1927: Airline companies officially recognized as airmail carriers


With the growing needs arising from the rapid development of international postal relations, the Universal Postal Union (UPU) was established on 7 July 1875 to promote the organization and improvement of world postal services in a spirit of international cooperation. The Universal Postal Union Congress is held every five years as the supreme authority of the UPU and brings together diplomats and postal operators from member countries.



8th UPU Congress

Stockholm - 1924


The period from 1920 to 1927 was a period of incipient development for air transport. After World War I, the possibility of using the airplane for the transportation of mails gained momentum. Postal administrations and airlines were still in the dark as to its future possibilities for international airmail. Air services were considered as “extraordinary” ground services under the UPU General Convention governing all international mail. The determination of the rates was left to the administrations using it.


At the Stockholm Ordinary Congress of UPU in 1924 (8th Congress), the possibility of using the airplane for the transportation of mail gained momentum. Although the latter agreement had been in existence for only one year, a need for modification was recognized to consider unifying airmail surtaxes demanded of the public and to simplify the method of remunerating the air transport companies. By 1927 however, use of air transport had become sufficiently widespread to justify the convening of a special airmail conference.



USSR – 1927

1st International Aero-

Postal Conference

As the signatory governments were bound by a five-year agreement during which time amendments to the Convention were practically impossible to obtain and, as the use of air transport had become sufficiently widespread, the Post Office of the USSR took the step in March 1927 of formally proposing a special Administrative Conference of UPU (First International Air Post Congress) for the consideration of the technical question of airmail provisions. 


Called at the suggestion from the Air Transport Committee of the International Chamber of Commerce (Chambre de Commerce Internationale, CCI) and the official initiative of the Postal Office of the USSR, this Conference met in the building of the Upper Chamber (Hall of Senat) at The Hague, Netherlands, from 1 to 10 September 1927; it was opened in the Ridderzaal in the Binnenhof at The Hague. The Conference was attended by seventy-nine representatives of thirty-eight members of the UPU; the large participation indicated an awareness of the importance which airmail would have. Fourteen air transport companies (although without vote) also took part in the discussions.


This Conference resulted in an agreement that established the airline companies as officially recognized carriers of mail; the basic rate to be applied in the settlement of the accounts for air transportation between administrations had been fixed at 6.5 centimes of gold franc for every indivisible fraction of 100 grams net weight and 100 kilometers. As a rule, this basic rate was limited to some European routes. The airline companies had requested 6 to 7.5 gold francs per ton-kilometer on European daytime flights and a considerable higher charge for European night flights and intercontinental links. It also initiated some significant rules and regulations concerning the acceptance and rapid delivery of airmail by the signatory powers, the expeditious handling of airmail by countries without air services, and the basis of accounting procedures for international airmail. Another provision agreed upon was that the PAR AVION labels should have a blue colour and, when the mail did not actually travel by air, such labels or annotations should be crossed out.


The monetary unit employed for all purposes of the UPU machinery was the “Postal Gold Franc”, defined by article 29 of the UPU Convention at that time, which is a franc of 100 centimes weighing 10/31 of a gram and having a fineness of 0.900. This special unit of currency is not employed for any other purpose.


9th UPU Congress

London - 1929

The The Hague Conference of 1927 laid down the first airmail provisions, an event of historic importance in view of the fantastic development of that means of transportation in the international post; the Conference unquestionably marked the beginning of a new era for the airmail. The UPU London Congress adopted in 1929 with minor changes the Air Mail Regulations that were established by this Conference. These provisions set the general pattern for international airmail arrangements up to the UPU Congress of Paris in 1947.


Later, more restricted meetings of countries directly concerned took place in Europe, with the participation of aeronautical authorities (e.g. the European Airmail Conferences held in Brussels, October 1930 and June 1938). The primary concern of these meetings was to take advantage of the speed provided by air transport for the benefit of the mail service between the principal cities.


During the conference, a special postmark was used to commemorate this occasion in the Netherlands. Text on the postmark reads as follows: CONFÉRENCE / POSTALE LA HAYE / 9-IX-1927-19-H, along the three equilateral sides of the triangle. In the middle, are the world globe and the letters U P U. Four privately produced postcards were issued to the participants; for each of these, the front side shows in black either the Knights Hall (i.e. Ridderzaal in Dutch; see below) or the main building of the PTT in The Hague.


Souvenir folder distributed by the Japanese Delegation at the Conference

Souvenir folder distributed by the Swiss Delegation at the Conference



Special postmark issued to commemorate this Conference.


Front-side of the above postcard (Knights Hall or Ridderzaal in The Hague).


Warren Irving Glover (1879-1956), Second Assistant Postmaster General and responsible of air mail, represented the United States at the first International Air Post Congress held at The Hague, Netherlands in September 1927.

The above cover was part of the first shore to ship mail destined for transportation to the SS Leviathan sailing from New York. (Photo Credit: Jerry A. Katz)

In the USA, the United States Post Office conducted experiments with aircraft flying mail to ships at sea in order to speed up delivery. The first ship to install a flying mail service was the SS Leviathan in 1927; a special deck was installed diagonally across the bow of the ship and extended over the sea. In a Fokker biplane, pilot Clarence Duncan Chamberlin, the second pioneer to cross the Atlantic on 4 June 1927, flew the maiden voyage on 31 July 1927.


UPU Postcard – The printed inscription reads as follows:



Service cover prepared by the Netherlands P.T.T. with UPU emblem – The printed inscription reads as follows: UPU 1927 CONFÉRENCE POSTALE LA HAYE.


UPU official cover from this Air Post Conference – Registered.


Commercial cover to Germany, with special triangular UPU cancels.


First Day Flight cover postmarked on 1 September 1927, sent from Moscow to Paris, France. Bilingual “Air Mail” label in Russian and French. Rate 50k.


Registered and flown cover from Moscow (14/09/1927) to Berlin, franked with 3x10k (one broken "7" in "1927" variety) and 1x15k. Rate 45k.


Commercial cover sent on 16 September 1927, with 3x15k and 1x10k. Rate 55k.



Registered cover sent on 24/09/1927, with 2x10k and 1x15k. Rate 35k.

Note the error: spot on the left wing of the 15k stamps; see details.