Navigation systems and radar services

Ground Lesson L - Navigation systems and radar services Schedule: 60-90mins

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Description: When we need to go on cross country, one way to help us get to our destination is to use VORs. They will prevent us from getting lost and make our trip go smoothly. 

 

Objective: To familiarize the student with a variety of navigation systems and radar services available to pilots. 

 

Reference: PHAK 

 

Elements

 

1.VOR, VORTAC, VOR/DME

1. Regardless of which VOR is utilized m the VOR indicator behaves the same.

2. Projects straight-line courses (radials) from the station in all directions. 

1. Distance depends on the power output of the transmitter. 

1. Line of sight restrictions. 

2. Radials are identified by numbers beginning with 001 and progress in sequence through all the degrees of a circle until reaching 360.

3. To aid in orientation, a compass rose reference to the magnetic north is superimposed on the charts at their location. 

1. On charts, you will also find the VOR name, frequency, morse code, and sometimes voice capabilities

1. If out of service, morse code won’t be heard. 

2. If there is not a strong enough signal, the warning flag will waive. 

2. VOR ground stations transmit within a VHF frequency band of 108.0 – 117.95 MHz

4. The VOR ground station is aligned with the magnetic north, and it emits two signals -- a 360-degree sweeping variable signal and an Omni-directional reference signal. The signals are compared by the aircraft's receiver, and a phase difference between them is measured, giving a precise radial position of the aircraft and displaying it on the OBI, HSI or RMI.

5. Antenna, receiver with tuning device, VOR nav instrument (CDI) makes up the VOR equipment. 

6. There are three classes of VOR according to operational use.

1. Terminal

2. Low 

3. High 

2.How to use VOR  

Parts of the HSI

1. The course selector (OBS knob) is an azimuth dial that can be rotated to select the desired radial or to determine the radial over which the aircraft is flying. In addition, the magnetic course “TO” or “FROM” the station can be determined.

2. When the course selector is rotated, it moves the CDI or needle to indicate the position of the radial relative to the aircraft. 

3. Turn the course selector until the needle is centered. 

1. We can only fly to and from the station 

2. The CDI does not take into account the heading of the plane. 

4. When you center the needle, it will indicate the course whether you are going “TO” the station or going away “from” the course of the station. 

5. To track inbound to the station, center the CDI needle until the “TO” indicator is shown. To track outbound from the station, center the CDI needle with the “from” indicator shown. 

1. Once centered, turn the airplane to whatever heading indicated on the VOR azimuth dial. 

2. If there is no wind, you just have to fly the same exact heading as the azimuth dial. 

3. However, wind will push you off course.

1. When the needle is deflected left or right of the center, each dot represents a 2 degree off course. 

2. If the needle is to the left then you are to the right of center and you need to turn to the left to center it again. 

3. • If Desired Course is ‘x’ Degrees Off, Correct Initially With a Correction Angle of 3x • 

1. E.g., You are 4 Dots to Right of Centerline (8 Degrees) Make a Correction of 24 degrees to the Left 

2. If More Than 10 Degrees Off, Make a Correction of 45 Degrees

4. Tracking takes some trial and error.

5. Try your best to minimize deflection. 

3.VOR checks

1. The accuracy of the course alignment of VOR radials is considered to be excellent.

2. However, certain parts of the VOR receiver equipment deteriorate, affecting its accuracy. 

1. This is particularly true at great distances from the VOR station.

3. The log must contain the date, location, bearing error, and signature of the pilot conducting the check.

4. The different ways to check VOR

1. VOT check 

1. The VOR Test Facility (VOT) is the most accurate and is the preference to check your VOR receiver. 

2. You can discover which airports do have a test facility in Section 4 of the FAA Chart Supplement 

3. Ensure you are situated at the airport in an appropriate area – the parking apron, taxiway, or end of the runway. The Supplement will make note of which areas on the airport will not work.

4. Tune to the appropriate frequency annotated in the Supplement.

5. Turn up the volume to identify the station, which is indicated by a series of dots or one continuous tone.

6. Twist the OBS to center the needle. The TO/FROM flag should indicate TO with 180 degrees (+/- 4) selected. 

2. VOR ground check and VOR airborne check - specific points on the surface

1. Tune to the appropriate frequency annotated in the supplement.

2. Identify the station by turning up the volume and ensure the Morse code or voice identifier is correct.

3. Twist the OBS knob to the azimuth listed in the Supplement.

4. Position your aircraft at the appropriate location annotated in the Supplement, either on the ground or over a geographic location in the air, ensuring you’re at an appropriate altitude if airborne.

5. If the needle is not centered, twist the OBS until it centers up.

6. The tolerance must be within four degrees for ground checkpoints or six degrees for air checkpoints. So if an airborne checkpoint azimuth is listed as being 177 degrees, the OBS must be centered in a range from 171 to 183 degrees.

3. Dual receiver check -A dual receiver check is valid if you have two separate receiver units in your aircraft. They can have a common antenna but the actual receivers must be separate. These checks can be done on the ground or airborne.

1. Tune both receivers to a nearby VOR station.

2. Identify the station in both receivers by turning up the volume and verifying the Morse code or voice identifier.

3. Compare the OBS settings for both receivers with the needle centered. They must be within four degrees of each other.

4. Landmark check 

1. You may also make your own airborne check by looking at the charts and picking a significant geographic landmark under a VOR airway. Fly over the landmark and note the azimuth that your aircraft VOR receiver indicates. It should be within 6 degrees of the annotated airway azimuth.

4. Reverse sensing 

1. The majority of pilots have been taught to “fly towards the needle” when learning VOR navigation. That in turn gets interpreted to mean fly either right or left in order to get on the desired course. 

2. You do not fly towards the needle. Instead you fly towards a heading, and that may mean fly either right or left. 

3. Some pilot would see the CDI and fly toward the right to try and fix the deviation but you actually 

4. 

5. Some students will try to follow the needle which is deflected to the left and turn the plane to the left. But turning the plane to the left will take you even more off course, in fact, you will never intercept the 270-degree radial. The student should just turn the heading to 180 to make the most direct intercept which is a turn to the left. 

6. When flying to a station make sure to put it to “to’

 

5. Satellite-based navigations 

1. The GPS is a satellite-based radio navigation system. 

1. The satellites broadcast in the UHF range (meaning they are virtually unaffected by weather) 

2.  Although they are subjected to line-of-sight references 

3.  Must be above the horizon (as seen by the antenna) to be usable for navigation

2. The receiver utilizes the signals of at least 4 of the best-positioned satellites to yield a 3D fix  

1. 3D - Latitude, longitude, and altitude

2. Using calculated distance/position info from the satellite, the receiver calculates its location

3. The GPS receiver verifies the integrity (usability) of the signals received from the GPS constellation through receiver autonomous integrity monitoring (RAIM) to determine if a satellite is providing corrupted information. 

4. RAIM needs a minimum of five satellites in view or four satellites and a barometric altimeter (baro-aiding) to detect an integrity anomaly. 

5.  For receivers capable of doing so, RAIM needs six satellites in view (or five satellites with baro-aiding) to isolate the corrupt satellite signal and remove it from the navigation solution

6. VFR Use of GPS

1. providing increased navigation capability and enhanced situational awareness while reducing operating costs due to greater ease in flying direct routes.

2.  VFR pilots should never rely solely on one system of navigation. GPS navigation must be integrated with other forms of electronic navigation, as well as pilotage and dead reckoning.

3. Many VFR GPS receivers and all hand-held units are not equipped with RAIM alerting capability. Loss of the required number of satellites in view, or the detection of a position error, cannot be displayed to the pilot by such receivers. 

4. an updatable database is used for navigation fixes, airports, and instrument procedures. These databases must be maintained to the current update for IFR operation, but no such requirement exists for VFR use

5. Without a current database, the moving map display may be outdated and offer erroneous information to VFR pilots wishing to fly around critical airspace areas

6. In many VFR installations of GPS receivers, antenna location is more a matter of convenience than performance.

7. WAAS 

1. Satellite-based augmentation system that improves GPS signals for use in precision approaches 

2. Augments the basic GPS satellite constellation with additional ground stations/enhanced info transmitted from geostationary satellites

8. LAAS 

1. Satellite-based augmentation system that improves GPS signals for use in precision approaches 

2.  Functions similar to WAAS but relies more on ground stations for signal correction/improvement 

3.  Considered to be less cost-effective than WAAS 

4.  Considered to be capable of handling Category III instrument approaches

6.RNAV

1. Area navigation allows a pilot to fly a selected course to a predetermined point without the need to fly overhead ground-based facilities. 

2. Allows you to fly directly to a destination waypoint to waypoint. 

1. A waypoint is a position that is determined by radial and distance from a VOR station or by using long longitude and latitude coordinates. 

3. When the position of a waypoint is entered, the pilot can navigate to it as it were a VOR. 

7. Radar services and procedures  

1. ATC facilities provide a variety of services to participating VFR aircraft on a workload permitting basis 

2.  You must be able to communicate with ATC, be within radar coverage and be radar identified 

3.  Services provided include:

1. VFR radar traffic advisory service (Flight Following) and safety alerts 

1. Can be requested on the ground at some airports or in the air with departure frequency.

2. Tell them your present location, destination, requested altitude, type of plane, and equipment. 

3. You will get squawk code, handoffs, and traffic advisories.

4. Inform ATC altitude or freq change. 

5. Inform them to end service if you are close to the airport 

2. Vectoring (when requested) 

3. Terminal Radar Programs (TRSA) – To separate all participating VFR aircraft and IFR traffic 

4. Radar assistance to lost aircraft 

5.  Class C services include a separation between IFR/VFR and sequencing of VFR traffic to the airport f

6. Class B services include separation based on IFR, VFR and/or weight and sequencing VFR arrivals

7. Weather alerts and vectoring around the weather. 

8. Services at KLGB

1. Clearance delivery - not found at all airports but used at busier airports to taxi clearance, IFR conditions, and squawk code. 

2. Ground control - coordinates and monitors aircraft and ground vehicles. Contact after clearance delivery. 

3. Control tower - coordinates and monitors aircraft active on the runway and within the airport airspace. 

4. Approach and departure control - KLGB do not have it but KSBA and KSNA have it. It provides traffic advisories and are used for sequencing of traffic in and out of busy airspace. 

5. ARTCC - Separates IFR operations and provides services to VFR also in the en-route structure.