Radio Discipline

Description

Communication between pilots and air traffic controllers is a process that is vital for the safe and efficient control Of air traffic. Pilots must report their situation, intentions and requests to the controller in a clear and unambiguous way; and the controller must respond by issuing instructions that are equally clear and unambiguous. The process of communication is important and must be successful even in the most difficult conditions. Good radio discipline is essential to this process.

Aspects of Radio Discipline

• Not listening out before transmitting - unless flight crew listen out before making a first call on a new frequency, they may interupt an exchange between other traffic and ATC;
• Use of standard phraseology;
• Message format and content;
• Language;
• Speed and Timeliness of Communication;
• The read-back/hear-back process;
• Inappropriate use of the frequency avoiding exchanges unrelated to the function of the frequency;

Effects

Poor radio discipline is the most common cause of breakdown in the RTF communication process.

Typical Scenarios

• Not listening out before transmitting. An ATC clearance for another aircraft is read back incorrectly but the error is not appreciated by ATC because of interference from the simultaneous initial call.

• Non-standard phraseology. The pilot of Rushair 1234 requests descent clearance as follows: “34, request FL120”. The ATCO mistakes the caller for Jetair 314 and responds: “314 descend FL120”. Rushair takes this clearance as intended for him and a level bust results.

• Message format and content. The ATCO issues a clearance: “Rushair 1234, climb FL240 heading 260”. The pilot climbs to FL260.

• Language. The ATCO clears a locally-based aircraft to climb using the local language. The clearance creates a conflict with another flight whose pilots do not undestand the local language and are thus unaware of the impending circumstance. Loss of separation results.

• Timeliness of communication. A pilot about to commence an approach to a runway is instructed to change to the parallel runway. The clearance is issued too late for the pilots to carry out a thorough re-brief but they proceed anyway having failed to assimilate the go-around procedure for this runway.

• Read-back/hear-back. The pilot mis-hears a clearance but instead of reading the clearance back responds “Roger”. ATC do not challenge this response and a level bust results.

• Inappropriate use of the frequency. For examples in the ATSB Study of congestion on GND frequencies due to this problem (See: Further Reading).

Contributory Factors

• Pilot workload;
• ATCO Workload.

Solutions

• Always use standard phraseology.
• Follow best practice on message format and content.
• Ensure the use of a high standard of English language use and pronounce as clearly as possible whilst speaking at a sensible pace.
• Do not communicate with aircraft in the national language when there is a risk of loss of situational awareness for non-local pilots.
• Follow best-practice with regard to speed and timeliness of communication.
• Always apply the read-back/hear-back procedure.
• Always request a repeat of a transmission when in any doubt as to the content or meaning of a it.