In regular 3-Dimensional space is used to calculate the trajectory of the flight in motion. But the fourth spatial co-ordinate Time is also important to calculate and plan the course of the flight. In the existing ground-based FMS (Flight Management System), the trajectory is formed by the system, but the prediction is very short timed in the order of 10-20 minutes. This helps the flight in planning the route without any conflicts with other flights flying in the given time.
With airborne communication systems in place, these trajectories are based on satellite communication rather than ground based radar systems. The Federal Aviation Administration(FAA) which is implementing a satellite based communication system based on the its new project NextGen is implementing an efficient model which will take Global Positioning System (GPS) to communicate with satellites and other flights. Apart from the information given from the ground based system the air-crafts will also be able to communicate among themselves to conflict with the ground based system and make a change in the trajectory, this process is defined as Required Navigation Performance (RNP).RNP deals with precise pre-determined paths, and optimally change the paths of navigation within the given air-space.
The system also helps in making the landing an easier job, with Optimized Profile Descent (OPD), the lowest thrust required to make a smooth landing is calculated. This takes into account wind, temperature and other flight paths. For this model to effectively operate other flight OPD's must communicate with each other to make an idle thrust for landing.
Figure : Operational Profile Descent
With the 4-D Trajectory Flight Management in place, a predictable path of the flights course and improve the efficiency of the flights in times of congestion. According to FAA, using GPS is known to increase route efficiency and reduce delay by 38%. It also greatly reduces the amount of fuel consumed by 1.4 billion gallons and carbon emissions by 14 million metric tons.
A European based Air Traffic Management (ATM) which is similar to FAA also working on a similar model being developed as Single European Sky ATM Research (SESAR).
Air Force Operations:
The US Air Force use these networks to a wide extent and their traditional sensor to display system is moving towards a machine to machine system. Flights such as bombers, fighter jets and unmanned aircrafts are supported by a space system comprised of satellites.
Airborne networks are used to provide details to a missile about the moving target or provide a pre-strike demonstration on the target. It was also employed in Joint Unmanned Combat Aerial Vehicle (JUCAV) where multiple aircrafts communicate with each other to give details about the target or its operations.
Sensors were also in the picture and were used along with the airborne networks to give a collaborative data. This data is induced to a machine learning system, where the system learns and solves problems based on the previous occurred situation, thus commanding a better warfare.
Advancements in Electronic Flight Bags (EFB):
An Electronic Flight Bag is an electronic equipment which helps in displaying information on the various operations in a plane such as charts, manuals, positional and weather data. EFB is almost used by all air-carriers. EFB's which are portable and are operated by satellite navigation provide details on the position of the aircraft in air-space as well are in ground level landing spaces. Satellite Broadband connections can be implemented on EFB when the flight is in air and in motion. They deploy moving maps to the system which give the location precisely in relation with the ground and the terrains.
Installed EFB's are also deployed in aircrafts and it supplies reliable aeronautical information to the cock-pit. It has also been upgraded to give more safety enhancements to the aircraft. The altitude of the flight in relationship with other flights in the current air-space can be calculated and a safe distance can be maintained.
One of the key enhancements in EFB's is while landing, in which it shows the precise location of the aircraft to the runway level. This greatly enhances the safety of the aircraft in very congested airports.
Weather Forecasting and Reporting:
With Airborne Networks in place a lot of data can be communicated between systems in the airways. Weather Forecasting is important for operation of flights, depending on the weather the course of the flight or landing can be altered to increase safety.
FAA has implemented systems such as Weather Camera Program (WCP) and Integrated Terminal Weather System (ITWS) for air traffic management at airports. ITWS obtains weather information from various sources and provides it in a simple understandable interface. This helps the airplanes and controllers to navigate appropriately depending on situations.WCP provide video surveillance on remote airports where weather forecasting cannot be done effectively. An almost near-real-time video is broadcasted to the arriving flights.
Figure : ITWS Application in Action
Weather and Radar Processor Sustain (WARP) is a system implemented to combine weather data with the existing controls of the on-board navigation systems.
Text Messaging, Web Services and VoIP:
IP based machines and applications can be run on airborne network, making way for the inclusion of web services to the machines. All airborne machines will act as nodes and will be used for Communication, Navigation and Surveillance (CNS). These nodes can be used to communicate among air systems or air-surface systems. The data being transmitted will have a high bandwidth comparable to cable modems present on the surface systems. It works similar to the common internet which uses TCP/IP as the communication protocol.
The basic idea for incorporating such mechanism is to be a replacement for the traditional ground based communication infrastructures which are susceptible to disasters. Short Messaging Service (SMS) or Voice over Internet Protocol (VoIP) can be used to relay messages during catastrophic times, which could save human lives. These systems are built to be weatherproof and also work in circumstances where the airborne systems are in an airdrop.
Challenges in Airborne Network
Airborne Networks maintenance is not as simple as an Internet connection. The infrastructure of the system varies dynamically from time to time. When a flight system goes from one network to the other network, it has to change the node properties to quickly adapt to the new setting available.
It requires a high level of automation as there will not be a technician sitting to control the system on the plane. So the network must form by itself allowing for operations depending on the situation. A very high fault tolerant machine must be installed to make this possible.
Optimization of Resources:
Aircrafts are known to have only a limited supply of resources on board. So the physical space for the equipments on the aircraft is limited. Airborne Network does not depend on one simple technology to do its operations. Commercial off-the-shelf (COTS) equipments can be a solution for cheap and readily available resource. But COTS has lots of engineering challenges, like it cannot adapt itself to various application and protocols. For example, according to the Radio Technical Commission for Aeronautics (RTCA), to set up the advanced equipments on a flight it would cost from $150,000 to $650,000 for Required Navigation Performance (RNP) package, which is an important resource to implement the precise systems. So a new breed of networking concepts are required to address the limitations based on the resources.
Huge volumes of data will be transmitted in an airborne network and the data which is transmitted needs to be secured. For Passenger carrier flights the security of data being transmitted may not be very important, as they only focus on less details such as flight details, navigation routes and weather data. But in case of military flights, there is a lot of confidential data being transmitted over the network so it is necessary to make it much more secure. The network should also have lower chances for congestion and interception.
Huge volumes of sensitive data are being transmitted through the airborne network in military infrastructures. Geo-coordinates of military vehicles are classified and require high levels of security. Data containing details of military images, warfare strategy information, and weapon characteristic data needs to be encrypted before they are transmitted. And the accreditationâ€©process to make this a standard takes more time to complete, than the time to build the product itself. So a faster means of accreditation is required to make it a standard.
Inherently the data speed rate of the Airborne Network is lower than the terrestrial networks. More number of optics is required to be incorporated into the system to increase the bandwidth and the latency. Some of these technologies are still under research, the Navy wing of US is working on an integrated photonics which will help in managing the sensor suites present in the aircraft for communication. This concept tries to implement radio signals to pass via fiber optics for better data speeds.
Airborne network does not have a dedicated bandwidth to support its operation. So there is a challenge to create more efficient data compression techniques. A temporary resolution is being provided by Northrop Grumman, a global aerospace technology company, where Dialup rate IP over existing radios (DRIER) is using the basic computer IP to make communications.