He has done a career of 20 years in air navigation.

Up until now, air navigation has been - and is still - managed by national systems.

This report made recommendations for the future of the Nation's air navigation and traffic control system.

Canada was required to control air navigation and traffic within its borders.

There are generally two types of air navigation depending on weather.

This is to prevent those structures from being a hazard to air navigation.

The Georef system has been used for air navigation, but is rarely seen today.

He has foreseen the future developments of the French civil and military air navigation.

His knowledge of air navigation put him in demand with pilots in the late 1920s and early 1930s.

This is fundamental for certain types of service, such as air navigation, for example.