DGCA RTR(A) Part 1 key terms

The mandatory repetition back to a controller of safety-related clearance elements such as route, altitude, heading, speed, runway and frequency, so the controller can confirm the instruction was received correctly.

The fixed set of internationally agreed words and sentence patterns used for radiotelephony, chosen so that messages are short, unambiguous and understood by pilots and controllers of different native languages.

The principle that transmissions should contain only what is needed to convey the message, avoiding polite filler and repetition, because airtime on a frequency is a shared and limited resource.

A single continuous radio broadcast by one station. In busy circuits it must be short, because while one station transmits, no other station on that frequency can be heard.

The unique identifier a station uses on the radio, such as an aircraft registration or a controller unit name, so that every message can be attributed to the correct sender.

The call sign or registration used to identify an aircraft in radiotelephony. Controllers may shorten it after initial contact, but the full form is restored whenever confusion is possible.

An authorisation from air traffic control for an aircraft to proceed under specified conditions. It is not an instruction to act and does not by itself relieve the pilot of responsibility.

A directive from air traffic control requiring a specific action, such as a heading, level or speed. Unlike a clearance, it must be complied with unless safety requires otherwise.

A clearance for an aircraft to enter the runway and position itself in preparation for take-off, without permission to begin the take-off roll.

The explicit authorisation for an aircraft to begin its take-off roll. It is never issued together with a line-up instruction and is always read back in full.

A clearance whose validity depends on a stated event, such as another aircraft landing or vacating. The condition is read back together with the clearance to prove it was understood.

The instruction to set a specific four-digit code on the aircraft transponder, so that the controller can identify the aircraft on radar and correlate it with its flight data.

Airborne radio equipment that replies to ground radar interrogations with an identification code and, when capable, pressure altitude, allowing the controller to track and separate aircraft.

The transponder reply that carries pressure altitude, referenced to standard pressure, so that a controller can see an aircraft's level on radar without a separate voice report.

The pressure value set on the altimeter subscale, such as QNH or standard pressure, so that the instrument indicates height above a defined reference rather than an arbitrary value.

The altimeter subscale setting that makes the altimeter read elevation above mean sea level when the aircraft is on the ground at that location. Used below the transition altitude.

The fixed altimeter setting of 1013.2 hectopascals, used above the transition altitude so that all aircraft share the same pressure reference and vertical separation is reliable.

A level expressed in hundreds of feet referenced to standard pressure, written as three digits such as FL 350, used above the transition altitude for cruising and separation.

The lowest flight level available for use above the transition altitude. Below it, aircraft fly on QNH altitudes; at and above it, they fly on standard pressure flight levels.

Standard Instrument Departure: a published route and procedure with a designator that aircraft follow after take-off, often issued as part of the initial clearance and read back by name.

Standard Terminal Arrival Route: a published arrival procedure identified by a designator, used to sequence inbound traffic and normally included in the approach clearance or arrival instructions.

Authorisation for an aircraft to conduct a specified instrument approach, which may include the approach name, runway and any level or speed restrictions to be observed.

The instruction or pilot decision to abandon an approach and climb away, usually because the runway is not clear or the approach is not stable. It is acknowledged and read back.

An instruction to stop before a specified runway or taxiway point and not proceed until further clearance, requiring an explicit readback to confirm the limit of the clearance.

Authorisation to move on the manoeuvring area along a specified route, which may include holding points and crossing instructions, and which must be read back accurately.

The international spoken distress signal, repeated three times, used when an aircraft is threatened by grave and imminent danger and requires immediate assistance.

The international spoken urgency signal, repeated three times, used for a situation concerning the safety of an aircraft or person but which does not require immediate assistance.

The designated VHF frequency 121.5 MHz used for emergency transmissions and direction finding, monitored by many stations and reserved for genuine distress and urgency traffic.

A communication mode in which both stations transmit on the same frequency and therefore cannot transmit simultaneously, which is why radio discipline and short messages matter.

An instruction to move to another radio channel for further communication, normally read back with the new frequency so errors are caught before contact is lost.

A transmission made without expecting a reply, used when a station cannot establish contact, to broadcast position and intentions so other stations are aware.

A message giving an aircraft's location and related details such as level, next position and estimated time, used where surveillance coverage is absent or as required by procedure.

Ordinary spoken wording used when no standard phrase is suitable, kept simple and unambiguous, and used especially in abnormal or emergency situations.

The Radio Telephone Restricted licence, Aeronautical, issued under the Indian RTR Rules, 2025, which authorises the holder to operate radiotelephony equipment on aeronautical frequencies.

The authorisation granted to a person to operate radio transmitting equipment. In aviation it is separate from the pilot licence and must be held before operating aeronautical radio.

The assessment required before a radiotelephony licence is issued, covering procedures, phraseology, regulations and equipment knowledge, and normally including a practical test.

The period for which a radiotelephony licence remains in force, after which renewal is required. Holders must check the expiry date and apply for renewal in good time.

Any installation authorised to transmit or receive on aeronautical frequencies, including aircraft stations and ground stations, each identified by its own call sign.

Unwanted radio energy that degrades reception, whether from other transmitters, equipment faults or external sources. Suspected interference should be reported to the controlling authority.