Communications (BAK)

Aviate, Navigate, Communicate

These are the pilot’s priorities during the flight – above all else, fly the plane!

It is suggested to practice radio calls in the shower – there is no reason why a private pilot can’t be as competent on the radio as a commercial pilot.

Here is the example radio call from the text:

“Hot Shower, this is Mike India Kilo Echo, request a straight-in approach?” “Mike India Kilo Echo you are cleared to land. The surface wind is light and variable. The temperature is two three. There is significant precipitation over the runway!”

How Radio Works

Basically, when a person speaks their vocal chords cause vibrations in the air. These vibrations travel through the air to our ears which convert them to signals which are sent to the brain.

A megahertz (MHz) is one million cycles per second.

Very High Frequency (VHF) radios have a frequency range of 30-300 MHz and are used in most aeroplanes.

VHF transmissions are direct, straight-line (line of sight) beams. Their effectiveness depends upon the distance to the other station and whether or not there are obstructions between the two stations.

The higher a plane goes above the ground, the further it can see and receive radio signals.

Aircraft altitude (feet)

VHF coverage (nautical miles)

Below 5,000ft

60 nm

5,000 to 10,000ft

90 nm

Recently VHF transmission distances have been lengthened by the use of satellite relay stations.

Radio Installation in the Cockpit

Electrical power is provided to the radio by the alternator (when the engine is running) or the battery (when the engine is not running). Power is supplied to the radios by the battery master switch or the avionics master switch.

Each headset has an attached microphone. This allows the intercom to the be used for cockpit communications and outside communications to be used when the Push-To-Talk (PTT) switch is pressed.

The squelch controls the sensitivity of the microphones. If the squelch is turned down, the background noise is removed but the first word spoken may be clipped because the intercom goes into passive mode when it hears no voices. If there is too much squelch, the background noise will keep the intercom active but may be distracting.

Use of the VHF COM

Switching on the radio

The sequence for switching on the radio:

  • Check the master switch is on (and avionics power switch if applicable)
  • Switch the radio on
  • Select the frequency
  • Adjust volume to desired level and adjust squelch control
  • Select transmitter to desired radio

Squelch Control

Squelch should be set so you can just hear a continuous hiss and the first word is not clipped.

To adjust squelch:

  • Turn the squelch up high until strong background noise is heard
  • Rotate the squelch knob anti-clockwise until the noise just disappears

If the radio doesn’t work – troubleshooting

Carry out the following checks:

  • If there is no noise in the headset, check the plug connections, check intercom on and volume and squelch is up (ANFA Note – check the headset is plugged in, I’ve fallen into that trap, much to the amusement of my instructor)
  • If you hear the instructor ok but not yourself, check the microphone plug is fully in
  • If you have to puff to trigger voice, the squelch is set too low
  • Check the radio is on, avionics master is on, radio on correct frequency, squelch set
  • Check if on correct frequency

Communicating

The intercom is voice activated. It is trigged when you speak and the sensitivity can be controlled by squelch.

To transmit outside the aircraft, press the PTT button.

Only one transmission from one station within range can occur on the frequency at one time – while you are transmitting, no one else can

Standard words and phrases

The phonetic alphabet is used to ensure correct understanding of transmitted letters.

THE PHONETIC ALPHABET

Letter

Word

Letter

Word

A

ALFA

N

NOVEMBER

B

BRAVO

O

OSCAR

C

CHARLIE

P

PAPA

D

DELTA

Q

QUEBEC

E

ECHO

R

ROMEO

F

FOXTROT

S

SIERRA

G

GOLF

T

TANGO

H

HOTEL

U

UNIFORM

I

INDIA

V

VICTOR

J

JULIETTE

W

WHISKEY

K

KILO

X

X-RAY

L

LIMA

Y

YANKEE

M

MIKE

Z

ZULU

GA aircraft call-signs are also pronounced in the phonetic alphabet (e.g. VH-KZY is Kilo Zulu Yankee).

There are a number of standard phrases used to make radio communications uniform. If I can be bothered, one day I will type them out here.

It may surprise some people to discover that no-one would ever say ‘Over and Out’. ‘Over’ means that you expect a response, ‘Out’ means that you expect no response. It’s rather obvious why they would never be used together!

Emergency Radio Procedures

There are two main types of emergency radio calls – mayday calls and pan-pan calls.

Mayday call

A mayday call is a distress message and the radio call should be prefixed by mayday repeated 3 times.

A mayday call has priority over all others. If you hear a mayday call, shut up and let them talk.

Pan-Pan call

A pan-pan call is an urgency message.

Typical situations where a pan-pan message is appropriate include the following:

  • If you are experiencing navigational difficulties and require the urgent assistance of ATC
  • If you have a passenger who has become seriously ill and will require urgent attention
  • If you see another aeroplane or a ship the safety of which is threatened and urgent action may be needed
  • If you are making an emergency change of level in controlled airspace and may conflict with traffic below you
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