Air Traffic Control Entities

     Within the United States, the Federal Aviation Administration (FAA) is responsible for controlling all air traffic within the National Airspace System (NAS).  It accomplishes this daunting task of keeping aircraft safe in ever-increasing crowded airspace through the coordinated efforts of various Control Entities. Each Control Entity is responsible for directing air traffic through, or sometimes over, their Area of Responsibility (AOR), which typically also coincides with a particular phase of an aircraft's flight from one location to another. 

    Focusing on the graphic at the top of this blog post, I'll explain the various domestic Control Entities within the United States and their responsibilities, helping to draw the similarities and differences between each. 

Ground- 

    Although not depicted above, "Ground Control" is responsible for the movement of aircraft and vehicles within an airport's taxiways, inactive runways, holding areas, and parking areas. Ground is responsible for preventing ground incursions or collisions and efficiently directing traffic to or from runways.

Tower-

    The tower is responsible for active runways and coordinates arrivals (landings) and departures (take-offs) within class B, C, and D airspace (FAA, 2016). An aircraft must have clearance from the tower to taxi onto a runway for a departure and must also be cleared to land when arriving. An aircraft that is preparing to depart has first had communications with Ground before switching over to the tower for take-off clearance. Conversely, an aircraft preparing to land will communicate with the tower after having been in communication with the Terminal Radar Approach Control (TRACON) controller.

TRACON-

    Also referred to as "Approach", TRACON is responsible for controlling air traffic between the take-off and landing phases and the en-route phase of flight (Martin, 2014). TRACON facilities are located at every major airport and every aircraft flying within an airport's airspace will communicate with the TRACOM of that area for directions into, out of, or through the airspace. When preparing to land, TRACOM will direct an aircraft to switch over to the Tower controller for clearance to land. After having departed an airport, TRACOM will direct an aircraft to contact the applicable Air Traffic Control Center (ATCC) that controls air traffic within that AOR.

Center-

    An ATCC, more commonly referred to as a "Center", is responsible for controlling traffic in the areas between airport airspace. Centers are designed to typically provide ATC services for aircraft operating under an Instrument Flight Rules (IFR) flight plan. Centers essentially "own" the airspace of their region providing route clearance, separation, and vectoring for approach on decent. It is also important to note that Centers are responsible for publishing Notice to Air Missions (NOTAM) notices that announce abnormal conditions or hazards within the National Airspace System (NAS) (Air Route, n.d.).

References

Air Route Traffic Control Center. (n.d.). CFI Notebook. https://www.cfinotebook.net/notebook/air-traffic-control/air-route-traffic-control-center

Martin, E. (2014, July 24). Airspace 201: The Air Traffic Control System. Phoenix East Aviation. https://pea.com/blog/posts/airspace-201-air-traffic-control-system/

Transportation, U.S. Department of & Federal Aviation Administration. (2016). Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25B - 2016): [B/W edition]. CreateSpace Independent Publishing Platform. https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak

The Effects of Airport Congestion on Air Pollution

 The Effects of Airport

Congestion on Air Pollution

    It's no secret that aircraft operations are a significant contributor to carbon emissions and air pollution, specifically the air pollution found around major airports.  Aircraft engines release many different types of byproducts into the surrounding air including carbon dioxide, nitrogen oxides, carbon monoxide, sulfur oxides, and hydrocarbons (from fuel) that are unburned or partially combusted, particulates, and other trace compounds (Schlenker & Walker, 2011).

Sources of Aviation Air Pollution

    When we think of aircraft operations, typically what comes to mind is takeoff, landing, and flying at cruise altitude from one location to another. There is, however, another aspect of aircraft contributing to air pollution that some may not consider: aircraft operations on the ground. This includes taxiing to or from the terminal gate, Auxiliary Power Unit operation while parked, and even ground support equipment operation (airfield vehicles, aircraft tow tractors, baggage vehicles, etc.).  Although they seem insignificant, these contributing sources are, in fact, very important when you consider their impact on pollution directly surrounding airports. In 2014 an air quality study performed by the University of Southern California's Keck School of Medicine found that pollution from aircraft at Los Angeles International Airport was affecting the airports surrounding neighborhoods more than had been previously believed (Peterson, 2014).

Aviation Air Pollution Quick Facts

-    Aircraft engine idling produces more CO and NO emissions per minute than any other stage of flight

-    Aircraft engine emissions are higher during low power when the engine is less efficient 

-    Average taxi time from gate to runway increased by 23% from 1995 to 2007

(Schlenker & Walker, 2011)

The following graphic shows the breakdown of emissions contributions at Frankfurt International Airport in 2005. As the data is old and improvements have been made since this time, the charts are shown here only to put into perspective the proportions of emissions each category contributes.

(Zaporozhets & Synylo, 2020)

What does this mean?

Simply put, congestion at airports directly impacts the emissions output of aircraft, and therefore overall air pollution, at a given airport. In 2011, Schlenker and Walker even found that airport delays on the east coast of the United States led to more airfield congestion at LAX, which directly impacts air pollution levels around the Los Angeles area.

Ways to Reduce Airport Air Pollution

-    Halt the use of Auxiliary Power Units at terminal gates and instead use ground power and externally supplied air conditioning

-    Reduce taxi times by keeping aircraft at the gate until its departure slot is confirmed

-    More Direct taxi routes that would limit idle power time of engines

-    Taxi procedures that limit aircraft to one engine when safe and practical

-    Use of electric, natural gas, hydrogen, or compressed air ground-support vehicles

-    Use of efficient tow tractors to move aircraft from gate to runway without using aircraft engines

-    Assigning aircraft to the closest open gate from the runway to lower taxi time

-    Optimizing arrival and departures when external delays may increase congestion

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References

Improving air quality. (n.d.). Aviation Benefits Beyond Borders. https://aviationbenefits.org/environmental-efficiency/improving-air-quality/

Peterson, M. (2014, May 30). Air pollution from LAX jets worse than previously known, says USC study. KPCC - NPR News for Southern California - 89.3 FM. https://www.kpcc.org/2014-05-29/air-pollution-from-lax-jets-worse-than-previously

Schlenker, W., & Walker, W. (2011, November). AIRPORTS, AIR POLLUTION, AND CONTEMPORANEOUS HEALTH. National Bureau of Economic Research. https://www.nber.org/system/files/working_papers/w17684/w17684.pdf

Zaporozhets, O., & Synylo, K. (2020). Modeling of Air Pollution at Airports. Environmental Impact of Aviation and Sustainable Solutions. https://doi.org/10.5772/intechopen.84172

ADS-B: Improving Controlled Airspace   

    Signed into law in December of 2003, the Century of Aviation Reauthorization Act introduced the concept of a Next Generation Air Transportation System (NextGen) (FAA, n.d.). NextGen aims to enable more efficient and safe management of the air transportation system. Since its inception, NextGen has grown and evolved to include various changes in the way air traffic is managed. One such recent mandate that has had an overwhelming impact on the safety of flight is the requirement for aircraft to utilize Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment. 

    ADS-B is a system that transmits an aircraft's GPS position to the ground to Air Traffic Controllers (ATC), enhancing their ability to safely direct air traffic through controlled air space. Another "mode", ADS-B "In", can also be used to enable air-to-air transmission of position data from one aircraft to another, greatly enhancing situational awareness. In the past, ATC relied solely upon radar-based systems and two-way radio communication to direct air traffic. The great benefit of ADS-B is that it is automatic and dependent, which means that in normal operation it requires no input from the pilot to transmit necessary data to ground stations about the aircraft's position, speed, or direction of flight.

    FAR § 91.225 mandates that after January 1, 2020, all aircraft operating within specific limits of various controlled airspace must be equipped with ADS-B "Out" equipment, unless otherwise authorized by the FAA (ADS-B, 2021). Specifically, aircraft are required to be equipped with ADS-B, and be operational, when they operate in the following controlled airspace areas:

• Class A, B, and C airspace;
• Class E airspace at or above 10,000 feet MSL, excluding airspace at and below 2,500 feet agl;
• Within 30 nautical miles of a Class B primary airport (the Mode C veil);
• Above the ceiling and within the lateral boundaries of Class B or Class C airspace up to 10,000 feet;
• Class E airspace over the Gulf of Mexico, at and above 3,000 feet MSL, within 12 nm of the U.S. coast. (AOPA, n.d.).

This graphical illustration helps to understand exactly where ADS-B Out is mandated to be used:

    

    This FAR has greatly benefitted the aviation industry on an international level. It has enhanced ATC's ability to safely direct air traffic both in the sky and on the ground, as well as enables reduced aircraft separation (Spire, 2022). Because ADS-B reduces the need for standard separation, aircraft can follow more direct flight routes, which lowers fuel consumption, further reducing operating costs and carbon emissions (Spire, 2022). ADS-B has also been proven to reduce aviation accident rates. In fact, when it was still being developed and tested, the accident rate in ADS-B-equipped locations in Alaska fell by nearly 50 percent (MITRE, 2015).

References:

ADS-B: Enabling the Next Momentous Transformation in Air Traffic. (2015, April 14). The MITRE Corporation. https://www.mitre.org/publications/project-stories/adsb-enabling-the-next-momentous-transformation-in-air-traffic-control

Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment and use, 14 U.S.C. 

            § 91.227 (2021). https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F/part-91/subpart- 

            C/section91.225

Spire. (2022, April 19). How ADS-B has Shaped the Modern Aviation Industry. Spire : Global Data and Analytics. https://spire.com/wiki/how-ads-b-has-shaped-the-modern-aviation-industry/

Where is ADS-B Out Required? (n.d.). AOPA. https://www.aopa.org/go-fly/aircraft-and-ownership/ads-

            b/where-is-ads-b-out-required

 Human Factors In Aviation Maintenance

                

    They say, that so long as there are humans involved in a process, there will be errors made. We refer to this as human error. However, no process is successful without human input and, in fact, is necessary under most circumstances because humans possess the ability to make rational and informed decisions. This creates somewhat of a "double-edged sword"; humans are necessary to ensure that safe decisions are made throughout many different areas of the aviation industry but are also the leading cause of mistakes and errors. In fact, human error is a major contributing causal factor in 80 percent of aviation-related mishaps (Begur & Babu, 2016). Of that 80 percent, it is said that between 15 and 20 percent of aviation mishaps are attributed to maintenance errors (Drury, 2000). Factors that lead to human error are known as Human Factors and come in many forms. Some examples include stress, fatigue, pressure to meet deadlines, lack of proper training, or even incompetence, to name just a few.

Combating Training Deficiencies 

    The complex nature of maintaining and repairing aeronautical systems and equipment calls for advanced technical training. As required by law, maintenance technicians must possess the necessary skills and credentials to ensure aircraft airworthiness. It is no secret, however, that the aviation industry is constantly evolving and changing, and so too must the maintenance technician. It's true that "you don't know what you don't know". Another factor that can lead to a lack of training is incomplete or insufficient on-the-job training. If a full spectrum of knowledge is not passed down from more senior technicians to those with less experience, it can lead to an extreme loss of knowledge within even just a few "generations" of technicians. A comprehensive training program can mitigate a lack of training within an organization, but it requires the full support of everyone within the organization from the most junior mechanic to the most senior executives. This is where the Team Resource Management concept becomes very useful.

WORD COUNT: 327

References:

Begur, S., & Babu, J. (2016). Human Factors in Aircraft Maintenance. International Advanced Research Journal in Science, Engineering and Technology, 3(3), 14–17. https://doi.org/10.17148/IARJSET.2016.3303

Drury, C. (2000, November). Human Factors in Aviation Maintenance. RTO AVT Lecture Series, Sofia, Bulgaria. https://skybrary.aero/sites/default/files/bookshelf/2504.pdf

Team Resource Management (TRM). (2021, May 24). SKYbrary Aviation Safety. https://skybrary.aero/articles/team-resource-management-trm