Article 38(2) of LOSC defines transit passage as:
the exercise in accordance with this Part [III] of the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit of the strait between one part of the high seas or an exclusive economic zone and another part of the high seas or an exclusive economic zone.
This provision continues that: ‘the requirement of continuous and expeditious transit does not preclude passage through the strait for the purpose of entering, leaving or returning from a State bordering the strait, subject to the conditions of entry to that State’. Thus the transit passage includes lateral and inward/outward-bound passage. The right of transit passage in international straits differs from the right of innocent passage in the territorial sea in four respects.
First, Article 38(1) makes it clear that all ships and aircraft enjoy the right of transit passage. It is clear, therefore that warships enjoy the right of transit passage.
Second, the right of transit passage includes overflight by all aircraft, including military aircraft.
Third, concerning submarines, the LOSC provides no explicit obligation to navigate on the surface and to show their flag. Article 39(1)(c) provides that ships and aircraft, while exercising the right of transit passage, shall ‘refrain from any activities other than those incident to their normal modes of continuous and expeditious transit unless rendered necessary by force majeure or by distress’. Arguably, the normal mode for submarines to transit is submerged navigation. Furthermore, Article 38(2) stipulates that transit passage means the exercise ‘in accordance with this Part [III]’ of the freedom of navigation and overflight. It would follow that the transit passage is to be subject only to provisions in Part III. There is no cross-reference to the specific provision on innocent passage which requires on-surface navigation. It appears that this interpretation is also consistent with the travaux préparatoires for UNCLOS III. In conclusion, there is room for the view that submarines and other underwater vehicles in transit passage are not required to navigate on the surface and to show their flag.
Fourth, unlike the right of innocent passage through the territorial sea in general, there shall be no suspension of transit passage by virtue of Article 44.
On the other hand, ships and aircraft are required to comply with three types of duties during transit passage: common duties for ships and aircraft in transit passage, duties of ships in transit passage and duties of aircraft in transit passage.
First, ships and aircraft are commonly obliged to comply with four duties enunciated in Article 39(1) of the LOSC:
(a) proceed without delay through or over the strait;
(b) refrain from any threat or use of force against the sovereignty, territorial integrity or political independence of States bordering the strait, or in any other manner in violation of the principles of international law embodied in the Charter of the United Nations;
(c) refrain from any activities other than those incident to their normal modes of continuous and expeditious transit unless rendered necessary by force majeure or by distress;
(d) comply with other relevant provisions of this Part. In essence, this provision has parallels in Article 19 of the LOSC.
Second, ships in transit passage are under duties to:
(i) comply with generally accepted international regulations, procedures, and practice for safety at sea, including the International Regulations for Preventing Collisions at Sea;
(ii) comply with generally accepted international regulations, procedures and practices for the prevention, reduction and control of pollution from ships;
(iii) refrain from carrying out any research or survey activities without the prior authorisation of the States bordering straits;
(iv) respect applicable sea lanes and traffic separation schemes;
(v) comply with law and regulations adopted by States bordering a strait under Article 42(1) of the LOSC.
Third, Article 39(3)(a) and (b) provides that aircraft in transit passage shall:
(a) observe the Rules of the Air established by the International Civil Aviation Organization as they apply to civil aircraft; state aircraft will normally comply with such safety measures and will at all times operate with due regard for the safety of navigation;
(b) at all times monitor the radio frequency assigned by the competent internationally designated air traffic control authority or the appropriate international distress radio frequency.
Concerning Article 39(3)(a), a question arises of whether or not States bordering straits have a right to issue and apply their own air regulations in the airspace of the straits used for international navigation. Upon signature and ratification of the LOSC, the Spanish government claimed such a right. However, the United States objected to the Spanish interpretation.
While opinions of writers are divided, the Secretariat of International Civil Aviation Organization (ICAO) took the view that the Rules of the Air as adopted by the Council of ICAO would have mandatory application over the straits and the States bordering the strait cannot file an alteration to Rules of the Air under Article 38 of the Chicago Convention with respect to the airspace over the straits.