Good question
The so-called “good question” is a phenomenon to be sought out on the way to uncovering the veil of everyday life wherever routine leads us. It is worth looking out for them, because even posing such a question generates satisfaction in the form of a pleasant feeling of stimulating curiosity. I think that the catalogue of good questions also includes the title question, which can be encountered, for example, while observing the flight of an aeroplane or the movement of the moon in the sky, which can happen even during an ordinary wait for a bus. The solution to this riddle – interesting though it may be – will not be easy and requires addressing such topics as balconies in ancient Rome, balloons over Paris and the 1440 orbits of Sputnik I.
HAPS and suborbital drones – the missing link in the world of “drones”
The conundrum contained in the title should also be put into context in such a way as to add to its usefulness for the person seeking knowledge about unmanned aerial vehicles and their future. For it turns out that the evolution of this form of air navigation forces us to seek an answer once again to the question of the limits of both the state and space.
If one were to ask the average passer-by about unmanned flying devices, they would probably indicate a drone in the form of a quadcopter in their response. With the ongoing war in Ukraine, an unmanned aerial vehicle is also slowly making its way into the public consciousness and such an answer could come second in the survey. Less frequently, but still aptly, satellites would be indicated and that would probably be the end of the list of answers.
There are, however, intermediate forms of unmanned aircraft that cleverly combine the functions of drones and satellites. These are the High Altitude Pseudo-Satellites (HAPS), i.e. devices in the form of aircraft, balloons or airships, which can stay in the stratosphere for weeks or even months over a well-defined area, serving as a relatively low-cost platform for research, measurement, communication or aerial photography. The altitude range at which such craft will eventually operate is assumed to be between 20 and 50 kilometres, which is about two to five times higher than conventional passenger aircraft. In addition to their relatively low price and ease of recovery, HAPS are expected to have the advantage of high precision and ease of operation. In such high layers of the Earth’s atmosphere, weather phenomena no longer occur, the temperature is essentially constant and the air is calm[i] .
On the horizon, there is a parallel concept of suborbital (primarily unmanned) flights, i.e. flights that reach 80 or 100 kilometres in altitude at the highest point of their trajectory (the issue of these two values will be discussed below)[ii] .
The characteristics and performance of HAPS and suborbital drones provoke a cluster of good questions, such as:
– How high does the state’s territory/jurisdiction extend?
– Do all countries have the same vertical border?
– Will states be able to prohibit HAPS and suborbital flights over their surface, fearing, for example, an increased risk of espionage, or will they have to treat them as satellites?
– Will and who provide air traffic services for HEPS and unmanned suborbital flights?
These questions seem to be all the more justified as, for example, according to § 3(3) of the Regulation of the Minister of Infrastructure on the structure of the Polish airspace and detailed conditions and use of this space[iii] , the highest altitude at which any air traffic services (here, flight information and emergency services) are provided is flight level 660, which – without going into details related to the vertical pressure distribution and the influence of the local temperature on the altitude of the aircraft at a given flight level – corresponds to the lowest HEPS flight altitudes, i.e. 20 kilometres, being well below the values reached by future suborbital drones.
Adapting law and technology to aircraft operating at such high altitudes has also become an endeavour of the European Commission, which, as part of the Single European Sky (SES) initiative, has developed the European Concept of operations for Higher airspace Operartions (ECHO). The aim is to ensure the safety, efficiency and scalability of this type of traffic by, among other things, cooperating on the frequencies used, transponder codes or monitoring the presence of hazardous junk for aircraft operating in the high atmosphere[iv] .
How many times have we asked the same thing?
The need to determine the owner of the space above the ground arose no later than in antiquity. We know of such a question being posed, for example, by the ancient Romans – very pragmatic people, lovers of good questions – who, among other things, tried to identify disputes over fruit from trees growing on one plot of land whose branches crossed the boundary of a neighbouring plot. The ancient legal scholars, of course, after lengthy disputes, were, for the most part, ultimately in favour of the legality of both the neighbour’s seizure of the fruit and even the neighbour’s pruning of ‘not their own’ branches. Similarly, they considered it illegal to hang balconies over other people’s plots[v] . Undoubtedly, therefore, they were stretching property rights ‘upwards’. Where did they put the vertical boundary? There were probably many concepts, but the one that deserves to be cited in particular is the one expressed by the paremia “Whose land is the sky up to the stars” (Latin: Cuius est solum, eius est coelum, usque ad sidera)[vi] . The uniqueness of such a view lies in the fact that it remains largely (but not entirely) valid to this day in countries whose substantive law is derived from Roman law, including Poland. This is reflected, inter alia, in the content of Article 143 of the Civil Code[vii] . It provides that “[…] within the limits defined by the socio-economic purpose of the land, ownership of the land extends to the space above and below its surface”.
The Roman Empire did indeed reach high – all the way to the stars; certainly far above what modern people claim. However, it is worth noting an indirect conclusion from the above considerations that is relevant to the topic of this article, i.e. that, since the scholars were concerned with space above the ground, they de facto recognised a kind of jurisdiction of their state over its surface.
The question of whether a state’s territory included the skies became a practical problem in the 18th century. The confusion created in the sky and on the ground by the first balloons led to the need to regulate the new phenomenon. In 1784, the prefect of the Paris police issued an ordinance on the rules of balloon flight and thereby – it seems – triggered the birth of a new branch of juridical science – aeronautical law[viii] . In turn, and more importantly for the present study, in view of the unquestionable competence to issue an act regulating balloon flight, he obtained the tacit approval of the local legal and diplomatic world to extend state jurisdiction to an altitude of at least a few hundred metres.
About a century later, in 1898, the first international agreement regulating the crossing of national borders by balloons was concluded. The signatories of this act, representing the German Reich and Austria-Hungary – no longer de facto, but explicitly – communicated to the world that the airspace constituted the territory of their states, without also establishing its upper limit[ix] .
Once again, the issue took the form of a practical problem during the First World War, when neutral states repeatedly forced landings or downed infringing aircraft of their warring neighbours and this was not protested about, so there was tacit acceptance of stretching territory high above the ground[x] .
The subsequent definition of the territory of the state is thus less and less linked to the sphere of civil law and the right to property. The already cited provision from Article 143 of the Civil Code, although its provenance lies in the concepts of the ancient Romans, is more modern by setting out blurred vertical boundaries of the right of ownership where such a right would no longer serve the socio-economic purpose of the land. This means, more or less, that the owner of the property still has the right to prohibit his neighbour from hanging a balcony that crosses the plot boundary, since according to social and economic norms such a low space above the plot should be at his exclusive disposal for any – in principle acceptable – purpose[xi] . However, the owner of such a property may not prohibit high-flying aircraft from flying, because according to social norms this space should first and foremost serve aviation, and, moreover, such a concept of economic use of land property, according to which ownership of a plot of land may serve to create invisible barriers for aircraft, is not worthy of recognition[xii] . The existence of such a boundary is confirmed by the Polish legislator by introducing into the legal order Article 119 of the Aviation Law[xiii] , according to which “the Polish airspace is available on equal rights to all its users, and the freedom of flight in it for civil aircraft may be restricted only on the basis of an express authorisation of the Aviation Law, with observance of the provisions of other laws and international agreements binding the Republic of Poland, including resolutions of international organisations”. The bifurcation of the territoriality and ownership issue discussed here has thus become written law.
Eventually, the consensus thus formed spread around the world and was further reaffirmed in sources of law such as the 1919 Paris Convention[xiv] , the 1926 Madrid Convention[xv] , the 1928 Havana Convention[xvi] and the 1944 Chicago Convention.[xvii] – the international agreement with the greatest impact on aviation, to which 193 states are currently parties[xviii] . They already establish by virtue of Article 1 that each State has complete and exclusive sovereignty over the airspace above its territory. Noteworthy – the provision should be understood to mean that the principle described therein does not apply only to those of the States bound by the Chicago Convention, but also to all others[xix] .
Interestingly, none of the above or any other international agreement sets an upper territorial limit for airspace[xx] .
Theories linking the vertical territorial extent of states to aspects such as the ceiling of a ballistic missile, the limit of human survivability at a given altitude or the equilibrium point of the forces of attraction of the earth and other celestial bodies should also be considered outdated[xxi] .
A silent answer?
We know, however, that some upper limit to the territory of the state must exist, since – unlike the ancient Romans – we do not claim territory or property ‘as far as the stars’. The 1963 UN Declaration on the Principles of the Law on the Activities of States in Outer Space[xxii] – although, to the anger of the author of this text, it did not define its lower limit – as much as it ruled out extending state sovereignty to this space and appropriating it by any entity.
Since it is the airspace of a state – as a body of space – that is included in its territory, which is the subject of attempts at definition, then its boundaries can be found in the vicinity of the Karman Line, located at an altitude of 100 kilometres above the Earth. Formally, this is the altitude at which the air is already so diluted that generating lift by the streamlining of any object would require a velocity that would place that object in Earth orbit. I use the word ‘formally’ because Theodore von Karman himself indicated a value of 83.82 km, and this was rounded off by the International Aeronautical Federation (FAI – Fédération Aéronautique Internationale). It should be further noted that crossing the Karman Line is a condition for a flight to be considered suborbital[xxiii] .
Looking 50-60 kilometres above the Karman Line, we encounter low earth orbits (LEOs)[xxiv] . These are the lowest paths along which an object can ‘perpetually fall’. It is common knowledge that there is no practice of knocking down satellites belonging even to hostile regimes, as long as these behave harmlessly. The birth of this customary law took place on 4 October 1957, with the departure of the Sputnik I satellite from the space above the horizontal borders of the USSR territory. Since the first artificial satellite of the Earth, made as many as 1440 orbits around the Earth in 3 weeks, without arousing any opposition[xxv] , it is possible to deduce the existence of the will of states not to interfere with the movement of orbiting vehicles. However, it is difficult to interpret the silence and state unequivocally that this custom consists of accepting the alternatively unwritten right of undisturbed flight of a satellite in the territory of a state, or whether it means a declaration that this space ends precisely in the vicinity of the lowest orbits and such flight within this territory does not take place. Certainly, however, the territory of Poland reaches at least the Karman Line, but does not reach other celestial bodies[xxvi] .
Summary
It is not possible to identify unambiguously the vertical, sharp boundary of any country’s territory. It seems reasonable to look for it in the vicinity of the lowest possible orbits around the Earth. It is comforting, however, that if a certain lime exists, it should be considered equal for all. Also, given the rather unquestionable sovereignty of states over stratospheric altitude airspace (up to 50 km), HEPS drones seem to be fully subject to the possibility of being banned from operations under the same rules that apply to other aircraft, so there does not seem to be any particular danger of this technology being used effectively for espionage. Also, air traffic services will be able to be provided to pseudo-satellites and this may well happen following the ECHO project. The situation will be different if we assume that tacit approval for overflights above the Karman Line (i.e. suborbital and orbital) is not just an authorisation for free flight, but constitutes recognition of the flight as already taking place beyond the borders of states. The consequence of such a position would be a practical problem with the legal competence to provide air traffic services (including its possible control) for such drones. The international community will therefore once again be confronted with the good question of the title, although I fear that there will be a traditional retreat into yet another non-specific cooperation agreement on the subject, where the boundary will not be drawn.
Artur Banach, attorney at law
References:
[i] European Space Policy Institute (2020, 8 April) The Perspectives of HAPS for the Space Sector Medium in English: https://www.espi.or.at/briefs/the-perspectives-of-haps-for-the-space-sector/ [accessed 20.09.2023];
[ii] Single European Sky ATM Research Joint Undertaking (2022, 16 December) European Concept for Higher Airspace Operations, ConOps Medium in English: https://www.sesarju.eu/sites/default/files/documents/reports/D4.3_ConOps_1.0_public.pdf [accessed 25.09.2023].
[iii] Ordinance of the Minister of Infrastructure of 27 December 2018 on the structure of Polish airspace and detailed conditions and use of that space (Journal of Laws 2019, item 619);
[iv] Single European Sky ATM Research Joint Undertaking (2022, 16 December) European Concept for Higher[…];
[v] B. Woźniak Historical Premises of the Unification of Property Law in the European Union, Studia Iuridica 2014/LIX, Warsaw 2014, p. 288;
[vi] M. Żylicz International, European and National Aviation Law, 2nd edition, Warsaw 2011, p. 35;
[vii] Act of 23 April 1964 Civil Code (i.e. Journal of Laws 2023, item 1610, as amended);
[viii] Ibid, p. 27;
[ix] Ibid;
[x] Ibid, p. 34;
[xi] A. Sylwestrzak [in:] Civil Code. Commentary updated, ed. M. Balwicka-Szczyrba, LEX/el. 2023, art. 143, Nb. 2;
[xii] B. Sitek [in:] Civil Code. Commentary updated, ed. J. Ciszewski, P. Nazaruk, LEX/el. 2023, art. 143, Nb. 6;
[xiii] Act of 3 July 2002. – Aviation Law (i.e. Journal of Laws of 2022, item 1235, as amended);
[xiv] Convention arranging air navigation, signed at Paris on 13 October 1919.
(Ratified in accordance with the Act of 23 September 1922. – Dz. U. R. P. No. 85, item 761);
[xv] The Ibero-American Air Convention – 1926, signed in Madrid;
[xvi] Havana Convention on Diplomatic Officers of 20 February 1928;
[xvii] Convention on International Civil Aviation, signed at Chicago on 7 December 1944 (Journal of Laws 1959, No. 35, item 212, as amended);
[xviii] International Civil Aviation Organization, The list based on information received from the depositary, the Government of the United States of
America about the Parties to the Convention on International Civil Aviation Signed at Chicago on 7 December 1944, Medium in English: https://www.icao.int/secretariat/legal/List%20of%20Parties/Chicago_EN.pdf [accessed 25.09.2023];
[xix] M. Żylicz International aviation law… p. 35;
[xx] Ibid;
[xxi] Ibid, p. 36;
[xxii] AGREEMENT ON PRINCIPLES FOR THE ACTIVITY OF STATES IN THE RESEARCH AND USE OF SPACE IN THE SPACE OF SPACE OF COSMIC INCLUDING THE MOON AND OTHER DARK BODIES, drawn up in Moscow, London and Washington on 27 January 1967 (Official Journal of 1968, No. 14, item 82);
[xxiii] Sanz Fernandez de Cordoba S. (2012, 20 December) 100 km Altitude Boundary for Astronautics Medium in English: https://archive.is/20121220160012/http://www.fai.org/icare-records/100km-altitude-boundary-for-astronautics [accessed 16.09.2023];
[xxiv] The European Space Agency (2020; 30 March) Types of orbits https://www.esa.int/Enabling_Support/Space_Transportation/Types_of_orbits#LEO [accessed 22.09.2023].
[xxv] A. Zak (2012, October 3) Sputnik Medium in English: https://web.archive.org/web/20130123225622/http://russianspaceweb.com/sputnik_mission.html [accessed 05.09.2023];
[xxvi] M. Żylicz International aviation law… p. 36.
