Basics of Aeronautics

06/18/22

ADM stands for Aeronautical Decision Making and it is a skill that all pilots need to ensure safety and avoid accidents. 

Despite of improvements in technology and the many advancements in aviation, accidents can still happen due to a variety of factors. ADM ensures that pilots are aware of human and technical errors that can occur and know how to handle emergencies, should they rise up. 

It is estimated that approximately 80 percent of all aviation accidents are related to human factors and the vast majority of these accidents occur during landing and takeoff. ADM is a systematic approach to assess situations and make well-informed decisions to try and solve issues if they arise. 

Steps for good decision-making are:

1. Identify personal attitudes hazardous to safe flight

2. Learn behavior modification techniques to make better decisions under pressure

3. Learn how to recognize and cope with stress

4. Develop risk assessment skills and heightened observation

5. Use all resources available when tackling issues.

06/18/22

Two defining elements of ADM are hazard and risk, though they should not be confused with one another. 

Hazard is a real or perceived event or situation that a pilot encounters. When faced with a hazard, a pilot must assess it completely and this assessment of the hazard is called the risk. Therefore, risk is an assessment of the single or cumulative hazard facing a pilot. However, risk can be seen differently and to different degrees by different pilots.  

For example, a pilot arrives to preflight and notices a nick on the aircraft's propellor. The nick is the hazard, and the risk perceived  by the pilot is a future propellor fracture if the engine is operated with damage to the blade.

Another pilot may see the nick as a low risk. He may say that this type of nick is located in the strongest portion of the propeller, and based on experience, he does not expect it to cause a propellor fracture that can lead to high risk problems. 

This shows how individuals are different and have different decision-making. These are called human factors and are caused due to differences in education, experience, health, etc.

06/20/22

The acronym P.A.V.E. is a method to mitigate risks to hazards. By incorporating it into preflight planning, examining risks becomes more strategic and structured. 

P = Pilot in Command: The pilot must assess if they are ready for the trip in terms of experience, skill, and emotional condition. 

A = Aircraft: Identify if the aircraft is suitable and adequately equipped for the upcoming trip. Are you familiar with the controls of the aircraft and confident flying it? Does the craft have enough fuel, etc.

V = Environment: Is the weather suitable for the flight? What is the current ceiling and visibility? Is the terrain familiar to me? How are the wind speeds?
E = External Pressures
External pressures can create a sense of pressure to complete a flight and leave room for error and compromised safety. Factors that can be external pressures include the following:
• Emotional pressure, stress, distractions
• A passenger the pilot does not want to disappoint
• The desire to get to the final destination fast

06/22/22

Being fit to fly depends on more than just facts, knowledge, and experience. Attitude plays a huge part in being a successful pilot. Studies have found 5 hazardous attitudes that can sabotage a pilot by interfering with good decision making. 

1.Anti-Authority: Doesn't like people telling them what to do, regards rules as silly or unnecessary. Questioning authority.

2.Impulsivity: Feel the need to make decisions quickly and without stopping and thinking about it. Doing the first thing that comes to mind. 

3.Invulnerability: Believing that accidents happen to others only, therefore taking unnecessary risks and chances.  

4.Macho:Trying to prove something to others and taking unnecessary risks to impress people. 

5.Resignation: Thinking, what's the use? Leaving important actions to others, playing it too safe,  and thinking too excessively. 

By identifying them, pilots can work towards removing these flawed mindsets and attitudes to improve decision making. 

06/23/22

5 Ps: the Plan, the Plane, the Pilot, the Passengers, and the Programming.

They are used to evaluate the pilot’s current situation at key decision points during the flight to avoid emergencies.

These 5 points should be checked over during preflight, pre-takeoff, hourly or at the midpoint of the flight, and pre-descent. The pilot uses this scheduled approach to review critical information regarding The Plan (Review elements of weather, routes, fuel, and modifying the plan if changes occur), The Plane (Review automation readings, plane functions, backup systems, etc.), The Pilot (Examine fatigue, illness, physiological challenges, risks, and correct them), The Passengers (Assess if the passengers are scheduled to reach the destination in a timely manner, make sure all procedures are stated to them clearly as well as emergency accommodations), and The Programming (Are the electronic instrument displays, GPS, and autopilot working as they should?)

In the article “Accident-Prone Pilots,” Dr. Patrick R. Veillette uses the history of “Captain Everyman” to demonstrate how aircraft accidents are caused by a chain of poor choices. 

In this incident, when Captain Everyman was interrupted by a radio call from the dispatcher, he neglected to complete the fuel cross-feed check before taking off. Everyman left the right-fuel selector in the cross-feed position. Once aloft, he did not realize that both engines were feeding off the left wing’s tank! After two hours of flight, the right engine quit and while he was trying to troubleshoot the cause of the right engine’s failure, the left engine quit. 

In another event, Everyman flew a plane, and when it landed, the aircraft veered sharply to the left, departed the runway, and ran into a marsh. Upon inspection, the nose wheel was in the fully deflected position! The after takeoff and before landing checklists require the tiller to be placed in the neutral position, but Everyman had overlooked that item.

Skipping details on a checklist appears to be a common theme in Everyman's stories. 

07/02/22

S.A.F.E.T.Y is an acronym to briefing passengers aboard a flight to ensure maximum safety and keeps pilots and passengers on the same page throughout the flight.

S : Seat belts fastened for taxi, takeoff, landing

  Seat position adjusted and locked in place 

A: Air vents (location and operation)

Action in case of any emergencies 

F: Fire extinguisher (location and operation) 

E: Exit doors (how to secure; how to open)

Emergency evacuation plan

Emergency/survival kit location 

T: Traffic and Talking expectations

Y : Your questions? 

In addition to the SAFETY list, it is good to discuss with passengers about smoking policies, flight routes, weather during flights, a bit about the aircraft, and control functions. 

Explain what a sterile flight deck is: one that is completely silent with no pilot communication with passengers or by passengers during the time of departure and descent.

07/3/22

Nowadays, more and more pilots are relying on electronic databases and automotive readings for flight planning and flying. All this is good, but a problem that has risen is that pilots rely too much on them for their basic flight information and decision making. They are unable to maintain basic airmanship skills and use those skills since there are easier ways to get the information. 

Although automation has made flying safer, they can still make some errors and In a study published in 1995, the British Airline Pilots Association voiced that “Airline pilots increasingly lack ‘basic flying skills’ as a result of reliance on automation.”

This reliance on automation causes the pilot to have a lack of basic flying skills that makes them inadequately equipped in case of an emergency!  Especially now, concerns surfaced that the manual flying skills of the automated flight crews deteriorated due to over-reliance on computers. 

07/09/22

Aviation and flying an airplane requires the pilot to know and understand basic aerodynamic forces and concepts of physics. There are 4 basic forces that affect an aircraft while it is in the sky. They are thrust, drag, weight, and lift. 

Thrust: The forward force that is produced by the propeller of the plane. 

Drag: The rearward force caused by air flowing around the plane. Opposite to thrust. Thrust has to be greater than drag for the plane to move forward. 

Lift: The upward force produced by the air acting on the wings. Acts perpendicularly to the flight's path through the CL (Center of Lift),

Weight: The combined downward force of the aircraft, crew, fuel, and cargo due to gravity. Opposes lift and acts through the CG (Center of Gravity). Lift has to be greater than weight to cause the aircraft to rise. 

The way the four forces act on the airplane make the plane do different things. Each force has an opposite force that works against it. Lift works opposite of weight. Thrust works opposite of drag. The plane goes up when lift and thrust are greater than weight and drag, and likewise, the plane goes down when drag and weight are greater than thrust and lift. 

07/11/22

An aircraft moves in 3 dimensions and has 3 different axis around which it rotates. 

The longitudinal axis which runs horizontally from the nose to the tail of the plane and controls roll. The lateral axis which runs from wing to wing horizontally controls pitching motions of the plane. The vertical axis controls the yaw of the plane. 

All control movements cause the aircraft to move around one or more of these axes and allows for the control of the aircraft in flight. 

All 3 axis cross through the CG (Center of Gravity), therefore, wherever they meet is the Center of Gravity. Simply put, CG is the special point of the aircraft where when mass of the aircraft is said to be centered. The position of the CG of an aircraft determines the stability of the aircraft in flight.

07/12/22

Whether an aircraft has analog or digital instruments, they falls into three different categories: performance, control, and navigation.

Performance Instruments: The performance instruments indicate the aircraft’s actual performance. These are the altimeter (The altitude can be referenced on the altimeter), airspeed or vertical speed indicator (The speed of the aircraft can be referenced on the airspeed indicator), heading indicator, and turn-and-slip indicator. 

Control Instruments: The control instruments display attitude and power changes and are used for precise and controlled adjustments to control the aircraft. 

Navigation Instruments: The navigation instruments show the position of the aircraft in relation to other landmarks and help the aircraft navigate. This includes course indicators, range indicators, glideslope indicators, and bearing pointers. 

Navigation instruments also include GPS, very high frequency (VHF) omni-directional radio range (VOR), nondirectional beacon (NDB), and instrument landing system (ILS) information.  

All these instruments combined lets a pilot control the aircraft and fly the plane!

07/20/22

Although there are many types of airplanes, these are the bare basic skeletal features that they all have. 

Fuselage: The fuselage is the central body of an airplane and holds the crew, cargo, and is what the tail, landing gear, and wings are attached to. There are many different kings, designs, and materials, but the most popular type used today are monocoque and semi monocoque. 

Wings: The wings are airfoils attached to each side of the fuselage and are responsible for producing lift in a plane. Wings can be attached to the top, middle, or lower portions of the fuselage and even the number of wings can vary, creating mono-planes and bi-planes.  Some planes have external braces to support the large wing structure, making them semi and full cantilever planes. 

Wings are made of spars, ribs, trusses, and stringers. In most planes, fuel is also stored inside the wing structure. 

Attached to the wings are control surfaces that cause and control movement of the plane. The most basic ones include flaps and ailerons on the trailing edge of the plane. Ailerons run form the midpoints of the wings to their tips and when used, they turn upwards or downwards. (Both wings' ailerons turn opposite of the other) causing the roll motion of the plane and is used when making turns. Flaps are usually not use during cruising, but heavily used during takeoff and landing. When extended, they move downwards to increase the lifting force of the wings by increasing the difference in air pressure above and below the wings. 

Empennage: The empennage includes the tail of the plane and its attachments, such as stabilizers, the rudder, elevator, and tabs. The rudder is attached to the vertical stabilizer and the elevator is attached to the horizontal stabilizer. The rudder causes left and right movements of the plane (Yaw) and the elevator's movements cause the plane to move up or down (Pitching). 

Landing Gear: The landing gear supports the plane while it is taxiing, taking off, and landing. The most common landing gear is wheels, but floats for water landings and skills for snow do exist. The landing gear usually consists of 3 wheels; There are 2 main wheels and one either positioned at the front (nosewheel plane) or the back (tailwheel planes) of the plane.

Powerplant: This includes the propeller and the engine. The engine provides power to turn the propeller and provides electrical power. It is covered with a housing unit called a cowling to cool the engine and streamline air around it. The propeller acts as the rotating force that stimulates thrust and pulls the plane forward.   

These components all together build a basic airplane and provide means for its movements (roll, yaw, and pitching).

07/22/22

Just like liquids, air is also fluid! It is a fluid in the sense that it takes the shape of the container that it is in, and it has the ability to flow. Just as a liquid flows and fills a container, air will expand to fill the available volume of its container. Misunderstanding this is vital to understanding flight. 

Like any fluid, friction occurs when it flow around or on an object. Friction is a force of resistance that causes drag to occur (one of the 4 basic forces of aviation). 

What is pressure? Pressure is the force applied and is measured in pounds of force exerted per square inch (PSI). The golden rule regarding pressure: If there is a difference in pressure exerted on an object, such as the wing of a plane, the object will always move in the direction of the lower pressure. 

The kind of pressure pilots are most familiar with is atmospheric pressure. Air has mass and weight, therefore it has force and pressure. The higher the altitude, the lower the weight of air and air pressure you encounter. 

07/22/22

An altimeter is a performance instrument that tells a pilot how high they are while in flight. It measures distance above sea level in feet. 

It essentially measures the pressure outside the aircraft (a pressure gauge) and translates that data into a measure of altitude. The rule of thumb it uses is simple: For every 30 feet you climb, pressure will drop by ~ 1 hPa (hectopascal).

 We use pressure to measure altitude because there is a key connection between the two. As you go higher in the atmosphere, pressure innately reduces, so by measuring pressure, we have a good idea of how high we are! 

For more detail and knowledge about a loophole as well as information regarding the standard Flight Level used by pilots, watch this helpful video. 

https://www.youtube.com/watch?v=4-ZRCupN2Ps

07/23/22

Density is very important in aviation. Density has significant effects on the performance of an aircraft. Density has a direct relationship with pressure and an invere relationship with both temperature and altitude. As pressure decreases in the air, so does density, but as density decreases, temperature and altitude increases. 

As density decreases in the air, it reduces an aircraft's power (because the engines take in less air), thrust (because a propeller is less efficient in thin air), and lift (because the thin air exerts less force on the airfoils).

Humidity is the water vapor that is in the air. Humidity causes air to get lighter since water vapor is lighter than dry air. Therefore, as water content in air increases, the air gets less dense and decreases performance. As stated above, when density is lowered, an aircraft's power, thrust, and lift is reduced. Humidity percent's differ in relation to temperature. Warm air holds more water vapor, therefore making it lighter and less dense. Cooler air holds less water vapor, therefore increasing density. When comparing two separate air masses, the first warm and moist, tens to be lighter than the second, cold and dry. 

07/25/22

In order for an aircraft to fly, it needs to overcome several obstacles. One large obstacle is the force of gravity. A heavier than air aircraft needs to defy gravity! How is it goin to do that? Simple. It generates lift. 

A wing moving through the air generates a force called lift, which is greater than gravity, allowing the aircraft to fly. This is due to Newton's 3 laws along with Bernoulli's principle of differential pressure.

08/01/22

Daniel Bernoilli's principle of differential pressure states that the pressure of a moving fluid (moving air in our case) varies with its speed. As velocity of a moving fluid increases, the pressure decreases. This perfectly explains what occurs when air passes over a curved wing.

As the wing moves through the air, the curved top part gains velocity, creating a low pressure area. As I specified earlier, when there is a difference in pressure, the object moves towards the lower pressure, therefore, the wings move up and generate lift. 

10/24/22

An airfoil is an integral structure of an aircraft that generates lift in a variety of ways. The camber (curvature) is one of them. If you observe a side view of an airfoil, you will see the curvature of the top is more than the bottom, which is relatively flat. 

A common reference line to measure camber and curvature is the chord line, a line connecting the leading edge to the trailing edge of the airfoil. The length of the line determines magnitude of camber. The more camber a wing has, the more lift it can produce because there is a higher difference between the pressures of the top and bottom. 

Another factor to generate lift is the Angle of Attack (AOA). The average of pressure variations on any given AOA is referred to CP. At a high angle of attack, the CP shifts forward, while at lower CPs, it moves aft (backwards). The change in AOP and therefore CP causes the dynamics of lift to change as shown in the figure above. 

08/02/22

In steady flight, the sum of opposing forces must be cancelled out. There can be no unbalanced force, and if there is, that means there is either acceleration, deceleration, or a change in altitude. 

Once again, this does not mean that these four forces are equal to each other. It means the opposing forces (drag / thrust and lift / weight) are equal, therefore cancelling out their effects. 

As defined in physics, when forces are baalnced, there is no change in motion. In the case of constant and level flight, keeping balaned forces means that the airplane is travelling witha constant altitude and speed.

08/02/22

The "Angle of Attack" is the acute angle between the chord line of the airfoil and the direction of the wing. Coordinating and paying attention to your plane's AOA is vital to keep altitude steady or to change it. It  also affects an aircraft's performance, stability, and control. General rule of thumb: As the AOA increases, your lift increases as well. When the AOA exceeds its max, wing stall occurs and lift diminishes rapidly. It is important not to cross the Critical Angle of Attack to avoid stalling. This is the stalling AOA, known as CL-MAX critical AOA.

Changing the AOA is used frequently during takeoffs and landings. Due to the nature of momentum and movement, an airplane cannot accelerate too fast, meaning that the takeoff and landings have to be relatively slow. With low airspeeds, it is quite hard to generate lift, but as you will learn in the next write-up, changing the AOA makes up for the low airspeed. When a pilot wants to takeoff from a standstill to flight, its speed accelerates slowly, so to make up for it, the AOA is increased, causing more lift to be generated and for the aircraft to fly!

For more info, visit https://youtu.be/zCDC4NgYyao 

08/03/22

We defined AOA above, but now let's go a little bit deeper. There is a very strong relationship between airspeed and AOA. Lift varies based on these 2 things. Therefore, a large AOA with low airspeed would generate the same amount of lift as an aircraft with low AOA but high airspeed. 

When airspeed is low, AOA has to be relatively high for there to be a balance between the opposing forces of lift and weight. If thrust increases, and therefore airspeed as well, the AOA has to be much lower to keep that balance. The AOA and airspeed can both be adjusted o maintain balance. If they are not adjusted as one or the other increases, you will not have balance anymore, lift will change, and so will altitude. For example: In level flight, when thrust is increased, the aircraft speeds up and the lift increases. The aircraft will start to climb unless the AOA is decreased just enough to maintain the relationship between lift and weight. 

08/5/22

It is known that lift is proportional to the square of the aircraft's velocity or airspeed (if all other things stay constant). This means that if an aircraft is flying at 100 knots versus another at 200 knots, it will have 1/4 of the lift.

The equation, L={C(l) x P x V^2 x S}/2 is used to determine lift. L stands for Lift, C(l) stands for Coefficient of Lift, P represents air density, V represents velocity or airspeed, and S represents surface area of a wing. If any one of these factors are changed, so is lift. 

Lift is also heavily dependent on air density. If you remember from previous write-ups, density and pressure increases as altitude and temperature decreases. Therefore, the higher you go, the less dense it is. That means that the air is thinner and your plane has reduced performance due to changes in power, thrust, and lift. 

Thus, based on the air's density, the factors of the equation have to be tweaked for higher performance. The factor usually increased is the airspeed or the AOA because these are controlled directly by the pilot.

For example: On a hot humid day, an aircraft must be flown at a greater true airspeed for any given AOA than on a cool, dry day.

Lift also varies with the surface area of the wing. The more the surface area is of the wing, the higher the lift of the aircraft. For example: If the wings have the same proportion and airfoil sections, a wing with a planform area of 200 square feet lifts twice as much at the same AOA as a wing with an area of 100 square feet.

11/3/22

This ratio is the amount of lift compared to drag generated by a wing or airfoil. The ratio indicates efficiency of lift. Aircrafts with higher lift to drag ratios (L/D) are more efficient than aircrafts with lower L/Ds. Typically, at a low AOA, the coefficient of drag is low, but at a high AOA, small changes can cause dramatic changes in drag and the L/D. At the critical angle of attack, you have maximum lift, but after it is passed, drag increases dramatically. AT this point, drag completely overcomes lift. When flight occurs at the L/D max level of AOA, the total drag is at a minimum and that at this angle, the most lift is obtained for the least amount of drag.

08/14/22

As you know, air flows around the top and bottom of an airfoil, but a third dimension also affects lift and airflow: The tip of an airfoil. The high pressured slower air on the bottom of the airfoil is pushed to the trailing edge and mixes with the low pressured top air. This causes a rotating flow to occur called a tip vortex. This creates a downwash at the trailing edge and reduces overall lift. 

There are a few ways to counteract this effect. Winglets can be added to reduce the size of this flow by acting as a sort of 'dam'. Another way is to taper the leading edge of the airfoil, reducing the difference between the upper and lower part of the wing. 

^^^Poster by NASA for National Aviation Day, 2018. 

Ever since 1939, National Aviation Day has been celebrated on August 19. This special day was selected since it is Orville Wright’s birthday, a pioneer and leader in aviation history.

This holiday was established by Franklin Roosevelt, who issued the presidential proclamation. On this day,  it is encouraged to fly the US flag, learn more about aviation, honor aviation history, and observe the day with activities that promote interest in aviation!

08/19/22

08/20/22

Drag is the force that resists movement and is opposite to thrust. 

There are 2 basic types: Parasite and Induced. 

Parasite drag does not aid flight, and Induced drag is just a result of generating lift. 

Parasite Drag: Slows down an aircraft’s movement. There are 3 types: Form drag, Interference Drag, Skin Friction Drag.

Form Drag is generated due to an airfoil’s shape and the airflow around it. When air goes around an object, the quicker and smoother it rejoins, the less form drag is there. Aircraft designers minimize this by making the aircraft more streamline. 

Interference Drag:This type of drag comes from the mixing of different airstreams which can create turbulence and currents. 

For example, the air flowing around the fuselage mixes with the air flowing around the wing mixing into a new air current. This is reduced by adding fairings to reduce the different currents and getting rid of unnecessary ‘sharp’ shapes.

Skin Friction Drag occurs due to the contact of air on the surface of the aircraft and the movement of molecules on the surface. The airflow around an aircraft depends on the shape of the wing, the ‘thickness’ of the air, and the irregularities of the wing. To reduce this drag, rivets and a smooth finish are added to the wings.

Induced drag is drag on an airfoil that arises from the development of lift and is an inevitable consequence of lift.

08/25/22

An airfoil produces lift from using the energy of pressure and the airstream around it. When differential pressures occur (Bernoulli’s principle), the high pressure air from the bottom of the wing flows up to the low pressure area. 

Near the tips, this outward flow from the bottom of the wing to the top causes new velocity to form and the development of a vortices trail behind the airflow. They flow either clockwise or anti-clockwise and as they roll up from the bottom, they form a spiral shape. This is called a downwash. This downwash is actually a source of induced drag. Downwash causes downward relative wind and as a result, causes drag. Also, vortices increase as altitude increases. 

The greater the size and strength of the vortices and consequent downwash component on the net airflow over the airfoil, the greater the induced drag effect becomes.

08/27/22

Stability in an aircraft comes from the CG or center of gravity. This is a point in an aircraft where the weight of the aircraft is concentrated. It is vital to an aircraft’s balance and stability. The position of the CG depends on the aircraft and design. The aerodynamic force of lift occurs at the CP or center of pressure. When the CG is in front of the CP, the nose tends to pitch down and when the CG is behind the CP, the nose pitches upwards. 

09/02/22

As AOA increases in the positive direction, lift increases, but so does induced drag! Rewinding a bit, as AOA increases, the differential pressure increases more, meaning that there is a greater difference in airspeed between the top and bottom of the wing.  This causes  more lateral airflow and more violent vortices to be set up as a result of that induced drag.

Violent vortices lead to a dangerous hazard in flight: wake turbulence. 

09/15/22

Wake turbulence occurs a lot of times during takeoff, climb, and descent due to the high AOA needed to generate lift. 

To minimize the dangerous hazard of wake turbulence, it is best to:

Avoid flying through the path of another aircraft and avoid going behind a different aircraft. Stay over 1000 feet in altitude away from other aircrafts. 

This is because other aircrafts generate downwash and vortices just like you, meaning that if you are too close to them, you can be affected by their downwash. Another factor affecting wake turbulence is wind. Wingtip vortices drift with wind. If you’re behind an aircraft with wind that is blowing your way, you may be affected. 

09/20/22

The ground effect has been seen since the beginning of manned flight. 

Right before an aircraft touches down during descent, it would suddenly feel as if the aircraft didn’t want to go lower and land. This is due to the pocket of air between the wing and the landing surface. When an aircraft is a few feet from the ground, the upwash, downwash, and wingtip vortices are affected. 

This is because the ground surface interferes with the airflow patterns around the aircraft. This causes changes in the needed AOA near the ground, the velocity needed near ground level, along with the amount of induced drag that is created as the aircraft gets closer to the ground.