A nation's civil air ensign

Ensign

An ensign is a national flag when used at sea, in vexillology, or a distinguishing token, emblem, or badge, such as a symbol of office in heraldry...

is its national flag (or a variation thereof) which represents civil aviation

Civil aviation

Civil aviation is one of two major categories of flying, representing all non-military aviation, both private and commercial. Most of the countries in the world are members of the International Civil Aviation Organization and work together to establish common standards and recommended practices...

 in that nation. Typically, it is flown from buildings connected with the administration of civil aviation and it may also be flown by airlines of the appropriate country.http://www.fotw.net/FLagS/vxt-dvc1.html#cae A civil air ensign is the equivalent of the civil ensign

Civil ensign

The civil ensign is the national flag flown by civil ships to denote nationality...

 which represents merchant shipping. Not all countries have civil air ensigns and those without usually fly their national flags instead.

List of civil air ensigns

Flag	|Date	|Description
	Australia Australia Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...	1935	Australian Civil Aviation Ensign Australian Civil Aviation Ensign The Australian Civil Aviation Ensign is an Australian flag that was used by the Australian Civil Aviation Authority.The design of the flag is based on the British Civil Air Ensign, which is divided into quarters by a dark blue cross with a white fimbriation. There is a Union Jack in the upper hoist...	An ensign based on the British Civil Air Ensign with the stars of the Southern Cross superimposed http://www.airwaysmuseum.com/Civil%20Air%20Ensign.htm
	United Kingdom United Kingdom The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...	11 August 1931	British Civil Air Ensign British Civil Air Ensign The Civil Air Ensign is the flag that may be flown at airports in the United Kingdom and from landed British aircraft.The ensign's field is light blue and has a dark blue Latin cross which is fimbriated white placed overall. The Union Flag is in the canton....	A light blue ensign with the Union Flag in the canton and a dark blue Latin cross fimbriated white placed overall
	Fiji Fiji Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...		Fijian Civil Air Ensign	An ensign based on the British Civil Air Ensign with the Fijian coat of arms superimposed
	Ghana Ghana Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...		Ghanaian Civil Air Ensign	A light blue ensign with the Flag of Ghana in the canton and the national star in the fly
	Guyana Guyana Guyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...		Guyanese Civil Air Ensign	An ensign based on the British Civil Air Ensign with the Flag of Guyana in the canton
	Luxembourg Luxembourg Luxembourg , officially the Grand Duchy of Luxembourg , is a landlocked country in western Europe, bordered by Belgium, France, and Germany. It has two principal regions: the Oesling in the North as part of the Ardennes massif, and the Gutland in the south...		Roude Léiw (Red Lion)	An ensign based on the Coat of arms of Luxembourg. Also used as the Luxembourgish civil ensign.http://www.fotw.net/flags/lu%5Eaf.html
	New Zealand New Zealand New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...	16 November 1938	New Zealand Civil Air Ensign New Zealand Civil Air Ensign The New Zealand Civil Air Ensign is the flag that represents civil aviation in New Zealand.The ensign consists of a dark blue Latin cross edged with white on a light blue field. A Union Jack is placed in the first quarter and the Southern Cross, as seen from New Zealand, are shown in red in the...	An ensign based on the British Civil Air Ensign with the stars of the Southern Cross as seen from New Zealand in the fourth quarter
	Pakistan Pakistan Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...	1951	Pakistani Civil Air Ensign	A light blue ensign with the Flag of Pakistan in the canton influenced by the British design http://www.radioprotezione.it/wof/page.php?flag=1&continent=asia&country=Pakistan&image_name=asia/pkCA.gif&first_name=CHANG

List of former civil air ensigns

Flag	|Date	|Description
	South Africa South Africa The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...	From or before 1935	South African Civil Air Ensign	An ensign based on the British Civil Air Ensign with the 1928 Flag of South Africa in the canton
	Greece Greece Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....	1935–1978	Greek Civil Air Ensign	A white cross on a blue field with a Greek roundel in the centre. Also used as the ensign of the Hellenic Air Force Hellenic Air Force The Hellenic Air Force, abbreviated to HAF is the air force of Greece. The mission of the Hellenic Air Force is to guard and protect Greek airspace, provide air assistance and support to the Hellenic Army and the Hellenic Navy, as well as the provision of humanitarian aid in Greece and around the...  (1973–1978).
	Canada Canada Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...	1922	Canadian Civil Aviation Ensign	Similar to the 1941 RCAF Ensign with a shield with three maple leafs and an eagle instead of roundel. Briefly used by Air Board (Canada) Air Board (Canada) The Air Board was Canada's first governing body for aviation that existed from 1919 to 1923. The Canadian government established the Air Board by act of Parliament on June 6, 1919 with the purpose of controlling all flying within Canada... .