One of the first ATAs after World War II was the Bermuda Agreement, signed in 1946 by Britain and the United States. The features of this agreement have become models for the thousands of such agreements that were to follow, although in recent decades some of the traditional clauses of these agreements have been modified (or “liberalized”) in accordance with the “open skies” policy of some governments, particularly the United States.  Method of separate bilateral negotiations: correction of changes made with 73 partner states representing 340 bilateral agreements. Air services agreements generally consist of an air services agreement at Treaty level, supplemented by agreements with a lower contractual status between aviation authorities, such as. B memoranda of understanding and/or exchanges of letters.