Foreign equity ownership is limited to 49% for domestic air transportation, and the chief executive officer and at least two-thirds of the board of directors and other key personnel must be citizens of the Kingdom. Reciprocity is required for foreign air carriers and airport ground services providers to be allowed to establish in the Kingdom. 
"Chapter Two - Air Carriage Regulation
Section One - Policies and Implementation [...]
Article (18): Prohibition of internal air carriage
Subject to the provisions of the Foreign Investment Law, no foreign operator may carry passengers, cargo or mail for a fee or consideration between two points within the territory of the Kingdom. Nonetheless, the Authority may authorize such carriage to cater for exceptional or special circumstances or to finish an incoming international flight. [...]
Section Two - Licensing and Operating Aviation Companies
[...]
Article (28): Licensing of offices, representation and agencies
1. No foreign air carriage or airline company or establishment may establish an office or representation thereof in the Kingdom without obtaining the necessary license from the Authority on the basis of reciprocity.
2. Foreign air carriage or airline companies or establishments may only assign representations or agencies in the Kingdom to licensed Saudi companies or agencies upon the approval of the Authority.
Article (29): Conducting aircraft ground services
Aircraft ground services may not be provided in civil aerodromes in the Kingdom without obtaining a license from the Authority. Such licenses may only be issued to foreign air carriage companies and establishments on a reciprocal basis.
[...]
Chapter Four - Aircraft
Section One - Aircraft Registration
Article (53): Striking aircraft off the Register
1. An aircraft shall be stricken off the Register in the following cases:
a- If the owner or lessee thereof loses the Saudi nationality.
b- If ownership thereof is transferred to a foreigner. [...] (Civil Aviation Law Royal Decree No. M/44, 18 Rajab 1426H / 23 August 2005) 
-----------------------------------
"Chapter One - Authority and Definitions [...]
Definitions
(A) The following words and expressions in these regulations shall have the meanings shown before each of them, unless the context requires a dispute that: [...]
(21) "Foreign citizen": a citizen of a country other the Kingdom;
(22) “Citizen of the Kingdom” means:
(i) An individual who is a citizen of the Kingdom;
(ii) A partnership each of whose partners is an individual who is a citizen of the Kingdom; or
(iii) A corporation or association organized under the laws of the Kingdom where: 
(A) The chief executive officer and at least two-thirds of the board of directors and other key personnel are citizens of the Kingdom;
(B) At least fifty-one percent (51%) of the voting interest is owned or controlled by persons that are citizens of the Kingdom; and
(C) The corporation or association is effectively owned and controlled by citizens of the Kingdom. The absence of such effective ownership and control is determined on a caseby-case basis by examining the totality of the corporation’s or association’s circumstances, including but not limited to the following factors: 1. Maximum total foreign equity ownership of the corporation or association is greater than forty-nine percent (49%); 2. Contracts with a foreign citizen(s), such as those comprising a significant portion of corporation’s or association’s revenue, are used to control the corporation or association; 3. Debt-instrument clauses or bankruptcy agreements allow a foreign citizen(s) to control the corporation or association; 4. Close business, employment or personal relationships between a foreign citizen(s) and the corporation’s or association’s leadership permit the foreign citizen(s) to exert control over the corporation or association; 5. Foreign citizens own or control significant portions of the corporation’s or association’s stock such that they exert disproportionate influence with their voting rights; 6. Minority foreign citizens possess veto rights over major corporate decisions concerning the corporation or association, or control other fundamental corporate actions, such as the exercise of buy-out clauses, which would jeopardize the corporation’s or association’s financial or operational ability to continue in business; 7. The corporation or association is a direct successor to a foreign entity and/or continues to do business as part of a system of foreign-controlled entities; and 8. Multiple and important links exist between the corporation or association and a foreign citizen(s). [...]" (GACA ECONOMIC REGULATIONS)
-----------------------------------
"Types of licenses / description / requirements / duration / Fees [...]
Requirements: The entity must be wholly Saudi or a mixed entity provided that the foreign partner does not exceed 49% [...]" (GACA Investor Guide in Civil Aviation Sector in Saudi Arabia (2018))
Civil Aviation Law Royal Decree No. M/44, 18 Rajab 1426H / 23 August 2005
GACA ECONOMIC REGULATIONS
GACA Investor Guide in Civil Aviation Sector in Saudi Arabia (2018)
[<a href="https://www.gaca.gov.sa/scs/Satellite?blobcol=urldata&blobheader=application%2Fpdf&blobheadername1=Content-Disposition&blobheadervalue1=inline&blobkey=id&blobtable=MungoBlobs&blobwhere=1442842616346&ssbinary=true">Law</a>],[<a href=" https://gaca.gov.sa/scs/Satellite?blobcol=urldata&blobheader=application%2Fpdf&blobheadername1=Content-Disposition&blobheadervalue1=inline&blobkey=id&blobtable=MungoBlobs&blobwhere=1442853660609&ssbinary=true">Rules</a>],[<a href="https://gaca.gov.sa/scs/Satellite?c=GACA_Media_C&cid=1440409543772&pagename=GACA%2FGACA_Media_C%2FGACA_LinkDocument_PT">Guide</a>]