[PRELIMS] TRANSMISSION OF INFORMATION USING RADIOTELEPHONY

General Operating Procedures

• Pilots and air traffic controllers communicate by using the radiotelephony phraseology that consists of a set of standardized words and phrases approved for the radiotelephony communications by ICAO in all routine aircraft situations.

• When both parties stick to the rules prescribed, problems in communication will rarely occur.

• First of all, good transmitting techniques are needed.

Transmitting Technique

ICAO Doc 9432 Manual of Radiotelephony - the following transmitting techniques will assist in ensuring that transmitted speech is clearly and satisfactorily received

ICAO Doc 9432 Manual of Radiotelephony

transmitting techniques will assist in ensuring that transmitted speech is clearly and satisfactorily received

1. Before transmitting, listen out on the frequency to be used to ensure that there will be no interference with a transmission from another station

2. Be familiar with good microphone operating techniques.

3. Use a normal conversational tone, speak clearly and distinctly.

4. Maintain an even rate of speech not exceeding 100 words per minute.

5. Maintain the speaking volume at a constant level.

6. A slight pause before and after numbers will assist in making it easier to understand.

7. Avoid using hesitation sounds such as "er'.

8. Depress the transmit switch fully before speaking and do not release it until the message is completed. This will ensure that the entire message is transmitted.

9. An irritating and potentially dangerous situation in radiotelephony is a “stuck’' microphone button.

Transmitting Techniques

1. ATC Clearance

2. Transmit

3. Listen

4. Pilot’s Feedback

5. Transmit

6. Listen

7. Controller’s hearback

8. Acknowledge or Correc

Cycle of Transmitting Technique

• The phonetic words shall be used when individual letters are required to be transmitted.

• Some abbreviations have become unmistakable through common usage and are transmitted without using the phonetic word for each letter (E.G

  ILS, QNH, QFE)

• The following words are to be used when it is required to transmit individual letters.

Rules of Transmission of Letters

Phonetic Words

shall be used when individual letters are required to be transmitted.

Abbreviations

Some ________ have become unmistakable through common usage and are transmitted without using the phonetic word for each letter (E.G ILS, QNH, QFE)

• All numbers except whole hundreds, whole thousands and combinations of thousands and whole hundreds shall be transmitted by pronouncing each digit separately.

• Whole hundreds and whole thousands shall be transmitted by pronouncing each digit in the number of hundreds or thousand followed by the word HUNDRED or TOUSAND as appropriate

Rules of Transmission of Numbers

except:

• except whole hundreds,

• whole thousands

• combinations of thousands

• whole hundreds

All numbers ____________ shall be transmitted by pronouncing each digit separately.

pronouncing each digit in the number of hundreds or thousand followed by the word HUNDRED or TOUSAND as appropriate

Whole hundreds and whole thousands shall be transmitted by

• All time references should be made in Co-ordinated universal time (UTC). This used to be called Greenwich Mean Time (GMT).

• This time zone is sometimes referred to as Zulu (Z).

  Time is always in the 24 hour clock. 2400 is midnight and 0001 begins the new day.

• When transmitting time, only the minutes of the hour are normally required, each figure being pronounced separately.

Rules in Transmission of Time

 Co-ordinated universal time (UTC

• All time references should be made in

• This used to be called Greenwich Mean Time (GMT).

• This time zone is sometimes referred to as Zulu (Z)

Aeronautical Stations

are identified by the name of the location, followed by a suffix denoting unit or the type of service provided.

CONTROL

AREA CONTROL CENTER

RADAR

RADAR (IN GENERAL

APPROACH

APPROACH CONTROL

ARRIVAL

APPROACH CONTROL RADAR ARRIVALS

DEPARTURE

APPROACH CONTROL DEPARTURES

TOWER

AERODROME CONTROL

GROUND

SURFACE MOVEMENT CONTROL

DELIVERY

CLEARANCE DELIVERY

PRECISION

PRECISION APPROACH RADAR

HOMER

DIRECTION FINDING STATION

INFORMATION

FLIGHT INFORMATION SERVICE

APRON

APRON CONTROL

DISPATCH

COMPANY DISPATCH

RADIO

AERONAUTICAL STATION

Categories of Message and Order of Priority

According to ICAO, Annex 10, Chapter 5 All the communication between pilots and air traffic controllers can be categorized into 6 categories of messages depending on the priority of information being transmitted

ICAO, Annex 10, Chapter 5

All the communication between pilots and air traffic controllers can be categorized into 6 categories of messages depending on the priority of information being transmitted.

Croatian regulations (AIC 403/08)

distinguishes the 7th type, called state telegram.

1. Distress Calls, Distress Messages, And Distress Traffic

2. Urgency Messages

3. Direction Finding Message/ Communication Relating To Direction Finding

4. Flight Safety

5. Meteorological Messages

6. Flight Regularity Messages

7. State Telegram

Categories of Message and Order of Priority

Distress Calls, Distress Messages, And Distress Traffic

A condition of being threatened by serious and or imminent danger and of requiring immediate assistance

MAYDAY - radiotelephony signal

Urgency Messages

• including messages preceded by the medical transports signal.

• A condition concerning the safety of an aircraft but does not require immediate assistance.

• PAN,PAN or PAN, PAN MEDICAL - radiotelephony signal

Medical transport

any means of transportation by land, water, or air, wes military or civilian, permanent or temporary assigned exclusively to medic transportation and under the control of a competent authority of a Party to conflict.

Direction Finding Message/ Communication Relating To Direction Finding

VDF using Q codes, radar vectors

Flight Safety

• movement and control messages originated by an aircraft operating agency or by an aircraft, of immediate concern to an aircraft in flight

• meteorological advice of immediate concern to an aircraft in flight or about to depart (individually communicated or for broadcast):

• Other messages concerning aircraft in flight or about to depart.

Meteorological Messages

reports, forecasts, warnings; comprise meteorological information to or from aircraft.

Flight Regularity Messages

messages regarding the operation or maintenance of facilities essential for the safety or regularity of aircraft operation;

State Telegram

New category

1. Ground-wave Propagation

2. Sky-wave Propagation

3. Line-of-sight (LOS) Propagation

4. Non Line-of-sight (NLOS) Propagation

5. Wave Polarization

Basics of Radiowave Propagation

Ground-wave Propagation

• The radio waves follow contour of the earth.

• The radio waves can Propagate considerable distances.

Direct Wave + Reflected Wave + Surface Wave

Formula of ground wave

• Medium Wave frequencies (300kHz to 3MHz)

• lower HF bands (3MHz to 30MHz

Frequency of Ground Wave Propagation

• Frequency

• Polarization

• Location

• Ground Conductivity

The range of Ground-wave propagation depends upon:

The surface waves die more quickly as the frequency increases:

Sky-wave Propagation

• In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere.

• Since it is not limited by the curvature of the Earth, skywave propagation can be used to communicate beyond the horizon, at intercontinental distances.

• Directly from one point to another.

• Along the ground, bending slightly to follow the curvature of the Earth for some distance.

Sky-wave Propagation (Short Waves) generally travel to their destination in four ways:

3MHz - 30 MHz

frequency of short wave propagation

Maximum Usable Frequency (MUF)

• The highest frequency at which the ionosphere bends radio waves back to a desired location on Earth.

• The MUF for communication between two points depends on solar radiation strength and the time of day.

• When sunspots are low, radiation and the MUF are lower.

HF (shortwaves) communication

is enhanced during times of greater sunspot activity.

LINE-OF-SIGHT PROPAGATION (LOS)

Is a characteristic of electromagnetic radiation or acoustic wave acoustic propagation which means waves travel in a direct path from the source to the receiver.

Electromagnetic transmission

includes light emissions traveling in a straight line.

direct path between the transmitter and receiver considering the curvature of radiowave trajectory.

main route of line-of-sight (LOS) radiocommunication

Non-line-of-Sight (NLOS)

is a radio transmission across a path that is partially obstructed, usually by a physical object in the innermost Fresnel zone.

• buildings,

• trees, hills,

• mountains,

• high voltage electric power lines.

Obstacles that commonly cause NLOS conditions include:

Wave Polarization

The plane of polarization of a radio wave is the plane in which the E-field propagates with respect to the Earth.

Vertically Polarized

In wave polarization, If the E-field component of the radiated wave travels in a plane perpendicular to the Earth's surface (vertical), the radiation is said to be

Circular Polarization

produces an electric field that rotates as it travels.

• RIGHT HAND CIRCULAR

• LEFT-HAND CIRCULAR

Circular polarization falls into two categories, depending on the direction of rotation:

The polarization of a radio wave can rotate as it propagates.

If a Linear polarized wave (vertical or horizontal) reflects off a surface that is not vertical or horizontal, its polarization will be changed.

• Free space loss

• Ducting

• Attenuation and Scattering

• Refraction

• Atmospheric absorption

• Reflection

• Multipath and Fading

LINE-OF-SIGHT WIRELESS TRANSMISSION IMPAIRMENTS: