How do bilateral air-service agreements determine which airline routes can be flown?

Because every state holds complete and exclusive sovereignty over its airspace, commercial scheduled air services require specific authorization to operate into or through foreign territories. Since efforts to establish a universal multilateral agreement on traffic rights were unsuccessful, these operations are governed by bilateral international agreements.1

These bilateral agreements determine airline routes by explicitly fixing the specific paths to be served. Beyond defining the routes, these agreements establish:1

• Traffic Rights: They regulate the exchange of the freedoms of the air, particularly the third, fourth, and fifth freedoms, which dictate the ability to discharge or pick up passengers, mail, and cargo.1
• Capacity: They set principles governing the frequency of service and the carrying capacity of the aircraft used.1
• Tariffs: They define procedures for government approval of fares, often requiring airlines to consult through the International Air Transport Association (IATA) before submission.1

Domestic traffic rights between points within a single state are typically reserved exclusively for that state's own airlines.1