Chapter 2 Propagation Theory

Question 1

What is the most common radio frequencies used for voice comms?

Answer 1

Very high frequency (VHF)

Question 2

What is the ICAO name for air to air or air to ground comms?

Answer 2

Aeronautical mobile service voice comms

Question 3

What is the airband?

Answer 3

108 MHz to 137 MHz (VHF)

Question 4

What are the two sections in the airband?

Answer 4

108-117.975 MHz (RNAV) and 118-137 (VHF voice comms)

Question 5

What is the range of transmission limited by?

Answer 5

Power, obstructions, transmitter height, receiver height and ducting (super refraction)

Question 6

What is the transmission signal degraded by?

Answer 6

Rain, fog, snow, hail and humidity

Primarily moisture

Question 7

What is the formula for max theoretical range?

Answer 7

1.23(Sqrt Tx + sqrt Rx)

Tx = elevation of transmitter (AMSL)
Rx = elevation of receiver (AMSL)

Units in feet

Question 8

What does attenuation mean?

Answer 8

Gets shitter

Question 9

When is attenuation worse?

Answer 9

At high pressure, low temperature and higher frequencies

Question 10

What is the typical frequency spacing?

Answer 10

Old = 25 KHz
New = 8.33 KHz

Question 11

In Europe above what flight level are aircraft required to have 8.33KHz capability?

Answer 11

FL195

Question 12

What must be done if 8.33 capability is not able?

Answer 12

Inform ATC by saying “negative 8.33”