- 21 - CDL-AD(2006)009 89. The Chicago Convention sets out the regime for civil aircraft and civil aviation. According to Article 3 (a), such regime does not apply to State aircraft. 90. Under the Convention, aircraft “used in military, customs and police services” are deemed to be state aircraft (Article 3(b)). This presumption, however, is not irrebuttable52. Moreover, aircraft engaged in other state activities such as coast guard and search and rescue could also be either state aircraft or civil aircraft in the sense of the Convention.53 91. It has generally been admitted54 that, in case of doubt, the status of an airplane as “civil aircraft” or “state aircraft” will be determined by the function it actually performs at a given time55. As a general rule, “aircraft are recognised as state aircraft when they are under the control of the State and used exclusively by the State for state intended purposes”56. Accordingly, the same airplane can be considered to be “civil aircraft” and “state aircraft” on different occasions. 92. Civil aircraft that are not engaged in scheduled international air services of a State party to the Chicago Convention57 are entitled to make flights into or in transit non-stop across the territory of another State party and to make stops for non-traffic purposes without the necessity of obtaining prior permission and subject to the right of the State flown over to require landing. The authorities of each State party have the right, without unreasonable delay, to search aircraft 52 The Secretariat of the ICAO Council stated that “the predominant view is that all such other aircraft [performing State services other than military, police and customs] would in fact be considered as falling within the scope of the Convention”. In the study, it is recalled that under the Paris Convention of 1919 all State aircraft other than military, customs and police aircraft were treated as private aircraft and subjected to all the provisions of the Paris Convention (see Doc. C-WP/9835 of 22/09/1993, Secretariat Study on “Civil/State aircraft” presented by the Secretary General at the ICAO Council 140th Session, § 5.2). 53 In Germany, for example, certain flights performing state functions, such as transports of high government officials or humanitarian/disaster relief flights are referred to as “civil State flights” (zivile Staatsflüge) and are regarded as civil flights in the sense of the ICAO Convention (but not necessarily in the sense of general public international law), see Bericht der Bundesregierung (Offene Fassung) gemäß Anforderung des Parlamentarischen Kontrollgremiums vom 25. Januar 2006 zu den Vorgängen im Zusammenhang mit dem Irakkrieg und der Bekämpfung des Internationalen Terrorismus, at http://www.bundesregierung.de/Anlage965868/Bericht+der+Bundesregierung+-+offene+Fassung.pdf., at pp. 62-67. 54 ICAO Secretariat Study on “Civil/State Aircraft” LC/29-WP/2-1, Pellet, Dailler, Droit International Public, LGDJ, 7è edition, 2002, pp. 1250; Combacau (J.), Sur (S), Droit international Public, Montchristien, 5è édition, 2001, p. 473; “Status of military aircraft in international law”, address at the Third International Law Seminar of 28 August 1999, by Professor Michael Milde, formerly the head of the legal bureau of the International Civil Aviation Organisation, at: http:// www.mindef.gov.sg/dmg/ls/Il399.doc; Diederiks-Verschoor, Introduction to air law, Kluwer, pp. 30 and following. 55 In the case of a civil aircraft (B-737, MisrAir flight 2843 from Cairo to Tunis) carrying, on the basis of charter by the Government, suspected terrorists out of the country under Military Police escort and intercepted and forced to land in Italy by the US military based in Italy, the US Government, in a letter to the International Federation of Air Line Pilots Association, stated: “It is our view that the aircraft was operating as a state aircraft at the time of interception. The relevant factors - including exclusive State purpose and function of the mission, the presence of armed military personnel on board and the secrecy under which the mission was attempted - compel this conclusion”. This case, quoted in ICAO document LC/29-WP/2-1, pp. 11-12, was cited by Professor Milde, see above, footnote 54. See also A. Cassese, Terrorism, Politics and Law, the Achille Lauro case, Polity Press, p. 39. 56 57 Diederiks-Verschoor, Introduction to air law, Kluwer, pp. 30 § 12 . See also footnote 52. Status of ratifications of the Chicago Convention available at: http://www.ICAO.int/ICDB/HTML/English/Representative%20Bodies/Council/Working%20Papers%20by%20Ses sion/163/c.163.wp.11641.en/C.163.WP.11641.ATT.EN.HTM