright and version information. Each operation may be configured to use a password, and displays a security login box such as the following: Enter your username and password to access the software. The Main Window, once opened, is displayed similar to the following: TELVENT Low Level Windshear Alert System Almos 38 LLWAS Low Level Windshear Alert System In addition to the action buttons in the main window, four additional status fields are given: 1. Archiver Status: This indicates the current state of the archiver application. 2. Instructions Pane: This provides information on the current state, and available options, if appropriate. 3. Connection State & Progress Type: This provides a text message indicating the state of the connection. If the archiver is performing a lengthy operation, this changes to indicate the type of operation being displayed in the Progress Bar (4). 4. Progress Bar: When performing a lengthy operation, this changes to indicate the current state of the operation. The action buttons present are: Archive: Click this button to resume archiving online data from MetConsole. Stop pauses the online data archive. Reload: Reloads (restores) data from removable media storage. See Reloading Data below. Re-Play: Replays the currently available data. See Replaying Data below. Backup: Manually Backs up data to the removable media storage. The archiver goes idle during this process. Report: Reports on the most recent media operations. This is a third party report provided by the media software vendor. About: Displays the copyright message and version information. Stop: Stops the action currently being carried out. Not available when Idle. 2.1.11 Maintenance NOTE: Comprehensive Maintenance sections exist in both the WAWS Hardware Manual and the MetConsole Reference Manual. Described below is an overview of the type of maintenance tools that are available to the technical staff. TELVENT Low Level Windshear Alert System Almos 39 LLWAS Low Level Windshear Alert System 2.1.11.1 Master Station Maintenance Screens A comprehensive set of maintenance and diagnostic screens are available to the user. These features are fully described in the BITE section of this document The ‘Maintenance’ windows will only be accessible by the Maintenance user and is not required for ATC users. 2.1.11.1.1 Help Extensive use of Tool Tips is made throughout the system. Positioning the mouse pointer over most controls will display a label with information about the control or the item of data being displayed. Example of tool tips Pressing F1 will bring a context sensitive Windows Help file with help, tips, and guidance and specific tasks. Extensive on-line help is available TELVENT Low Level Windshear Alert System Almos 40 LLWAS Low Level Windshear Alert System Right clicking on any variable brings up more information about the point including details about any fault status. 2.1.11.1.2 Alarms and Events The system monitors all incoming weather variables and can detect a variety of faults in the data stream. Data faults include: • Primary/Secondary Server Failure. • Communications faults. • Sensor faults. • Missing data. • Value too high or too low. • Value higher or lower than airport operating maxima. • Value jumping too rapidly from value to value • Value “frozen” within a small range of value. Acceptable ranges can be set arbitrarily on any point. And any test can be omitted. As alarms occur they are printed on the system printer, stored in the Windows NT event log, stored in a database file, and if the alarm or event requires acknowledgment is placed in an alarm list in a toolbar the server. The current alarm list is displayed in a toolbar. 2.1.11.1.3 Technicians functions There are a number of trouble shooting screens built in to the system to assist technicians. The “Technical Reference Manual” provides descriptions of how to use these screens. TELVENT Low Level Windshear Alert System Almos 41 LLWAS Low Level Windshear Alert System Terminal data for sensor interface 2.1.11.1.4 GPS Time Sync Our time synchronisation system reads the external time messages and compares the time to the server’s clock. If the time is inaccurate then the software will: 1. Remove or insert milliseconds off each tick of the clock until the PC time matches the external clock, and the server becomes in sync. 2. Compute the exact inaccuracy of the PC clock compared to the reference, and then remove or insert milliseconds from each clock tick to proactively ensure that the time remains in sync. Because we are always making minor changes to the time there cannot be “jumps” in the data set caused by the time changing rapidly. The unique proactive correction of the PC clock ensures that accuracy is maintained even if the time source is lost for an extended period of time. The time setting functions provide a facility for entering the time in the absence of an external time source. These allow the user to enter the time on the primary server; the time is simultaneously broadcast across the network, with each PC updating its time as required. TELVENT Low Level Windshear Alert System Almos 42 LLWAS Low Level Windshear Alert System All system functions are timed relative to the server’s PC clock, and all other PCs time is set to match the server’s time. Each master station computer is fitted with a removable, rechargeable battery backup on the internal clock, ensuring maximized lifetime on the real-time clock components. 2.1.11.1.5 Watchdog Almos supplies watchdog hardware that monitors all system operations. An independent hardware card installed in the machine monitors the MetConsole software. In the event of any failure of hardware, operating system, or the application program, (which prevents normal operation) the PC is completely reset. This substantially reduces the number of fault callouts and significantly improves the MTTR. 2.1.11.1.6 Remote Access We provide a remote dial in server utilising Microsoft Remote Access Service (RAS). This facility permits access to monitoring and diagnostics of the system by Almos. This port can also be used for centralised monitoring of the system. This can also be used to remotely upgrade or reconfigure the system. Of course this feature is password protected and can be enabled and disabled as required. 2.1.11.2 Built–In Test Equipment - BITE In an airport environment, due to the requirements to keep repair and downtime to the absolute minimum, an automatic failure detection and isolation system referred to as built-in-test equipment (BITE) is implemented on all equipment. BITE functions are primarily performed by software resources. The primary objective of BITE is to correctly detect system malfunctions and accurately fault-isolate to a single replaceable unit so that maintenance staff with a minimum of training are able to perform this function. Failures undetected by BITE will be kept to a minimum. The BITE will be capable of isolating faults down to LRU level in most fault cases. 2.1.11.2.1 BITE Requirements BITE functionality is integrated into the different equipment in order to avoid external test equipment for stimuli and measuring purposes. BITE functions do not interfere with the operational of the system. TELVENT Low Level Windshear Alert System Almos 43 LLWAS Low Level Windshear Alert System 2.1.11.2.2 BITE Functions include: • Intelligent wind sensor is offered with BITE functions. Results are continuously received and checked by the Remote Station in the form of Status messages. • *Sensor data is checked both for data format errors and for data quality errors. Error checks include sampling the status information provided by the sensors. • Remote station serial interface to Wind Sensor can be tested by executing a loop-back command that results in receiving characters transmitted on the Tx line. This way serial interface errors can be differentiated from sensor errors. • *Remote station basic operational parameters, such as availability of mains supply, internal enclosure temperature, battery status, EPROM CRC etc are monitored and the results are reported back • Full Remote Station testing facilities, including built-in software and hardware diagnostic functions, are available through a Maintenance Interface Port. Operational status, current sensor data and raw sensor data can be displayed. • Radio BITE features are available through a serial interface. • *Remote Station radio communication quality can be tested using a built-in Bit Error Rate Mode. This mode can be activated by a remote command. • Communication ports are tested by heart beat packets sent between computers • Analog signals are tested to cross acceptable low and high levels • Watchdog cards in all PCs and Remote Stations test fatal system errors. Automatic restarts are generated after error detection. • RAM memory is tested in PCs and the Remote Stations at system reset. • All memory components in the Remote Stations are checksum tested at system reset. TELVENT Low Level Windshear Alert System Almos 44 LLWAS Low Level Windshear Alert System • Software execution integrity is tested and fault information including Detailed CPU instruction information) logged prior to watchdog intervention. Note: BITE functions marked * are sufficient to satisfy the latest FAA LLWAS Remote Station BITE requirements. Additional BITE was added by Almos to further simplify installation and maintenance. 2.1.11.2.3 Features: Unit Fault detectio n Isolation False Alarm Sensor Yes Automatic No Remote Station Yes Automatic Communication link fault can be isolated by communication LEDs No Server computer Yes Automatic. Communication link fault can be isolated by communication LEDs on modems and network hub. No Workstation Yes As above No Printer Yes Semi-automatic, as provided by manufacturer (Status display indicates LRU fault). No 2.1.11.3 Site Performance Evaluation System (SPES) A very attractive module is the Site Performance Evaluation System (SPES). This software module runs a Data Quality Analysis algorithm developed by MIT’s Lincoln Laboratories to analyse the performance of the wind sensors in real time. The algorithm compares the raw values of all sensors to the network mean and then makes judgments about possible siting problems or accuracy problems with each sensor. Provided as a standard item with Almos LLWAS systems, is an additional PC for the purpose of running and displaying SPES Data Quality Analysis. The additional SPES workstation provides technical monitoring facilities for network data quality analysis. An additional MetConsole component (Module) is installed and configured on the server pair for processing of SPES data. TELVENT Low Level Windshear Alert System Almos 45 LLWAS Low Level Windshear Alert System 2.1.11.3.1 Introduction The integrity of wind data received from each remote weather station is evaluated by the SPES. This is achieved by constantly comparing the wind speed and direction information received from each station with the overall network mean values. Note For a data poll to be valid for SPES, there must not be a windshear or microburst indicated on the LLWAS system. Also, the wind speed must be greater than 3 metres per second (6 knots) at the time of the poll. 2.1.11.3.2 Integrity Evaluation The SPES wind data evaluation is based upon two separate, but related, tests. These are: • Wind speed • Wind direction 2.1.11.3.2.1 Wind Speed Test Wind speed data is collected from all the weather station sensors and a mean value calculated. The ratio of variation with the mean value is then calculated for each individual weather station. The calculated variation ratios are stored in groups, based upon wind direction. This enables the system to determine whether the variations in wind speeds for a particular station are related to a few directions only, or all directions. Sensor status in relation to wind speed data is given by the following SPES messages: • Sheltering • Frictional drag or sensor situated too low • Wind channelling. • Sensor situated too high 2.1.11.3.2.2 Wind Direction Test Wind direction data is collected from all the weather station sensors and a mean value calculated, similarly to wind speed. Wind directions are compared TELVENT Low Level Windshear Alert System Almos 46 LLWAS Low Level Windshear Alert System to the mean wind direction for the network and the mean variation is stored. The variations are stored in groups of similar variations for each station. If the percentage of ratio differences is greater than a predetermined figure over a certain time, it may be determined that there is a problem with the sensor, or that the orientation of the station is not correct. Sensor status in relation to wind direction data is given by the following SPES messages: • Sensor orientation incorrect • Electrical grounding fault • Loose mounting or sticky wind-vane bearings 2.1.11.3.3 SPES Screens The SPES has two types of screen: • A” Site Performance Evaluation System” screen • (Shows the general status of all weather stations) • A “Station Analysis” screen for each individual weather station in • The LLWAS system • (Provides more detailed information about each weather station) 2.1.11.3.3.1 “Site Performance Evaluation System” Screen This screen shows the wind speed and wind direction status of each weather station on the system. TELVENT Low Level Windshear Alert System Almos 47 LLWAS Low Level Windshear Alert System 2.1.11.3.3.2 “Station Analysis” Screen By clicking on a Details button on the “Site Performance Evaluation System” screen, specific information about a particular station can be viewed on its Analysis screen. A typical Station Analysis screen is shown below. Figure 2-16 SPES “Station Analysis” Screen A station’s Analysis screen displays data integrity information about its wind sensors on 3 graphs and a wind gauge. Each graph provides the user with a different perspective on the data received from the weather station. Each Analysis screen also has a Windrun gauge and Wind Rose display related to that station. Although not actually part of the SPES, they provide useful wind related information to the user. The Windrun gauge plots the amount of wind in meters per second, measured by the sensor, on a rotating time axis. The axis is configurable, but set to 24 hours for Chaing Kai Shek airport. The Wind Rose provides a real-time graphical indication of wind direction and speed in accordance with the LLWAS system 10-second wind data. TELVENT Low Level Windshear Alert System Almos 48 LLWAS Low Level Windshear Alert System Speed Ratio over Direction Graph This graph shows the sensor performance as a ratio to the network mean value, over the last large sample of polls. This ratio is represented on the bar graph horizontal axis for every direction with a vertical incremental scale of 0.00 to 2.00. In a “perfect” system a weather station would return a value that is the same as the network mean, thus registering a ratio of unity. The graph would then plot a value of 1.00 for all directions. Difference from Mean (Wind Gauge) The wind gauge displays the ratio shown on the “Speed Ratio over Direction Graph” on a rotating axis. The gauge axis is the same as the graph, i.e. 0.00 to 2.00. For the “perfect” system referred to above, the sensor would display a ratio of 1.00 in all directions and plot a circle halfway into the gauge. If a calculated ratio is low, then the gauge plot will be nearer the centre for that direction. If the ratio is high then the plot will be nearer the outside of the gauge for that direction. In practise, wind speed ratios can differ from 1.00 for various reasons. For example, if all the ratios are low his may indicate a wind speed sensor bearing problem causing it to rotate slowly. Both the “Speed Ratio over Direction Graph” and the “Difference from Mean” wind gauge indicate to a user if there is an obvious problem with a station sensor and whither the problem is directional or not. Speed Ratio Frequency Graph This graph shows the ratio of the weather station wind speed sensor data average against the network wind speed average, for all directions. A “perfect” system would register a ratio of 1.00 in all directions. Direction Difference Frequency Graph This graph shows the percentage difference between the weather station’s sensor direction average against the network direction average. A difference of ±5º is considered acceptable. TELVENT Low Level Windshear Alert System Almos 49 LLWAS Low Level Windshear Alert System 2.1.11.4 Installation and Maintenance Tools 2.1.11.4.1 Communications Testing Tools Due to the fact that the entire communication system is based on digital radios and a digital protocol, all communication analysis is done in software. Other devices are not needed to isolate faults and monitor the communications however the IFR 1600 is quoted as an option. 2.1.11.4.1.1 Communication Service Monitor The equivalent of the Communication Service Monitor is a software package that is delivered with the digital radios. Please see the Maintenance section in the WAWS Installation and Maintenance Manual. 2.1.11.4.1.2 Serial Communication Analyser The Technicians Screens in the MetConsole software running on the Master Station Servers may be used to analyse the digital communication traffic. These screens are described in the Maintenance Section of the MetConsole Reference Manual. 2.1.11.4.2 Installation Tools The following is a list of the tools which will be provided for the installation and servicing of the LLWAS equipment : 1) Adjustable Spanners- • 6" • 10" 2) Crimp Tools- • Suitable for Bootlace Ferrules • Suitable for crimp lugs used • Suitable network RJ45 plugs (8 way 8 contact) • Suitable for RF connectors used 3) Drill Bit Set - 4) Drill – Battery type 5) Hexagon Key Set - Imperial Sizes 6) Pliers - • Long Nose TELVENT Low Level Windshear Alert System Almos 50 LLWAS Low Level Windshear Alert System • Linesman’s • Sidecutters 7) Knife with snap-off blades 8) Scissors 9) Screwdrivers - • 3.5mm Flat Blade • 5mm Flat Blade • No.0 Posidriv • No.1 Posidriv • No.2 Posidriv 10) Weller Soldering Iron & Solder 11) Wire Strippers 12) 60mm Mini Bench Vice 2.1.12 System Modes (States) The LLWAS software runs in a number of states based on the availability of remote stations in the network, and the presence of maintenance activities being carried out on the system. These states are described in detail below. 2.1.12.1 Real Time Normal All remote stations and text displays (AADs) are fully operational. 2.1.12.2 Real Time Degraded At least one remote station is not operational and at least a specified number of remote stations are operational. This specified number is a parameter defined in the CAA furnished configuration files. The system is also in the Real Time Degraded state when fewer than all of the text displays (AADs) are operational. 2.1.12.3 System Support Fewer than a specified number of remote stations have been operational for a period of time. The specified number of remote stations is a parameter defined in the CAA furnished configuration files. The period of time is defined by the algorithm's ability to fill data gaps. (Refer to the algorithm specification in Appendix A) TELVENT Low Level Windshear Alert System Almos 51 LLWAS Low Level Windshear Alert System The system is also in the System Support state whenever the system determines that at least one of the configuration files is invalid or whenever other serious unexpected system problems are encountered. 2.1.12.4 Initialization The system state during the period of time required for the system to start up from the powered off condition until it is processing adequate data to start displaying wind data, wind shear and microburst alerts (as defined in the algorithm specification). The system shall complete its initialization procedures and restore itself to real time operational capability within five (5) minutes (MAXINIT) after the restoration of the facility power sources. During initialization wind and windshear alert information is not displayed on the Text Displays (AAD). 2.1.12.5 Off No power is being provided to the master station controller. The Text Displays shall indicate that they are no longer receiving data from the LLWAS master station. 2.2 Configuration File All MetConsole stations are configured through a single shared configuration database. This database file contains configuration information pertaining to the role of each station on the network (primary server, secondary server, archiving PC, SPES workstation, operator workstations, displays etc). In addition, the configuration database contains LLWAS parameters contained in the ACF, SPES thresholds & parameters, DCF configurations and other configuration data. TELVENT Low Level Windshear Alert System Almos 52 LLWAS Low Level Windshear Alert System Figure 17 - LLWAS System Configuration (Typical) The advantage of this shared configuration database approach is that systemwide configuration can be achieved through reconfiguration of a single central source file. The configuration database is centrally stored and changes to this file are automatically integrated by MetConsole instances operating across the network. MetConsole operates through ODBC, Microsoft’s Open Database Connectivity technology. ODBC makes the choice of database dependant only on system requirements. Microsoft Access can be used; likewise Oracle 8, SQL Server 7 and other technologies can be used. The configuration database is accessible using common tools (i.e. Microsoft Access) and providing a simple and easy to learn interface for all users. This open architecture does not limit the MetConsole system to any single database technology. This advantage allows Almos MetConsole users to operate a database that best suits their unique individual requirements, rather than a single database that is not perfectly suited to their situation. The final database format is yet to be determined; the final database format will be chosen based on the overall performance of the system and will be formally tested and approved at the Factory Acceptance Test. Changes to ACF (Airport Configuration File) and DCF (Display Configuration File) are implemented directly in the configuration database, which is in turn secured via Windows NT security (only accessible from the master station to authorized users). Facilities are provided for the import of these files, allowing easy implementation of future siting changes. SYSTEM CONFIGURATION (SCF) and MAINTENANCE CONFIGURATION (MCF) (Averaging constants, Displays, Parameters, etc) AIRPORT CONFIGURATION FILE (ACF) DISPLAY CONFIGURATION FILE CONFIGURATIO DATABAS (METCFG.MDB AAD DISPLAY SYSTEM INPUT DEVICE ARCHIVE STATION KEYBOAR D & MOUSE AAD DISPLAY SYSTEM INPUT DEVICE AAD DISPLAY SYSTEM INPUT DEVICE RAW CONFIGURATION FIL ES & PARAMETER S SHARED (BOTH LLWAS MetConsole Overvie TELVENT Low Level Windshear Alert System Almos 53 LLWAS Low Level Windshear Alert System 2.2.1 ACF The Airport Configuration File (ACF) shall be created by Almos Systems based on the results of the Site Survey and expertise and software from NCAR. This procedure has already been successfully performed at two Phase III LLWAS Installations. 2.2.2 DCF A standard Display Configuration File (DCF) shall be created by Almos Systems. This may be altered to suit the customers individual needs. 2.2.3 MCF, SCF The MCF (Maintenance Configuration File) and SCF (System Configuration File) are standard parts of the LLWAS Configuration database. They may be altered but there is generally no need to do so. 3. Reliability, Maintability, Availability (RMA), and Supportability 3.1 RMA Characteristics This section describes Almos RMA performance, including but not limited to Mean Time Between Failure(MTBF), Mean Time Between Corrective Maintenance Action(MTBCMA), Mean Time Between Critical Failures(MTBCF), Built in Test and Fault Isolation capability, Mean Time To Repair(MTTR), and inherent availability. 3.1.1 Mean Time Between Failure (MTBF) / Mean Time Between Critical Failures (MTBCF) The equipment offered, including computer software, have been proven in a number of airport installations. They are of high quality, off-the-shelf and commercially available, and are capable of operating continuously with a high degree of reliability. Particulars of existing installations using the type of equipment offered are attached. The most critical component in the system is the central computer. The solution offered is based on a Hot Standby solution, which has been used in a number of AWOS systems. The failure rates of all components were considered. Note that neither Compaq nor IBM would publish MTBF figures for their workstations or servers (even though we are a Compaq distributor). Consequently we have used TELVENT Low Level Windshear Alert System Almos 54 LLWAS Low Level Windshear Alert System estimates based on our experience with this equipment. Assuming that the MTBF of the PC is as low as 5,000 hours (about half a year) and assuming that the MTTR for the PC is one hour (swapping with spares). In this case duplicating the server will increase the MTBF beyond the lifetime (20 years) of the system. The sensor interface units offered are identical with the ones used in the Almos Automatic Weather Stations. These stations are currently used by the Australian Bureau of Meteorology. Almos has been the exclusive supplier of Automatic Weather Stations to the Australian National Weather Network since 1993. Based on official service records MTBF calculations are shown below (Error! Reference source not found. MTBF Evaluation), which show MTBF better than 30 years. On the basis of above considerations the Mean Time Between Critical Failures (MTBCF), which would stop operation of the Central Computer or one of the Remote Stations is larger than 20 years. Mean Time Between Failures (MTBF), which includes wind sensor errors and potential display errors is estimated to be 10,000 hours. 3.1.2 Mean Time Between Corrective Maintenance Action (MTBCMA) The only component that requires regular maintenance in the proposed system is the wind sensor. MTBCMA = 1 year 3.1.3 Built in Test and Fault Isolation capability Due to the requirements to keep repair to the absolute minimum, the impact on operational readiness and the maintenance concept adopted, automatic failure detection and isolation, referred to as built-in-test equipment (BITE) will be implemented on all equipment and monitored. BITE functions are mostly performed by software resources. The primary objective of BITE is to correctly detect system malfunctions and accurately fault-isolate to a single replaceable unit so that maintenance staff with a minimum of training is able to perform this function. Failures undetected by BITE will be kept to a minimum. The BITE will be capable of isolating faults down to LRU (SRU) level in at least 80% of fault cases. BITE function will be integrated into the different equipment in order to avoid external test equipment for stimuli and measuring purposes. BIT functions will not interfere with the operational of the system. BITE functions include: TELVENT Low Level Windshear Alert System Almos 55 LLWAS Low Level Windshear Alert System • Sensor data is checked both for data format errors and for data quality errors. Error checks include sampling the status information provided by intelligent sensors. • Communication ports are tested by heart beat packets sent between computers • Fatal system errors are tested by Watchdog cards in all PCs and Remote Stations. Automatic restarts are generated after error detection. • RAM memory is tested in PCs and the Automatic Weather Stations at system reset. • All memory components in the Remote Stations are checksum tested at system reset. 3.1.4 Mean Time To Repair (MTTR) The computer equipment will be repaired by swapping complete units with spare, which will take average 15 minutes. Remote Stations will be repaired by swapping cards. Using the advanced Almos Diagnostic Tools faults can be diagnosed and cards swapped within 30 minutes plus traveling time. Sensors will be repaired by swapping them with spares. Due to the fact that access to some sensors is cumbersome the repair time would take one hour average. Unit Fault detection Isolation False Alarm Sensor yes The system will detect most sensor faults no Remote Station yes As above. Communication link fault can be isolated by communication LEDs no Server computer yes Automatic. Communication link fault can be isolated by communication LEDs on modems no Display Workstation yes As above no Printer yes Automatic no TELVENT Low Level Windshear Alert System Almos 56 LLWAS Low Level Windshear Alert System 3.1.5 MTBF Evaluation 3.1.5.1 Purpose The purpose of this evaluation is to calculate the reliability of the Almos supplied hardware. 3.1.5.2 References Collection of reliability, availability and maintainability data for electronics and similar engineering use - AS2529, 1982 Presentation of reliability data on electronic and similar components (or parts) AS2530, 1982 Reliability and maintainability - Introductory guide - AS3930, 1992 Reliability Prediction Procedure For Electronic Equipment - Bellcore TR-NWT- 000332, Issue 4, September, 1992. 3.1.5.3 Definitions MTBF - (Mean Time Between Failure) - Average time (expressed in hours) that a component works without failure. It is calculated by dividing the total number of failures into the total number of operating hours observed. Also, the length of time a user may reasonably expect a device or system to work before an incapacitating fault occurs. MTTF - Related acronym (Mean Time To Failure) which is frequently used interchangeably with MTBF. 3.1.5.4 Approach Almos established via test data obtained under the operating environment required for the REMOTE STATION hardware and by analysis of existing data, that the supplied hardware will meet the mean-time-between failure (MTBF) of 30,000 hours. 3.1.5.5 Reliability Data The data used in this analysis was extracted from the population of equipment installed for the Australian Bureau of Meteorology and relates to similar hardware operating under similar conditions to those proposed for the REMOTE STATION. Upon request, a spreadsheet is available which provides the raw data used to obtain the figure shown below as Total Hours. TELVENT Low Level Windshear Alert System Almos 57 LLWAS Low Level Windshear Alert System Data Item Value Used in Calculations Oldest Unit (Years) 3.6 Yes Machine Population 222 Yes Total Hours 3,162,240 Yes Failures 11 Yes NFF 0 No User Caused 3 No Table 1 - Field Failure Data 3.1.5.6 Reliability Calculations MTBF is Mean Time Between Failure and is typically expressed in hours. The hours are calculated by dividing the total number of failures into the total number of operating hours observed. For Almos, MTBF represents the average number of hours a field population will work before a failure occurs. 3.1.5.6.1 General Assumptions 3.1.5.6.1.1 User caused failures Any failure that was directly attributed to user negligence or abuse has been shown in Table 1 but has not been included in the MTBF calculation. 3.1.5.6.1.2 No fault found Units returned are subjected to extensive testing before release back to the customer. Units with “No Fault Found” have been shown in Table 1 but have not been included in the MTBF calculation. 3.1.5.6.2 Method 1 3.1.5.6.2.1 Basis of Calculation Age of units - The population of equipment used in this analysis was supplied over a period of time. It is assumed that the rate of supply of equipment is a constant and the average age of all units is therefore half the age of the oldest unit. Operating Hours - The equipment is assumed to be in service for 100% of the time. (24x7x365) TELVENT Low Level Windshear Alert System Almos 58 LLWAS Low Level Windshear Alert System 3.1.5.6.2.2 Calculation MTBF = MTBF = = 318,227 hours = 36.3 years 3.1.5.6.3 Method 2 3.1.5.6.3.1 Basis of Calculation Actual Operating Hours - The population of equipment used in this analysis was supplied over a period of time. The actual year and month of supply for each individual unit was used to obtain the age of the equipment. This was used to calculate the total hours since supplied. (Refer to attached Spreadsheet) Operating Hours - It was assumed that each item was not installed for one month after being supplied and thereafter has been in service for 100% of the time. (24x7x365) 3.1.5.6.3.2 Calculation MTBF = MTBF = = 272,945 hours = 31.2 years 3.1.5.7 Results The lowest figure provided by the two methods used has been selected as the more accurate, being based on actual dates rather than an assumption about the linearity of supply. MTBF = 31.2 Years. 3.2 Supportability The system has many built in test (BITE) and diagnostic features, which make the maintenance of the system very efficient for trained personal. Remote diagnostics means that engineers from Almos Systems headquarters may dial into the system and analyse any faults that are being reported. The Site Performance Evaluation Subsystem which is offered as a standard tool, aids in the long-term accuracy of the LLWAS system. Local support and warranty service is usually provided through appointed subcontractors

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Technical Proposal Low Level Windshear Alert System