What Is The International Civil Aviation Organization (ICAO)?

In many articles on Simple Flying, there are quotes or comments from an organization called ICAO. Who are they? And why are they essential in international aviation?

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What is ICAO, and what does it do? Photo: Getty Images

What does ICAO stand for?

ICAO stands for the International Civil Aviation Organization – a United Nations organization that recommends and helps establish air traffic standards for 193 countries (although they can only act with the permission of the host country, regulation is performed by the local authorties). Essentially, nearly every single regional government in the world has agreed to follow the advice, except for some who have either waived their rights to other nations (like Liechtenstein allowing Switzerland to sign on its behalf), or areas with no central government (West Sahara). However, that list is few and far between, with even nations like North Korea signing up.

The ICAO logo. Photo: ICAO

When did it start?

To understand the history of the organization, we need to go back to the first serious convention of world powers in Paris in 1910 to discuss air transport navigation. Heavier than air flight had been achieved in 1903 by the Wright Brothers, and there had been a few half-hearted attempts to discuss flying internationally – although all had failed to agree on any rules so far. 

The 1910 Paris talks had 18 European states attend, and they discussed some initial principles governing air travel. But aviation governance would not become urgently required until World War One. In the war, aircraft flew for transport, scouting, and logistics – as well as being war machines.

Different groups realized that for aviation governance to work, it had to be an international effort or not attempted at all. After the war, 38 states came together to create the International Commission for Air Navigation (ICAN). This body would convene to promote aviation, and went as far as to allocate the first radio callsigns to aircraft.

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When aviation was young, ICAN helped connect Europe and North America. Photo: Getty Images

What happened to ICAN?

During World War Two, it became apparent that aviation was the new backbone of the modern world. US forces used aircraft extensively throughout Europe during and after the war, and many aircraft operations served the military first and civil traffic second. Thus it was decided that it would be best for civilian aviation management to resemble military administration as closely as possible – forcing the evolution of ICAN.

In 1944 in Chicago, fifty-two countries returned and signed the Chicago Convention on International Civil Aviation – one item of which created the office of Provisional International Civil Aviation Organisation. This agency would fall under the new United Nations and would have unmatched ‘powers’ to declare best practicies for managing aviation around the world. In a nice twist, the previous 1922 ICAN general secretary Albert Roper would go on to lead ICAO (and retire in the 1960s), thus cementing the continuity between the two organizations.

Today the agency is located in Montreal and recommends many aviation rules and regulations throughout the world that countries can choose to follow (and fortunately, nearly all do so).

What does ICAO manage today?

There are a variety of different areas that ICAO regulates, that without them, international travel would be incredibly complicated to do.


  • ICAO determines the infrastructure for aviation, from communication rules, navigation, air traffic management (such as speaking in English), as well as standards for passports.
  • They also manage the measure units in aviation, such as units pf pressure, temperature, altitude, and more, so all aircraft and operations are in sync no matter what country you are in.
  • ICAO also chooses how big an airport needs to be to take particular aircraft. There are six levels of airports. The smallest, A, can only handle small prop-planes, and the biggest, F, can take 747s and A380s.
  • ICAO issues airport codes to new and existing airports. IATA, another organization, also supplies codes, but this is only for airports that operate airline services. ICAO is for all airstrips, big or small.
  • ICAO issues three-letter airline codes use for radio designations. While these are sometimes similar to the IATA two-letter codes you see on a flight number (QF001, for example, for Qantas), they can be very different when it comes to radio transmissions.
  • ICAO is also helping the aviation industry face climate change. They are bringing together members and proposing various solutions such as different fuels to carbon offset scenes. However, some critics have said its not enough.

What do you think of ICAO? Let us know in the comments.