VHF comms fundamentals (17-07-18) Flashcards
What is the frequency range of the air band?
108 - 137MHz
What is the frequency range of th aeronautical mobile service?
118 - 137 MHz
What is the VHF frequency range?
30 - 300 MHz
How does VHF propagate and how is it affected by terrain and buildings?
LOS, relatively unaffected by buildings
but can be very affected by terrain.
What is super refraction?
Ducting of radio signals
layers form in the atmosphere that facilitates conducting of these waves
increases range of VHF waves
Why is VHF used instead of HF signals?
VHF is less affected by static from noise and electrical interference than HF.
What can fading be caused by?
Multiple A/C transmitting on the same channel, having the same frequency, causing destructive interference.
What is the range of a transmitted VHF signal?
Range = root(Power)
What is the normal max range planned for VHF transmission?
Approx 25nm
What is the minimum frequency separation of VHF signals in Europe?
8.33kHz
What is the normal frequency separation for VHF signals?
25kHz
Where must an A/C have a frequency separation capability of 8.33kHz?
Above FL195 in EU airspace.
When is the word ‘point’ used instead of ‘decimal’ when reading out numbers?
When talking about radio capability
eg: 8.33 is 8 ‘point’ 33 NOT 8 ‘decimal’ 33
wheras 118.090 would be 118 ‘decimal’ 090
What is the general procedure for speaking over radio?
Before transmission, listen for any ongoing communication
Think about what to say
Speak clearly with a normal tone
Speak at 100 words per minute
Use standard RT, but if unsure use plain english
Release transmit button after finished speaking
If no response is given, wait at least 10 seconds before trying again
What are some non phonetic ‘standard’ readbacks?
QNH
QFE
ILS
VOR
NDB
RVR
How are numbers read out?
1-9, 100, 1000
(only altitude is fully pronounced)
If QNH is lower than 1000 then what must be added to the end of the number read out?
hectopascals
In what case do you only need to read out the first digit after a decimal point?
If the last 2 digits are 0
When reading out time, when do you not need to read the hour?
When you can be certain about what the hour is.
What is the accuracy of time measured to?
The nearest half minute
How long should a test transmission be?
no longer than 10seconds.
How is a test transmission structured?
1- aeronautical station
2- call sign
3- ‘radio check’
4- frequency
What does ‘readability 1’ mean?
Unreadable
What does ‘readability 2’ mean?
Readable now and then
What does ‘readability 3’ mean?
Readable but with difficulty
What does ‘readability 4’ mean?
readable
What does ‘readability 5’ mean?
Perfectly readable
What is the structure of a transmission for establishing contact with a station?
1- station being addressed
2- call sign
3- A/C type
4- Position
5- other info (eg ATIS)
6- request
What should be at the end of every radio transmission from an A/C?
Call sign
What are mandatory read backs?
Clearances (taxi, TO, landing, routes etc.)
Altimeter settings
Transponder operating instructions
Heading, altitude and speed instructions
VHF direction finding
Type of air traffic service (eg. Traffic Service UK)
Frequency changes
Anything to do with runway other than runway state
What is not a mandatory read back?
Wind information
A/C confliction instructions
