Foreign ownership in airline companies is limited to less than 50%. Aircraft may not be registered by foreign nationals, foreign corporations or Korean-incorporated corporations where 50% or more of shares or equity stakes are in foreign ownership.
"Article 10 (Restrictions on Aircraft Registration)
(1) No aircraft owned or leased by any of the following persons shall be registered: Provided, That the foregoing shall not apply to an aircraft which citizens or corporations of the Republic of Korea have the right to lease and use:
1. A person who is not a citizen of the Republic of Korea;
2. A foreign government or foreign public organization;
3. A foreign corporation or organization;
4. A corporation at least half of whose shares or equity stakes are owned by a person falling under any of subparagraphs 1 through 3 or whose business is substantially controlled by such person;
5. A corporation whose representative in its business registration certificate is a foreigner or in which foreigners account for at least half of the number of its executives in the business registration certificate.
(2) Notwithstanding the proviso to paragraph (1), no aircraft with the foreign nationality shall be registered.[...]" (Aviation Safety Act (No. 14116 of 2016), last amended by Act no. 17463 of 2020, Article 10 [unofficial translation])
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"Article 9 (Grounds for Disqualification for Granting License to Operate Domestic Air Transport Services and International Air Transport Services)  
The Minister of Land, Infrastructure and Transport shall not grant a license to operate domestic air transport services or international air transport services to any of the following persons:
1. A person who falls under any of the subparagraphs of Article 10 (1) of the Aviation Safety Act; [...]
6. A corporation that has a person as its executive officer falling under any of subparagraphs 1 through 5.[...]" (Aviation Business Act (No. 14115 of 2016), last amended by Act No. 17462 of 2020, Article 9 [unofficial translation])
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"Article 4 (Liberalization, etc. of Foreign Investment)   
(1) Except as otherwise prescribed by the Acts of the Republic of Korea, a foreigner may engage in, without restraint, various activities of foreign investment in the Republic of Korea.
(2) No foreigner shall be restricted from making any foreign investment prescribed in this Act, except in the following circumstances:
1. Where he or she threatens national security and public order;
2. Where he or she has harmful effects on public health and sanitation or environmental preservation or is against Korean morals and customs;
3. Where he or she violates any Act or statutes of the Republic of Korea.
(3) The categories of businesses in which foreign investment is restricted in accordance with any of the subparagraphs of paragraph (2) and the details of restrictions shall be prescribed by Presidential Decree. [...]" (Foreign Investment Promotion Act (No. 5559 of 1998), last amended by Act No. 17799 of 2020, Article 4 [unofficial translation])
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"Article 5 (Types of Business Restricted by Foreign Investment) 
(1) In accordance with Article 5 (1) 1 of the Decree, the types of businesses subject to restrictions on foreign investment announced by the Minister of Trade, Industry and Energy in consultation with the competent minister are as shown in Attached Table 2.
(2) When a foreign investor invests in a business that has permissible standards among the industries listed in Attached Table 2, foreign investment may be made within the permissible standard.
[...]
[Appendix 2] Categories of Business with Restrictive Foreign Investment and Criteria for Permission (pursuant to Article 5)
Classification | Type of Business| Criteria for Permission [...]
51 | [International, domestic and small-scale] air transport business | Permitted if foreign investment ratio is below 50% [...]" (Regulations on Foreign Investment (Ministry of Commerce, Industry and Energy Notice No. 1999-58 of 1999), last amended by Notice No. 2021-106 of 2021, Article 5 and attached Table 2 [google translation / unofficial translation of Table 2, source: Kotra])
Aviation Safety Act (No. 14116 of 2016), last amended by Act no. 17463 of 2020, Article 10
Aviation Business Act (No. 14115 of 2016), last amended by Act No. 17462 of 2020, Article 9
Foreign Investment Promotion Act (No. 5559 of 1998), last amended by Act No. 17799 of 2020, Article 4
Regulations on Foreign Investment (Ministry of Commerce, Industry and Energy Notice No. 1999-58 of 1999), last amended by Notice No. 2021-106 of 2021, Article 5 and attached Table 2
[<a href="https://www.law.go.kr/LSW//lsInfoP.do?lsiSeq=191167&lsId=012524&chrClsCd=010202&urlMode=lsInfoP&viewCls=lsInfoP&efYd=20170330&vSct=&ancYnChk=undefined">Act</a>],[<a href="https://www.law.go.kr/LSW//lsInfoP.do?lsiSeq=191167&viewCls=engLsInfoR&urlMode=engLsInfoR&chrClsCd=010203#0000">Act_Eng</a>],[<a href="https://www.law.go.kr/LSW/lsEfInfoP.do?lsiSeq=200240#">Act</a>],[<a href="https://elaw.klri.re.kr/eng_service/lawView.do?hseq=53100&lang=ENG">Act_Eng</a>],[<a href="https://www.law.go.kr/LSW/lsInfoP.do?nwJoYnInfo=Y&ancNo=16131&chrClsCd=010202&efYd=20190401&lsiSeq=206503&efGubun=Y&ancYd=20181231#0000">Act</a>],[<a href="https://elaw.klri.re.kr/eng_service/lawView.do?hseq=44627&lang=ENG">Act_Eng</a>],[<a href="https://www.law.go.kr/LSW/admRulLsInfoP.do?chrClsCd=&admRulSeq=2100000136409#AJAX">Reg</a>],[<a href="http://openknowledge.kotra.or.kr/handle/2014.oak/23472">Other</a>]