DELIMITATION OF AIRSPACE AND OUTER SPACE:
A LEGAL VIEW
Prof. Yuri Kolossov*
Dmitry V. Gonchar**
*Professor of International Law, Moscow Institute
of International Relations (University).
** Diretor da Seçao de Direito Internacional do Depto. Jurídico do Ministério das
Relaçoes Exteriores da Federação Russa
The issue of establishing a clear legal
definition of outer space and thus achieving delimitation of outer space and airspace is
not a new one, in fact, it has been on the agenda of space-faring states, international
organizations and the world community in general since the beginning of the space era. The
significance of this issue is boosted by the fact that there exists no clear physical
boundary between airspace and outer space as there exist no easily discernable technical
attributes that would aid in establishing such a boundary. But what is the legal and
political significance of trying to formulate a legal definition and delimitation of outer
space today? One might argue, and it is quite often the case, that the existing system of
International space Law is quite sufficient to regulate the activities of states in outer
space and that the issue of delimitation is out-dated and impractical. To give a
definitive answer to this question we must first examine the legal attributes of outer
space and airspace and look at the issues that stand unresolved because of the fact that
no such delimitation exists today.
The first and obvious difference in the legal regime of outer space and
airspace is that, according to Article II of the Outer space treaty of 1967 outer space
cannot be subjected to national appropriation, either by way of establishing national
sovereignty over it, or by occupation or use. On the contrary, airspace contained within
national boundaries of a state is subject to national sovereignty of that state and
constitutes, subject to the relevant norms of international law, part of its national
It can be thus stated that the absence of a clear-cut boundary between
airspace and outer space undermines the very principle of national sovereignty of a state,
because no state can define the limits of its territorial sovereignty, which, in turn,
makes uncertain the exercise of that states jurisdiction. Such an uncertainty can
lead to very practical problems and even, in some cases, can pose a threat to
international peace and security.
One may point out a number of further differences in the legal regimes
of outer space and airspace, based on the contemporary state of international law.
Airspace is divided into national and international parts while outer
space is indivisible and is in its entirety in common use.
According to Article 4 of the 1967 Outer space treaty states-parties
take upon themselves not to deplay nuclear weapons or any other weapons of mass
destruction in Earth orbit, on any other stellar bodies or in outer space as a whole.
There exists no such limitation in relation to airspace.
States have no obligation to explore and utilize airspace for the
benefit and in the interests of all countries, as it is the case with outer space (Article
1 of the Outer space treaty). Furthermore, the exploration and utilization of outer space
is the "common province" of all mankind.
States are not liable for damages caused by aircraft which are
registered to and constitute the property of nonstate entities (such as companies and
private citizens). On the other hand, States are internationally responsible for national
activities in outer space whether or not such activities are carried out by state or
non-state actors (Article 6 of the Outer Space Treaty). It is also responsible for the
conformity of these activities with the said Treaty.
Furthermore, according to the provisions of the Convention on
international liability for damage caused by space objects of 1972, and, in particular,
its Article II, the launching state has absolute liability to compensate for the damages
caused by its space objects on the surface of the Earth or to an aircraft in flight. On
the other hand, according to Article III of the Liability convention, if damages to a
space object of one state-party are caused by a space object of another state-party in any
location other than the surface of the Earth the Launching State is only liable if such
damages constitute fault of persons it is responsible for.
Thus, we see here that the absence of delimitation of airspace and
outer space can lead to ambiguity concerning the limits of liability of a launching state
and whether its liability must be deemed absolute or fault-based.
Further, according to Article III of the 1975 Registration Convention,
the Secretary General of the United Nations is entrusted with keeping an international
registry of objects, launched into Outer space, while no such provision exists for
According to the UN Principles on the Remote Sensing of the Earth from
outer space it is not necessary to obtain a permission form a state to conduct remote
sensing of its territory from outer space, although there is the obligation to share
primary data and information obtained from such sensing on a non-discriminatory basis and
on the conditions of reasonable payment. Remote sensing from airspace is subject to
international agreement between the interested parties, any activity conducted without
such agreement would constitute an infraction on international law.
According to Article V of the Outer Space Treaty and relevant
provisions of the 1968 Agreement on the Rescue of Astronauts, the Return of Astronauts and
the Return of Objects Launched into Outer Space astronauts are regarded as envoys of
mankind into outer space and states must render them all possible assistance in the event
of an accident. Furthermore, astronauts must be promptly returned to the launching State
in the event their craft has landed on foreign territory or in international waters, or in
a region with a special legal regime (i.e. Antarctica). States are required to cooperate
in that regard. No such obligation exists in relation to the crews of aircraft outside of
the relevant international search and rescue agreements.
Given the differences in the legal regimes of airspace and outer space
listed above and the potential for conflicting situations they may give rise to it is not
surprising that the last 40 years have seen numerous theories of principles that might be
used to develop a legal definition and delimitation of outer space. These may be
classified into two broad categories - spatial concepts and functional concepts. In turn,
spatial concepts may be else divided into two groups - those that propose to find a
natural physical barrier between airspace and outer space or to establish the boundary in
relation to the maximum flight altitude of aircraft. Others think that such a barrier is
impossible to establish and a political solution to the issue must be found, i.e. to
conclude an international treaty to this regard.
Among those who think that the best way to proceed to solve the issue
of delimitation is to find a natural physical barrier between airspace and outer space.
Several approaches may be pointed out:
approach - the boundary between airspace and outer space is proposed to be established
subject to the latest developments in aerospace technology. Again, this approach does not
point to a fixed boundary between the two, subjecting it to the ever-rising level of
flight altitude of the latest aircraft. This in practice limits the possibility of a state
to exercise its sovereignty over its territory, and, on the other hand, gives new rise to
theories of "effective sovereignty", which, in this case, violates the principle
of sovereign equality of states, since the technological level of advancement in various
countries will inevitably be different.
* orbital approach - first proposed by Uruguayan lawyers A.B.Araucho in 1958, it
places the boarder between airspace and outer space at the lowest altitude that an
artificial Earth satellite can effectively execute a full round orbit around the planet.
It must be pointed out that this approach requires further development of some objective
criteria concerning the aerodynamic shape of a satellite that would be used for such
calculations as well as the conditions of the effects of the upper layers of the
atmosphere upon its flight.
* jurisdictional line approach proposed by Theodore von Karman and A.Hailey
(US). They propose to set the height limit of a states jurisdiction at an altitude
of approximately 83 km over sea level where a body travelling at a velocity of 7 km/sec is
not affected by aerodynamic lifting force and is instead affected by centrifugal force in
relation to the Earth.
There have been several possible approaches proposed on how to solve
the issue using political means, i.e. establishing a boundary between airspace and outer
space by way of international negotiations, through a norm of international law. Several
factors have been taken into account, inter alia, the fact that the International Aviation
Federation (IAF) has established rules according to which a space flight is considered a
flight reaching the altitude of more than 100 km above sea-level. At the same time it has
to be noted that it is considered impractical to launch satellites to an altitude less
than 110 km due to too much atmospheric drag, which forces the satellite orbit to decay
There have been proposals to declare a sui generis
"intermediate" zone between the highest altitude of flight of aircraft and the
lowest altitude of flight of satellites (i.e. approximately between 40 and 100 km). In
this proposal, made by L.Nonchich (Austria), such a zone was supposed to have a special
legal regime, analogous to the law of the sea "innocent passage" of space craft
flying to or returning from Earth orbit.
On June 20 1979 the USSR has submitted a proposal on the issue of
definition and delimitation of outer space for the consideration of the UN Committee on
the peaceful uses of outer space (UN COPUOS). The Committee has been instructed to
deliberate on the issue of delimitation in 1966, according to the UN General Assembly
Resolution 2222 (XXI) of 19 December 1966, and since has been constantly on the agenda of
the COPUOS Legal Subcommittee.
The Soviet proposal on delimitation contained 3 major elements:
1. Over-earth space higher than 100/110 km over sea-level will be
deemed outer space.
2. The boundary between airspace and outer space shall be subject to
negotiations between states and will be fixed by international treaty at a height of no
more than 100/110 km above sea-level.
3. Space objects launched by one state shall enjoy the right to fly
over the territory of another state at heights less than 100/110 km above sea-level for
the purposes of getting into Earth orbit and
returning to Earth, to the territory of the Launching State.
On March 30 1983 the Soviet delegation has submitted a working paper to
the XXII Session of the UN COPUOS Legal Sub-committee which further clarified the 1979
delimitation proposal. The words "to the territory of the Launching State" have
been deleted from paragraph 3 of the proposal, thus enabling returning spacecraft to
"splash-down" in the world oceans. It will be further specified that such space
objects should enjoy the right of "innocent overflight" over the territories of
A few words must now be said about the so-called "functional"
approach in the delimitation of outer space. Most advocates of this theory deem the
over-Earth space indivisible and subject to two international legal regimes acting in
parallel which regulate the outer space and aeronautical activities of states. They
further believe that all over-Earth space should be covered by a unified legal regime, the
rights and obligations of states according to which would vary in relation to the aims and
functions of the spacecraft and aircraft. They suppose that, if the goal of the state was
to launch a craft into Earth orbit such a craft, or object, would be covered by norms of
international space Law. On the other hand, if the purpose of the launch was to effect a
flight through the Earths atmosphere without the aim of reaching orbit, such a
flight would be governed by norms of international aeronautical law.
Advocates of this approach further believe that outer space activities
can be conducted by states safely and legally without establishing a clear-cut boundary
between airspace and outer space, on the basis that up to now the absence of such a
boundary has had no noticeable adverse effect on outer space activities of states.
The real danger in accepting such an approach, as we see it, is that
many of the lawyers who favor it bring forward the idea that the principle of state
sovereignty over its airspace has no absolute character and must be also regarded as
"functional", or "relative".
Here we believe that state sovereignty over its airspace cannot be put
into question. It is a serious infraction upon the universally acclaimed principle of
international law that a state possesses full and complete sovereignty over its territory,
comprising land, territorial waters and the airspace over them. The establishment of the
legal regime of that airspace is the prerogative of that state, subject to relevant norms
of international law. Attempts to undermine the principle of state sovereignty over
airspace can have serious connotation, as they may be further used to undermine the
concept of state sovereignty as a whole.
Furthermore, the functional concept stipulates that it will be always
possible to differentiate between the goals of a given mission, whether they are to reach
outer space and Earth orbit or to just simply fly to another destination on Earth. This
belief is now being put into question, however, by the recent advances made in aerospace
science and technology leading to the development of aerospace objects or vehicles. These
objects will have the ability to undertake flight and maneuver in outer space and airspace
and have the necessary propulsion plants and fuel reserves to effect multiple transit
between Earth orbit and the upper layers of the atmosphere. So far we have seen only one
type of aerospace object in existence the US space shuttle, although it is common
knowledge that such craft are in full-scale development in many countries of the world. In
their case it would be impossible to predict what the aims of their mission would be, in
fact, each mission could contain several goals, both in airspace and outer space.
Accordingly, it would be impossible to say which legal regime such an object falls under
at any given moment of time. This state of events creates, in our view, serious
difficulties for most states which, in a few years from now may be faced, with the
appearance of such craft over their territory. This may well cause international
misunderstandings, if not potential for conflict.
Realizing potential difficulties that aerospace objects pose for the
current international space law, the Russian Federation proposed in 1993 to distribute to
all members of UN COPUOS a questionnaire concerning the definition, status and main
attributes of aerospace objects. To-date, more than 40 countries have provided replies to
that questionnaire. The analysis of those replies shows that the majority of COPUOS
members favor the approach to the delimitation of outer space first proposed by the USSR
in 1979 - the establishment of a treaty-based legal boundary between airspace and outer
space with the special right of space objects to effect "innocent transit"
through the airspace of other countries while proceeding to and returning from orbit. The
Russian Federation will continue to support and promote this approach within the UN COPUOS
Legal Sub-Committee until the successful resolution has been found, for the benefit of all
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