VHF Communications

Question 1

VHF Communications is found under what ATA?

Answer 1

23-10

Question 2

VHF Communications, or in short VHF COM, for aviation is found in the frequency range from:

Answer 2

118.00 - 136.99163 MHz

Question 3

VHF waves propagate as:

Answer 3

Space waves

Question 4

VHF transmissions and reception is over a relatively ______ range.

Answer 4

short

Question 5

A fairly recent change to the VHF spectrum for aviation was that the subdivision for channels now has what spacing?

Answer 5

8.33 KHz spacing

Question 6

What VHF channel is reserved for emergencies?

Answer 6

121.5 MHz

(1215 if you wanna stay alive)

Question 7

What VHF channel is reserved for flight testing?

Answer 7

123.4 MHz is reserved for flight testing
Most flight schools use 123.3 MHz

(Testing.. Testing… 123)

Question 8

Aviation VHF communication systems are Amplitude Modulated and transmit between what wattage?

Answer 8

One (1) and Fifty (50) Watts

Question 9

Some maintenance data states the VHF Comms range as 118- 136.992 MHz. The actual range is:

Answer 9

118.00 to 136.99163

Question 10

What type of antenna is used for VHF communications?

Answer 10

Marconi type
May be mounted on the top or bottom of the airframe

Question 11

VHF antennas can be one of two designs, which are:

Answer 11

Whip or Blade

Question 12

How many VHF COM antennas are there?

Answer 12

typically 3

Question 13

Whip antennas are used on slower aircraft while blade types are normally used on high-speed aircraft. How do the blade type antennas normally differ from whip antennas?

Answer 13

shorter in length than the whip antennas

Question 14

The heart of the VHF COM system is a:

Answer 14

Transceiver

(in order to communicate you need to be able to talk and listen. TRANSmit and reCEIVE. Transceiver.)

Question 15

What is a transceiver?

Answer 15

a radio transmitter and receiver enclosed in one common housing

Question 16

What does the VHF COM control head contain?

Answer 16

Channeling switches, displays, volume control, and squelch control.

(Think of a cell phone.
Channeling switches - keyboard
Displays - screen
Volume Control - volume buttons
Squelch Control - Ringtone on/off up/down)

Question 17

Many times the microphone input and audio output are connected to:

Answer 17

the Audio System (or Audio Control Panel) in the aircraft.

Question 18

On small aircraft the transceiver and control head are:

Answer 18

combined into a single unit

Question 19

Most large aircraft, use an integrated flight management system (FMS) which includes what functions?

Answer 19

navigation and communication functions

Question 20

The FMS system has modules also known as:

Answer 20

Line Replacement Units (LRUs) that are connected to a common power supply and data buses

(The FMS is a software.
The LRU is the computer box.)

Question 21

Aircraft with an FMS do not have control heads but are controlled through a:

Answer 21

Multifunctional Control Display Unit (MCDU for AirBus, CDU for Boeing).

(If FMS is software
And LRU is a computer
The MCDU/CDU is just the screen and keyboard)

Question 22

In many smaller aircraft the VHF communication system is combined with:

Answer 22

the navigation system and mounted in the instrument panel

(Navigation and communications go hand in hand)

Question 23

Typical testing of VHF communications includes checking:

Answer 23

SWR (Standing Wave Ratio), antenna and transceiver signal/power strength

Question 24

The IF 4000 verifies the operation and installation of:

Answer 24

ILS, VOR, and Marker Beacon receivers, and VHF/UHF, AM/FM, and HF AM/SSB transceivers

Question 25

The SelCal Decoder is designed to:

Answer 25

relieve the pilot and copilot from continuously monitoring the aircraft radio receivers.

Question 26

The decoder is, in effect, an automatic monitor that listens for:

Answer 26

a particular combination of tones that are assigned to the individual aircraft.

Question 27

When a coded transmission is received from a ground station, the signal is decoded by the Selcal unit which then does what?

Answer 27

alerts the flight crew to an incoming
message.

(SelCal = Steve from Blue’s Clue’s
“Here’s the mail, it never fails
It makes me want to wag my tail
When it comes I want to wail
MAIL!”)

Question 28

The SELCAL system automatically activates what?

Answer 28

the correct radio for the flight crew

Question 29

When the proper tones are received from the ground station, the decoder does what?

Answer 29

Operates an external alarm circuit to produce a chime, light, buzz, or combinations of thes signals.

(Decoder = Mailman bringing the mail to Steve)

Question 30

How many channels are available in VHF COM?

Answer 30

2280 channels