Thunderstorms

A thunderstorm is the weather hazard that should concern pilots the most because it represents different types of risks. For instance, near and inside a storm, you could encounter low-level wind shears, lighting, hail, icing, severe turbulence, and tornadoes. All those weather phenomena are hazardous for the aircraft and its occupants. For that reason, pilots must avoid thunderstorms at all times.

For a thunderstorm to develop, it is required three conditions moisture, unstable air, and lifting action. Storms form when warm air evaporates water (moisture) and raises (lifting action) because of its less density, disturbing the stability of the environment (unstable air).

Thunderstorms have three stages: the cumulus, mature, and the dissipating stage. Strong updrafts characterize the cumulus stage. Next, the storm takes about 15 minutes to reach the mature stage, where precipitation falls in the form of rain showers or hail, and turbulence is present around the thunderstorm. Updrafts and downdrafts are present. Finally, when liftin action slows down, and the wind changes the cell’s shape into an anvil form, the dissipating stage begins, just downdrafts are present.

References:

Federal Aviation Administration. (2016). AC-00-6B. Retrieved from: https://www.faa.gov/documentlibrary/media/advisory_circular/ac_00-6b.pdf

Federal Aviation Administration. (2016). Pilots handbook of aeronautical knowledge. Washington, D.C.

The FAA Class D airspace and the Ecuadorian (ICAO) ATZ

The control tower is in charge of the active runways and the airport’s surroundings inside the FAA Class D airspaces and the Ecuadorian (ICAO) Air Traffic Zones (ATZ). Both are controlled airspace, and two-way radio communication is required. Aircraft on the traffic pattern will be inside the Class D airspace and the ATZ. Therefore, pilots must be in contact with the tower control at all times.

The control tower of the Class D airspace is in complete charge of the traffic around the airport. That includes takeoffs and landings. Inside an ATZ in Ecuador, the control tower must have continued communication with approach control. That means the tower must ask the approach controller before giving a takeoff clearance. Additionally, Class D airspaces are designated for non-busy airports while the ATZs in Ecuador are around busy airports such as Quito and Guayaquil. Also, the VFR weather minimums between a Class D and an ATZ are different too. The weather minimums on the ATZ will vary on the airspace it is inside. 

The dimension of these airspaces is different. For instance, the FAA “Class D airspace extends upward from the surface to 2,500 feet above the airport elevation (charted in MSL)” (FAA, 2020). It is essential to know that the ceiling and the dimension of this airspace (usually four nautical miles around the airport) could vary. For that reason, the pilots must refer to supplemental charts to verify the information. On the other hand, the ATZ in Ecuador differs as well. For example, Quito located at 7900ft; the ATZ extends from the surface up to 10500ft. The radius is 15 nautical miles from the center of the airport.

Sources:

Aeronautical Information Manual - AIM - Controlled Airspace. (2020, January 30). Retrieved        from             https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap3_section_2.htmlDi rection 

General de Aviation Civil - Ecuador. (n.d.). SEQM AD 2.1 INDICADOR LOCALIZACIÓN Y NOMBRE DEL AERÓDROMO. Retrieved from http://www.ais.aviacioncivil.gob.ec/ifis3/aip/AD 2   SEQM

HavKar. (n.d.). Icao airspace classification. Retrieved from   http://www.havkar.com/en/blog/view/airspace-classifications-and-the-air-traffic-            control-services/124

Air Pollution and Airport Operations

The majority of emissions produced at airports comes from airplanes. Although, according to the International Civil Aviation Organization (ICAO), “aircraft engines produce the same pollution as any other engine burning fuel” (n.d.). Also, “The ICAO databank provides a compilation of aircraft engine emission data measured at four thrust levels: 100% (takeoff), 85% (climb out),  30% (approach) and 7% (idle) of maximum thrust available for takeoff under normal operating conditions at ISA sea level static conditions” (authors, 2019). However, the problem is the time the aircraft consumes from starting the engines until takeoff. Furthermore, at busier airports, due to traffic congestion, airplanes spend more time idle. Consequently, air pollution increases at and in the vicinity of the airport. Also, it is essential to understand that this emission is not significant at higher altitudes.

A solution could be to increase airport efficiency by adding more runways and designate certain runways for takeoffs only and others for landings only. Also, add taxiways that go around runways rather than intersecting them. For instance, Atlanta Hartsfield-Jackson International Airport is designed this way. It is no doubt this configuration reduces the time spent on the ground.

Another solution could be to tax air carriers operating with older aircraft or prohibit the operation of those airplanes. On average, old planes consume 51% more fuel than new airplanes. Technology allowed engine manufacturers to produce high-bypass turbofan engines that consume less fuel and produce less noise pollution. However, this solution could bring other problems like an increase in airfares and consequently a lower demand.

References:

International Civil Aviation Organization. (n.d.). Aircraft Engine Emissions. Retrieved from https://www.icao.int/environmental-protection/Pages/aircraft-engine-emissions.aspx

Rutherford, D., & Zeinali, M. (2009). Efficiency trends for new commercial jet aircraft 1960-2008.

Schlenker, W., & Walker, W. R. (2016). Airports, air pollution, and contemporaneous health. The Review of Economic Studies, 83(2 (295)), 768-809. doi:10.1093/restud/rdv043

 Visser, H., Hebly, S., & Wijnen, R. (2009). Management of the environmental impact at airport operations. New York: Nova Science Publishers.

The Air Commerce Act of 1926

During World War I, the military used airplanes to carry mail. After the war finished, there was a surplus of aircraft, and civilians used them to continue sending mail, this time in the US. However, many accidents happened, and for various reasons, some airplanes were not in the right conditions to fly, sometimes the weather was not suitable for flying but, the air carries would pressure the pilots to fly anyways.



The United States Congress passed the Air Commerce Act 94 years ago in 1926. Then, the Government will (FAA),  “designate and establish airways, establish, operate, and maintain aids to air navigation (but not airports), arrange for research and development to improve such aids, license pilots, issue airworthiness certificates for aircraft and major aircraft components, and investigate accidents.”

This event was necessary for the aviation industry since accidents were not frequent anymore, as it used to be before 1926. Further, the general public started to trust airplanes and later became a “common” public transportation method. Many air carriers took advantage of the trust and became larger airlines. Aviation would not be what it is today if this Air Commerce Act of 1926 never became law.

References:

A Brief History of the FAA. (2017, January 4). Retrieved from https://www.faa.gov/about/history/brief_history/

Air Commerce Act. (2015, December 7). Retrieved from https://www.transportation.gov/content/air-commerce-act

Glass, A. (2013, May 20). Congress passed Air Commerce Act, May 20, 1926. Retrieved from https://www.politico.com/story/2013/05/this-day-in-politics-091600

Human Factors and CRM.

Human factors are “issues affecting how people do their jobs” (Australian Civil Aviation Safety Authority (CASA), 2020). Those issues are social and personal skills. The skills are required to maintain the operations running safely and efficiently (CASA, 2020). Therefore, those skills are essential in aviation. However, we need to understand that not just pilots need to have those skills, but everyone around the operations such as “air traffic controllers, management, maintenance, regulatory bodies and policymakers” (Stanton N. A., Li W. and Harris D, 2019).

For pilots, Crew Resource Management (CRM) is the correct use of resources available for the crew. The purpose of CRM is to increase operational efficiency by reducing stress and error. Further, social and personal skills or human factors, as well as other skills, are essential for functional CRM. Also, it is necessary to understand that accidents are a chain of mistakes, and as mention early, CRM lowers the risks for errors.

In a multi-crew environment, CRM is essential to prevent accidents. The reason is that communication between the two pilots, aeronautical decision making (ADM), and situational awareness help to avoid mistakes. For instance, both pilots should divide the workload, decide who is flying, and who is complying with the proper in-flight emergency (communication). Then, to deal with less stress, the pilot flying should engage the autopilot, so he/she doesn’t need to stress about maintaining altitude or a heading (ADM). Next, both pilots need to know the condition of the airplane like fuel remaining and flight path, as well as suitable runways nearby, terrain, and weather around the aircraft (situational awareness).

A good example of a lack of CRM is United Airlines Flight 173. In this accident, the crew failed to monitor fuel quantity after having an issue with the landing gear. Clearly, the pilots and the flight engineer were distracted, dealing with the unusual situation while neglecting the remaining task. However, it is important to understand that before this accident, CRM did not exist. More information about the accident in the following video:

References:

AOPA. (2019). Crm. Retrieved from https://www.aopa.org/-/media/Images/AOPA-Main/News-and-Media/Publications/Flight-Training-Magazine/1907f/1907f_ap_crm/1907f_ap_crm_16x9.jpg?h=675&w=1200&la=en&hash=4EDF84E3D13EE1C96F185FD0CE7A16EB

Neville A. Stanton, Wen-Chin Li & Don Harris (2019) Editorial: Ergonomics and Human Factors in Aviation, Ergonomics, 62:2, 131-137, DOI: 10.1080/00140139.2019.1564589

Safety Management Systems. (2016, February 16). Human factors. Retrieved from https://www.casa.gov.au/safety-management/human-factors

TACG. (n.d.). Flight Deck. Retrieved from https://www.tacgworldwide.com/portals/23/Images/pilot-sighting.jpg?ver=2016-10-12-130534-967

Improvised Explosive Devices (IED)

According to the Transport Security Administration (TSA), “Terrorist become increasingly interested in circumventing airport security screening by concealing improvised explosive devices inside commercial electronics, physical areas of the body, cargo, shoes/clothing, and cosmetics/liquids” (2015). Terrorists and suicide bombers use these improvised explosive devices (IED) to target the general public, airport facilities, and aircraft. The reason these individuals try to use this type of explosive is that since it is homemade, it can come in many forms, and it is harder to detect by airport security. Additionally, terrorists use IEDs because they can cause several adverse health effects, loss of life, as well as massive damage to structures and infrastructure.

IED attached to a cellphone. 

As previously mentioned, IEDs come in different forms, such as pipe bombs or sophisticated devices. However, the components of this type of explosive are the same. The United States Department of Homeland Security (DHS) says the “ingredients” include, “an initiator, switch, main charge, power source, and a container.” and “additional materials or ‘enhancements’ such as nails, glass, or metal fragments designed to increase the amount of shrapnel propelled by the explosion. (2003). For instance, the power source could be hydrogen peroxide, fertilizers, and gunpowder.

Metal detectors.

Fortunately, airport security has implemented many screening layers to prevent terrorists bring IEDs inside security areas in the airport terminal as well as onboard the aircraft. As mention before, terrorists carry these explosives in checked bags, clothing, shoes, commercial electronics, and liquids. For that reason, TSA screens each passenger and checked bags. 

Checked bag screening.

Passengers have to go through a magnetometer, which will detect metals in cloth and adjacent to the body. If the magnetometer detects metals, security personnel will pat-down the passenger as far as the carry-on and personal items that are scanned on an x-ray machine. 

For the checked bags, those go through another x-ray machine, and sometimes random checks are performed. Another layer that security uses is the canine unit. Depending on the airport, this unit can be before the screening area or moving around the terminal or a combination of both.

Canine unit.

All the layers of security previously mention made airport security better than in the last century. Further, in the US, it has been more than ten years since the previous incident relating to IEDs. Although the system is not perfect, it is clear it has been effective. Currently, most online stores do not products that can be a source of power for IEDs, but third-party stores do. Products used for a power source can be more controlled by the federal or local government.

References:

Bloomberg. (2013, July). A Transportation Security Administration employee moves a checked piece of passenger luggage toward a scanning machine at a security check point at O'Hare International Airport in Chicago, Illinois. Retrieved from https://api.time.com/wp-content/uploads/2015/06/gettyimages-137370194.jpg?w=800&quality=85

Juste. C. (2018, November 21). Miami International Airport started using bomb-sniffing dogs to screen passengers at terminals with heavy traffic. Using the canines enables the Transportation Security Administration to move passengers up to 30 percent faster than normal. Retrieved from https://www.miamiherald.com/news/business/tourism-cruises/article222021750.html

MEDIAPRODUCTION. (n.d.). Metal Detector. 
Retrieved from https://www.rd.com/wp-content/uploads/2020/02/GettyImages-182440070-e1582922201512.jpg

National Academies of Sciences, Engineering, and Medicine, Division on Earth and Life Studies, Committee on Reducing the Threat of Improvised Explosive Device Attacks by Restricting Access to Chemical Explosive Precursors, & Board on Chemical Sciences and Technology. (2018). Reducing the threat of improvised explosive device attacks by restricting access to explosive precursor chemicals National Academies Press. doi:10.17226/24862

U.S. Department of Homeland Security. (n.d.). DHS Science and Technology Directorate Checked Baggage Program [Fact sheet]. 
Retrieved from https://www.dhs.gov/sites/default/files/publications/Checked%20Baggage%20Fact%20Sheet%2014OCT16.pdf

U.S. Department of Homeland Security. (n.d.). DHS Science and Technology Directorate Pat-Down Accuracy Training Tool (PATT) [Fact sheet].
Retrieved from https://www.dhs.gov/sites/default/files/publications/OPSR_PATT-170208-508.pdf

U.S. Department of Homeland Security. (n.d.). Explosives Detection Canines – Protecting the Homeland [Factsheet]. 
Retrieved from https://www.dhs.gov/sites/default/files/publications/19_0807_st_updated-pbied-factsheet_508.pdf

U.S. Department of Homeland Security. (n.d.). IED Attack Improvised Explosive Devices [Factsheet]. 
Retrieved from https://www.dhs.gov/xlibrary/assets/prep_ied_fact_sheet.pdf

Landing Gear System

The Landing Gear System

The landing gear system supports the aircraft's weight on the surface. Also, it is responsible for resisting high loads on landings without damage while providing comfort to everyone on board. (Makhlouf & Aliofkhazraei, 2015 ). This system usually consists of wheels; however, skies or floats are an alternative, depending on the type of aircraft (FAA, 2016). Additionally, other components, such as the brakes assembly and hydraulic lines, are part of the system.

The Main Gear of a B737NG

Like any other system, the landing gear is subject to malfunction, even on aircraft with rigorous maintenance. Also, a failure on this system can endanger people on board, the airplane itself, and other people or airport facility near the aircraft. For this reason, pilots have to inspect the system before each flight thoroughly.   

Many things could go wrong with the landing gear system. Nevertheless, pilots are familiar with the troubleshooting procedures, and they have handbooks on the flight deck and electronic flight bags that describes the procedures to follow after a failure. Typically, the malfunction of this system represents a time threat, which means pilots will have time to deal with the problem and does not constitute an immediate danger to the aircraft.

One of the least issues this system could have is a flat tire. Similar to a car, this could happen for many reasons; the most common is due to a tire worn out. If this happens, the aircraft should stop immediately. Otherwise, the friction could damage the wheel disk. However, in extreme cases, a flat tire could lead to a fatal accident such as on the Air France Flight 4590.

G450 abnormal gear position

For instance, if the gear is stuck down, the airplane won't be able to accelerate due to the amount of drag generated by the structure. Therefore, the engines would have to produce more thrust to climb at an average climb speed and to maintain a normal cruise airspeed. Consequently, more fuel is needed, a fuel that was not planned, and most likely, a return to the field would be required.

E190's nose gear did not deploy.

Conversely, one of the gears might not come to the down and locked position. This problem usually happens in the approach phase; at this time, pilots should discontinue the approach and deal with the issue. The gear is kept in the up position by hydraulic pressure; therefore, pilots must remove that pressure following the appropriate procedure. However, if pilots are unable to bring the gear down, gear up landing must be planned.

A320 nose gear failure.

The worst issue the landing gear system could experience is a structural failure. Many factors could lead to this problem, from the environment to overloading the landing gear. If the structure is damaged, the gear could collapse. This failure could happen without any noticeable indication, and that is why this is the worst. Often maintenance technicians can recognize this issue on aircraft inspections.

References:

• 737NG nose landing gear. (n.d.). Retrieved from http://www.b737.org.uk/landinggear.htm#General

• Landing Gear 101. (n.d.). G450 Abnormal Gear Condition. Retrieved from http://code7700.com/g450_landing_gear_abnormals.htm

• Pilot’s handbook of aeronautical knowledge : 2016 (First Skyhorse Publishing edition.). (2016). New York, NY: Skyhorse Publishing. 

• Makhlouf, A. S. H., & Aliofkhazraei, M. (2015). Handbook of materials failure analysis with case studies from the aerospace and automotive industries: With case studies from the aerospace, chemical, and oil and gas industries. Burlington: Elsevier Science. 

• The Associated Press. (2019). Rescue team gather near a plane of Myanmar National Airline (Mna) after an accident at Mandalay International airport Sunday, May 12, 2019, in Mandalay, Myanmar. All passengers and crew are reported safe and uninjured after a Myanmar National Airlines plane made a scheduled but emergency landing at Mandalay International Airport on only its rear landing wheels after the front landing gear failed to deploy. (Aung Thura via Ap). Retrieved from https://abcnews.go.com/International/wireStory/myanmar-passenger-jet-lands-safely-landing-gear-fails-62986476

• The rear-most tire is dragging and about to catch fire. (2005). Retrieved from http://www.airlinesafety.com/editorials/JetBlueLAX.htm

Atmospheric Pressure and Aircraft Performance

Atmospheric Pressure

The atmospheric pressure is a variable factor that pilots must know very well since it is not only used in the essential instruments of the flight deck but is one factor that affects aircraft performance. Also, aircraft engineers need to understand all elements in the environment that affects performance, including pressure.

Sadraey defines pressure (2017) “as a normal force exerted by a fluid (gas or liquid) per unit area on which the force acts.” (p. 12). Considering pressure changes with altitude, temperature, and location, the International Civil Aviation Organization (ICAO) established a worldwide standard referred to as the International Standard Atmosphere (ISA). At sea level, the surface pressure is 29.92 inches of mercury or 1013.2 millibars. (FAA, 2016).

Standard sea level pressure.

Moreover, atmospheric pressure decreases as altitude increases. To illustrate, we must understand that air is compressible. Near the surface, the air is compressed by the air above it, but at higher altitudes, the air becomes less dense and pressure becomes less. Consequently, the rate at which pressure decreases with altitude is not linear (Sadraey, 2017). However, for simplicity, under the ISA, the rate at which pressure decreases with altitude is 1 “Hg per 1,000 feet of altitude gain to 10,000 feet.

The rate at which pressure decreases. 

Properties of a standard atmosphere.

As noted above, atmospheric pressure is one factor that affects performance, with it and the standard pressure we calculate pressure altitude. On the performance charts, we use pressure altitude to calculate different numbers, such as takeoff roll and landing roll. However, the performance calculated is valid only in standard atmospheric conditions, which is very unlikely to exist. For that reason, density altitude is calculated. 

References:

Pilot’s handbook of aeronautical knowledge : 2016  (First Skyhorse Publishing edition.). (2016). New York, NY: Skyhorse Publishing.

Sadraey, M. H. (2017). Aircraft performance: An engineering approach. Boca Raton, FL: CRC Press, Taylor & Francis Group. doi:10.1201/9781315366913