AS 121 Exam 3 Questions with Verified Answers Latest Update 2025/2026
Standard pressure at 10000 feet is (according to the values on the FAA table) - Answers 20.57
inches of mercury
Which of the following helps determine the shape of the airfoil? - Answers Purpose of the
specific aircraft
As angle of attack increases, the center of pressure (CP) - Answers Moves forward
What will happen to an object immersed in fluid when pressure on one surface of the object
becomes less than pressure on the other surface of the object? - Answers The object will move
in the direction of the lower pressure
The standard atmosphere at sea level is - Answers 15 degrees C and 29.92 inches of mercury
The weight of the atmosphere at 18000 feet is ______ what it is at sea level. - Answers 1/2
Why is pressure altitude important to pilots? - Answers It is used to determine airplane
performance
Newton and Bernoulli have stated laws that fully explain how lift is formulated. - Answers false
What are the effects of less dense air on aircraft performance? - Answers Reduces power,
thrust, lift
Most of the atmosphere's oxygen is contained below ___________ feet. - Answers 35,000
Which statement relates to Bernoulli's principle? - Answers Air traveling faster over the curved
upper surface of an airfoil causes lower pressure on the top surface.
When are the four forces that act on an airplane in equilibrium? - Answers During unaccelerated
level flight.
What is the relationship of lift, drag, thrust, and weight when the airplane is in straight-and-level
flight? - Answers Lift equals weight and thrust equals drag.
What happens when an aircraft reaches the critical angle of attack? - Answers Any further
increase in angle of attack causes the wing to stall
Ground Effect becomes effective within - Answers One (1) wingspan above the surface
An aircraft always will Stall when - Answers The Critical Angle of Attack is exceeded
The penalty for a wing producing lift is called - Answers Induced drag
Wingtip vortices are greatest when the generating aircraft is - Answers Heavy, clean (gear and
flaps up), and slow
, Aspect ratio is the ratio of - Answers The wing span to the wing chord
The acronym used in class for the engine used in our Cessna 172 aircraft is - Answers HAND FL
An increase in aspect ratio with a constant velocity will - Answers Decrease the drag
Which of the following is affected significantly by aircraft stability? - Answers Maneuverability
Induced drag is a by-product of - Answers Lift
What is dihedral and what is its purpose? - Answers Outer wing tips are higher than the wing
roots - helps the aircraft with roll stability
Angle of attack is defined as the acute angle between the chord line of the airfoil and - Answers
The direction of the relative wind
Aircraft stability is primarily due to - Answers The design characteristics of the aircraft
In order for an airplane to maintain level flight the pilot must coordinate the - Answers Angle of
attack (AOA) and thrust
In steady flight, the sum of the opposing forces is - Answers Zero
Where is the CG located in most aircraft? - Answers In front of the wing's CL (Center of Lift)
What are the 4 forces acting on an airplane in flight? - Answers Thrust, lift, drag, weight
A moment is said to be equal to the product of the force applied and the - Answers Distance at
which the force is applied
Low cost, low speed airplanes favor which kind of wing? - Answers Rectangular
An aircraft leaving ground effect during takeoff will - Answers experience an increase in induced
drag and a decrease in performance.
Ground effect is most likely to result in which problem? - Answers Becoming airborne before
reaching recommended takeoff speed.
The four forces acting on an airplane in flight are - Answers lift, weight, A. thrust, and drag.
What is ground effect? - Answers The result of the interference of the surface of the Earth with
the airflow patterns about an airplane.
What must a pilot be aware of as a result of ground effect? - Answers Induced drag decreases;
therefore, any excess speed at the point of flare may cause considerable floating.
Floating caused by the phenomenon of ground effect will be most realized during an approach
to land when at - Answers less than the length of the wingspan above the surface
Standard pressure at 10000 feet is (according to the values on the FAA table) - Answers 20.57
inches of mercury
Which of the following helps determine the shape of the airfoil? - Answers Purpose of the
specific aircraft
As angle of attack increases, the center of pressure (CP) - Answers Moves forward
What will happen to an object immersed in fluid when pressure on one surface of the object
becomes less than pressure on the other surface of the object? - Answers The object will move
in the direction of the lower pressure
The standard atmosphere at sea level is - Answers 15 degrees C and 29.92 inches of mercury
The weight of the atmosphere at 18000 feet is ______ what it is at sea level. - Answers 1/2
Why is pressure altitude important to pilots? - Answers It is used to determine airplane
performance
Newton and Bernoulli have stated laws that fully explain how lift is formulated. - Answers false
What are the effects of less dense air on aircraft performance? - Answers Reduces power,
thrust, lift
Most of the atmosphere's oxygen is contained below ___________ feet. - Answers 35,000
Which statement relates to Bernoulli's principle? - Answers Air traveling faster over the curved
upper surface of an airfoil causes lower pressure on the top surface.
When are the four forces that act on an airplane in equilibrium? - Answers During unaccelerated
level flight.
What is the relationship of lift, drag, thrust, and weight when the airplane is in straight-and-level
flight? - Answers Lift equals weight and thrust equals drag.
What happens when an aircraft reaches the critical angle of attack? - Answers Any further
increase in angle of attack causes the wing to stall
Ground Effect becomes effective within - Answers One (1) wingspan above the surface
An aircraft always will Stall when - Answers The Critical Angle of Attack is exceeded
The penalty for a wing producing lift is called - Answers Induced drag
Wingtip vortices are greatest when the generating aircraft is - Answers Heavy, clean (gear and
flaps up), and slow
, Aspect ratio is the ratio of - Answers The wing span to the wing chord
The acronym used in class for the engine used in our Cessna 172 aircraft is - Answers HAND FL
An increase in aspect ratio with a constant velocity will - Answers Decrease the drag
Which of the following is affected significantly by aircraft stability? - Answers Maneuverability
Induced drag is a by-product of - Answers Lift
What is dihedral and what is its purpose? - Answers Outer wing tips are higher than the wing
roots - helps the aircraft with roll stability
Angle of attack is defined as the acute angle between the chord line of the airfoil and - Answers
The direction of the relative wind
Aircraft stability is primarily due to - Answers The design characteristics of the aircraft
In order for an airplane to maintain level flight the pilot must coordinate the - Answers Angle of
attack (AOA) and thrust
In steady flight, the sum of the opposing forces is - Answers Zero
Where is the CG located in most aircraft? - Answers In front of the wing's CL (Center of Lift)
What are the 4 forces acting on an airplane in flight? - Answers Thrust, lift, drag, weight
A moment is said to be equal to the product of the force applied and the - Answers Distance at
which the force is applied
Low cost, low speed airplanes favor which kind of wing? - Answers Rectangular
An aircraft leaving ground effect during takeoff will - Answers experience an increase in induced
drag and a decrease in performance.
Ground effect is most likely to result in which problem? - Answers Becoming airborne before
reaching recommended takeoff speed.
The four forces acting on an airplane in flight are - Answers lift, weight, A. thrust, and drag.
What is ground effect? - Answers The result of the interference of the surface of the Earth with
the airflow patterns about an airplane.
What must a pilot be aware of as a result of ground effect? - Answers Induced drag decreases;
therefore, any excess speed at the point of flare may cause considerable floating.
Floating caused by the phenomenon of ground effect will be most realized during an approach
to land when at - Answers less than the length of the wingspan above the surface
