Communications - PPL

Aeronaturical Radiotelephony (RT)

based on procedures and terms that serve to standardise the exchange of messages within the communications network

- ICAO Annex 10 volume 2

- convention on international civil aviation

Aeronautical fixed telecommunication network (AFTN)

exchange info:

- flight plans

- NOTAMs

- weather

- various other data between other aeronautical fixed stations

aeronautical mobile service

between:

- aircraft stations

- survival craft stations

- emergency position-indicating radio beacon stations

aeronautical station

- land based station in aeronautical mobile service

- also located on marine vessel

aircraft station

- mobile station

- within aeronautical mobile service

- excluding survival craft stations

- located onboard an aircraft

air-ground communication

- two way communication

- between aircraft stations and aeronautical stations

blind transmission

- transmission from one station to another station

- two-way communication cannot be established

- believed the called station is able to receive the transmission

broadcast

transmission of info relating to air navigation

- not addressed to a specific station

clearance limit

- point to which an aircraft has clearance to proceed

- as specified by air traffic control

expected approach time (EAT)

- time which ATC expects an arriving aircraft, following a delay

- will leave the holding fix to complete its approach to land

holding fix

point in space

- serves as a reference for a holding procedure

Common abbreviations

1. VMC (visual meterological conditions)

2. ILS (instrument landing system)

3. FIR

4. CTR (control zones)

a) CAVOK

b) GBAS

- ground based augmentation system

c) ICAO

d) VOLMET

Standard words and phrases

APPROVED

- permission for proposed action granted

- from ATC

BREAK BREAK

- indicates separation between messages transmitted to different aircraft in a very busy environment

CLEARED

- authorised to proceed under the conditions specified

REPORT

- transmit the following information on...

- asked from ATC to pilot

WILCO

- will comply

- pilot to ATC message

Morse code: Q-codes

- 3 letter format

- transmitted using constituent letters

- represent defined values in aeronautical radiotelephony

In aeronautical RT used for:

- altimeter sub scale settings

- bearing and heading

1) QFE

- defines altimeter sub scale setting

- height above reference aerodrome

- QFE set = 0 ft

2) QNH

- QFE converted to MSL

- using ISA standard temp and pressure lapse rate

- QNH set = aerodrome elevation and altitude referenced to MSL when flying above aerodrome

3) QNE

- altimeter sub scale setting of 1013 hPa or 29.92 inHg

- known as standard pressure setting (SPS)

Bearing and heading Q-codes

1) QDM

- magnetic bearing to the station

2) QDR

- magnetic bearing from the station

3) QTE

- true bearing from the station

4) QUJ

- true bearing to the station

Categories of messages

prioritisation of messages by category:

1) Distress

- aircraft requiring immediate assistance

- priority indicator SS (Sierra-sierra)

- major equipment failure

- MAYDAY call be aircraft in distress

2) Urgency

- Aircraft (medical included) not requiring immediate assistance

- priority indicator DD (Delta delta)

- minor equipment failure or medical assistance request

- PAN-PAN or PAN-PAN Medical call by aircraft in urgency

3) Direction finding

- aircraft uncertain of position

- request of heading or beating to a facility

- flight safety

- meteorology

- flight regularity

4) Flight safety

- ATIS control and movement messages

- aircraft operation agency messages

- messages of immediate concern to aircraft in flght/ preparing to depart

- signifying weather info: SIGMET, AIRMET, SPECI, ASHTAM

5) Meteorological messages

- weather forecast and observations

6) Flight regularity messages

- Maintenance and servicing of aircraft

- aircraft operating schedules

- non-route landings

- administrative messages

ICAO 4444

4.1 Q0025 : What is the priority indicator for a meteorological message?

GG

Define the Aeronautical Mobile Service.

A mobile service between aeronautical stations and aircraft stations, and survival craft stations. Emergency position-indicating radio beacon stations may also participate in this service on designated frequencies.

Considerations to ICAO SARPS

Aeronautical RT:

- cannot be fully covered by ICAO SARPS

- If communication needs fall outside ICAO standards and Recommended procedures (SARPs) = communication should always remain clear and concise

- plain language communication may be used when necessary

Standard ICAO alphabet:

- underlined syllables require emphasis

- Pilots required to know ICAO alphabet

- Spelling normally avoided

spelling of words

situations requiring spelling

- poor radio reception

- unreadable accent

- trouble identifying words e.g waypoints

transmitting numbers

- pronounce each number separately

- syllables in BOLD require emphasis

decimal = DEY-SEE-MAL

9 = NIN-er

3 = TREE

exceptions:

- altitude

- cloud height

- visibility

- RVR

= can say whole number in 100/1000's

Transmitting frequencies

- each number pronounced separately

- last 2 zeros omitted (applies to 25 kHz and 8.33 kHz separated VHF frequencies)

e.g 118.000

= Wun wun ait day-see-mal zero

Transmitting time

- each number pronounced separately

- 24 hr UTC format

- transmission of minutes as standard

- transmission of hours to avoid confusion

e.g 12:20 UTC

= too-zero OR

= wun too too zero

Time checks

- time specified to the nearest half minute

- preceded by word "time"

Pilot = Evionica 780 REQUEST time check

ATC = Evionica 780 TIME 1105 and a half

Technique

proper technique ensures:

- safe operating environment

- clarity

transmitting equipment

pilots must be familiar with operating:

- communication panel

- headphone/speakers

- microphone

frequency scan

- establish whether channel is being used

- do not transmit simultaneously

technique

recommended:

- use normal speaking tone

- speak clearly

- 100 words per minute

- keep messages short as possible using standard RT phraseology

en route

initial call to FIS:

- aircraft type

- position information

- level information

- flight intentions

initial call to join circuit pattern

- aircraft type

- position information

- level information

- intentions

circuit pattern position reports

mandatory

Standard circuit pattern:

1. Departure

2. Crosswind Leg

3. Downwind leg

4. Base Leg

5. Final

Event of a go-around:

- upwind leg...crosswindleg.... (same order)

landing

- uncontrolled airports

- aircraft advised to land at own discretion

after landing: taxi

Pilots shall report:

- runway back track

- runway crossing

- runway vacated

- taxi intentions

aeronautical station call signs

- location name

- suffix specifying type of service

abbreviations:

- full call sign on initial contact required

- call sign maybe abbreviated after communication established

- location name or suffix maybe omitted in abbreviated call sign

aircraft call signs

- aircraft registration

- telephony designator

- flight number

- 3 types of call signs: A (most used), B, C

Type A call sign:

- based on aircraft registration

- transmitted phonetically

- abbreviated using 1st and last 2 characters

- aircraft manufacturer or model maybe used as prefix

e.g SP-ABC/S-BC/Diamond-ABC

Type B call sign:

- operating agency designator and last 4 characters of registration aircraft

- transmitted as complete word

- markings transmitted phonetically

- abbreviated using designator and last 2 characters of aircraft registration

e.g Evionica P-ABC/Evionica BC

Type C call sign:

- operating agency telephony designator and flight number

- transmitted as complete word

- flight number transmitted according to ICAO standard for numbers

- No abbreviation

e.g Evionica Airlines 780

aircraft call signs by vortices they create

Super:

MTOW = A380-800 and An225

Heavy:

MTOW = >300,000 lb (136,000 kg)

change of call sign

- situation where two or more aircraft have similar call signs

- transmitted as "change your call sign to [new call sign]".

revert to call sign

- situation no longer requiring amended call sign

- transmitted as "revert to flight plan call sign"

change of frequency

- initiated by ATSI when providing service

- aeronautical station call sign and frequency

- Pilots initiate communication on new frequency using full call sign

reporting a change of frequency:

- in uncontrolled airspace

- pilots may report changing frequency

- standard phraseology includes aeronautical station call sign and frequency

monitor frequency

change to a frequency without initiating communications

radio check

- confirms serviceability of equipment and frequency in use

- standard call includes aeronautical station aircraft call sign, "radio check", and frequency being used

- based on readability scale

1 = unreal

2 = readable now and then

3 = readable but with difficulty

4 = readable

5 = perfectly readable

read back requirements

- route clearances

- clearances to enter any runway

- runway-in-use information

- altimeter settings

- SSR codes

- Level

- transition level

- heading and speed

conditional clearance

- allow ATSU to expedite certain operations

- contains aircraft call sign, condition, clearance, and condition

- read-back must include condition, clearance, condition, call sign

timeliness of read-back

failure to read-back:

- original message from ATSU will be retransmitted and require read back

- ATSU will notify the aircraft of an incorrect read-back using the term "negative"

What is the correct way of transmitting 11,000 ft altitude?

Wun wun tou-sand

contents of aerodrome weather report

- ICAO aerodrome name

- Time in UTC

- Surface wind velocity [true bearing degrees; magnitude in kt or m/s]

- Visibility/ RVR [km or m]

- Present weather

- Cloud

- Temperature (degrees) & Dew point (celsius degrees)

- Altimeter setting (hPa or inHg)

- Recent weather

- Trend information

present weather and cloud

describes weather phenomena and sky coverage using abbreviations

- set out by ICAO

SKC, CAVOK, NSC

SKC = Sky clear

CAVOK = Ceiling and visibility OK

NSC = No significant cloud

meteorological information for aircraft in flight

meteorological reports through:

- ATIS

- VOLMET

- ATC and FIS officers

Automatic Terminal Information Service

ATIS:

- meteorological and operational information

- voice broadcast on discrete VHF frequency

- Similar to METARs

- Pilots should receive ATIS before contact with ATC

ATIS content

- ICAO aerodrome name

- ATIS sequence designator

- Time in UTC

- Runway in use and status

- Surface wind

- Visibility/RVR

- Present weather

- Significant cloud

- Temperature and dew point

- Altimeter setting

- Transition level

- Type of approach expected

- Warnings of operational significance

Runway state

Code, Measured Coefficient, Estimated Breaking Action

5 = >=0.40 = Good

4 = 0.39-0.36 = Medium to good

3 = 0.35-0.30 = Medium

2 = 0.29-0.26 = Medium to poor

1 = <=0.25 = Poor

VOLMET

- comprised mainly of METARs

- May include SIGMETs, TAFs, TRENDs

- divided to cover geographic regions

- voice broadcast over discrete VHF/HF frequency

- provides overview of weather phenomena in given area

causes of communication failures

- aircraft equipment malfunctions

- weather phenomena

- radio wave propagation effects

suspecting a communication failure

- correct frequency

- correct volume and squelch settings

- headset connection

range considerations

formula for calculating maximum range of direct wave reception is:

Range (NM) = 1.23 (sqrt(h1) + sqrt(h2))

h1 = height of ground aerial (feet AMSL)

h2 = aircraft altitude (feet ASML)

Practical VHF range depends on:

- topography

- transmitter power

- weather phenomena

recommended actions

- attempt communication on a different frequency e.g 121.5 MHz

- continue on the initial frequency and perform blind transmissions if different frequency confirms radio is operational

blind transmissions

- message twice preceded by phrase " Transmitting blind"

- message preceded by "Transmitting blind due to receiver failure".

Radio receiver failure:

- continue to transmit blind

- Squawk 7600 to alert ATS units

procedures for VFR aircraft

ICAO annex 2

- continue in VMC

- land at nearest suitable aerodrome

- report arrival to ATS asap

arrival to an uncontrolled aerodrome

- approach with caution

- transmit blind and report aircraft position

arrival to an controlled aerodrome:

- adhere to light gun signal instructions

- follow joining instructions and communication failure procedures

distress message

an aircraft in a state of emergency being threatened by serious and imminent danger and of requiring immediate assistance

MAYDAY MAYDAY MAYDAY

action:

- mayday call

- active frequency / 121.5 MHz

- aircraft ID

- nature of distress

- pilot intentions

- position

- level

- heading

- squawk 7700

actions for station receiving a distress message

- acknowledge distress message

- take control or transfer communications

- inform ATS units and operating agency concerned

- Alert other stations to prevent the transfer of traffic to the frequency

actions by all other stations

distress message has priority

Actions for other stations:

Stop transmitting unless:

- assisting

- distress ended

- distress transferred

- permission given

- monitor the frequency and ensure assistance is provided

termination of distress message

- message may be cancelled by aircraft in distress

- "Cancel mayday"

- station controlling communications shall inform the distress has ended

- "Distress traffic ended".

urgency message

pan pan pan pan pan pan

action by aircraft in urgency:

- pan pan call

- active frequency / 121.5 MHz

- name of the station addressed

- aircraft ID

- nature of distress

- pilot intentions

- position

- level

- heading

- other useful information

- Squawk 7700

action by station:

- acknowledge urgency message

- exercise control of communications if necessary

- inform ATS units and operating agency concerned

Urgency message has priority except for distress messages

Actions by all other stations:

- take care not to interfere with transmissions of the urgency aircraft

radio-frequency spectrum

3kHz - 300GHz

In order from small to large:

VLF = maritime radio, navigation

LF = maritime radio, navigation

MF = AM radio, aviation radio, navigation

HF = Shortwave radio

VHF = VHF television, FM radio

UHF = UFH television, mobile phones, GPS, WIFI, 4G

SHF = WIFI, Satellite communications

EHF = Radio astronomy, satellite communications

Frequency bands

IEEE

3-30 kHz = VLF (very low frequency)

30-300 kHz = LF (Low frequency)

300-3000 kHz = MF (Medium frequency)

3-30 MHz = HF (high frequency)

30-300 MHz = VHF (very high frequency)

300-3000 MHz = UHF (Ultra high frequency)

3-30 GHz = SHF (super high frequency)

30-300 GHz = EHF (extremely high frequency)

VHF band

aeronautical services within VHF:

- broadcasting = 88-107.95 MHz

- radio navigation = 108-117.95 MHz

- aeronautical mobile service = 118-136.975 MHz

VHF frequency separation

aeronautica services within VHF:

- minimum 8.33 KHz (EASA radios)

- most frequencies 25 kHz

channelling

- frequency identification replaced with channel identification

- channel ID corresponds to assigned transmission in use

VHF propagation

behaviour of radio signals as they travel between 2 points

Space wave:

2 component waves:

- sum of direct + reflected wave

- signals travel in straight line

Range limited by:

- curvature of earth

- terrain features

- protruding objects

factors affecting VHF transmissions

equipment:

- power of transmitter

- sensitivity of receiver

- reflection

- refraction

- diffraction

- attenuation (decrease of radio wave strength as range increases)

- interference

- freak propagation (super refraction due to warm front on top of cold front, temp inversion, increases range of radio waves)

SKC

sky clear

other abbreviations

NSC = No Significant Clouds.

NCD = No Cloud Detected.

SKC = Sky Clear.

CAVOK = Ceiling And Visibility OK.

Which frequency band represents frequencies between 3-30MHz?

High frequency band