Bilateral Overflight Agreements Explained
Every commercial flight that crosses a national border does so under a legal instrument — usually a bilateral agreement between the carrier's state of registration and the state whose airspace is being transited. When Pakistan closed its airspace to Indian carriers in April 2025, or when Russia suspended overflight in February 2022, those actions worked through the same legal architecture that normally permits the flights to exist. This page explains how that architecture works.
The Chicago Convention Foundation
The Convention on International Civil Aviation — signed in Chicago in 1944 and administered by ICAO — is the foundational document. Article 1 affirms that every state has complete and exclusive sovereignty over the airspace above its territory. There is no inherent right for foreign civil aircraft to enter that airspace; any entry must be permitted by the sovereign state.
Chicago 1944 also established the "freedoms of the air" framework, which states subsequently grant to each other — individually or collectively — through bilateral and multilateral agreements.
The Freedoms of the Air
| Freedom | What it grants |
|---|---|
| 1st | Overflight another state without landing |
| 2nd | Land for technical reasons (fuel, maintenance) without commercial purpose |
| 3rd | Carry passengers/cargo from home state to another state |
| 4th | Carry passengers/cargo from another state back to home state |
| 5th | Carry traffic between two foreign states on a flight originating / terminating in home state |
| 6th | Carry traffic between two foreign states via home-state hub |
| 7th | Stand-alone service between two foreign states not touching home |
| 8th / 9th | Cabotage: traffic within a foreign state |
Overflight (1st freedom) is the specific concern for airspace closures. Without a granted first freedom, an aircraft cannot pass through foreign airspace even without landing.
Bilateral vs Multilateral Instruments
First-freedom overflight is often granted through the International Air Services Transit Agreement (IASTA) of 1944 — a multilateral instrument covering first and second freedoms. Most ICAO member states are parties, but not all. Russia, Indonesia, and some others have not acceded to IASTA, so their first-freedom rights are negotiated bilaterally.
Third through fifth freedoms — the freedoms that actually enable commercial service — are negotiated bilaterally through air service agreements (ASAs). "Open skies" bilaterals (US-EU is the largest) grant broad rights; restrictive bilaterals cap frequencies, routes, and carrier designation.
How Closures Work Through the Framework
A state closing its airspace acts on its sovereign Article 1 authority. For overflight, closure suspends the first freedom previously granted under IASTA, the relevant bilateral, or customary practice. The closure can be published as a NOTAM or formalised in a bulletin issued by the state's civil aviation authority.
Bilateral closures targeting specific carriers — such as Pakistan's 2019 and 2025 closures of OPKR/OPLR to Indian operators — work the same way, applied selectively. The carrier's home state may object diplomatically, but the sovereign right to control airspace access is recognised by Article 1. ICAO does not override it.
Educational reference. Not legal advice. Aviation agreements are interpreted by qualified aviation counsel and bound by specific treaty text. See Terms of Service.