At the beginning of aviation, navigation was done by sight. In the event of degraded visibility conditions, aeronautical headlights marked out certain sections of roads regularly taken.
During the second half of the 20th century, radio navigation developed. At the beginning of the 21st century, air navigation makes extensive use of GPS.
Types of navigation
– Visual Flight Rules (VFR)
– Instrument Flight Rules (IFR)
– Celestial navigation
– Inertial navigation system (INS)
– Radionavigation
– Satellite navigation
Visual Flight Rules (VFR)
Visual navigation has been practiced since the origins of aeronautics and is still the means most used by light aviation. The pilot knows his position by looking for landmarks on the ground that appear on his map. It follows a path by moving from landmark to landmark or following a continuous landmark such as a highway or a river.
Visual navigation does not require any instruments but it is only possible when the VMC (Visual Meteorological Conditions) permitted visual flight rules (VFR) flight. However, in controlled airspaces, the controller can issue a special VFR authorization that allows flying outside VMC conditions.
Instrument Flight Rules (IFR)
Instrument Flight Rules (IFR) are a set of regulations under which a pilot operates an aircraft in weather conditions not clear enough to use VFR.
IFR approaches allow a pilot to safely transition from the IFR navigation phase to the IFR approach phase and align a flying aircraft with a runway.
Celestial navigation
60 years ago, computers and Global Positioning System satellites weren’t on hand to help pilots find their way across oceans at night. For very long distances, this type of navigation, used in the navy, was also used in airplanes. For celestial navigation, the planes were equipped with a bubble on the back of the fuselage to allow the use of a sextant.
A sextant is used to measure the altitude of a celestial body above a horizontal line of reference. (“Altitude” in this case is a special use of the word describing an angular measure, not a distance in feet above sea level.) A mariner can use the horizon as this line of reference, but when an airplane is above the clouds or flying at night, its navigator can’t see the horizon. The bubble sextant solves this problem by providing an artificial horizon. It takes its name from an air bubble in a liquid-filled chamber that functions like a carpenter’s level, indicating when the sextant is aligned horizontally.
Inertial navigation system (INS)
An inertial navigation system (INS) is a self-contained device consisting of an inertial measurement unit (IMU) and a computational unit. which has a set of accelerometers and gyroscopes capable of measuring accelerations and rotational speeds along the three axes of space. The integration of these measurements over time makes it possible to calculate the speed and attitude of the aircraft and therefore its trajectory. This technique is completely independent of external means, discreet since it does not use radio, and remains the most precise for military needs (circular error of the order of one kilometer per hour of flight).
Radionavigation
Radio navigation instruments are radio aids that use ground stations or satellites to provide reliable indications of the aircraft’s position in space.
Radionavigation equipment
ADF: Automatic Direction Finder
VOR: VHF Omnidirectional Range
DME: Distance Measuring Equipment
ILS: Instrument Landing System
MLS: Micro-waves Landing System
GPS: Global Positioning System
Other navigational aid equipment :
– Radio altimeter
– Primary and secondary radar
– weather Radar
Satellite navigation
In 1990, the United States set up a navigation system, the GPS, using beacons on satellites.
GPS offers seamless satellite navigation services that satisfy many of the requirements of aviation users. Space-based position and navigation enable three-dimensional position determination for all phases of flight from departure, to airport surface navigation.
The advantage of satellite systems over conventional radio navigation systems is their accessibility and constant accuracy over the entire globe.
