GPS is everywhere — you will find it in your car, in your smartphone, even in your watch. It is also in aircraft. It helps you get from point A to point B effortlessly. It also helps you arrive at the right place, indicating the safest and easiest route.
This is narrated by "Nova TV".
The navigation system of an aircraft is an electronic system that is responsible for providing all the necessary information for the flight to the pilot so that he can focus on controlling the aircraft. It is a key element during the flight. It is one of the tools that a professional pilot must know and master to ensure that the machine will reach its final destination, regardless of environmental conditions.
Aircraft navigation system
A navigation system is defined as a set of devices in the cockpit that assist the pilot in determining the position of the aircraft. Navigation systems include both aircraft onboard systems and radio navigation aids.
There are several types of onboard navigation systems, which can be divided into:
► Global Navigation Satellite System – GNSS
► Inertial Reference System – IRS
► Flight Management System – FMS
Before the flight, the pilot must load the route to be flown into the system. Once it is programmed, the pilot will be able to follow it. The navigation system will detect elements that can affect the flight, such as airports, other aircraft, bad weather, mountains, etc.
Global Navigation Satellite System (GNSS)
GNSS is a set of navigation systems that help the pilot know the coordinates, speed, altitude and other parameters of the aircraft. The three most established systems worldwide are:
► GPS (Global Positioning System)
► GLONASS (Global Navigation Satellite System of Russia – Global’naya Navigatsionnaa Sputnikovaya Sistema)
► Galileo (European Satellite System for Positioning and Radionavigation)
Inertial Reference System (IRS)
An inertial reference system is a navigation system that does not require external data during flight. The IRS, through an accelerometer and gyroscope, measures the displacement along each axis and calculates the aircraft's position.
Its operation is completely autonomous and the only requirement is that at the beginning of the flight, before takeoff, the pilots enter the current position of the aircraft in latitude and longitude into the system.
Flight Management System (FMS)
This navigation system can be considered the "brain" of the aircraft. Its function, as its name suggests, is flight management. Through the entered data for the set route, the FMS provides the pilots with calculations of the flight parameters.
Some functions of the flight management system are:
• Autopilot configuration.
• Setting takeoff and approach routes, as well as information transmitted by air traffic controllers.
• Recommendations for reducing fuel consumption.
Origin of the air navigation system
Initially, the magnetic compass and the map were the only tools for air navigation. Using airspeed and measured time, pilots could roughly determine their position and reach their final destination.
This navigation technique, known as “dead-reckoning“, was an inaccurate method in which errors easily accumulated due to unreliable information. This technique was improved with the introduction of radio waves, which allowed for significantly more accurate navigation.
What is GPS and how does it work?
The Global Positioning System (GPS) is a navigation system that uses satellites, a receiver, and algorithms to synchronize location, speed, and time data for air, sea, and land travel.
The satellite system consists of a constellation of at least 31 satellites, located in six orbital planes around the Earth, each with four satellites. They orbit at an altitude of 20,000 km above the planet and travel at a speed of 14,000 km/h.
To determine a location on the Earth's surface, only three satellites are needed. However, a fourth satellite is often used to correct the error in the receiver's clock, allowing for more precise positioning. It also allows the device's altitude to be calculated, giving us information in three dimensions.
What are the three components of GPS?
GPS consists of three different components, called segments, that work together to provide location information.
The three segments of GPS are:
► Space (satellites): Satellites orbit the Earth and transmit signals to users about their geographic location and time of day. For vehicles, these satellites allow for real-time tracking and precise route navigation, even in remote areas without cellular coverage.
► Ground Control: The control segment consists of ground monitoring stations, master control stations, and ground antennas. The control segment's activities include tracking and controlling satellites in space, as well as monitoring the transmitted signals. Monitoring stations are located on almost every continent, including North and South America, Africa, Europe, Asia, and Australia.
► Consumer Equipment: Includes GPS receivers and transmitters, such as watches, smartphones, and telematics devices. Devices such as telematics modules or drivers' smartphones receive satellite signals and calculate precise positions to aid in vehicle dispatch and safety.
How does GPS technology work?
GPS works using a technique called trilateration. It is used to calculate location, speed, and altitude by collecting signals from satellites to provide position information.
Here's how it works:
Satellites orbiting the Earth send signals that are received and interpreted by a GPS device located on or near the Earth's surface. To calculate location, a GPS device must be able to receive signals from at least four satellites.
Each satellite in the network orbits the Earth twice a day and sends a unique signal, orbital parameters, and time. At any given time, a GPS device can receive signals from six or more satellites.
A satellite emits a microwave signal that is received by the GPS device and used to calculate the distance between the device and the satellite. Because the GPS device only provides information about the distance to the satellite, a single satellite cannot provide precise location information. Satellites do not transmit angle information, so the location of a GPS device can be anywhere on the surface of a sphere with a radius equal to the distance to the satellite.
When a satellite sends a signal, it creates a circle with a radius measured from the GPS device to the satellite. After a second satellite is added, a second circle is created and the location is narrowed down to one of two points where the circles intersect. With the third satellite, the device's location can be definitively determined, as it is located at the intersection of the three circles.
It should be borne in mind that we live in a three-dimensional world, which means that each satellite creates a sphere, not a circle. The intersection of three spheres is two points, choosing the one that is closer to the Earth.
When GPS devices move, the radius (distance to the satellite) changes. When the radius changes, new spheres are created, which gives us a new position. This data, combined with the time from the satellite, is used to determine speed, calculate the distance to the destination, and the estimated time of arrival (ETA).