【仪表工程】AIRBORNE NAVIGATION DATABASES.pdf
《【仪表工程】AIRBORNE NAVIGATION DATABASES.pdf》由会员分享,可在线阅读,更多相关《【仪表工程】AIRBORNE NAVIGATION DATABASES.pdf(15页珍藏版)》请在三一文库上搜索。
1、A-1 EVOLUTION OF AIRBORNE NAVIGATION DATABASES There are nearly as many different area navigation (RNAV) platforms operating in the National Airspace System (NAS) as there are aircraft types. The range of systems and their capabilities is greater now than at any other time in aviation history. From
2、the sim- plest panel-mounted LOng RAnge Navigation (LORAN), to the mov- ing-map display global positioning system (GPS) currently popular for general aviation aircraft, to the fully integrated flight management system (FMS) installed in corpo- rate and commercial aircraft, the one common essential e
3、lement is the database. Figure A-1 RNAV systems must not only be capable of determining an air- crafts position over the surface of the earth, but they also must be able to determine the location of other fixes in order to navigate. These systems rely on airborne navigation databases to provide deta
4、iled information about these fixed points in the airspace or on the earths surface. Although, the location of these points is the pri- mary concern for navigation, these databases can also provide many other useful pieces of information about a given location. HISTORY In 1973, National Airlines inst
5、alled the Collins ANS- 70 and AINS-70 RNAV systems in their DC-10 fleet; this marked the first commercial use of avionics that required navigation databases. A short time later, Delta Air Lines implemented the use of an ARMA Corporation RNAV system that also used a navigation database. Although the
6、type of data stored in the two sys- tems was basically identical, the designers created the databases to solve the individual problems of each sys- tem. In other words, the data was not interchangeable. This was not a problem because so few of the sys- tems were in use, but as the implementation of
7、RNAV systems expanded, a world standard for air- borne navigation databases had to be created. In 1973, Aeronautical Radio, Inc. (ARINC) sponsored the formation of a committee to standardize aeronauti- cal databases. In 1975, this committee published the first standard (ARINC Specification 424), whi
8、ch has remained the worldwide-accepted format for coding airborne navigation databases. There are many different types of RNAV systems certi- fied for instrument flight rules (IFR) use in the NAS. The two most prevalent types are GPS and the multi- sensor FMS. Figure A-1. Area Navigation Receivers.
9、A-2 Most GPSs operate as stand-alone RNAV systems. A modern GPS unit accurately provides the pilot with the aircrafts present position; however, it must use an air- borne navigation database to determine its direction or distance from another location unless a latitude and longitude for that locatio
10、n is manually entered. The database provides the GPS with position information for navigation fixes so it may perform the required geo- detic calculations to determine the appropriate tracks, headings, and distances to be flown. Modern FMSs are capable of a large number of func- tions including basi
11、c en route navigation, complex departure and arrival navigation, fuel planning, and precise vertical navigation. Unlike stand-alone naviga- tion systems, most FMSs use several navigation inputs. Typically, they formulate the aircrafts current position using a combination of conventional distance mea
12、suring equipment (DME) signals, inertial navigation systems (INS), GPS receivers, or other RNAV devices. Like stand-alone navigation avionics, they rely heavily on air- borne navigation databases to provide the information needed to perform their numerous functions. DATABASE CAPABILITIES The capabil
13、ities of airborne navigation databases depend largely on the way they are implemented by the avionics manufacturers. They can provide data about a large variety of locations, routes, and airspace segments for use by many different types of RNAV equipment. Databases can provide pilots with informatio
14、n regard- ing airports, air traffic control frequencies, runways, special use airspace, and much more. Without airborne navigation databases, RNAV would be extremely lim- ited. PRODUCTION AND DISTRIBUTION In order to understand the capabilities and limitations of airborne navigation databases, pilot
15、s should have a basic understanding of the way databases are compiled and revised by the database provider and processed by the avionics manufacturer. THE ROLE OF THE DATABASE PROVIDER Compiling and maintaining a worldwide airborne navi- gation database is a large and complex job. Within the United
16、States (U.S.),the Federal Aviation Administration (FAA) sources give the database providers information, in many different formats, which must be analyzed, edited, and processed before it can be coded into the database. In some cases, data from outside the U.S. must be translated into English so it
17、may be analyzed and entered into the database. Once the data is coded following the specifications of ARINC 424 (see ARINC 424 later in this appendix), it must be continu- ally updated and maintained. Once the FAA notifies the database provider that a change is necessary, the update process begins.1
18、The change is incorporated into a 28-day airborne database revision cycle based on its assigned priority. If the information does not reach the coding phase prior to its cutoff date (the date that new aeronautical information can no longer be included in the next update), it is held out of revision
19、until the next cycle. The cutoff date for aeronautical databases is typically 21 days prior to the effective date of the revision.2 The integrity of the data is ensured through a process called cyclic redundancy check (CRC). A CRC is an error detection algorithm capable of detecting small bit-level
20、changes in a block of data. The CRC algorithm treats a data block as a single (large) binary value. The data block is divided by a fixed binary number (called a “generator polynomial”) whose form and magnitude is determined based on the level of integrity desired. The remainder of the division is th
21、e CRC value for the data block. This value is stored and transmitted with the cor- responding data block. The integrity of the data is checked by reapplying the CRC algorithm prior to dis- tribution, and later by the avionics equipment onboard the aircraft. RELATIONSHIP BETWEEN EFB AND FMS DATABASES
22、 The advent of the Electronic Flight Bag (EFB) dis- cussed in Chapter 6 illustrates how the complexity of avionics databases is rapidly accelerating. The respec- tive FMS and EFB databases remain independent of each other even though they may share some of the same data from the database providers m
23、aster naviga- tion database. For example, FMS and GPS databases both enable the retrieval of data for the onboard aircraft navigation system. Additional data types that are not in the FMS database are extracted for the EFB database, allowing replace- ment of traditional printed instrument charts for
24、 the 1The majority of the volume of official flight navigation data in the U.S. disseminated to database providers is primarily supplied by FAA sources. It is supplemented by airport managers, state civil aviation authorities, Department of Defense (DOD) organizations such as the National Geospatial
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 仪表工程 【仪表工程】AIRBORNE NAVIGATION DATABASES 仪表 工程 AIRBORNE
链接地址:https://www.31doc.com/p-3803885.html