An air services agreement (also known as the ATA or ASA) is a bilateral agreement that allows international commercial air services between signatories. The bilateral system is based on the Chicago Convention and related multilateral treaties. The Chicago Convention was signed in December 1944 and has governed international air services ever since. the convention also contains a number of annexes covering issues such as aviation safety, safety monitoring, seaworthiness, navigation, environmental protection and facilities (acceleration and departure at airports). One of the first AAS after World War II was the Bermuda Agreement, signed in 1946 by the United Kingdom and the United States. The characteristics of this agreement have become models for the thousands of agreements that were to follow, although in recent decades some of the traditional clauses of these agreements have been amended (or “liberalized”) in accordance with the “open skies” policy of some governments, particularly the United States.  to impose or authorize a fair and fair fee for the use of such airports and other facilities for such a service; these charges cannot be higher than those paid for the use of these airports and facilities by their domestic aircraft using similar international services, provided that the fees levied for the use of airports and other facilities on the representation of an interested State party are subject to review by the Council of the International Civil Aviation Organization established by the aforementioned Convention. report to and make recommendations to the state or states concerned. Made in Chicago, December 7, 1944, in English. A text written in English, French and Spanish, which must have the same authenticity, is open for signature in Washington, D.C. Both texts are filed in the archives of the United States Government of America and certified copies are forwarded by that government to governments of all states that can sign or accept this Agreement. Air Services Agreements (ASAs) are formal contracts between countries – Memorandums of Understanding (Memorandum of Understanding) and formal diplomatic notes.
It is not mandatory to have an ASA for the operation of international services, but cases where contract-free services exist are rare. In 1913, a bilateral exchange of notes  between Germany and France was signed in the first agreement to provide airship services. This agreement remains in force as long as the above agreement is in force; However, provided that any State Contracting Party to the Agreement can denounce it on a one-year note addressed to the Government of the United States of America, which promptly informs all other States Parties of this communication and its withdrawal.