11.5.2 - Avionic Systems Flashcards
1
Q
What does the VHF communication system provide?
A
Allows radio comms over distances of up to 200nm
2
Q
What does the HF system provide?
A
Uses earth’s ionosphere to reflect radio communication systems
3
Q
ACARS
A
Aircraft Communication, Adressing and Reporting System. exchange of flight and maintenance data
4
Q
What does all communication require? (2)
A
Information (audio, video, digital) and a carrier (transport the info.)
5
Q
Radio frequency bands (8)
A
Radio frequency bands
VLF = up to 30Khz - military RF LF = 30 kHz to 300 kHz - public radio MF = 300 kHz - 3 MHz - public radio HF = 3mhz - 30 MHz - Long distance comms VHF = 30mhz - 300mhz - comms up to 200nm UHF = 300mhz - 3ghz - military radar SHF = 3ghz - 30 ghz - satcom, weather and altimeter EHF = 30hg - 300ghz - not used in comms and navigation
6
Q
What do microphones transform?
A
Acoustic info into electrical signals
7
Q
What do loudspeakers transform?
A
Electrical signals back into acoustic info
8
Q
Purpose of static wicks?
A
Discharge static build up, which could cause damage to electrical systems.
9
Q
What is the ACP and it’s main components?
A
Audio Control panel.
3 VHF transceiver selectors
2 HF transceiver selectors
Cabin, flight, PA and SATCOM knob
10
Q
What are the 3 positions for the filter selector knob?
A
V - Voice, voice information only
R - Range, indent code only
B - Both, both
11
Q
Priority of PA amplifiers (5)
A
- Cockpit
- Purser
- Cabin crew
- Prerecorded announcements
- Boarding music
12
Q
Types of CVR - Cockpit voice recorder
A
Analogue - stores the last 30 mins and erases the previous automatically
Digital solid state - stores the last 120 minutes, previous is overwritten
13
Q
When does the CVR operate?
A
Starts on engine start up, and finishes when last engine shutdown on ground
14
Q
What is the CVR erase switch?
A
Allows the crew to maintain privacy when parking brake is applied on the ground
15
Q
VHF system components (3)
A
System 1 is for the CAPTAIN’S voice comms
System 2 is for the FIRST OFFICER
System 3 is for the ACARS system
Each system has its own antenna located on the fuselage.
16
Q
What can indicate a system failure?
A
A missing side tone.
17
Q
What is the RMP and its function?
A
Radio Maintenace Panel - used to select the required frequency for VHF and HF systems.
18
Q
Why is Satcom advantageous over HF?
A
HF is affected by solar activity, satcom is not.
19
Q
HF components (3)
A
Antenna, antenna coupler and transceiver.
20
Q
What is satellite signals to earth, and vice versa, known as?
A
Downlink and uplink, respectively.
21
Q
Two types of ACARS reporting systems?
A
Automatic (engine, eta, out, in) and manual (ATC, Load sheet, report)
22
Q
What does satcom provide?
A
SATCOM provides reliable worldwide digital data transfer for ACARS, cockpit voice and telex communications and passengers voice, telex and fax communications.
23
Q
SATCOM components (3)
A
Aircraft earth station ( AES)
Ground earth station (GES)
Satellites, obvs
24
Q
3 types of Emergency locator transmitter (ELT)
A
Fixed, portable and fixed/portable.
25
What can activate an ELT?
A fixed ELT can be activated by 5G or more force in the longitudinal axis and a portable one can be activated upon contact with water.
26
3 components of the radio navigation system
ADF
VOR
ILS
27
Radio Nav - What is the ADF system?
The automatic directional finder uses radio signals from ground stations to calculate the direction to the station, which is indicated in the cockpit.
28
Radio Nav - What is the VOR system ?
The VHF omnidirectional range system uses radio signals from VOR ground stations to calculate the direction to the station. The information is used by the autopilot.
29
Radio Nav - what is the ILS system ?
The Instrument Landing system uses ground signals to determine position from the runway using a localiser, glide slope and marker beacons.
30
What are the two types of navigation chart
ICAO and enroute
31
What are VFR and IFR?
Visual flight rules and Instrument flight rules.
32
What are the two types of North?
True North (TN) - Is the direction to the geographical North Pole.
• Magnetic North (MN) - Is where the magnetic field lines are gathering
33
What is Track? (TK)
The movement of flight over the earth in relation to Heading.
34
What is ‘drift’ in relation to heading and track?
The angle at which the track deviates from the heading, usually due to wind.
35
What is Bearing?
The direction of an aircraft to the position of an object, in degrees.
36
What is the frequency band for ADF?
190Khz - 1750 KHz.
37
What is the principle behind the VOR system?
The lighthouse principle.
1. The flashes in all directions occur when the rotating light beam passes through magnetic north.
2. Measure the time between the all directions flash light and seeing the rotating beam, enable the direction of the lighthouse to be worked out.
38
ILS - how does the Localizer work?
Splits the runway into halves (lobes) of different frequency.
Left side is 90 KHz.
Right side is 150 kHz.
Deviation from the centreline is shown as a deflection pointer in cockpit.
39
ILS - How does the Glide slope work?
The same as the Localizer, but with upper and lower lobes.
Upper lobe is 90khz.
Lower lobe is 150khz.
Deviation is shown in the cockpit as a deviation pointer.
40
ILS Autopilot poor weather landing categories (3)
CAT 1 - 800m of runway visiablity at 200ft
CAT 2 - 400m of runway visibility at 100ft
CAT 3 - 200m of runway visibility below 100ft
41
ILS - How do Marker beacons work?
Outer marker - 7km from runway omits a 400Hz tone
Middle marker - 1km from runway omits a 1300hz tome
Inner marker - 300m from runway omits a 300hz tone
42
What is the Radio altimeter and At what altitude is it active ?
Determines the vertical distance between aircraft and ground.
Below 2500ft
43
What is decision height?
Set on the Radio altimeter, it is the altitude at which the pilot must decide if visability is sufficient for a safe landing.
44
What is GPWS and when is it active?
The ground proximity warning system uses aural and visual announciations to alert the pilot if he (not she) is too close to the ground.
It is active below 2500ft.
45
What are the main GPWS inputs? (4)
Glide slope,
Flap and gear positions,
Radio altimeter,
Vertical speed.
46
What is GPWS mode 1?
Excessive sink rate mode.
Alerts when AC decends below 2500ft at too fast vertical speed. ‘SINK RATE’
47
What is GPWS mode 2?
Excessive terrain closure rate mode.
Alerts when AC height dramatically increases. Eg an approaching mountain. ‘TERRAIN’ or ‘WHOOP WHOOP PULL UP’
48
What is GPWS mode 3?
Altitude loss after takeoff mode.
Alerts if altitude is being lost after takeoff. “‘DONT SINK”’
49
What is GPWS mode 4?
Terrain clearance mode
Alerts when approaching the ground with incorrect flap or gear settings. ‘“TOO LOW FLAPS, TOO LOW GEAR”
50
What is GPWS mode 5?
Below Glideslope mode.
Alerts if an AC drops below the glideslope on approach.
Active below 1000ft
51
What is GPWS mode 6?
Radio altitude callouts and bank angle mode.
Alerts of approaching distances to the runway and if the bank angle of the AC exceeds critical. “400, 300, 200, minimums” or “BANK ANGLE”
52
What is GPWS mode 7?
Wind shear mode.
Alerts the crew of wind shear conditions during takeoff or landing. “WIND SHEAR”
53
What does the DME measure?
Distance measuring equipment measures the slanting distance to the ground via ground stations
54
How does the weather radar system operate?
Provides a map type display of the weather conditions, using 180° pulses from the radome. Objects like water droplets reflect signals back.
55
When must you take extra care before operating the weather radar system?
On the ground. The microwaves and radiation emitted are hazardous of life. 10ft-15ft clearance advises.
56
What are the 3 reply modes for ATC?
Mode A - ATC transmits a four digit ident code.
Mode C - ATC transmits the ident code and the ACs barometric altitude.
Mode S - ATC transmits a 24-bit ICAO address, to help ATC deal with increasing levels of traffic.
57
What are the 3 emergency ATC codes?
7500 - identifies a hijacking,
7600 - Radio failure,
7700 - If the AC is in any other emergency.
58
What is TCAS?
Traffic alert and Collision Avoidance System.
59
How does TCAS operate?
It uses other aircraft equipped with an ATC transponder to determine position, bearing, altitude etc. to determine a possible collision.
Warnings given as “traffic traffic” and “climb climb”
60
How does TCAS communicate to detect conflicts? (3)
TCAS to ATC transponder,
TCAS to Mode S transponder,
TCAS to TCAS.
61
What are the four TCAS symbols found on the Nav Display?
(1) Other traffic - Hollow white diamond,
(2) Proximate traffic - Solid white diamond,
(3) Traffic alert - Solid amber circle,
(4) Resolution advisory - Solid red square.
62
What satellites are used by the GPS system?
24 primary and 3 spare. They orbit around about 10900nm above the earth.
63
How does GPS operate?
The GPS unit in the AC calculates the travel time of the signals, comparing it against what time the signal was sent.
64
What can improve accuracy of GPS?
Differential GPS (DGPS). Increases accuracy to about 3m.
65
What is FANS?
Future Air Navigation System.
66
What does FANS provide?
Uses GPS and SATCOM to enhance communication between the aircraft and ATC.
67
What do Gyros measure?
The rotation around the 3 axis (Pitch attitude, role attitude and heading). The angular rates are know as Pitch, roll and yaw rate.
68
What do accelerometers measure?
Movements along the X, Y and Z axis to calculate speeds.
69
What are the 3 types of gyro and what do they provide?
1. 2 gyros with 3° of freedom.
2. 3 gyros with 2° of freedom.
3. 3 rate gyros, 1 for each axis
70
How does a laser gyro function?
Uses rotating light beams to measure angular rate.
1 beam rotates clockwise, the other rotates anti-clockwise.
Comparison between the two beams is measured.
71
What are the types of accelerometer? (3)
Electrolyte accelerometer- uses two resistors.
Mass and spring - uses a mass movement against a spring.
Pendulum - pendulum moves with acceleration.
72
What is the preferred type of Accelerometer?
Pendulum accelerometer.
73
What are the types of inertial stabilised platform? (2)
The gimbal platform.
| The strap down system.
74
What does the gimbal platform system use?
A stable element (the platform) with 3 gyros (one for each axis) and 3 accelerometers.
75
What does the Strap down system use?
All components are fixed (strapped down). It also has 3 gyros and 3 accelerometers.
76
What is the AHRS?
Attitude Heading Reference System.
It contains the Gyros, accelerometer and a computer.
It Provides pitch and roll attitude without any other inputs.
77
What is the IRS?
Inertial Reference System.
78
What is the INS?
Inertial Navigation System.
79
What does the INS contain?
Inertial navigation unit.(gyros accelerometers, computer),
Mode selector unit,
Control and display unit,
Separate battery unit.
80
What is the Flight management system?
The FMS reduces pilot workload and improves flight safety and economy by calculating flight track, best profile and eta.
81
What are the subsystems to an AFS (autoflight) System? (5)
```
Autopilot,
Flight director,
Auto throttle system,
Automatic pitch trim system,
Yaw damper system.
```
82
What does auto pilot do?
Controls flight automatically, including landings.
83
What does the flight director do?
Shows the pilot how to manually fly the aircraft using command bars on the flight display.
84
What does the Auto throttle system do?
Automatically controls engine power levels.
85
What does the auto trim system do?
Maintains pitch stability during flight by automatically adjusting the THS to compensate for C of G and C of L changes.
86
What does the Yaw damper do?
Controls the rudder to dampen Dutch roll oscillations.
87
What does the flight envelope system do?
Monitors all operations of the auto flight systems to prevent any abnormal flight condition during automatic operation.
88
What are the 3 main parts to the auto flight system?
Computers, control panels and outputs.
89
What are the positions of the lever for autopilot on older aircraft? (2)
Up position - autopilot engaged and connected to flight controls.
Down position - autopilot disengaged from the servos.
90
What does the autopilot inner loop control?
The pitch channel and the roll channel. It calculates the difference between the actual attitude (current position) and commanded attitude (pilot or outer loop selections) of the flight control surfaces.
91
What does the autopilot outer loop control?
It controls the aircraft to capture and stabilise a flight path. It provides the commanded altitude for the inner loop, by comparing a commanded value and the actual flight path.
92
What can disengage autopilot?
Pressing the ‘disengage bar’ or moving the lever to off.
There is also a red quick disengage button on the control wheel. (Side-stick for airbus)
93
What alert occurs when autopilot is disengaged?
An aural and visual warning to inform the pilot to take back manual control of the aircraft.
94
What are the 3 ways of integrating autopilot into flight controls?
1. A servomotor connected directly into the cable system near the control column.
2. An autopilot hydraulic motor inside the hydraulic power unit. Uses servos or transfer valves.
3. A whole separate hydraulic motor. Mainly for large commercial aircraft. Uses the aft cable quadrant.
95
How does the flight director operate?
Uses input signals from the control surfaces to calculate output signals for indications to the pilot.
96
What indications does the Flight director give?
Roll commands via the roll bar on the artificial horizon.
Pitch commands via the pitch bar on the artificial horizon.
97
What two types of system are used by the auto throttle system?
The classic system - uses a servomotor to adjust throttle position and mechanical linkage to the engine.
The second system - fly by wire, delivers digital signal to the engine computer.
98
What two modes can auto throttle use to control the engines?
Thrust mode - controls engine pressure ratio or N1 rotational speed.
Speed mode - controls calibrated airspeed of the aircraft’s desired value, coming from the FMS or by the pilot.
99
What are the 6 phases of auto throttle?
```
Climb phase.
Cruise phase.
Descent phase.
Approach phase.
Landing phase,
Go around phase.
```
100
How is the auto throttle system engaged?
Engage interlock circuit, where the auto throttle computer must be valid and the sensors must be valid.
101
How can you disconnect auto throttle?
Using the quick disconnect button on the side of the levers, or When either of the conditions become invalid
