儀表飛行員地面課程Lesson4課件

1、Sierra Academy of Aeronautics IR GroundLesson 4VOR/DMECurrent Navigational Equipment in UseVOR (VHF Omni-directional Range)Very High Frequency Omni-Directional Range (VOR)Currently the primary navigational aid used by civil aircraft in the National Airspace System2 typesBasic VOR provides only cours

2、e guidance and basic orientationVOR DME & VORTAC provides course guidance, orientation & distance informationVOR (cont.)Provides 360 magnetic courses called radialsConsists of ground-based transmitter and airborne receiverVOR aircraft componentsTypical Nav/Com radio & AntennaVOR aircraft componentsT

3、he typical VOR indicatorVOR aircraft componentsTypical SIU NAV/COM radio stackVOR TransmitterThe VOR rotates a signal electronically at 1800 RPM2 navigational signal components are contained in the transmitted signalThe reference signal has a constant phase at all points around the VORThe 2 signals

4、are out of phase in all directions except magnetic northThe airborne receiver measures the phase difference for magnetic orientation from the VORVOR FactsVORs operate within the 108.0-117.95 MHz frequency band.Accuracy of course alignment is plus or minus 1 degree.VOR is subject to line of sight res

5、trictions.Local magnetic and electronic disturbances can have minor effects on course accuracy.Certain Prop RPM settings can also cause VOR course deviation indications.VOR identificationStandard 3 letter code every 5 secondsSome VORs have code and voiceReceipt of positive station ID is the only way

6、 to verify reliable signal transmissionPositive TO-FROM flag is the only way to verify reliable navigational signal receptionConditions that cause the OFF/NAV flag to appear on the VOR indicator:Cone of confusion Zone of ambiguityVOR station power failureVOR OTSOut of rangeRadio turned off Wrong fre

7、quencyVOR cautions/considerationsZone of AmbiguityA line perpendicular to the course selectedVOR cautions/considerationsCone of ConfusionThe region directly above the station which gives unreliable readingsStandard Service Volumes (SSV)Each VOR is classified according to its SSV, which defines the r

8、eception limits in terms of altitude and distanceGuarantees signal for off airway navigationThe three SSVsHighLowTerminalStandard Service VolumesVOR depiction on L-chartsVOR info as found in the A/FDVOR Receiver CheckFAR 91.171 specifies Equipment Check for IFR within preceding 30 daysEach person ma

9、king the VOR check under 91.171 must record Date, Place, Bearing error, and SignatureThere are 5 checks you can do as a pilotVOR Receiver ChecksAirborne known (Designated)Airborne unknown (Made up)Airport surface (Designated)Dual VORVOTRadiated VOT (Repair Station)VOR Receiver Check (Dual VOR MDH)Th

10、e Airport/Facility DirectoryA/FD listing of VOR Checks You should know thatVOR info received by an aircraft is not influenced by attitude or headingThe farther the distance from the VOR, the slower the needle movesThe needle does not begin to move until you are within 10 deg. of the selected courseV

11、OR OrientationVOR OrientationVOR OrientationVOR OrientationVOR OrientationVOR Time and Distance InfoTo determine time/distance to StationWhen tracking inbound, make a 90 deg. turn and measure time and degrees of bearing change:Distance Measuring Equipment (DME)Provides distance, groundspeed, and tim

12、e to stationDME operates on the frequencies between 962 MHz and 1213 MHz in the UHF spectrumFrequency pairing allows DME receivers to display the VHF frequency of the paired VOR rather then actual UHF frequency of the DMEDME (cont.)Navaids which provide distance information as well as azimuthVOR/DME

13、VORTACsTACANsILS/DMEDME (cont.)DME OperationAirborne equipment sends an electronic interrogation to the ground station, which gives an electronic response. By timing the interval between interrogation and response, the airborne DME calculates how far the signals are traveling.Ground based station ha

14、s a finite number of DME interrogations. Turn off DME when not needed (ie. On ground).DME cautionsSlant Range ErrorThe difference between the actual horizontal distance and the slant rangeDME measures the distance between the aircraft and the ground stationSlant range error is considered negligible

15、when the airplanes altitude in thousands of feet is less the distance in nautical miles (10 miles out, 5000 feet)DME Slant Range ErrorDME (cont.)DME IdentificationDME has its own identifierMorse code is the same as that for the associated VOR, but with higher pitchDME identification is transmitted a

16、bout every 30 secondsDME AccuracyLimited to line of sightReliable signals at distances of 199 NM with accuracy of better then mile or 3% distance whichever is greater DME (cont.)Typical DME receivers/antennaHorizontal Situation Indicator (HSI)Combines information from DG and VOR into one displayImproves orientation by eliminating “reverse sensing” and dire