Kansai: The Airport That Sank - Pager Power
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Kansai: The Airport That Sank

Kansai: The Airport That Sank
January 16, 2024 Harry Watson

On an artificial atoll created within the Osaka Bay lies Japan’s third airport, a feat of modern engineering which serves over 25 million passengers annually [1]. It boasts two runways, the size of which are on a par with those at Heathrow, and the longest terminal building in the world [2, 3].  The whole complex is accessed by a bridge which is almost two miles in length, carries six lanes of traffic and was completed on a budget of $1 billion [4]. The airport is also furnished with a rather serious problem: it has sunk at a considerably faster rate than was to be expected over the three decades following its construction. 

kansai airport


Figure 1 An aerial view of Kansai International Airport [12].

A New Airport for Osaka

Osaka doubled in population between 1960 and 1990 from three million to six million. The expansion brought industry and commerce, a harbinger of which was the 1970 world’s fair – Expo ’70 – the first of its kind to be held in Asia [5]. There was a greater demand on the infrastructure of the city, and somewhat paradoxically such infrastructure was more difficult to build for lack of space. It was a result of this that the existing Itami airport, which is now used for domestic flights only, could not be expanded [6]. A solution was proposed in the form of man-made islands on which the airport might be built. The site was chosen in 1974, a desirable proposition as the relative lack of noise pollution would make 24-hour operations permissible [1]. Construction of the first island began in 1987 and lasted 7 years, opening in 1994. A second island was built to increase capacity bringing with it a second runway, which was completed in 2007. In total, over 400 million cubic metres of material was used in the creation of islands [7]. In 2023, the thirtieth year of the airport’s operation, Kansai handled over 140,000 domestic and international air traffic movements [8].

An Ongoing Battle

From its inception the airport has faced the problem of its sinking due to the burden placed on the islands by the infrastructure built upon them. Such a problem was expected, its magnitude was not. It was expected that while the islands sank, the airport would remain 4 metres above sea level, the amount specified in the design. This has turned out not to be the case. [7] The first island has sunk by 13.12m since its completion, leaving inadequate protection against the effects of extreme weather events, the sinking already being 50% greater than expected by the end of the 1990s [1, 9]. The effects of the sinking on the future of the airport are exacerbated by the rising sea levels caused by climate change. The result is that within the next decade or so the second island will also be below the required 4 metres above sea level and by the end of the century both islands could be below sea level [7]. In future, expansion will need to be made to the sea walls which currently protect the island from tsunami, and indeed these walls will eventually have a more permanent use [1].

Lessons Learned

Since Kansai, a multitude of other airport construction projects have made use of land reclamation, including Hong Kong International Airport. Hong Kong International Airport has not suffered the same issues with the sinking of land, as precautions were taken including the removal of the layer of mud which caused much of the settlement at Kansai, before putting the filler material on top for the sections of the land being reclaimed [10]. It is as a result of this that Hong Kong International Airport has remained over 8 metres above sea level [11].

Pager Power’s Contribution Towards Aviation Safety

Pager Power is a technical and environmental consultancy which offers aviation consultancy services. These include studies for instrument flight procedures, obstacle limitation surfaces, glint and glare, navigation aids and radar. The rules that exist in place for aviation safety today are as a result of learning that has taken place in the past. In the same way that this has happened with the construction of Hong Kong International Airport, it has also recently happened with Obstacle Limitation Surfaces – three dimensional planes which specify building height limits around airports with the intention of managing collision risk. 

To find out about Pager Power’s aviation services, click here.

To find out more about the new obstacle limitation surfaces, click here. 


[1] Wikipedia – Kansai International Airport. Accessed January 14th 2024. <https://en.wikipedia.org/wiki/Kansai_International_Airport>

[2] NATS AIP: Heathrow Airport. Accessed January 14th 2024. <https://nats-uk.ead-it.com/cms-nats/opencms/en/Publications/AIP/>

[3] Google Maps: Imagery ©2024 Digital Earth Technology, Maxar Technologies, Map Data ©2024 (Digital Imagery)

[4] Wikipedia – Osaka. Accessed January 14th 2024. <https://en.wikipedia.org/wiki/Osaka>

[5] Itami Airport Website. Accessed January 14th 2024.  <https://www.osaka-airport.co.jp/en/>

[6] Mesri, G. (2015). Settlement of the Kansai International Airport Islands. Journal of Geotechnical and Geoenvironmental Engineering. Vol 141 Issue 2. Accessed January 14th 2024. <https://ascelibrary.org/doi/10.1061/%28ASCE%29GT.1943-5606.0001224>

[7] Kansai Airport Traffic Report. Accessed January 14th 2024. <http://www.kansai-airports.co.jp/en/news/2023/1024/E_231225_TrafficReport_November2023.pdf>

[8] Kansai International Airport Land Company. Accessed January 14th 2024. <http://www.kiac.co.jp/en/tech/sink/sink3/index.html>

[9] Zuckerman, Laurence. (1982). Sinking Feeling at Hong Kong Airport. International Herald Tribune. Archived from the original on 26 October 2005. Accessed January 14th 2024. < https://web.archive.org/web/20051026170422/http://www.iht.com/articles/1992/01/22/hang.php

[10] Hong Kong AIP. Accessed January 14th 2024. <https://www.ais.gov.hk/eaip_20231228/2024-02-22-000000/html/index-en-US.html>

[11] Westbrook, Caroline. (2024). Japan spent £15,000,000,000 on an airport – now it’s sinking into the sea. Metro. Accessed January 14th 2024. < https://metro.co.uk/2024/01/10/inside-japans-15-billion-airport-sinking-sea-20091652/>

[12] Kansai Airport (August 2022) from Wikicommons. Accessed January 16th 2024. Available at: < http://www.kansai-airports.co.jp/en/company-profile/about-airports/kix.html>



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