11:5:2 Instruments Avionic Systems Flashcards
What 3 groups can communication systems be split into on modern aircraft
- Aircraft Communication (inside/outside the aircraft called the interphone and passenger address system PA)
- Radio Communications (VHF, HF, SATCOM, ACARS
- Accident Investigation (Cockpit Voice Recorder (CVR), Emergency Locator Transmitter (ELT)
What does SATCOM stand for
Satellite Communication System
What does ACARS stand for
Aircraft Communication, Addressing and Reporting system
What are the 3 different microphones used in the cockpit
- Integrated microphone (Headset and oxygen mask)
- Hand held microphone (For passenger announcements)
- Area microphone ( For Cockpit Voice Recorder)
What distances is VHF suitable for
Up to 200 nautical miles
What type of communication is HF suitable for
Very long distances as HF radio waves are reflected by the earths ionosphere
Using what means can ACARS communicate with the ground to provide its data
VHF, HF or SATCOM
The two main components of the communication system are located in the cockpit, what are they
- Audio Control Panel (ACP)
- Radio Management Panel (RMP)
What 2 things does all communication need
- Information (Audio, video, digital)
- Carrier (To transport the data on)
What is the main ‘carrier’ for information during flight
Radio Frequency signal (RF)
Radio frequencies in aviation are divided in to how many bands
8
What frequency is used for HF comms
3MHZ to 30MHZ
What radio frequency is used for VHF comms
30MHZ to 300MHZ
What is the point of static diss chargers/ static wicks?
To ensure static energy is continuously discharged to prevent a build up of high voltages on the fuselage which could damage electronic equipment and interrupt radio signals
A central computer connects and controls all necessary crew communication systems, what is it called
The Audio Management Unit (AMU)
What is the purpose of the Passenger Address system (PA)
To give information to the passengers
After what 2 incidences is the cabin PA system volume automatically increased
- 1st is when the engines start (automatically by oil pressure switch)
- 2nd is when oxygen masks release upon cabin depressurisation (done by 14,000ft switch
What 2 types of voice recorders are currently in use
- Analogue tape recorder (stores last 30 mins of flight on tape the rest is automatically deleted)
- Digital solid state recorder, stores last 120 mins of flight
Where is the voice recorder normally found in an aircraft
Next to the data recorder in the tail of the aircraft
When does the underwater locator beacon start its transmitting
When the battery of the transmitter comes in contact with water
How long will the underwater locator beacon transmit for once it has started transmitting
A minimum of 30 days
What sort of depths of water can the underwater locator beacon withstand
More than 3,000 meters
What is the case of the cockpit voice recorder made from and how many g’s of force can it withstand
A steel casing and can withstand force of more than 1000gs
When does the voice recorder start recording
Automatically when one engine is started or when the aircraft is in flight
How can the voice recorder be tested
A test switch in the cockpit. 600hz tone when park brake is set
How can the voice recorder be tested
A switch in the flight deck. Sends a 600hz tone when the park brake is set
When does the voice recorder stop recording
5 mins after shutdown of the last engine on the ground
What is the international emergency frequency
121.5MHz this should never be used for transmissions
What is normally the spacing between communication channels
25KHz
In Europe they require more frequencies and a lower spacing is required between them what is it
8.3KHz
How many independent VHF systems do most aircraft have
3
- Captain
- 1st O
- ACARS
What is a common tell tale sign of a VHF system failure
No side tone
When making a transmission the user should be able to hear their own voice in headphones along with a side tone
What is the RMP
Radio Management Panel
How many frequency windows does the RMP have
2
If the HF system cannot be used reliably for long range communication what do most aircraft use
SATCOM
What are the 3 main HF components
- Transceiver
- Antenna
- Antenna coupler
What is the antenna coupler used for in the HF system
Is used to select HF frequency
What is ACARS data transfer from satellite to ground called
Downlink
What is ACARS data from ground to satellite called
Uplink
What automatic reports does ACARS transmit
ETA (Estimated Time of Arrival report)
This is done 120 mins, 20 mins and 7 mins before arrival
What are the 3 main SATCOM components
- Satellites
- Aircraft Earth Station (AES)
- Ground Earth Station (GES)
What 3 types of Emergency Locator Transmitters are used
- Fixed (Always in tail of A/c)
- Fixed/portable (Small A/c)
- Portable
What two radio navigation systems are there
- Automatic Direction Finder (ADR) (Oldmsystem)
- VHF Omnidirectional Range (VOR) (most common)
Other than ADF and VOR what other radio navigation system is used in aircraft
Instrument Landing System (ILS)
What is the purpose of ILS
Gives information to aid landing in bad weather
What are ILS’s 3 sub systems
- Localiser
- Glide slope
- Marker beacon
What two types of navigation charts are used by flight crew
- ICAO charts
- Enroute charts
What navigation charts are used on commercial flights
Enroute charts
What is the difference between true north and magnetic north
True North - Direction to the geographical North Pole
Magnetic North - Magnetic field lines are gathering
Because there are 2 North poles the aircraft must have 2 headings, what are they
- True Heading (TH)
- Magnetic Heading (MH)
What is Track (TK)
Is the direction in which an aircraft is moving over the earth
What is heading
Where the aircraft is panning on heading
What is Drift
The angle (difference) between track and heading
What is Bearing (BRG)
Is the direction from the aircraft position to an object
How many ground stations can be used for ADF navigation
3
Non Directional Beacons (NDB)
Locators
Public radio stations
What 2 signals does the VOR ground station transmit
- Reference Signal
- Variable signal
What types of ground stations are used for VOR
- Conventional VOR
- Doppler VOR
What position data is supplied by the ILS system to assist the aircraft approach the runway
Lateral and vertical position data
Where are the localiser and glide slope antennas normally located
Under the nose radome
The ILS receiver has how many receivers
2
- Localiser receiver
- Glide slope receiver
Where are ILS indications on modern aircraft shown
The PFD and ND
How is localiser deviation worked out
1 dot = 1° out
What are the 3 poor weather landing categories (ILS)
CAT 1 - Needs 800m of runway visibility, called runway visibility range (RVR) at a height of 200ft
CAT 2 - Requires about 400m of runway visibility at a height of 100ft
CAT 3 - Needs less than 200M runway visibility at a height below 100ft
What is the decision height known as (ILS)
The minimum
Is the Marker Beacon system a part of ILS
Yes
What is the purpose of the Marker Beacon
It provides visual and aural indications when the aircraft flies over a Marker Beacon transmitter
Originally 3 Marker beacons were used what were they
- Outer Marker (OM)
- Middle Marker (MM)
- Inner Marker (IM) - no longer used
What do all Marker Beacons transmit on a frequency on
75Mhz
What are the characteristics of the Outer Marker (Marker Beacon system)
- Located around 7KM from the runway
- 75Mhz transmitted signal modulated with a 400Hz tone
- Turns blue lamp on Marker Beacon on
- Morse code identifier of dashes
What are the characteristics of the middle Marker (Marker Beacon)
- Located around 1000M from the runway
- 75Mhz transmitted signal modulated with 1300HZ tone
- Amber lamp on Marker Beacon panel on
- rose code identifier of dots and dashes
What are the characteristics of the inner Marker
- Located around 300m from the runway
- 75Mhz transmitted signal modulated with a 3000Hz tone
- White lamp on Marker Beacon on
- Morse code identifier of dots
What is the Radio altimeter also called
The Rad Alt
What is the purpose of the radio altimeter
To measure the vertical distance between the aircraft and ground
When is the radio altimeter system normally used
During take off, approach and landing also known as the Low Range Radio Altimeter (LRRA)
The Radio Altimeter system only indicates below how many feet?
2500ft
What are the 2 main components of the radio altimeter
- Transceiver
- Antenna
What is GPWS
Ground Proximity Warning System
What is the purpose of the Ground Proximity Warning System
To warn the flight crew when the aircraft accidentally comes too close to ground
How does the GPWS warn the flight crew
- Aural alert
- Annunciator lights
- Alert messages
The basic GPWS operates automatically when the aircraft is under how many ft
2500
What does the Enhanced Ground Proximity Warning System do from the regular GPWS
Shows terrain around The aircraft and shows it on the Navigation display (ND)
What is GPWS mode 7
Wind shear mode
How does the DME measure distance to the ground station
It sends a signal to the ground station
Indicated in nautical miles
How is DME tuned
The DME ground station is paired with a VOR or localiser ground station therefore is automatically tuned when you select the corresponding VHF NAV frequency
What is the antenna for the DME identical to
The air traffic control, both systems work off the same frequency range
What type of pulse sweep area does the weather radar system produce
180° sweep area in front of the aircraft
Why must precautions be followed when operating the weather radar system on the ground
Because of the heat and radiation that it produces
What are the rules of refuelling when operating the weather radar system on the ground
Refuelling aircraft and large metallic objects must be at least 200-300ft away
What are the 3 ATC identification codes that must never be transmitted on the ground as they are emergency codes
7500 - Hijacking
7600 - Radio Failure
7700 - If the aircraft is in an emergency
What does TCAS stand for
Traffic alert and Collision Avoidance System
What is the purpose of TCAS
Protect airspace around a TCAS equipt aeroplane
What is the TCAS Traffic Advisory (TA) aural alert
TRAFFIC TRAFFIC
How does the GPS system calculate the aircrafts position so accurately
By receiving data from a minimum of 4 GPS satellites
How many satellites are used for GPS
24 and 3 spare
How often do GPS satellites complete an orbit
Once every 12 hours
What 2 services does GPS provide
- Precision Positioning Service (PPS) : Military
- Standard Positioning Service (SPS) : Civilian
How accurate is the Standard Positioning Service (SPS)
Accurate to a range between 15-25m
How can SPS Standing Positioning Service accuracy improved to a range of 3m
By a Differential GPS (DGPS)
How many GPSs are normally installed
2
What are the 2 main GPS components
- GPS antenna
- GPS unit
What is FANS
Future Air Navigation System
What FANS do Boeing use
1+2
What FANS do Airbus use
A, A+ and B
How many different types of gyros are used on aircraft
3
How many gyros with 3° of freedom are used
2
Vertical gyro
Directional Gyro
How many gyros are used with 2° of freedom
3
1 for each axis
Apart from gyros with 3° and 2° of freedom what other gyro is used on aircraft
Rate gyros
1 for each axis and a computer to calculate the attitude from the rate signals
How do laser gyros work
A laser gyro uses rotating light beams to measure the angular rate
How many types of accelerometers are used on aircraft
3
- Electrolyte accelerometers
- Mass and spring accelerometers
- Pendulum accelerometers
Which accelerometer is the preferred type
Pendulum accelerometer
What is the AHRS
Attitude Heading Reference System
What does the AHRS contain
- Gyros
- Accelerometer
- Computer
What is the more modern version of the AHRS
(IRU) Inertial Reference Unit from the IRS
What must the IRS do upon startup
Carry out an ‘Align Phase’ to set the system up so it is ready to operate
How long does it take for the IRS to carry out its align phase
Around 10 mins
During the first 5 mins of the Aligning phase of the IRS what is the activity called
Levelling
What is the purpose of the (FMS) Flight Management System
It is a computer system which reduces pilot workload ND improves flight safety and economy
What 3 main functions does the FMS carry out
- Optimum flight track
- Best profile
- Estimated time for each flight
What 5 sub systems does autopilot normally have
- Autopilot (AP)
- Flight Director (FD)
- Auto Throttle System (ATS)
- Automatic Pitch Trim System (Auto trim)
- Yaw Damper system (YD)
What subsystem does the Auto Trim and Yaw Damper systems have
Stability Augmentation System (SAS)
The autopilot can control the aircraft from which 2 axis
Longitudinal - Aileron - Roll
Lateral - Elevator - Pitch
What are the biggest autopilot advances that came about in the 1990s
- Fly by wire
- Integrated FMS
- Autothrottle
- FADEC
How is the autopilot disengaged
On the control panel or by pressing the disengage bar
Also red quick disengage button
