4 Avionics and Instruments Flashcards
What are the 3 groups of Basic Flight Instruments?
Primary Flight Instruments
Engine Instruments
Navigation Instruments
Name the 2 types of sensing
Direct (Analogue)
Remote (Digital)
Advantages of digital displays over analogue
Reliability
Accuracy
Flexibility
Cost
Name the 6 Primary Flight Instruments
Attitude Indicator (ATI) Airspeed Indicator (ASI) Altimeter (ALT) Vertical Speed Indicator (VSI) Horizontal Situation Indicator (HSI) Turn and Slip Indicator (T+S)
In terms of flight instruments
???? + ???? = PERFORMANCE
POWER
ATTITUDE
What are the CONTROL instruments?
Power Instruments Attitude Indicator (ATI)
Control instrument indications are direct and respond immediately to control changes
What are the PERFORMANCE instruments?
Airspeed Indicator (ASI) Altimeter (ALT) Vertical Speed Indicator (VSI) Horizontal Situation Indicator (HSI) Turn and Slip Indicator (T+S)
Pressure instruments use what two kinds of pressure?
Pitot Pressure and Static Pressure
Digitally this is fed to the Air Data Computer (ADC)
What are the DIRECT and INDIRECT indications from the ASI?
DIRECT - Airspeed
INDIRECT - Pitch
What are the DIRECT and INDIRECT indications from the ALT?
DIRECT - Altitude
INDIRECT - Pitch
What are the DIRECT and INDIRECT indications from the HSI/Compass?
DIRECT - Heading
INDIRECT - Bank or Yaw
What are the DIRECT and INDIRECT indications from the VSI?
DIRECT - Vertical Speed
INDIRECT - Pitch
What are the DIRECT and INDIRECT indications from the Turn Indicator?
DIRECT - Rate of Turn
INDIRECT - Bank or Yaw
What are the DIRECT and INDIRECT indications from the Slip Indicator?
DIRECT - Balance
INDIRECT - Yaw
What is the purpose of a standby flight instrument?
In-case of a system failure of the main displays
How long is a standby flight instrument required to be reliable for?
30 mins
What are the 2 ways of determining performance altitude?
Pressure altitude = Elevation + 30(1013-QNH)
Density Altitude = Pressure Alt + 120(ISA temp deviation)
How is the static pressure measured?
2 static ports at opposite sides of the aircraft. With an average taken to negate potential influence of slip.
Static pressure is provided to what 4 instruments?
ALT, ASI, Machmeter, VSI
Pitot pressure is provided by what piece of equipment?
Pitot tube
Pitot pressure = ….. pressure + ….. pressure
Static + Dynamic
Pitot pressure is supplied to what 2 instruments?
ASI, Machmeter
The altimeter actually measures ….. but is calibrated to read ……
pressure
height/altitude
Name the 5 types of altimeter
Simple Sensitive Servo-Assisted Digital Display Cabin Altitude
What are the 8 errors of an altimeter or most other pressure instruments?
Pressure Instrument Temperature Hysteresis Blockages and leaks Lag Orographic Transonic jump
On a cold day do you need to correct/adjust your altimeter/decision heights?
Yes - Potentially up to 10%
What type of capsule is used in an Altimeter?
Aneroid capsule
What type of capsule is used in an ASI?
Differential capsule
What are the different instruments that use a differential capsule and an aneroid capsule?
Differential - ASI, VSI
Aneroid - ALT
Name the 4 different ASIs
Simple
Sensitive
Servo-assisted
Digital Display
What do each of the colours on the rim of the ASI refer to?
White - Flap operating range
Green - Normal operating range
Yellow - Caution range
Red dash - Never exceed
Indicated Air Speed (IAS) corrected for instrument and pressure error becomes…
Calibrated Air Speed (CAS)
Calibrated Air Speed (CAS) corrected for compressibility error becomes ….
Equivalent Air Speed (EAS)
Equivalent Air Speed (EAS) corrected for density error becomes ….
True Air Speed (TAS)
What additional component does the Machmeter have over an ASI?
Aneroid Capsule
What type of capsule does a VSI have?
Differential Capsule
What are other names could a VSI be known as?
Rate of climb & descent Indicator (RCDI)
Vertical Velocity Indicator (VVI)
Instantaneous Vertical Speed Indicator (IVSI)
What does an ISVI have that eliminates lag error?
Counter/bob weights counter act lag error to move the needle ‘Instantaneously’.
Weights calibrated to provide correct reading
What does ADS stand for?
Air Data System
What does the ADS consist of?
- Probes and Sensors (Press, Temp, AoA, Slip).
- Transducers to convert air data to electronic signals.
- Air data computer to process signals for systems/displays.
What are the advantages of an ADS?
- Less bulky
- Replaces numerous instruments
- Eliminates analogue error
- Errors automatically eliminated
- Increased accuracy and sensitivity
- Minimal lag time
- Digitised air data enables flexibility
What converts analogue readings to digital signals?
Transducer
Name the 3 different types of gyroscopes
Spinning
Optical
Vibrating
Define the 5 terms associated with gyroscopes
Inertia - Resistance of an object to change its state of motion
Momentum - Mass x Velocity
Angular Vel - Speed of rotation/spin
Moment of Inertia - Mass x Moment arm distance from spin axis
Angular Momentum - Ang Vel x Moment of Inertia
What is special about angular momentum?
Angular momentum is conserved
What is the 1st Law of gyrodynamics?
Spin axis remains fixed in inertial space. RIGIDITY
What is the 2nd Law of gyrodynamics?
If a torque is applied perpendicular to spin axis, the spin axis will precess steadily about an axis perpendicular to the spin and torque axis’. PRECESSION
Name the 3 classifications of SPINNING gyroscopes
Rate
Rate Integrating
Displacement
The main gyroscopic error is known as …..
Wander
Gyroscopic wander breakdowns into 2 types. These are?
Real
Apparent
Depending on the plane of error what are the 2 terms used?
Drift - Wander of the spin axis in the horizontal plane
Topple - Wander of the spin axis in the vertical plane
Apparent wander varies with …. from the equator to the poles as the Earth rotates
Latitude
Transport wander is the …. of the gyroscope from the meridian it is set from.
Divergence
OPTICAL gyroscopes operate off of what effect?
SAGNAC
Name the error other than wander that can impact a gyroscopes functionality?
Gimble Lock
Advantages of a Ring Laser Gyro? (5)
- Minimal ‘spin up’ time
- Unaffected by high ‘g’
- No moving parts therefore minimum maintenance
- Wide dynamic range
- Very small drift rates
Disadvantages of a Ring Laser Gyro? (3)
- Precision machining required
- Costly due to high quality mirrors/sensors required
- Careful balance of gases required (He + Ne)
Fibre Optic gyroscopes are c….. and more e….. than Ring Laser gyroscopes.
CHEAPER + more EFFICIENT
What are the 2 different types of OPTICAL gyroscopes?
Ring Laser Gyroscope (RLG)
Fibre Optic Gyroscope (FOG)
Vibrating Structure Gyroscopes are also known as what?
Coriolis Vibrating Gyro (CVG)
Vibrating gyroscopes take advantage if what effect?
Coriolis Effect
How big are modern Micro Electro-Mechanical Systems?
Finger nail
What gyroscopes take advantage of the SAGNAC effect?
Optical Gyroscopes
An elementary radar consists of 3 components. These are?
Transmitting Antenna
Receiving Antenna
An energy detecting device or antenna
Radar clutter can come from …. (Name some examples)
Land Sea Rain Birds Chaff
Describe Pulse Width
Time duration of a single pulse (represented by tau).
Describe Pulse Length
Distance between the leading and trailing edges of a pulse.
Describe Pulse Repetition Interval (PRI)
The time period between the start of one pulse and the start of the next pulse.
Describe Pulse Repetition Frequency (PRF)
The number of pulses occurring in one second.
As the frequency of a radar increases, what happens to the;
- Resolution
- Equipment and Weight req’d
- Power and Operating range
- Interference
Resolution - Increases
Equipment and Weight req’d - Decreases
Power and Operating range - Decreases
Interference - Increases
Name the 3 radar transmission characteristics
Directional Information
Range Information
Relative Velocity between target and radar
How does a radar determine the relative velocity between itself and a target?
Doppler Effect
Radars fall broadly into what 3 types?
Pulse System, Continuous Wave, Pulse Doppler
Increasing the refraction occurs with what in changes in; Pressure, Temp, Moisture
Pressure - No difference
Temperature - Decreasing
Humidity - Increasing
What does MTI stand for? (radar)
Moving Target Indicator
What 4 characteristics are used to describe a radar?
Installation Env - Ground/Airbourne etc
Functional Characteristics - Search, Track etc
Transmission Char. - Pulse, CW etc
Oper. Freq - D-Band etc
Radar visual displays are usually of what 2 kinds?
Raw Video
Synthetic Video
3 applications of Radar are?
Search
Tracking
Fire-Control
Describe what a Search Radar does?
Scans wide areas at a lower frequency of return to the same point.
Can only distinguish targets that are far apart.
Describe what a Tracking Radar does?
Scans a narrow area more frequently.
Must be directed onto a target as their beams are narrower.
Describe what a Fire-Control Radar does?
Specifically direct weapon systems onto a target.
Emits a very narrow, intense beam to ensure accurate tracking information.
Describe a Search Radar’s characteristics? (PRF, Antenna Rotation etc)
- Low PRF
- Slow Antenna Rotation
- Low Freq, Scan rate
- Large in Size
- Serves predominantly as an early warning indicator
Describe a Tracking Radar’s characteristics? (PRF, Antenna Rotation etc)
- High PRF
- Higher Antenna Rotation
- Used when continuous flow of data required on discrete targets.
Describe a Fire-Control Radar’s characteristics? (PRF, Antenna Rotation etc)
- Highest PRF
- Very high Antenna Rotation (Often electronically scanned)
- Very narrow beam width
- Extreme accuracy, limited range
- Initial target detection difficult
- Multiple modes: Designation, Acquisition, Track
Least is _____
____ is best.
East
West
To operate efficiently a Direct Indicating Compass System (DICS) must have
Horizontality
Sensitivity
Aperiodicity
What does DICS stand for?
Direct Indicating Compass System
How can you make a compass more sensitive?
Longer magnet
Increase pole strength
Reduce friction
A magnetic compass is subject to disturbance and movement caused by ….
Acceleration/ Deceleration
Manoeuvre (pitch/roll/turns)
Turbulence
A gyro-magnetic compass may also be known as ….
Direction Indicator (DI)
The Detector Unit in the GMC may also be known as a ….
Fluxvalve
What will impact the accuracy of GMC when traveling in an E/W direction?
Acceleration
What will impact the accuracy of GMC when traveling in an N/S direction?
Turning
What happens to the signal from the fluxvalve when the a/c is manoeuvring?
The signal is cut-off
What are you looking for in a good compass swing area?
Low Magnetic Interference
List some reasons for conducting a magnetic swing
- Following a/c major servicing
- Doubt in accuracy
- Following a lightning strike
- When compass components are replaced
- After compass subject to a significant shock
- When carrying unusual ferromagnetic loads
What does ADF stand for?
Automatic Direction Finding (ADF)
An ADF is a NDB. What does NDB stand for?
Non-Directional Beacon (NDB)
What frequency do NDBs typically operate?
190-690 kHz
What instruments may show the you the relative bearing of a ADF?
- HSI
- Radio Magnetic Indicator (RMI)
- Multifunctional Display (MFD)
An Auto Dir. Finding (ADF) system is made up of what components?
- 2 perpendicular magnet cores wrapped with 2 coils of wire (Fixed Loop Coils).
- Field Coils -Search Coil
- Goniometer - Control Circuits
- Sense Aerial
Name some of the different errors an ADF may face
- Night Effect - Changing ionosphere behaviour.
- Synchronous Transmission - Two separate signals interfering.
- Bank - When turning due to the movement of the coils over the EM wave.
- Coastal Refraction - Will be along the coast.
- Quadrantal - Electrical field along longitudinal axis of a/c
What does VOR stand for?
VHF Omnidirectional Range
How many signals does a VOR transmit?
2
Omnidirectional + Rotating
Describe the 2 signals that a VOR transmits.
Omnidirectional REFERENCE signal (30 Hz)
Rotating DIRECTIONAL signal (30 Hz, 1800RPM)
What physics concept does a VOR take advantage of in order to determine bearing?
Phase difference between 2 EM signals
The VOR transmits the Omnidirectional signal when the radial antenna is pointing _____.
NORTH
VOR uses what type of EM wave?
Space Wave (LOS)
How many reserved bandwidths are there for VOR and ILS?
3
VOR performance will depend on?
A/C altitude
Transmitter Power
Transmitter Height
How accurate do we say a VOR is?
+/- 1 deg
Ground Beacon error can be caused by:
Uneven terrain (valleys, hills etc), trees, buildings etc
When VOR radials deviate from their standard track due to terrain and start reflecting off of buildings, it is known as?
Scalloping
Describe VOR Interference and Ambiguity
Interference - Receive 2 signals from separate ground beacons.
Ambiguity - When the a/c converges on the VOR the radials tighten.
What does DME stand for?
Directional Measuring Equipment
In relation to a DME, what is the TRANSPONDER and what is the INTERROGATOR?
Transponder - Ground Beacon
Interrogator - A/C
The a/c transmits how many pulse pairs per second?
25 pulse pairs per second
The DME transponder alters the reply frequency by +/- 63 MHz to prevent _______ ________
Destructive Interference
What does protected range and altitude mean?
The range and altitude outside which signals of the same frequency may have originated from a different transmitter.
What does TACAN stand for?
TACtical Air Navigation
TACAN is the Military equivalent of _____
VOR/DME
TACAN is ____ accurate than civilian ______
MORE accurate than civilian VOR/DME
In a TACAN, the DME operates in the UHF band, with every UHF frequency paired with _______
a VHF band frequency.
A TACAN can be co-located with a VOR. This is known as ____
VORTAC
In a TACAN, the Omnidirectional pulse fires when the directional pulse is pointing _____
EAST
TACAN has ___ channels.
Each channel is number _ to ___ with each having an _ or _ designation.
252 channels
Number 1 to 126, with X or Y.
What is the bearing accuracy of the TACAN?
+/- 0.5 deg
What frequency band does a DME operate on?
UHF
VOR determines _____
DME determines _____
VOR - DIRECTION
DME - RANGE
What does HSI stand for?
Horizontal Situation Indicator
The desired heading to a Beacon is set using the ___
CRS (Course)
List common inputs to the HSI.
- Magnetic Heading
- VOR/ILS
- DME
- TACAN
- NDB
What does VOR stand for?
VHF Omnidirectional Range
What does TACAN stand for?
TACtical Air Navigation
What does ILS stand for?
Instrument Landing System
What does DME stand for?
Directional Measuring Equipment
What does NDB stand for?
Non-Directional Beacon (NDB)
In addition to the common nav inputs, what other information can be displayed on the HSI?
TCAS - Term. Coll Avoid Sys INS - Inertial Nav Sys IRS - Inertial Ref Sys Radios Special purpose - Threat warning, Weather, moving map, A2A radar.
What does LLZ stand for? (in relation to ILS)
Localiser
What does GP stand for? (in relation to ILS)
Glidepath
What does an ILS enable?
Runway approach under instrument flight conditions.
The right lobe of the LLZ (Localiser) is amplitude modulated by how much?
150Hz
The left lobe of the LLZ (Localiser) is amplitude modulated by how much?
90Hz
As you drift from centreline, the _____ of a LLZ (localiser) lobe increases.
STRENGTH
If you approach from right of centreline the aircraft will receive more of the ____ Hz signal.
150Hz
If you approach from left of centreline the aircraft will receive more of the ____ Hz signal.
90Hz
The LLZ (localiser) operates in HF/VHF/UHF band? (Choose one)
VHF
The glidepath transmitter operates in the HF/VHF/UHF band? (Choose one)
UHF
The localiser (LLZ) modulates signal in the _________ direction.
HORIZONTAL
The glidepath(GP) transmitter modulates signal in the _________ direction.
VERTICAL
The UPPER LOBE of the glidepath signal is modulated at ___ Hz.
90Hz
The LOWER LOBE of the glidepath signal is modulated at ___ Hz.
150 Hz
If you are receiving more of the 90 Hz modulated signal, you are ____ the glidepath.
ABOVE
If you are receiving more of the 150 Hz modulated signal, you are ____ the glidepath.
BELOW
Aircraft using ILS can fall into one of how many ILS Operational Performance categories?
5
Information about the specific associated with glideslope can be found in the __ ____
UK AIP
Name the 5 ILS Operational Performance categories.
Category I Category II Category IIIA Category IIIB Category IIIC
What is the Decision height and Runway Visual Range (RVR) limits of an ILS Category I a/c?
DH - Not below 200ft.
RVR - Not less than 550m.
What is the Decision height and Runway Visual Range (RVR) limits of an ILS Category II a/c?
DH - Not below 100ft.
RVR - Not less than 300m.
What is the Decision height and Runway Visual Range (RVR) limits of an ILS Category IIIA a/c?
DH - With dual autopilot; Not below 50ft.
RVR - Not less than 200m.
What is the Decision height and Runway Visual Range (RVR) limits of an ILS Category IIIB a/c?
DH - With dual autopilot; Lower than 50 ft or no DH.
RVR - Not less than 75m.
What is the Decision height and Runway Visual Range (RVR) limits of an ILS Category IIIC a/c?
DH - With dual autopilot; No DH limits. Guidance to and along runway & taxiways.
RVR - No external visual reference.
List some ILS errors
Scalloping - Rapidly oscillating indications.
Beam bend - Gentle curve of the approach path.
FM Transmission - Frequencies just below 108MHz can produce spillage into LLZ frequencies causing interference.
Weather - Heavy snow or rain may attenuate ILS signals. Reducing range and degrading accuracy.
What does MFD stand for?
Multi-Function Display
What does EFIS stand for?
Electronic Flight Information System
List the key components of EFIS
- ADS (Air Data System)
- ADC (Air Data Computer)
- AHRS (Attitude and Heading Reference System)
- EICAS (Engine Indicating and Crew Alerting System) or ECAM (Engine Central Aircraft Monitor)
- Integrated Avionics Unit
- Data Bus
- PFDs (Primary Flight Displays)
- MFDs (Multi-Functions Displays)
- IESI (Integrated Electronic Standby Instrument)
What does AHRS stand for?
Attitude and Heading Reference System
What does ADAHRS stand for?
Air Data Attitude and Heading Reference System
What does EICAS stand for?
Engine Indicating and Crew Alerting System
Why might you need to be careful when reading fuel flow to the engines on MFDs?
The display may be presenting individual feeds if you have separate engines. Summing of flows needs to be done to determine total flow.
The data bus contains what? (List L to R with respect to the diagram in notes)
Bus Controller
3 x Remote Terminal
Bus Monitor
The two main types of display are
MFDs and PFDs
A total failure of display will be indicated by a _______
BLANK SCREEN
Failure of the feed to the display will be indicated by ______
RED CROSSES (X)
The MFD can display various information. This can be …
Airspace Info
Charts
Airways
TCAS
MIL_STD-……. is the high speed data bus network used to connect equipment.
MIL-STD-1773
What piece of equipment is known as the “Heart of processing” and processes all the data from the a/c’s avionics and formats it.
Integrated Avionics Unit
What does INS stand for?
Inertial Navigation System
What does GPS stand for?
Global Positioning System
An INS uses accelerometers and gyros to determine and track ____, ____ and ___.
POSITION
ORIENTATION
and
VELOCITY
List the components of the INS (5)
- Frame mounted Gimbals and motors
- Accelerometers and Gyros on a gyro-stabilised platform
- A computer
- Aircrew interface
- Cockpit displays
INS gyros are contained in a ____ ______ unit
FLUID FILLED
How many Gyros do you need to cover ROLL, PITCH and YAW?
3
Gyros are used in an INS for what purpose?
Keep the platform holding the accelerometers stable
The integrator is used to convert acceleration to _____
VELOCITY
The FIRST stage of the alignment process of the INS is ______
HEATING
What is the rate of INS heating during warmup?
15degC/min
During INS heating the operating temp is about _____
70degC
What are the two kinds of levelling done to an INS?
Fine
Coarse
The gyro compassing during alignment of the iNS aligns the platform with ____ ______
TRUE NORTH
The E-W gyro detects the _____ ________
EARTHS ROTATION
Once the - gyro reads zero azimuth gimbal is stopped.
E-W
This is when the Earth’s rotation has no component affecting the platform.
Once aligned a _____ ‘____’ light is illuminated
GREEN ‘READY’
Strapdown INS/IRS systems are typically c_____, more r_____ and more r_____ than gimballed systems.
CHEAPER
more RELIABLE
more RUGGED
Maximum error in SCHULER tuning occurs at __._ minutes and __._ minutes following disturbance.
- 1 mins
63. 3 mins
Some INS errors are
- Gimbal lock (Gimballed system)
- Compounding of disturbances from turbulence or vibration
Name the 3 SEGMENTS associated with GPS
SPACE
CONTROL
USER
GPS satellites are in the ___ segment
SPACE
GPS sats transmit on what 2 frequencies?
L1 - 1575.42 MHz
L2 - 1227.6 MHz
C/A code is transmitted on what freq(s)?
L1
P code is transmitted on what freq(s)?
L1 and L2
The 2 services available from GPS are ____ and ____
SPS - Standard Positioning Service
PPS - Precise Positioning Service
What GPS service will provide you with the most accurate service?
PPS - Precise Positioning Service
PPS is primarily intended for …..
Military Users
US, NATO and AUS
What does GNSS stand for?
Global Navigation Satellite System
List types of GPS receiver
- Continuous tracking
- Sequential
- Multiplex
- All-in view
List some GPS errors
- Insufficient satellite availability
- Ionospheric Effect
- External interference and masking - LOS
- Multipath effects (signal reflection from buildings)
Describe Differential GPS
The use of a ground station to minimise GPS errors.
When utilising Differential GPS; corrections are applied to the GPS signal at the ____ receiver.
USER’S
What does GNSS stand for?
Global Navigation Satellite System