Aviation Applications

Applications
Title	Aviation Applications
Author(s)	GMV.
Level	Medium
Year of Publication	2011

Overview of Aviation Applications

GNSS Augmentation

There are 3 main types of augmentation to allow the use of GNSS applications in aviation, ABAS (Aircraft Based Augmentation Systems), GBAS (Ground Based Augmentation System) and SBAS (Satellite Based Augmentation System).

The original GNSS equipment is also evolving due to the development of augmentations, while the introduction of Galileo and the modernization of GPS and GLONASS will further improve GNSS performance. The use of GNSS/inertial integration is also expanding.

• ABAS

The Aircraft based augmentation can provide this GNSS information as necessary for supplemental means of navigation. An augmentation system is basically a system that augments and/or integrates the information obtained from the other GNSS elements with information available on board the aircraft.

The Aircraft based augmentation system can be implemented by:

• Receiver Autonomous Integrity Monitoring (RAIM) whereby a GNSS receiver processor determines the integrity of GNSS position using GPS signals augmented with altitude (baroaiding). The RAIM limit for en route operations is 2.0 NM and for terminal operations is 1.0 NM.

• Aircraft Autonomous Integrity Monitoring (AAIM) whereby the GNSS signal is integrated with other sensors, such as the Inertial navigation system (INS) which can detect and reject spurious information from the GPS.

Nowadays, around 70 % of European flights are made by aircraft equipped with GPS and RAIM.

• GBAS

The GBAS provide GNSS integrity monitoring through data obtained from the ground. They also increase the accuracy of satellite navigation, clearing the way for GNSS precision approach and landing.

A ground station at the airport transmits locally-relevant corrections, integrity data and approach data to aircraft in the terminal area in the VHF band.

GBAS, or ground-based augmentation systems, will increasingly support CAT II/III operations where economically beneficial once enhanced GNSS become available. It is assumed that all GBAS for CAT I stations will be upgraded to CATII/III stations.

• SBAS:

• WAAS

The WAAS system implemented in USA improves the accuracy, reliability and integrity of the GPS signal. GPS-WAAS navigators that meet Federal Aviation Administration (FAA) WAAS regulations may be used for sole means of navigation for all phases of flight, including precision approach at airports.

The Wide Area Augmentation System offers an opportunity for airports to gain Instrument Landing System (ILS) approach capability without the purchase or installation of any ground-based navigation equipment at the airport.

The WAAS vertically guided approach procedures are considered LPV (Localizer Performance with Vertical guidance) and provide ILS (Instrument Landing System) equivalent approach minimums as low as 200 feet at qualifying airports. Actual minimums are based on an airport’s current infrastructure, as well as an evaluation of any existing obstructions.

• EGNOS

EGNOS is the satellite-based augmentation system that improves the accuracy of satellite navigation signals over Europe. The signals are guaranteed to the extremely high reliability set out by the International Civil Aviation Organisation standard.

EGNOS offers the aviation industry the means to provide accurate and safe vertically guided approaches to smaller airports and its introduction will reduce delays, diversions and cancellations of flights into and out of these airfields while improving passenger safety.

The EGNOS Safety-of-Life signal was recently formally declared available to aviation. For the first time, space-based navigation signals augmented by this system have become officially usable for the critical task of vertically guiding aircraft during landing approaches.

En Route Navigation

GNSS overcomes many of the deficiencies in today’s air traffic infrastructure thanks to its accurate, continuous, all-weather positioning. During en-route flight, the availability of GNSS will ensure high robustness through the redundancy and high reliability of the service.

In the future, higher accuracy and service integrity will allow aircraft separation to be reduced in congested airspace, to cope with traffic growth. GNSS will be used in en-route flight phase of commercial aircraft.

Detailed information about En Route Navigation can be found here.

Approach

Approach, landing and take-off are critical flight phases and the major need of commercial operators is to have full operations in all weather conditions. As a consequence, precision approach is a mandatory requirement.

The GNSS, with the aid of ground-based augmentation (local elements), will satisfy the needs for precision approach as defined in the aeronautical standards, and could replace or complement the navigation infrastructure of airports in regions where the system is inadequate. The most prominent example is the airports that not equipped with instrument landing systems.

Detailed information about Approach can be found here.

Attitude Determination

The Attitude Determination is one of the many applications where GNSS can be effectively employed.

The attitude of an aircraft, i.e., the orientation in space, can be determined by measuring the relative positions of multiple GNSS receivers mounted on different positions of the aircraft. Usually, a set of 3 or more GNSS receivers placed on board of an aircraft can provide the complete information to compute the aircrft's attitude.

Detailed information about Altitude Determination can be found here.

Air Traffic Control

Air traffic controllers need position, heading, speed and time information for the continuous management of all aircraft. Some areas of the world, lack the appropriate ground infrastructure, including secondary radar and communication links. Standardized transmission of GNSS navigation data will lead to advanced systems and techniques for safer air traffic monitoring.

The Automatic dependent surveillance-broadcast (ADS-B) is currently the most important system used in ATC side, which relies on GNSS as primary data source, to obtain aircraft's horizontal positions.

Detailed information about Air Traffic Control can be found here.