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1. Introduction

1.1 General Provisions​

The annotation phraseology denotes the prescribed words and/or phrases to be used in communications. Controllers are required to use standardized procedures and phraseologies when communicating with pilots. When needed, controllers can rephrase the message to ensure the content of the transmission is understood.

Radiotelephony standards are developed to provide efficient, clear, concise, and unambiguous communications between pilots and ATS personnel operating within Saudi airspace. Care should be taken the current use of ICAO phraseology in all instances.

All communications shall be delivered in a clear, concise, and unambiguous manner.

1.2 Standard Phrasesolgy​

Standardised phraseology shall be used in all situations wherever applicable. However, plain language may be used when standardised phraseology is unable to serve the intended purpose, or to avoid confusion or misunderstanding. The use of excessive courtesies should be avoided.

The word “IMMEDIATELY” should only be used when immediate action is required for safety reasons.

The expression “TAKE-OFF” shall only be used in radiotelephony when an aircraft is cleared for take- off or when cancelling a take-off clearance.

1.1 Appropriate Transmitting Techniques​

  • Listen! Before you transmit, listen, and make sure the frequency is clear.
  • Think! Before keying your transmitter, know what you want to say.
  • Be confident! Speak normally in a confident tone.
  • After pressing the PTT button, a slight pause (a milisecond) may be necessary to be sure the first word is transmitted.
  • Release the button after the message is completely transmitted.

1.3 Blocked frequency​

Frequency blocking is a phenomenon that occurs when two or more stations transmit on the same frequency or when a station makes an unnecessary transmission that lasts for too long. In the former case, the result is a signal that is a mix of all transmissions, and the receiving stations hear a garbled message which is often completely unreadable.

1.3.1 Frequency blocking reasons​

Frequency blocking can occur between pilot-pilot or pilot-ATC transmissions. The most common reasons for frequency blocking are:

  • Stuck microphone button. It often prevents the normal use of the frequency because if any other station tries to transmit, the others will likely hear a garbled message.
  • Lack of radio discipline. While most communication manuals advise against it, there are occasions where a pilot presses the transmit key as soon as they change the frequency. This may cause an overlap with someone who is already transmitting.
  • Coincidence. Sometimes even if the two operators listen out before transmitting, it is possible that they press their buttons at precisely the same moment. The probability of such an event increases in busy frequencies.
  • Callsign confusion. Sometimes messages by air traffic controllers are considered relevant by more than one flight crew. This usually (but not always) happens due to callsign similarity (e.g., SVA078 and SVA778). The result is that both pilots reply and block the frequency.

1.3.2 Frequency blocking results​

A frequency blocking may lead to:

  • Inability to communicate. If the frequency is unavailable for a prolonged period, some stations may be unreachable on the frequency.
  • Aggravation of frequency congestion due to the need to repeat messages.
  • Misunderstandings due to the reluctance to ask for repetition.
  • Receiving wrong information. Blocking frequency may lead to aircraft accepting a clearance intended for another, with the controller unaware of the situation.

1.3.3 Restoring normal communications​

The following procedures are helpful to mitigate the consequences of frequency blocking and restore normal communications:

  • Using the word BLOCKED to alert the others that a frequency blocking has occurred so that they may act accordingly to the specific circumstances (e.g., transmit again, wait to be called for, etc.).
  • In case of frequency blocking due to traffic congestion controllers may choose to take the initiative and initiate dialogues. Some clues may help identify the aircraft that have transmitted during the blocking or are about to transmit (and may cause a blocking). For example, if pilots block the frequency, and the controller has heard and understood the messages from the pilots, the controller can call the pilots and reply to them one by one according to importance instead of saying blocked.