A320导航简述

jinyuhemuyu · 发表于 2007-3-17 15:10:14

Lesson Twenty
Navigation (I)
Part One
Warming-up activities
I. Basic Vocabulary Study
VOR (Very-High-Frequency Omini-directional Range): 甚高频全向信标
VOR orientation  VOR 定向, 定位
Air Data Inertial Reference Units (ADIRU)
Digital Distance and Radio Magnetic Indicator (DDRMI) 数字距离无线电磁指示器
Ground Proximity Warning System (GPWS)
ATC transponders
ADF (Automatic Direction Finder: 自动定向仪
DME (Distance Measuring Equipment):测距仪
dead-reckoning       推测领航
pilotage         地标领航
AGL  above ground level    离地高度
PFV  flight path vector 飞行航经引导
Laser gyro          激光陀螺
Beacon    信标台

II. Background knowledge
It is many years since a pilot had to keep glancing at a simple magnetic compass to tell him which way he was heading .As air travel itself has developed ,so have the navigational aids both aboard the aircraft and on the ground. The first of these ‘navaids ’to be carried aboard was the direction-finding loop aerial. It rotated, picking up signals from ground stations which be identified on a map carried by the pilot. Information from two ground stations enabled him to fix his position. By today’s standard it sounds long-winded but it was a great advance on a naked eye. On today’s aircraft there is no need for pilot to make any calculations himself as it is all done automatically by far more sophisticated equipment.
The airspace above our heads is teeming with aircraft all flying off to different destinations at different altitudes. Regardless of where they are heading they must all rely on the ground to guide them at least in the initial part of their flight. However sophisticated the equipment on the flight deck, nearly all will still require some signal from the ground from which to take bearings. At present the most common ground system is the Very High Frequency Omni-directional Range (VOR) beacon. The pilot finds his way along a route by flying from one VOR beacon to the next. He knows where they are from a map of the area, which shows each beacon represented by a large compass rose with a six- side symbol in the center. Each one shown on the map will be identified by its station name, frequency and Morse call sign.
The VOR station itself is usually housed in a solid, pillbox structure standing on an unobstructed hill top, in open fields or on other exposed ground. Transmissions from the beacon are made on the VHF radio band between 112MH/z and 118MH/z. because the pilot steers by a direction indicator synchronized with a magnetic compass, magnetic rather than true information is used. The idea of the beacon is to inform the airborne receiver of the bearing of the aircraft in relation to the ground station which sends out two signals. One signal sent out from the ground is ‘omni-directional’ and the other is a rotating directional signal. The airborne receiver ‘listen’ to both signals, compares the time lapse between receiving them and then uses this information to calculate the bearing in degrees from magnetic north. If the signals are simultaneous or “in phase’, the aircraft is positioned along the Magnetic North bearing or ‘radial’. The time difference between the signals enables the aircraft’s instrument to calculate along which radial the aircraft’s position lies.
Aboard the aircraft itself the equipment consists lf a receiver, an indicator unit and a V-shaped aerial. The receiver has an on /of switch with an identification position to bring in the three-letter Morse signal transmitted at intervals by the ground station to identify itself.
An aircraft following a particular radial will in time reach the ground station and pass over its. If the pilot continues on the same course without resetting his VOR equipment, the instrument will tell him that he is still flying the course of the selected radial but that his position is now on the line of the radial extended beyond the station. It tell him this by a small sign or flag on the indicator unit which changes from ‘TO’ to FROM’.
Comprehension exercises
1. What was the mostly used by a pilot to find his way in the past?

2. How many ground stations information can a pilot fix his position?

3. What can you find on symbol of the VOR station in the map of area?

4. Where can you find the VOR station?

5. For VOR navigation what equipments should you have onboard ?

6. In the last sentence what does the word “To” and “from “mean?

Part Two Navigation (I)
Text Study
General Presentation
The navigation system is divided into three main groups: Air Data and Inertial Reference System (ADIRS) plus stand-by instruments; Radio navigation; Additional navigation systems. There are several subsystems within each group. The first group includes Air Data Inertial Reference Units (ADIRU), Global Positioning System (GPS), Stand-by instruments. The radio navigation group includes radio navigation aids, radio altimeters, digital Distance and Radio Magnetic Indicator (DDRMI). Additional navigation systems include: •Ground Proximity Warning System (GPWS), ATC transponders, weather radar.

Air Data Inertial Reference System
The purpose of the Air Data Inertial Reference System (ADIRS) is to provide air data and  inertial information to the EFIS system, the FMGC and other users.
   The A320 is equipped with three separate but identical Air Data Inertial Reference Units. Each ADIRU combines an Air data reference computer, or ADR and a laser gyro inertial reference system, or IR. The ADR and IR systems of each ADIRU operate independently, and failure of one system will not cause failure of the other.
   The ADR part receives information from aircraft probes and sensors and provides various air data to the Flight Management and Guidance Computers (FMGC) and other users. The air data provided include; Mach, Airspeed, Temperature, Over-speed warnings, barometric altitude, and angle of attack.

   The IR part provides inertial data to the FMGC, EFIS and other users. The inertial data provided include: Track, Heading, Acceleration, Flight Path Vector, Airplane Position, Ground speed and Attitude.
   The three ADIRS are controlled through the ADIRS panel located on the overhead panel. Their initialization is done through the two MCDU located on the pedestal. And by two of the switches on the SWITCHING panel located at the front of the pedestal. Independent data are supplied by each ADIRU.


   In the EFIS system ADIRU 1 supplies the captain’s EFIS, and ADIRU 2 supplies the first officer’s EFIS. ADIRU 3 is available as a stand-by to either EFIS system via the switching panel.
   Now let’s look at the ADIRS Control Display Unit. The panel is divided into two parts. The upper section for the IR and the lower section for the ADR. The three rotary mode selectors have control over both the IR and the ADR. The controls and indicators for the individual ADIRU are grouped and arranged in the order of 1,3 and 2. Each ADIRU has an associated IRS rotary mode selector. In the ‘OFF’ position, the ADIRU is not energized, so ADR and IR data are not available. The three ADR switches normally remain on, but they can be selected off in response to ECAM procedures. In the ‘NAV’ position the ADIRS are energized. The ‘NAV’ position is the normal mode of operation and full inertial data is provided to the aircraft systems.

The ON BAT light illuminates to inform the crew that the ADIRU system is being powered by aircraft battery only.
Each Inertial Reference Unit has an associated indicator. The ALIGN light illuminates steady white when the respective IRU is operating normally in ALIGN sequence mode. The ALIGN light flashes white if : There is an IRU alignment fault, or no present position entry has been made after 10 minutes or the difference between the position at shutdown and the entered position exceeds 1 degree of latitude or longitude.
   Present position information for ADIRS alignment is normally entered via the INIT page of the MCDU.
The system selector enables the crew to switch the display off, or select one of the three ADIRU for display. For example we select system 3. The display now contains the present position, or PPOS, information for ADIRU3.
The ‘STATUS’ position displays IRU status and guidance to the pilot in abnormal situations.  For example the display shows ENTER PPOS asking you to enter the present position of the aircraft.
The  ‘TRACK AND GROUND SPEED’ position indicates the true track and ground speed of the aircraft.
   The ‘TEST’ position tests the lights on the keyboard and produces a test pattern in the main display. The keyboard is a standby facility allowing, for example, entry of present position for alignment of the IRS.
   The ‘ATT’ position is an IR mode providing only heading and attitude information in case of loss of navigation capability.
The radio navigation
The radio navigation aids enable the crew to navigate and monitor its position. The A320 family is equipped with Two VOR, Two DME, Two ILS, and two ADF.The FMGC can automatically tune the VOR, DME and ILS for position updating and display purposes. Note that the ADF cannot be auto tuned and are not used for navigation by the FMGC.

   The radio navigation itself is controlled by both FMGC and can be monitored through MCDU pages. Either MCDU via the RAD NAV page enables the crew to manually tune a specific navigation aid including both ADF. FMGC auto tuning continues normally in the normal operation.
   PLAN mode is recommended when entering and checking the flight plan. However, notice that navigation aid data cannot be displayed in this mode. In all the other modes ROSE ILS, ROSE VOR, ROSE NAV and ARC modes, the navigation aids can be displayed provided the ADF-VOR selectors have been switched to VOR or ADF position.
ADF are shown as green pointers, VOR are white pointers, Note also that the receiver 1 data is displayed on the left side of the ND and the receiver 2 data on the right side. The associated nav aid data is displayed at the bottom of the ND in their respective colors and sides.

   In the unlikely event of a double FMGC failure, the back up tuning mode provides radio navigation redundancy to the crew. The back up tuning mode is accessed via the Radio Management Panels (RMP).For navigation aid tuning, RMP 1 STBY NAV keys are associated with VOR/DME 1 and ADF 1 while RMP 2 keys are associated with VOR/DME 2 and ADF 2.The ILS keys are slightly different. The ILS frequency tuned on either RMP is sent to both ILSs.To access the back up tuning mode, the NAV key has to be pressed.

   When the back up tuning mode is selected, i.e. NAV key illuminated, the control of the associated receivers is transferred to the RMP and the navigation aid tuning capability of both FMGC is lost. This is indicated on the MCDU by a change to the RAD NAV page which shows only the titles now. To return the control to the FMGC, the NAV key has to be pressed again. In back up tuning mode, the selection of one of the STBY NAV keys enables the crew to tune the associated navigation aid.
.We will now study the Digital Distance and Radio Magnetic Indicator (DDRMI). The DDRMI is fitted on the main panel. The DDRMI displays ADF, VOR and DME raw data and combines a traditional RMI and bearing pointer presentation. Two bearing pointers are provided, each with a different distinguishable shape.

   Each can display either VOR or ADF information. Each pointer has an associated control knob.The left knob selects either VOR 1 or ADF 1; The right knob selects VOR 2 or ADF 2. The compass card displays the bearing scale that is supplied from ADIRU 1.The counters indicate the DME distance. However, the window will display only dashes if an ADF is selected. Here, ADF 2 is selected.
Rdio altimeters
Two radio altimeters are installed in the A320. They measure the aircraft height above the ground accurately. There are no radio altimeter controls in the cockpit. Both radio altimeters come on automatically when AC power is applied to the aircraft. After a brief self test, the radio altimeters are in a standby mode during ground operations. They become active at lift-off and then operate continuously until touchdown.
   Radio height is always expressed as the number of feet between the bottom of the wheels and ground. Radio Altimeter data is supplied to several different users and is displayed on both PFD at all times below 2500 feet AGL. Normally, Radio Altimeter 1 (RA1) height is displayed on the captain’s PFD and RA 2 on the First Officer’s PFD.
The radio altitude display on the PFD changes in color and size based on height above ground and / or proximity to the decision height.. This color coded digital readout is coupled with a white ground indication line and a red ground ribbon on the Altimeter scale.
The ground indication line and the red ground ribbon correspond to the raising ground level when the aircraft is descending. As the aircraft descends below approximately 500 feet AGL the red ribbon appears at the bottom of the altimeter scale and begins to move up.
   The white ground line moves from the bottom of the PFD towards the horizon.
At touchdown, the ribbon is in the centre of the altitude readout and the white ground line is merged with the horizon, as shown. These are designed to be used as a ground reference during autoland operations. In addition to the visual indications, during approach, there is a synthetic voice for radio height announcement.

Depending on individual airline requirements, auto call-out announcements are made at pre-determined radio-altimeter heights. Example, “FOUR HUNDRED” at four hundred feet radio altitude. These call-outs will be heard even if the loudspeakers are turned off.

Part Three    Exercises
I. Listen to the tape and interpret the sentences into Chinese
1. Of the many types of navigation systems available to you, the VOR system is the one you will probably use most frequently.

2. A basic VOR system provides course guidance, automatic wind correction, and magnetic headings. The VOR system actually uses three different types of ground facilities to help you navigate through the sky.

3. The basic VOR station provides you with course guidance, while VOR DME and VIOR TAC facilities provide both course and distance information.

4. A VOR station transmits radio beams, called radials, outward in every direction. Actually, there is a infinite number of radials, but you will be concerned with the 360 which are numbered clockwise from magnetic north.

5. VORs are depicted on sectional charts. The compass rose surrounding the station helps you to visualize the radials as they travel outward. Many VOR stations are connected by specific radials, which form direct routes called Victor airways.

6. The VOR signals are transmitted in the very high frequency range of 108.00 through 117.95MHz. They travel on a line- of -sight basis.

7. Any obstacle, such as a mountain or the curvature of the earth, can reduce the reception distance of the signal. In certain situations, terrain features can render the signals unusable for navigation purposes.

8. At low altitudes you must be very close the station to receive the signal. As your altitude increases, you can use the VOR at greater distances from the station.

9. To navigate effectively with VOR you must complete certain preliminary steps. The first is to obtain the VOR frequency from the appropriate aeronautical chart and enter it into the VOR receiver with the frequency selector. Next, you need to identify the station to ensure that you have picked the right frequency. You must also determine that the station is operating properly, and that you have a reliable navigation signal.

10. You airborne equipment consists of an antenna, a receiver, and an indicator. VOR signals are received through the antenna. Next, they are relayed to the VOR receiver, which interprets the signals and send the information to the VOR indicator.

11. The VOR indicator has three different components which give you related navigation information. The components are the course deviation indicator, the TO-FROM indicator and the course selector. They work together to help you navigate along the course you have selected.

12. it is important to remember that radials travel outward from the VOR station. If you are flying away from the VOR on a given radial, your heading and the VOR course will be approximately the same. If you are going to the station, your heading will be 180 degrees different than the radial you are following. Of course wind can cause some heading variation.

13. It is important for you to remember that the aircraft’ heading has no direct relationship to the course selected in the VOR indicator. The VOR indicator reflects your position relative to the station you are receiving, regardless of the direction you are flying.
II. Translate the followings into English
盲降系统装有三个接收机。他们由一个控制面板操纵。如三套自动驾驶都在CMD模式，航向道和下滑道截获后频率改变受到抑制。姿态指引仪显示航向道和下滑道的偏离情况。备用姿态仪也可显示航向道和下滑道的偏离情况。当水平位置指示器在盲降模式时，相应的水平位置指示器在显示预选航道的同时显示航向道和下滑道的偏离情况。

The basic instruments in the aircraft for navigational purposes are the compass, the airspeed indicator and the clock. The simplest form of navigation used by pilots of small aircraft-called dead-reckoning –depends on the recognition of landmarks and the compass bearing of those landmarks at regular intervals of time during the journey. The planes, position and progress can thus be plotted.
Part Four
Supplementary Study
Aeronautical navigation
1. The basic instruments in the aircraft for navigational purposes are the compass, the airspeed indicator and the clock (chronometer). The simplest form of navigation used by pilots of small aircraft-called dead-reckoning(or deductive reckoning)-depends on the recognition of landmarks and the compass bearing of those landmarks at regular intervals of time during the journey. The plane’s position and progress can thus be plotted.
2. More complicated reckoning depends on radio landmarks. These ground stations(or beacons)transmit signals on known frequencies, and these signals are picked up by the plane’s radio magnetic indicator or horizontal situation indicator. Radio waves are effective pointers without being visible. They can travel all over the world either in long or short waves. Modern radio navigation systems depend on a combination of signals from ground based navigational aids and equipment in the plane. (There are exceptions – see Para 8 below).
3. The most widely used radio navigation system is VOR(VERY HIGH FRE-OUENCY OMNIDIRECTIONAL RANGE). Hundreds of ground-based VOR stations, positioned at regular intervals along airways, act as signposts by transmitting signals which are picked up by the aircraft’s receiving equipment. VOR stations are depicted on aeronautical charts as small triangles (see Unit 26 Jeppeson’ high altitude chart )or as a compass rose (a circle marked off from 0 to 360 )on low altitude charts. Airways converge on these VOR station, or routes may simply change direction at these points.
4. NDBs (NON-DIRECTIONAL BEACONS)are installed at certain locations near airports to assist with instrument approach and holding pattern procedures. (see Units 22and28). Located about 5 miles from the runway, an NDB enables the pilot to home onto the Instrument Landing System(ILS). In China, low frequency, high-powered NDBs are used as primary navigational aids. The aircraft’s ADF picks up directions to beacon in front of its path, and to the beacon in the aircraft’s track (to the rear).
5. R-NAV.(AREA NAVIGATION) is particularly useful for aircraft navigating out-side the airways. The system gives greater lateral freedom, enabling the pilot to navigate across country; neither this starting point nor his destination need to be serviced by any kind of navigational aid.
6. OMEG. A number of Omega transmitters are situated around the world, each transmitting powerful, long-range, very low frequency radio signals. These signals are complex and must be decoded by special equipment in the aircraft, but they are more accurate than any other system at present in universal use. They enable the aircraft to fix its position to within one mile by day and two miles by night.
7. SATELLITES . As more satellites are placed in orbit , equipped with navigational transmitters (Navstar is one such system being perfected), very accurate position fixing will be possible ,with an accuracy down to 20 feet.
8. DOPLER . This system is self-contained , i.e. it does not depend on ground –based beacons or satellite station. It is more widely used by military aircraft which have to fly over hostile terrain without ground aids. Like R-Nav, it enables the pilot to fly direct routes outside airways. R –Nav, However, is not self-contained.