11.05.2 Navigation Flashcards
Which two systems are used for en route navigation?
- Automatic Direction Finder (ADF) system - which is the oldest system.
- VHF Omnidirectional Range (VOR) system - which is the most common system.
What system is used for approach/landing?
Instrument Landing System (ILS) which gives information to aid landing the aircraft in poor visibility.
What are the 2 types of flight rules?
- Visual Flight Rules, VFR - Means flying in good weather conditions and with visual ground references. This is only used by small private aircraft.
- Instrument Flight rules, IFR - Means flying without visual ground references, day and night, or in bad weather conditions. These rules are used by all commercial flights.
What are the 2 norths in navigation?
- True North (TN) - Is the direction to the geographical North Pole.
- Magnetic North (MN) - Is where the magnetic field lines are gathering. In this example the two directions are 10° apart.
What is the difference between the 2 norths called?
Variation (Var) and can be east or west.
What is heading?
The direction in which the nose of the aircraft is pointing is called heading (HDG) and is measured clockwise from North.
What is track?
Track (TK) is the direction in which an aircraft is moving over the Earth. It is also measured from True or Magnetic North.
What is the difference between heading and track called?
The difference between the two angles is called drift
What is relative bearing?
Relative Bearing (RB) - is measured in degrees clockwise from the longitudinal axis. 0° means that the object is straight ahead of the aircraft.
What is magnetic bearing?
Magnetic Bearing (MB) – is measured from Magnetic North.
How can you calculate magnetic bearing?
The Magnetic Bearing can be calculated by adding the Magnetic Heading to the Relative Bearing.
How can navigation tuning be carried out?
- Automatic tuning - from the Flight Management System (FMS) which is the normal way of operation.
- Manual tuning - via the FMS by selecting a frequency on the Nav radio page on the MCDU.
- Manual tuning – via the Nav Control Panel or Radio Management Panel (RMP)
What does ADF stand for?
The Automatic Direction Finder (ADF)
Which bearings does ADF calculate?
The ADF receiver calculates the Relative Bearing
Where are the bearing that ADF calculates indicated?
Indicated on Radio Magnetic Indicator (RMI) and to the Navigation Display (ND)
What aural signal is given to the pilot with ADF?
aural output to the aircraft audio system for transmitter identification.
What are the three types of ADF station?
- Non Directional Beacons (NDB)
- Locators
- Public radio stations
What are the two types of ADF antenna?
- Loop antenna
- Sense antenna
What frequency does transponder receive interrogations?
1030MHz
What frequency does transponder transmit replies on?
1090MHz
What are the three reserved codes in ATC transponder?
- 7500 - which identifies a Hijacking
- 7600 - For radio failure and
- 7700 - If the aircraft is in an emergency.
What are the three modes of ATC operation?
STANDBY - The transponder is ON but replies are inhibited. This is the
normal mode on the ground.
- ALT RPTG (Alt Reporting) OFF - The transponder will reply only to MODE
A or MODE S interrogations, but the altitude reporting of MODE C is
inhibited.
- XPNDR - The transponder is fully operative and replies to all
interrogations.
What does the ATC XPNDR mode do?
The transponder is fully operative and replies to all interrogations.
What does the ATC ALT REPORTING OFF mode do?
The transponder will reply only to MODE A or MODE S interrogations, but the altitude reporting of MODE C is inhibited.
What does the ATC STBY mode do?
The transponder is ON but replies are inhibited. This is the normal mode on the ground.
What is TCAS used for?
TCAS monitors the trajectory of other aircraft to determine if there is any danger of a collision and provides the pilots with aural and visual advisories for a vertical avoidance manoeuvre.
What are the four groups of TCAS alerts?
- Resolution advisory group (RA),
- Traffic alert group (TA),
- Proximate traffic or
- Other traffic
What are the two protective areas in TCAS?
- Resolution advisory protection area (RA)
- Traffic alert protection area (TA)
What does a sense antenna eliminate in ADF?
The ambiguity regarding direction of station
What two ADF modes are available?
- ADF mode
- ANT mode
What does ANT mode do?
- Only the sense antenna is active.
- There is ‘NO’ relative bearing indication but the Morse code identifier is heard more clearly.
- This mode is used when the station identifier reception is weak
What signals does VOR station transmit?
- Reference signal
- Variable signal
How doe a VOR receiver calculate position from signals?
The VOR receiver compares the 2 radio signals and, from the difference, calculates the position of the aircraft relative to the VOR station
What is VOR calculate position called?
Radial
How is bearing to VOR station calculated?
the bearing to the station is always the radial plus or minus 180°
What is bearing to VOR station independent of?
Aircraft heading
In manual VOR, what is the difference between AC radial and selected radial called?
VOR deviation
In manual VOR, how is VOR deviation indicated?
by a moving deviation bar
In VOR, what is a selected radial called?
Preselected Course (PSC)
In VOR, how many degrees does each dot on the deviation bar represent?
one dot corresponds to 5 degrees
What tests can be carried out on VOR systems?
- Operational Test
- Ground Test
- System Test
Which VOR test requires a ramp test set?
System test
What does ILS do?
The Instrument Landing System (ILS) provides lateral and vertical position data necessary to line the aircraft up on the approach to the runway
Where are outputs of ILS fed to?
- indicators for display
- FMS and auto flight system.
How many marker beacons are there in ILS?
- Outer Marker (OM),
- Middle Marker (MM),
- Inner Marker (IM) - No longer used.
What are localizer modulation frequencies for left and right?
- Left lobe 90Hz
• Right lobe 150Hz
How many localizer channels are there?
- 40
- 108.10 to 111.95MHz
Does ILS use odd or even tenths for channels?
Odd tenths
How much deviation does 1 dot represent for localizer offset?
1 degree
What angle is glide slope centreline?
2.5° to 3°
How are glide slope channels selected?
- for each of the 40 Localizer channels there is a paired Glide slope channel
- When the pilot selects an ILS frequency from the approach chart, the Localizer receiver is directly tuned.
- The Glideslope receiver automatically tunes to the Localizers paired Glideslope frequency (channel).
What extra ILS information is shown on the PFD?
- Tuned frequency or ground station identifier if received.
- Localizer deviation
How is localiser displayed on PFD?
Localiser deviation - Displayed by a magenta diamond deviation pointer on a white, four-dot deviation scale
At the end of an ILS approach, how does localiser indication change?
- normally one dot = 1 degree of deviation
- change to the expanded two-mark deviation scale at the end of the approach, making one dot equal to about 0.5° of deviation.
How much glide slope deviation does 1 dot represent?
One dot normally equals 0.35°, which corresponds to 200ft of deviation from the glide slope path at the Outer
Marker
Why is ILS localiser and glideslope deviation information fed to autopilot?
With these 2 signals the autopilot can carry out an automatic approach and landing by controlling the aircraft to fly down the centre beam
What does the pilot still need in during an automatic approach and landing?
To see the runway
What are CAT1 visibility requirements?
800m of the runway visibility, called Runway Visibility
Range (RVR) at a height of 200ft
What are CAT2 visibility requirements?
400m runway visibility at a height of 100ft
What are CAT3 visibility requirements?
less than 200m runway visibility at a height below 100ft.
When does the pilot check the visibility requirements?
The decision height (also called the minimum)
What frequency does marker beacon transmit at?
75MHz
What are marker beacon distances and frequencies?
- Outer, 7km from the runway, 400Hz tone.
- Middle - 1000m from the runway, 1300Hz tone
- Inner - 300m from the runway, 3000Hz tone
How are marker beacons indicated to the pilot?
- Outer - blue lamp on the Marker Beacon Panel ‘on’ and morse code dashes
- Middle - amber lamp on the Marker Beacon Panel ‘on’ and morse code dots and dashes
- Inner - white lamp on the Marker Beacon Panel ‘on’ and morse code dots.
What is radio altimeter LRRA used for?
The function of the Radio Altimeter is to measure the vertical distance between the aircraft and ground (height)
What height is rad alt (LRRA) used up to?
2500 ft
How does LRRA calculate height?
- Transceiver generates a radar signal which is transmitted to the ground by an antenna.
- Signal is reflected off the ground and then received by a second antenna
- Transceiver now calculates the time delay which is converted into height
Where are LRRA antennas located?
The 2 flush skin type antennas mounted on the bottom of the fuselage. They are identical and interchangeable.
What frequency range does LRRA work in and what power level?
- Frequency between between 4200 to 4400 MHz
- Power output of about 100mW
How is LRRA height displayed to the pilot?
The height can be indicated to the pilots on conventional indicators or integrated into the PFD.
How does LRRA indication on PFD change as height increases?
When the height decreases, an analogue indication is added to the digital number. This is a horizontal bar which moves up as the aircraft descends and touches the horizon at ‘touch down’
How is total loss of LRRA height indicated?
replaces the digital indication by a red “RA” label
How else is height indicated on modern aircraft?
In modern aircraft the radio height is not only indicated - it is also announced by the Radio Altitude call-out system
using an artificial voice.
How is decision height selected?
The Decision Height selection is made by turning a selector knob either on the instrument or on a remote control panel
How is decision height indicated?
The selected decision height is indicated either with a decision height cursor in the Radio Altimeter indicator or as a numeric indication on the PFD.
When decision height is reached, what are the indications?
- a voice gives an aural alert.
- the height indication changes from green to amber and the label DH is added to it
What is the purpose of the GPWS system?
to warn the flight crew when the aircraft mistakenly comes too close to the ground.
When does the basic GPWS system automatically become active?
when the aircraft height is less than two thousand five hundred feet.
How many basic GPWS functions are there?
7
What is GPWS mode 1?
- ’excessive sink rate’ mode
- alerts when aircraft descends below 2500ft with high vertical speed
What is GPWS mode 2?
- ’excessive terrain closure rate’ mode
- alerts when the aircraft height decreases dramatically, for example when the aircraft approaches rising terrain, like a mountain
What is GPWS mode 3?
- alerts the flight crew when the aircraft loses altitude during a take-off
What is GPWS mode 4?
- alerts when the aircraft approaches the ground with incorrect gear and flap positions
What is GPWS mode 5?
- alerts if the aircraft deviates below the glideslope during an approach below a radio altitude of 1000 ft.
What is GPWS mode 6? (two functions)
- radio altitude callouts
- An aural alert can also happen if the bank angle of the aircraft exceeds a critical value
What is GPWS mode 7?
- warns the flight crew about a dangerous windshear condition during take off or approach
What does DME measure?
the slant distance from the aircraft to ground station
What does actual DME ground station distance depend on?
aircraft altitude and the slant distance to the station
How does DME measure slant distance?
by transmitting a signal to the ground station, called the interrogation, and by counting the time it takes to receive a reply signal.
What is DME paired with?
The DME ground station is either paired with a VOR or a localizer ground station.
How is DME tuned?
DME is automatically tuned when you select the corresponding VHF NAV frequency
Where is DME information displayed? (3)
- RMI (radio magnetic indicator)
- Navigation Display (ND)
- Primary Flight Display (PFD)
In DME, what is displayed for no reply?
The numeric presentation is replaced by dashes
In DME, what is displayed for system failure?
- amber DME warning box or it is completely erased
Where does weather radar transmit?
a 180° area forward of the aircraft and the objects in this region, like water droplets, reflect the pulses back.
How is different signal intensity displayed on weather radar?
Different colours
What else can weather radar display?
- land contours
- turbulences and
- wind shear
What does an elevation scan motor do?
keeps the antenna horizontally independent of the aircraft attitude by signals from the Inertial Reference System (IRS) or Vertical Gyro (VG)
Where does an elevation scan motor get its attitude information from?
Signals from the inertial reference system (IRS) or the vertical gyro (VG)
What are the two types of weather radar antenna?
- Flat plate antenna and
* Parabolic reflector antenna.
What are the power outputs from the weather radar?
- 60kW in old systems and
- 25W in modern systems
How is RF (radio frequency) fed to antenna?
Wave guide
Where are the weather radar components usually located?
Nose radome
What is displayed in weather radar WX mode?
Just weather information (red, yellow and green)
What are red areas in WX mode?
Very heavy rainstorms
What are yellow areas in WX mode?
intermediate level rainstorms
What are green areas in WX mode?
for moderate level rainstorms
How is WX/Turb displayed?
The area of turbulences is shown on the display in magenta
What does the gain knob adjust in weather radar?
sensitivity
In weather radar, the frequency of of echoes increases as the target (rain) moves toward and reduces as the target moves away. What is this effect known as?
The doppler effect
What is wind shear?
first the aircraft gets a strong head wind which changes in a very rapidly to a tail wind
How is wind shear displayed on weather radar?
- wind shear icon is added to the ND with red and black bars in the critical area with additional yellow bars from the edges of the symbol to the compass rose. This shows the heading that the pilot should avoid.
- The warning is accompanied by a red wind shear message on the PFD and the ND
What is heard on approach for wind shear?
’Wind shear ahead, go around’
How is a successful WX test displayed?
- The system displays a test pattern on the ND
- mode annunciator on the left side shows a test pass message
How is a WX test fail displayed?
- If there are any failures in the system, there will be no test pattern displayed.
- WXR fail message is displayed.
- Faulty LRU is displayed.
What must you do if operating the weather radar on ground?
Follow safety precautions:
- Personnel should remain at a distance greater than about 10 to 15ft,
• Refuelling aircraft and large metallic objects must have a safety distance of more than 200 to 300ft,
• Safety area must be 180° in front of the aircraft due to the scan possibility of the antenna.
Where is the weather radar danger area?
180° in front of the aircraft due to the scan possibility of the antenna.
What does ATC system do?
Monitors and controls air traffic
What are the three modes of ATC system?
- Mode A
- Mode C
- Mode S
What does ATC mode A do?
The transponder transmits the aircrafts four digit (number)
identification code
What does ATC mode C do?
As well as the 4 digit code the transponder transmits the aircraft’s barometric altitude, which it receives from the Air Data Computer (ADC)
What does ATC mode S do?
Is an advanced digital system which uses a 24-bit ICAO address to helps ATC control increasing levels of air traffic
What unique feature do Mode S aircraft have?
- The selective interrogation is possible because aircraft equipped with mode S transponders have a unique airframe address code.
- This code is given by the authorities during certification of the aircraft and is set on a program switch module in the avionic compartment.
What are permanently transmitted signals of mode S aircraft called?
Squitter signals
How do you select TCAS on EFIS control panel?
Push button
What are the four TCAS symbols?
- Altitude separation on 100’s of feet
- +/- sign indicates if the traffic is above or below
- up/down sign indicates if the traffic is climbing or descending
- Resolution advisories
What is not displayed in TCAS TA mode?
No aural and No visual resolution advisories are calculated.
Additionally, the ‘red’ symbols are also hidden on the ND
What are TCAS test indications?
Successful test:
- ‘TCASTEST’ (cyan) message,
- ‘TRAFFIC’ (red) message,
- All four different traffic symbols.
Test fail:
- ‘TCAS TEST FAIL’ replaces the ‘TCAS TEST’ message and - no traffic symbols are shown.
How many satellites does GPS use?
- It uses 24 primary and 3 spare satellites
- Only four REQUIRED
What are 2 levels of GPS service?
- Precision Positioning Service (PPS) - Only available for military use,
- Standard Positioning Service (SPS) - For civilian use
What is the GPS service accuracy?
- PPS (military) - Unknown
- SPS (civilian) - 15 - 25m
How can GPS accuracy be improved?
- Differential GPS (DGPS)
- utilises a reference station at the airport to calculate position error
The FMS navigation database must be updated every…
28 days
What is FANS?
Future Air Navigation System?
