Free flight (air traffic control)

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Free flight is a developing air traffic control method that uses no centralized control (e.g. air traffic controllers). Instead, parts of airspace are reserved dynamically and automatically in a distributed way using computer communication to ensure the required separation between aircraft. This new system may be implemented into the U.S. air traffic control system in the next decade.[ citation needed ] Its potential impact on the operations of the national airspace system is disputed, however.[ citation needed ]

Contents

Overview

Free flight is a new concept being developed to take the place of the current air traffic management methods through the use of technology. True free flight eliminates the need for air traffic control (ATC) operators by giving the responsibility to the pilot in command. This gives the pilot the ability to change trajectory in mid-flight. With the aid of computer systems and/or ATC, pilots will be able to make more flight path decisions independently. As in most complex systems, distributed yet cooperative decision making is believed to be more efficient than the centralized control characterized by the current mode of air traffic management.[ citation needed ]

History

Free flight began as an effort to become less dependent on the human factor and more dependent on the growing technology of its day. As airlines expanded their fleets in the 1960s, they increased the need for air traffic management (ATM).[ citation needed ] ATM created instrument flight rules (commonly known as "IFR") to manage the growing numbers of aircraft. This helped control air traffic, but required a significant amount of time, effort, and resources to maintain IFR flight.[ citation needed ]

In 1968, the Federal Aviation Administration issued the High Density Airport Rule to reduce the number of aircraft in a given airport.[ citation needed ] Twenty years earlier Crocker Snow used television cameras to locate his position when flying an aircraft.[ citation needed ] He sent up signals to the aircraft so they could get a third person perspective of the aircraft's surrounding. This idea worked but was too costly and was impractical. In the 1960s transponders removed the need to use television cameras.

Other problems that occurred in the air traffic industry were the OPEC fuel crises and the Professional Air Traffic Controllers Organization (PATCO) strike of 1982 resulting in the firing of thousands of controllers by President Ronald Reagan. This showed how vulnerable air transportation was to economic forces.[ citation needed ]

The key components of free flight were identified in 1971 by United Airlines systems manager William Cotton, although the technology to implement it was not available for another two decades. [1]

In the 1970's the GPS satellite navigation system was deployed by the US Department of Defense and the aviation industry saw the opportunity to use GPS for potentially more efficient air traffic management capabilities through an increased use of this capability coupled with automation enabled by it.[ citation needed ]

In 1991 the International Civil Aviation Organization created the Future Air Navigation System Panel. The panel produced descriptions of satellite-based technology applications and their use in air traffic management. A larger role emerged for "user-defined trajectory" that became known as "free flight" by the mid-1990s.

The first hearings on implementing free flight were held in August 1994 by Representative Collin Peterson (D-Minnesota), chair of the House subcommittee with investigative jurisdiction over the FAA. [1]

In 1995 David Hinson, the FAA administrator, organized a task force to draw up detailed plans to implement free flight. The report, issued in October that year called for three phases; [1] [2] phase I ended at the end of 2002, the others have not been started. A method and system for an automated tool to enable en route traffic controllers to optimize aircraft routes dynamically was patented by the NASA in 2001. [3]

True free flight applications exist only on a small scale in selected airspace operations where only the most well equipped aircraft operate, such as at high altitude by commercial airliners.[ citation needed ] There are many versions of free flight being conceived for the Next Generation Air Transportation System (NGATS). The free flight vision is expected to slowly emerge over the next 20–30 years as NGATS emerges from billions of dollars of development, testing, careful transition planning, training, and deployment of ground-based and airborne systems by all types of aircraft. Key elements of NGATS include the automatic dependent surveillance-broadcast (ADS-B) and what can be expected to be an ever-evolving, net-centric information application called the System Wide Information Management System or "SWIM".

Regions

The regions are broken up into unrestricted, transition, and restricted.

Unrestricted
In the unrestricted region there will be very little guidance from ATC since aircraft density will be low. Pilots will have a great deal of flexibility to exercise free flight in this area. However, it may become complicated when bad weather is calculated into the equation. Pilots may have to adjust their course to avoid inclement weather. In doing so other pilots attempting to avoid the conditions may cross path with each other. ATC will have to assist the pilots and guide them through this issue.
Transition
Slightly restricted however pilots retain some flexibility to exercise free flight.
Restricted
The freedom of the pilot has been restricted significantly.

Approaches of free flight

There are several approaches that free flight can move towards.

Airborne

In the airborne approach, the separation responsibility is entirely with the pilots, operating under self separation conditions. The pilot is responsible for detecting and resolving problems while in flight. Computers will help aid the aircrew in this matter. Information, such as weather reports or other aircraft position, is forwarded from ATC (or automated stations) to the aircraft so the pilots can decide the best course of action to take. The surveillance system can either be on the ground or on board the aircraft.

Problems with this method include complete surveillance information assurance, communication with different equipment, smaller aircraft incapable of carrying the equipment, and the possibility of a system malfunctioning. It is extremely difficult to have total assurance of all air traffic. If two aircraft flying with different equipment encounter each other, the equipment's data will have to be sent to the receiving equipment as well as the normal information such as speed. Larger planes will have no problems with the equipment, but smaller aircraft will have problems communicating to each other if it lacks an essential component. Surely, if this was a one-on-one scenario, it would be easy to solve, but if multiple aircraft were involved, the difficulty of finding a solution compounds. Lastly, if a system fails or the software has a computer programming error, the aircraft and other aircraft will be flying blind.

Ground

All of the data are sent to ATC and pilot requests a particular flight path. Communication will be from aircraft to ATC instead of aircraft to aircraft.

In this approach the aircrew will not have the full situational awareness experience in the airborne approach. Aircrew will not be able to handle uncertainties or help out with the uncertainties in this approach. If one aircraft does not follow the directive ATC issues, the directive will have to be reissued and in turn increase the workload of ATM operators.

Mixed focus

Mixed focus approach which is a combination of both the airborne and ground approach. AOC initially sends route to aircraft and ATM. If the aircrew does not like the route, it sends the route changes to ATM and AOC.

Separation

Aircraft separation is divided up into the protected zone and the alert zone. In the larger zone, called the alert zone, the system informs the aircraft through one of the three approaches that an aircraft is in the vicinity. It acts as a flag and merely alerts the aircrew. In the protected zone, the area must remain sterile of all foreign objects. It is the minimum distance anything can approach. The system should alert the aircrew before anything comes close to it, but if it manages to enter the protected zone, aircrew will take evasive maneuver to avoid a collision.

Conflict and detection method using center-TRACON automation system

Center-TRACON automation system (CTAS) receives data from aircraft trajectory, atmospheric model, aircraft performance, and other contributing factors. Based on the information it receives it will calculate the best trajectory though equations and logic. CTAS is currently being used on a small scale.

See also

Related Research Articles

Avionics

Avionics are the electronic systems used on aircraft, artificial satellites, and spacecraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searchlight for a police helicopter or as complicated as the tactical system for an airborne early warning platform. The term avionics is a portmanteau of the words aviation and electronics.

Instrument flight rules

Instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR).

In aviation, visual flight rules (VFR) are a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minima, i.e. in visual meteorological conditions (VMC), as specified in the rules of the relevant aviation authority. The pilot must be able to operate the aircraft with visual reference to the ground, and by visually avoiding obstructions and other aircraft.

Air traffic control A public service provided for the purpose of maintaining the safe and orderly flow of air traffic

Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of air traffic, and provide information and other support for pilots. In some countries, ATC plays a security or defensive role, or is operated by the military.

Airspace Portion of the atmosphere controlled by a country

Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as aerospace, which is the general term for Earth's atmosphere and the outer space in its vicinity.

Traffic collision avoidance system Aircraft collision avoidance system

A traffic collision avoidance system or traffic alert and collision avoidance system is an aircraft collision avoidance system designed to reduce the incidence of mid-air collisions between aircraft. It monitors the airspace around an aircraft for other aircraft equipped with a corresponding active transponder, independent of air traffic control, and warns pilots of the presence of other transponder-equipped aircraft which may present a threat of mid-air collision (MAC). It is a type of airborne collision avoidance system mandated by the International Civil Aviation Organization to be fitted to all aircraft with a maximum take-off mass (MTOM) of over 5,700 kg (12,600 lb) or authorized to carry more than 19 passengers. CFR 14, Ch I, part 135 requires that TCAS I be installed for aircraft with 10-30 passengers and TCAS II for aircraft with more than 30 passengers. ACAS/TCAS is based on secondary surveillance radar (SSR) transponder signals, but operates independently of ground-based equipment to provide advice to the pilot on potentially conflicting aircraft.

The world's navigable airspace is divided into three-dimensional segments, each of which is assigned to a specific class. Most nations adhere to the classification specified by the International Civil Aviation Organization (ICAO) and described below, though they might use only some of the classes defined below, and significantly alter the exact rules and requirements. Similarly, individual nations may also designate special use airspace (SUA) with further rules for reasons of national security or safety.

Area control center Air route control entity

In air traffic control, an area control centre (ACC), also known as a center or en-route center, is a facility responsible for controlling aircraft flying in the airspace of a given flight information region (FIR) at high altitudes between airport approaches and departures. In the US, such a center is referred to as an air route traffic control center (ARTCC).

Required navigation performance

Required navigation performance (RNP) is a type of performance-based navigation (PBN) that allows an aircraft to fly a specific path between two 3D-defined points in space.

The Future Air Navigation System (FANS) is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting. In the FANS-B equipped Airbus A320 family aircraft, an Air Traffic Services Unit (ATSU) and a VHF Data Link radio (VDR3) in the avionics rack and two data link control and display units (DCDUs) in the cockpit enable the flight crew to read and answer the controller–pilot data link communications (CPDLC) messages received from the ground.

Transponder (aeronautics)

A transponder is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have transponders to assist in identifying them on air traffic control radar. Collision avoidance systems have been developed to use transponder transmissions as a means of detecting aircraft at risk of colliding with each other.

Controller–pilot data link communications (CPDLC), also referred to as controller pilot data link (CPDL), is a method by which air traffic controllers can communicate with pilots over a datalink system.

The Next Generation Air Transportation System (NextGen) is an ongoing modernization project of the United States National Airspace System (NAS). The U.S. Federal Aviation Administration (FAA) began work on NextGen improvements in 2007 and plans to have all major components in place by 2025.

The National Airspace System (NAS) is the airspace, navigation facilities and airports of the United States along with their associated information, services, rules, regulations, policies, procedures, personnel and equipment. It includes components shared jointly with the military. It is one of the most complex aviation systems in the world, and services air travel in the United States and over large portions of the world's oceans.

Air Traffic Organization

The Air Traffic Organization (ATO) is America's air navigation service provider, as the operations arm of the Federal Aviation Administration. Its customers are commercial and private aviation and the military, and it employs more than 35,000 controllers, technicians, engineers and support workers.

Automatic Dependent Surveillance–Broadcast Aircraft surveillance technology

Automatic Dependent Surveillance–Broadcast (ADS–B) is a surveillance technology in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation. ADS–B is "automatic" in that it requires no pilot or external input. It is "dependent" in that it depends on data from the aircraft's navigation system.

ICAO performance-based navigation (PBN) specifies that aircraft required navigation performance (RNP) and area navigation (RNAV) systems performance requirements be defined in terms of accuracy, integrity, availability, continuity, and functionality required for the proposed operations in the context of a particular airspace, when supported by the appropriate navigation infrastructure.

Next Generation (NextGen) Data Communications, an element of the Next Generation Air Transportation System, will significantly reduce controller-to-pilot communications and controller workload, whilst improving safety.

This is a list of the acronyms and abbreviations used in avionics.

Aircraft self-separation is the capability of an aircraft maintaining acceptably safe separation from other aircraft without following instructions or guidance from a referee agent for this purpose, such as air traffic control. In its simplest forms, it can be described by the concept of see and avoid, in the case of human-piloted aircraft, or sense and avoid, in the case of non-human piloted aircraft. However, because of several factors such as weather, instrument flight rules and air traffic complexity, the self-separation capability involves other elements and aspects such as rules of the air, communication technologies and protocols, air traffic management and others.

References

  1. 1 2 3 Free Flight
  2. ↑ Final report of the RTCA Task Force 3, Free Flight Implementation. RTCA, Inc., Washington, DC, Oct 26, 1995 Archived 2008-04-08 at the Wayback Machine
  3. ↑ US 6314362 Method and system for an automated tool for en route traffic controllers
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