History of ATC terminology

“Mayday! Mayday!”

This is a term that has become indoctrinated in our society – even by those outside of the aviation industry.

This, alongside other words, acronyms and phrases, are used day-in day-out.

But what do they mean? Where do they originate?

We’ve outlined some below.

Squawk

Air traffic controllers use the term squawk when assigning an aircraft with a transponder code. Once a pilot has entered the squawk code, air traffic controllers can identify the aircraft, track it and it gives an additional form of communication between the pilot and controller if the aircraft becomes in any trouble or for when general aviation pilots become close to entering – or actually infringe – controlled airspace.

The word squawk comes from a system used in World War Two called identification, friend of foe (IFF), which was code-named “Parrot”.

It worked by responding to a radar interrogation signal with a secret coded transmission, allowing the British to distinguish their own aircraft from German aircraft on radar as the IFF would “talk back” or “squawk” like a parrot.

IFF may be used by both military and civilian aircraft.

Mayday

This is the 999 call equivalent in aviation. Immediate attention is needed and the situation could be life-threatening.

It originated in 1923 by Frederick Stanley Mockford, who was a senior radio officer at Croydon Airport in London. He was asked to think of a word that would indicate distress and would easily be understood by all pilots and ground staff in an emergency.

At the time, most of the traffic was between Croydon and Le Bourget Airport in Paris, so he suggested the word “Mayday“ from the French “m’aidez“, which translates to “help me”.

The call is always given three times in a row –“mayday, mayday, mayday” – so it cannot be mistaken in noisy conditions for a similar-sounding phrase.

PAN

This stands for “Possible Assistance Needed” or “Pay Attention Now”. It is the equivalent of dialing 101 for needing the police. It signifies urgency on board, but there is no immediate danger to anyone’s life or to the aircraft itself.

Pan-pan is the anglicised spelling of the French word “panne”, which means “broken/failure/breakdown”.  Similar to mayday, it should be stated three consecutive times – “pan-pan, pan-pan, pan-pan”.

Radar

Most will know radar as a system that uses reflected radio waves to detect the presence, direction, distance and speed of an aircraft (as well as ships, spacecraft, missiles and other objects).

This actually stands for Radio Detection And Ranging and was secretly developed by several nations before and during the second world war. As early as 1886 a German physicist showed that radio waves could reflect off of solid objects.

From then on, researchers across various nations experimented with radio waves, including in the UK in the 1920s where researchers established many advances in techniques, such as probing the ionosphere and detecting lighting at long distances.

In the 1930s the use of radio waves evolved using a pulsed system. It was in 1940 that the American navy coined the term radar that is so fondly used to this day.

A NOTAM explaining assistance to be given to aircraft on a taxi-way due to a lighting fault

NOTAM

This stands for Notice to Airmen. It is a notice filed with an aviation authority to alert pilots of potential hazards en route or at a location that could affect the safety of the flight.

NOTAMs are created and transmitted by government agencies and airport operators under guidelines specified in the Convention on International Civil Aviation (CICA). It was signed in December 1944 in Chicago and came into effect in April 1947 – when ICAO came into being.

Amendments and developments to the CICA have been made over time resulting in the more automated system currently available. NOTAMs are typically exchanged over AFTN circuits. They use various codes to explain what is happening, where and what advice is given to the air traffic controllers for the particular circumstance.

NOTAMs are issued (and reported) for various reasons, including:

• hazards such as air shows, parachute jumps, kite flying, lasers, rocket launches
• military exercises with resulting airspace restrictions
• temporary erection of obstacles near airfields – e.g. cranes
• passage of flocks of birds through airspace – known as a BIRDTAM
• closed runways
• notifications of runway/taxiway status with respect to snow, ice, and standing water – known as a SNOWTAM

Drone

This is formally known as an unmanned aerial vehicle (UAV). It is an aircraft without a human on board controlling it and it can be guided remotely or autonomously. Today they are mostly used for military operations, but have been adopted into civil use, by police, fire fighters, search and rescue, filmmakers for capturing aerial shots and non-military security work, such as pipeline or power inspections.

Early use of UAVs was in the mid 1800s when Austria sent balloons filled with bombs to attack Venice, Italy. During the 1900s these were developed and used by the military in World War Two.

In the 1980s a prototype UAV was made to test the concept of flying high altitudes by solar power. Test flights were conducted using radio control and battery power, as the aircraft had not been fitted with solar cells. It was determined that photovoltaic cells or energy storage technology was not practical at that time.

A decade later a NASA research programme developed the use of solar-powered unmanned aircraft that could successfully take-off and land from an airport and can be flown to extremely high altitudes.

Today, more work is being done by companies across the globe to develop small solar-powered UAVs.

Quiz:

Test your knowledge on some of these acronyms. Do you know what they stand for? Leave your answers in the comment box below. Answers will be revealed next week via our NATS Twitter account – @NATS.

1. A&D

A) Arrival and Depart

B) Arrive and Depart

C) Arrival and Departure

D) Arrive and Departure

2. ACAS

A) Airborne Collision Avoidance System

B) Airborne Colliding Avoidance System

C) ATC Collision Avoidance System

D) Aircraft Collision Avoidance System

3. HIRTA

A) High Intensity Radio Transmission Arena

B) High Intensity Radio Transmission Area

C) Highest Intensity Radio Transmission Area

D) High Intensity Radio Transmitter Area

4. HIRO

A) High Interim Runway Operations

B) High Intensity Runway Operatives

C) High Intensity Runway Operations

D) Huge Intensity Runway Operations

5. CTOT

A) Calculating Take Off Time

B) Calculated Take Off Time

C) Calculating Time Of Take Off

C) Callback Take Off Time

6. RVR

A) Route Visibility Range

B) Runway Visibility Range

C) Route Visual Range

D) Runway Visual Range