Why did the Chicago Convention’s rules for commercial nonscheduled flights become less effective in practice?

Under the Chicago Convention on International Civil Aviation, contracting states agreed to allow aircraft from other member states engaged in commercial nonscheduled flights to enter their territory, pick up, and discharge passengers, cargo, and mail without requiring prior diplomatic permission.

In practice, however, this provision has become a "dead letter." While the convention established this framework, the practical application of these rights has been largely superseded by the broader reality of international air law, where states maintain complete and exclusive sovereignty over their airspace. Because states are entitled to regulate the entry of foreign aircraft into their territory, the intended multilateral openness for nonscheduled commercial flights has not been consistently realized, as states often prioritize their sovereign control over commercial aviation activities.1