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Avionics and operations Flashcards

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1
Q

Shortcomings of ANS

A

ANS = Aircraft navigation system

En route:
1. Mixture of direct tracks, fixed airways or organized tracks
2. Indirect routes
3. Lack of uniformity in procedures
4. Lack of ATC support for advanced on-board systems

Terminal Area & Approach
1. Complexity due to aircraft variation
2. Seperation requirements cause inefficiencies
3. Lack of automation
4. SID/STARs fixed - Indirect routings
5. Noise abatement policies

The current system is incapable of making optimum use of ATC system capacity, available airspace, and aircraft capabilities

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2
Q

AFS and AMS + Communications shortcomings

A

Aeronautical Fixed Service

ground-ground communication between ATS units

Aeronautical Mobile Service

Air-ground comms bw A/C and ATS units
Air-Air comms bw A/C

Shortcomings:
1. Voice limited
2. Radio wave propagation limitations constrain VHF comms to line-of-sight coverage.

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3
Q

Navigation shortcomings

A
  1. Coverage limited due to line-of-sight systems constraining to land and coastal areas.
  2. Air routes based on navigation aides causing choke points
  3. Unable to keep up with future air traffic growth
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4
Q

Surveillance shortcomings

A
  1. No radar surveillance coverage possible over oceanic /mountaneous areas meaning only procedural ATC support, with little ATFM support
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5
Q

FANS (what are the CNS goals?)

A

Future Air Navigation System

Communication:
- Network centric data exchange, VHF datalinks, SSR mode S, satellites

Navigation
- GNSS as sole means for navigation
- Trajectory-Based Operations, 4D flight plans, RNP requirements
- Performance-based operations

Surveillance:
- Broadcasting nav. information over ADS-B and SSR mode S
- Shift of ATC tasks toward the flight deck (ACAS and ASAS)
- More automated ATC

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6
Q

VDL

A

VHF (Very high Frequency) Data Link

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7
Q

SWIM

A

System Wide Information Management

Jnformation managed and shared between all stakeholders

DownLink:
1. Aircraft flight identification
2. Aircraft navigation state
3. Intended flight plan

UpLink:
1. ATC messages
2. Weather information
3. ATIS (Automatic Terminal Information Service)

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8
Q

GNSS

A

Global Navigation Satellite System

Needs augmentation
1. on-board (GNSS receiver monitors integrity of navigation signals from GNSS satellites)
2. Local/Regional ground-based reference stations monitor the health of GNSS satellites and determine the range error at its location, which is then transmitted to aircraft (DGPS)

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9
Q

RNP

A

Required Navigation Performance

Specification of navigation system accuracy required to operate in specified piece of airspace.

ATS provider and Aircraft operator responsible

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10
Q

4D Trajectories

A

Each aircraft needs to be at a certain location at a specific time. Increasing airspace capacity.

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11
Q

ADS

A

Automatic Dependent Surveillance

ADS is an on-board avionics function that automatically transmits via digital data link, aircraft position data from the ONS (on-board navigation system) it provides real-time surveillance information to ATS units and other entities in the ATN. It allows surveillance in oceanic and other areas which lack radar or line-of-sight coverage.

  1. Time of day
  2. AIrcraft ID
  3. Position in 3D
  4. Velocity/Heading
  5. AIrcraft intent
  6. Meteorological data
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12
Q

ADS-B

A

Broadcasts ADS information.

Over continental/coastal: VHF data links (VOR or SSR mode S)
Over remote areas: Satellites

Facilitates ASAS

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13
Q

ASAS, ACAS, and TCAS

A

Airborne Seperation Assistance System
-Keep aircraft seperated

Airborne Collision Avoidance System
- Airborne system that prevents midair collisions as backup of ATC by alerting flight crew of potential collisions, entirely on board the aircraft. One example is the TCAS

Traffic Collision Avoidance System
-when seperation violation occurs gives warning in form of TA (Traffic Advisory) and RA (Resolution advisory)
Main problems:
1. Lack of precision; only vertical resolutions, not lateral
2. Nuisance warnings due to lack of resolution .

Remember: Use SSR to communicate

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14
Q

FIR definition + organization

A

Flight Information Region

Airspace around the world is divided into FIRs, which are then subdivided into sectors where each sector has a team of ATC responsible for flow of air traffic.

Organization:
Controlled airspace: ATC, FIS, AL
Uncontrolled airspace: FIS,AL

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15
Q

ATS

A

Air Traffic Services

ATS = ATM + FIS + AL

Purpose of Air Traffic Services is to enable aircraft operators to meet planned times of departure and arrival and adhere to flight profiles without compromising safety

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16
Q

ATM

A

Air Traffic Management

ATM = ATC + ASM + ATFCM

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17
Q

ATC

A

Air Traffic Control

Maintain safe distance between aircraft and obstacles

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18
Q

ASM

A

Air Space Management

Maximize utilization of available airspace by triage

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19
Q

ATFCM

A

Air Traffic Flow & Capacity Management

Ensure optimum flow of air traffic when demands exceed capacity of ATC service

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20
Q

FIS

A

Flight Information Service

Collect, handle, and disseminate flight-related information to assist pilot

Example: ATIS

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21
Q

AL

A

Alerting Service

Initiate search and rescue for aircraft in distress

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22
Q

ATIS

A

Automatic Terminal Information Service

Repeated message (VHF) containing information about

  1. Runway in use
  2. Transition level (QNE to QNH)
  3. Weather
  4. QNH
  5. Operational issues
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23
Q

Airspace organization
CTR, TMA, CTA, UTA

A

CTR: Control zone
- Local ATC
TMA: Terminal Control Area
- CTRA - CTA connection
CTA: Control Area
- General ATC, within FIR
UTA: Upper Control Area
- Across FIRs

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24
Q

STAR

A

Standard Terminal Arrival Route

Defines route flown between ATS route and approach fix. Connects CTA with CTR through TMA

  1. Noise abatement
  2. Communication minimisation
  3. Seperating in and outgoing traffic
  4. Terrain clearance
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25
ACC
Area Control Center Controls traffic within CTA
26
APP
Approach / Departure Control Provides connection between ACC (CTA) and TWR (CTR) Incoming traffic from CTA to airport CTR follow STAR's and outgoing follow SID's
27
TWR
Controls air traffic in CTR 1. VFR Traffic 2. Taxiing 3. Traffic ready for departure 4. In and outgoing traffic -Airport surface Detection Equipment (ASDE)
28
SID
Standard Instrument Departure Defines route flown between ATS routes (Connects CTR with CTA, through TMA) 1. Noise abatement 2. Communication minimisation 3. Seperating in and outgoing traffic 4. Terrain clearance
29
Radio-transceivers (Voice) types
VHF (Very high frequency) -limited to Line-of-Sight HF (High Frequency) -over-the-horizon
30
AFTN
Aeronautical Fixed Telecommunications Network Communication between Air Traffic Services (Flight Plan)
31
ACARS
Aircraft Communications Addressing and Reporting System -Between aircraft and airline Transmitted via VHF radio. Allows airline operator to communicate with aircraft in fleet.
32
CPDLC
Controller Pilot Data Link Communications. -Digital messages between Between air traffic controllers and pilots, avoiding need for VDL
33
Navigation means
-Land routes: VOR/DME -Long range: INS/GPS -Main trend: RNAV
34
RNAV
Area/Random Navigation Area navigation is a method of navigation which permits the aircraft to navigate along any desired path within coverage of station navigation aides, within limits of self-contained aides, or a combination
35
Surveillance Means
Continental and Coastal: -Primary and Secondary surveillance radar Oceanic and Remote: -Procedural voice reporting. Pilots must report position to ATC
36
Primary and Secondary surveillance radar
(PR) Primary Surveillance Radar: Purpose: slant range, azimuth, radial velocity -Pulses of radio-frequency energy transmitted and signals scattered back by the surface of an aircraft are received (SSR) Secondary Surveillance Radar: Purpose: pressure altitude -Signal transmitted by this radar initiates transmission of a reply signal from transponder of an aircraft. Primary Radar + SSR mode A/C provides ATC info about: aircraft position, heading, slant range, altitude, radial velocity, identification
37
Primary radar limitations
Range resolution: determined by pulse width, ability to distinguish two objects on the same bearing. Objects should be spaced more than half the pulse width Bearing resolution: Minimum angular seperation at which two objects can be seperated at the same range. Objects should be spaced more than range x beam width. Minimum range: Pulse width Maximum range: Pulse repeat time Maximum range: Rotational velocity
38
SSR modes
SSR mode A: 8 milliseconds: replies aircraft identification code SSR mode C: 21 milliseconds: replies aircraft pressure altitude SSR mode S: Selective, discrete addressing of aircraft unique adress assigned to each aircraft.
39
SSR side lobes
Weak P2 omnidirectional antenna pulse is given out, if its found to be as strong as P1 and P3 then you are talking to a side lobe.
40
SSR limitations
1. Over-interrogation Too many interrogating SSRs for one aircraft. 2. Fruiting Solved by jitter. Aircraft considers answer to different interrogation as its own 3. Garbling Two AC at same time and distance reply to same interrogation, response is garbled
41
Why Satellite Navigation
1. Line of sight coverage over vast areas 2. Remote areas reach 3. Radio signals penetrate ionosphere overcoming HF radio disadvantages 4. Motion of satellites increase chance of good GDOP anywhere on earth
42
GPS broadcasting Signals
L1 and L2 high frequency carrier signals PRN (Pseudo Random Noise) Code -Calculate part of pseudo range by matching received PRN code with database reference to find phase -Identify which satellite is sending signals Navigation message -Position,Velocity,Orbital parameters, Atmospheric model -HOW (Hand Over Word) contains time the data has been sent by the satellite First NM --> PRN
43
GPS Errors
1. Satellite clock (General relativity (Mass) ) or (Special relativity (Velocity) ) 2. Atmospheric delays - Solve by atmospheric models or dual frequency 3. Receiver clocks -NM and PRN 4. Multi-path -filter weak signals 5. GDOP -spread out is better
44
DGPS
Differential GPS Ground-based receiver to measure GPS timing errors and then provide correct information to nearby receivers
45
LAAS
Ground-Based Augmentation System Aircraft landing system based on real-time DGPS
46
WAAS
Space-Based Augmentation System Geostationary satellites broadcast correction data to users of GPS satellites
47
VFR
Visual Flight Rules
48
IFR
Instrument Flight Rules
49
DH
Decision Height Height above runway at which landing must be aborted if the runway is not in sight
50
RVR
Runway Visual Range Visibility at the runway surface
51
ICAO landing categories
Cat I : ILS and Marker beacons, one pilot Cat II: Dual ILS, radar altimeter, autopilot coupler or dual flight director, two pilots, missed- approach attitude guidance Cat IIIa: Fail-passive autopilot or head-up display Cat IIIb: Fail-operational autopilot, automatic rollout Cat IIIc: Not approved anywhere
52
ILS
Instrument Landing System Localizer -left/right based on phase differences -end of runway Glideslope -up down based on the phase lobes, remember higher multipath transmitter is smaller lobes - runway treshold -False glide slope at 15 deg Marker beacons - in front of runway NILETO (ninety left top) Hz
53
Radio principle
Wire is placed in space and excited with ALTERNATING CURRENT, power not dissipated in wire is radiated into space, and a similar wire will intercept the power and a detector connected can indicate the magnitude, frequency, phase or time of arrival of the transmitted energy.
54
Lobe Pattern
Radiation/Reception gain and directional patterns of an antenna
55
Cone of silence
Inverse cone above radar will not detect any aircraft
56
Modulation types
PM Pulse modulation (on-off) FM Frequency Modulation - not affected by noise AM Amplitude Modulation
57
Propagation of Radio Waves
< 3 MHz (30 MHz (VHF) Line-of-sight
58
Reducing Vertical Nulls between Lobes
1. Lowering the antenna 2. Placing a horizontal Counterpoise
59
LOP
Line Of Position 1. Theta system (VOR) 2. Rho system (DME) 3. Rho-Theta system, greatest geometrical accuracy
60
VOR
VHF Omnidirectional Range Combining an omnidirectional AM signal and a rotating array FM signal for phase comparison.
61
DME
Distance Measuring Equipment Active, two-way navigation system, calculates the SLANT RANGE between aircraft and DME station. Jitter introduced to ensure no syncing with other transmitters. That way other aircraft will see your signal be inconsistent along their measurement periods, whereas for you it is consistently the same after you send it out.
62
Dead Reckoning System
Derive the state vector from a continuous series of measurements relative to initial position - Related to inertial navigation systems - Must be reinitialized to remove accumulated errors
63
INS
Inertial Navigation Systems 1. Stable Platfom Directly measured in Geodetic inertial frame -Gyroscopes 2. Strapdown Must be algorithmically transformed to geodetic from body -Optical gyroscopes, MEMS Advantages: - Continuously available - Self-Contained - Autonomous - Passive, not jammable - High accuracy Disadvantages: - Expensive - Error accumulation, must be corriged by GPS
64
Schuler Tuning
Undamped closed loop corrective action to constrain system tilt errors. Oscillate around zero value with a 84.4 minute period. Corrects transport wander by feeding back vehicle rate turns to torque the vertical gyro so the platform follows local vertical.
65
Optical Gyroscopes
Photon of light send out in CW and CCW directions, when input rate is zero transit time is equal. During rotation, travel length shifts and so doppler effect causes frequency shift, which can be measured. Small jitter effect necessary at low turning rates to prevent light beams from 'sticking to eachother' which is filtered out later.
66
MEMS Gyro
Uses Coriolis effect. Advantages: -Small -Low power consumption -Inexpensive -Low maintenance -Reasonable reliability Disadvantage: low accuracy
67
AOM
Aircraft Operating Manual Contains and describes performance-related data needed for operation of the aircraft. Flight crew would have to find data for optimal settings for flight conditions and external factors High pilot workload. System that manages aircraft performance and guidance along optimal route needed: FMS
68
FMS
Flight Management System Drivers: - Economic benefits - Pilot Workload - Growth of air traffic - Accurate nav sources: GPS, INS - Computer system capacity - Ability to connect various subsystems FMS = FMC + FDSU + CDU FMC = Flight Management Computer FDSU = Flight Data Storage Unit CDU = Command/ Display Unit FMS is mission critical as opposed to the autopilot which is safety critical, thus these will not be mixed.
69
FMS tasks
1. Flight planning enables major revisions of the flight plan in flight based on data such as [Radio navaids, waypoints, airways, airports, runways, airport procedures, company routes] 2. Navigation and Guidance Combines data from nav sources (INS, GPS, Navaids) to derive best estimate of ac position and velocity. Computes ground speed, track, weather data. 3. Optimization and performance prediction FMS selects speed, altitude, and engine power settings during all phases of flight.
70
Navigation system categories
- Sole means - Supplemental means - Primary means
71
Sole means
Navigation system category: -For a given phase of flight, must allow aircraft to meet all four navigation system performance requirements Accuracy, Integrity, Availability, and Continuity of service (Does not exist yet, INS comes closest)
72
Supplemental Means
Must be used in conjuction with a sole means navigation system (GPS)
73
Primary Means
Navigation system that for a given phase of flight must meet accuracy and integrity standards, but not full availability and continuity requirements. Safety achieved by limiting flights to specific time periods or procedural restrictions. (VOR, DME)
74
Types of Navigation Systems
1. Positioning Systems -Celestial navigation, mapping -Radio navigation systems 2. Dead Reckoning Systems -Classical DR -INS
75
Dead reckoning systems
Derive state vector from a continuous series of measurements relative to initial position -Classical DR -Inertial Navigation Systems Require positioning systems to recalibrate
76
Navigation Errors
1. Sensor errors 2. Computer errors 3. Data entry errors 4. Display errors 5. Flight-Technical Errors 1-4: NSE: Navigation System Errors 5: FTE: Pilot error
77
GDOP
Geometric Dilution of Precision Navigation error depends on your position
78
Software Classification
Mission-critical code Safety-critical code Software architecture developed to segregate safety and mission critical code from eachother
79
Cockpit information
1. Primary flight info -Attitude, Airspeed, Altitude, Heading 2. Airborne systems data -Hydraulics, Electronic systems 3. Airframe data -Undercarriage, Flaps, Slats 4. Navigation information -Position, Velocity, Flight-Plan 5. Engine data -Thrust, RPM, Fuel-flow 6. Warning information -Traffic, Terrain, Weather
80
Flight instrument positioning
-Basic six (outdated) -Basic T (new)
81
Display types
-Additive One information source, checked incidentally -Accumulative Multiple information sources, checked incidentally (can even be two engines) -Integrative Multiple information sources, checked continuously
82
FD
Flight Director Aircraft Symbol (V-bars) Command Bars
83
FD modes
You can set all sorts of commands in the Mode Control Panel: L NAV, VORLOC, lvl chg, hdg sel, app, alt hld, v/s IF you then choose to use FD you get commands to follow to satisfy these setups yourself. If you choose to use autopilot the aircraft will move to the specified demands itself.
84
EFIS
Electronic Flight Instrument System 1. HUD 2. PFD 3. ND 4. MFD 5. EICAS 6. ECAM 7. CDU
85
HUD
Head Up Display
86
PFD
Primary Flight Display
87
ND
Navigation Display
88
MFD
Multi-Function Display
89
EICAS/ECAM
Engine Indication & Crew Alerting System (boeing) Electronic Centralised Aircraft Monitor (airbus)
90
CDU
Command/Display Unit
91
Magnetic Variation
Angle between LOCAL MAGNETIC MERIDIAN and the GEOGRAPHIC MERIDIAN. If magnetic north lies to east of North it is positive.
92
Magnetic Dip
Inclination angle of lines of magnetic force with respect to the earth. 0 at magnetic equator and 90 at magnetic poles.
93
Direct reading compass
Freely suspended. Compass pivot point above center of gravity. In the northern hemisphere the southern tip goes up and vice versa
94
ANDS/ASDN
Aircraft going east on northern hemisphere will find that accelerating makes the compass overshoot north and decellerating overshoot south. Vice versa in southern hemisphere
95
UNOS/ONUS
Aircraft going east on northern hemisphere will find that the compass undershoots when turning north and overshoots when going south and vice versa.
96
Direct reading compass deficiencies
1. Compass must be readable by crew 2. No means of obtaining simple electrical input 3. Damping action of liquid causes lag in turns 4. Erronenous indications during turns and acceleration
97
Fluxgate Magnetometer
remote compass that uses electro-magnetism principles to convert earth magnetic field into measurable voltage. Solves problems of magnet having to be readable and obtaining simple electrical input from it.
98
Gyrosyn compass
Magnetic slaving principle. Combining a magnetic compass (fluxgate magnetometer) and a directional gyroscope solves problems during acceleration and turns. Magnetometer compensates for deficiencies of directional gyro: namely the drift (long term, low frequency) Directional gyroscope compensates for deficiencies in magnetometer: namely the errors during accelerations and turning (short term, high frequency)
99
Geodetic reference frame
NED reference frame but attached to aircraft center of gravity
100
Body reference frame
Geodetic reference frame including attitude (pitch, roll, yaw/heading)
101
Rigidity
Property which resists force tending to change direction of spin axis
102
Precession
Angular change in direction of rotation under influence of an applied force. Change in direction takes place not in line with force but point 90 degrees away in direction of rotation.
103
Free gyroscope
Gyroscopes which remain a fixed orientation relative to inertial space
104
Gyroscope compensations necessary
-Apparent drift (rotation of earth) -Transport wander (movement of vehicle) fixed by feeding velocity data back Learn how to derive these
105
Rate gyroscope
Only one degree of freedom and uses precession property and angular rates Still needs to be compensated for transport wander
106
QFE
absolute altitude , 0 when on runway - height above runway
107
QNE
relative to 101325, - flight levels
108
QNH
relative to MSL - altitude

Avionics and Operations (1 decks)

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