### Q1: In a glider cockpit, the levers colored red, blue, and green correspond to which controls? ^t20q1 - A) Speed brakes, canopy lock, and landing gear. - B) Canopy hood release, speed brakes, and elevator trim. - C) Landing gear, speed brakes, and elevator trim tab. - D) Speed brakes, cable release, and elevator trim. **Correct: B)** > **Explanation:** EASA standardises cockpit lever colours in gliders: red for the canopy hood (emergency) release, blue for speed brakes (airbrakes), and green for elevator trim. This colour coding ensures pilots can identify critical controls instantly under stress. Option A incorrectly assigns red to speed brakes and blue to the canopy lock. Option C incorrectly assigns red to landing gear. Option D incorrectly assigns red to speed brakes and blue to cable release. ### Q2: Wing thickness is measured as the distance between the upper and lower surfaces of a wing at its... ^t20q2 - A) Outermost section. - B) Thinnest cross-section. - C) Innermost section near the root. - D) Thickest cross-section. **Correct: D)** > **Explanation:** Wing thickness is defined as the maximum perpendicular distance between the upper and lower wing surfaces, measured at the thickest part of the airfoil cross-section (typically 20-30% of chord from the leading edge). This is the aerodynamically and structurally significant measurement. Option A (outermost section) would measure near the wingtip where the profile is thinnest. Option B (thinnest cross-section) gives a minimal, less useful value. Option C (innermost/root) describes a spanwise location, not the airfoil thickness definition. ### Q3: What is the term for a tubular steel framework with a non-load-bearing skin? ^t20q3 - A) Monocoque construction. - B) Semi-monocoque construction. - C) Grid construction. - D) Honeycomb structure. **Correct: C)** > **Explanation:** Grid (or truss/lattice) construction uses a framework of tubes or members to carry all structural loads, with the skin serving only as a fairing that does not contribute to structural strength. Option A (monocoque) is the opposite -- the skin carries all loads with no internal framework. Option B (semi-monocoque) uses both a frame and a load-bearing skin working together. Option D (honeycomb structure) is a core material used in sandwich panels, not a fuselage construction type. ### Q4: What are the typical structural components of primary fuselage construction in wood or metal aircraft? ^t20q4 - A) Girders, ribs, and stringers. - B) Ribs, frames, and covers. - C) Frames and stringers. - D) Covers, stringers, and forming parts. **Correct: C)** > **Explanation:** The primary structural members of a traditional fuselage are frames (also called formers or bulkheads, running circumferentially) and stringers (running longitudinally). Together they form the skeleton over which the skin is attached. Option A introduces "girders" which is non-standard fuselage terminology. Option B includes "ribs" which are wing components, not fuselage. Option D lists "covers" and "forming parts" which are not primary structural terms. ### Q5: What is the name for a structure built from frames and stringers with a load-bearing skin? ^t20q5 - A) Grid construction. - B) Honeycomb structure. - C) Wood or mixed construction. - D) Semi-monocoque construction. **Correct: D)** > **Explanation:** Semi-monocoque construction uses both an internal framework (frames and stringers) AND a skin that actively bears structural loads (tension, compression, shear). This is the most common modern aircraft fuselage design. Option A (grid construction) has a non-load-bearing skin. Option B (honeycomb) is a material type, not a structural concept. Option C (wood/mixed) is a material classification, not a structural design. ### Q6: What are the principal structural components of an aircraft's tail assembly? ^t20q6 - A) Ailerons and elevator. - B) Horizontal tail and vertical tail. - C) Rudder and ailerons. - D) Steering wheel and pedals. **Correct: B)** > **Explanation:** The tail assembly (empennage) consists of two principal structural groups: the horizontal tail (stabiliser and elevator, providing pitch stability and control) and the vertical tail (fin and rudder, providing yaw stability and control). Option A incorrectly includes ailerons, which are wing-mounted. Option C also incorrectly includes ailerons. Option D lists cockpit controls, not aircraft structure. ### Q7: A sandwich structure is composed of two... ^t20q7 - A) Thin layers bonded to a heavy core material. - B) Thick layers bonded to a lightweight core material. - C) Thick layers bonded to a heavy core material. - D) Thin layers bonded to a lightweight core material. **Correct: D)** > **Explanation:** A sandwich structure uses two thin, stiff face sheets (typically CFRP, glass fibre, or aluminium) bonded to a lightweight core (foam, balsa wood, or honeycomb). The thin skins carry bending loads while the light core resists shear and maintains separation, providing exceptional stiffness-to-weight ratio. Options A and C specify a heavy core, which defeats the weight-saving purpose. Options B and C specify thick layers, which add unnecessary mass. ### Q8: Which structural elements define the aerodynamic profile shape of a wing? ^t20q8 - A) Spar. - B) Planking. - C) Ribs. - D) Wingtip. **Correct: C)** > **Explanation:** Ribs are chordwise structural members that define the airfoil cross-section shape of the wing, running perpendicular to the spar. They establish the precise curvature of the upper and lower wing surfaces. Option A (spar) is the main spanwise load-bearing beam but does not define the profile shape. Option B (planking/skin) covers the structure but follows the shape determined by the ribs. Option D (wingtip) is the outer end of the wing, not a profile-shaping element. ### Q9: The load factor "n" expresses the ratio between... ^t20q9 - A) Thrust and drag. - B) Lift and weight. - C) Weight and thrust. - D) Drag and lift. **Correct: B)** > **Explanation:** The load factor n equals Lift divided by Weight (n = L/W). In straight and level flight, n = 1 (1g). In a banked turn, lift must exceed weight to maintain altitude -- for example, in a 60-degree bank, n = 2 (2g). Load factor is critical for glider structural design, as exceeding maximum positive or negative g-limits risks structural failure. Options A, C, and D describe unrelated force ratios. ### Q10: What are the key benefits of sandwich construction? ^t20q10 - A) Good formability combined with high temperature resistance. - B) Low weight, high stiffness, high stability, and high strength. - C) High temperature durability coupled with low weight. - D) High strength paired with good formability. **Correct: B)** > **Explanation:** Sandwich construction excels at combining low weight with high stiffness, stability, and strength -- the ideal combination for aerospace applications. The bending stiffness increases dramatically when stiff face sheets are spaced apart by a lightweight core. Options A and C emphasise temperature resistance, which is not a primary advantage since most cores are temperature-sensitive. Option D focuses on formability, which is actually limited in sandwich construction. ### Q11: Among the following materials, which one exhibits the greatest strength? ^t20q11 - A) Wood. - B) Aluminium. - C) Carbon fiber reinforced plastic. - D) Magnesium. **Correct: C)** > **Explanation:** Carbon fibre reinforced plastic (CFRP) has exceptional strength-to-weight ratio with tensile strength exceeding steel at a fraction of the weight. Modern high-performance gliders are predominantly CFRP. Option B (aluminium) is strong but significantly weaker than CFRP. Option D (magnesium) is lighter than aluminium but lower in absolute strength. Option A (wood) has good specific strength but is the weakest in absolute terms among those listed. ### Q12: The trim lever in a glider serves to... ^t20q12 - A) Minimize adverse yaw effects. - B) Reduce the required stick force on the rudder. - C) Reduce the required stick force on the elevator. - D) Reduce the required stick force on the ailerons. **Correct: C)** > **Explanation:** The trim system adjusts the elevator trim tab (or spring trim) to hold a desired pitch attitude without continuous pilot input on the control stick, reducing elevator stick force to zero at the trimmed speed. Option A (adverse yaw) is addressed by rudder coordination, not trim. Options B and D refer to rudder and aileron forces, which are not adjusted by the standard glider trim lever. ### Q13: Structural damage to a fuselage may result from... ^t20q13 - A) A stall occurring after the maximum angle of attack is exceeded. - B) Reducing airspeed below a certain threshold. - C) Flying faster than maneuvering speed in severe gusts. - D) Neutralizing stick forces appropriate to the current flight condition. **Correct: C)** > **Explanation:** Exceeding manoeuvring speed (VA) in turbulent conditions can cause structural damage because gusts impose sudden load factors that may exceed the design limit. VA is the speed at which a full control deflection or maximum gust will not exceed the structural limit load. Option A (stall) is an aerodynamic event that does not damage structure. Option B (low airspeed) reduces loads. Option D (neutralising stick forces) does not create structural loads. ### Q14: How many axes does an aircraft rotate about, and what are they called? ^t20q14 - A) 4; optical axis, imaginary axis, sagged axis, axis of evil. - B) 3; x-axis, y-axis, z-axis. - C) 3; vertical axis, lateral axis, longitudinal axis. - D) 4; vertical axis, lateral axis, longitudinal axis, axis of speed. **Correct: C)** > **Explanation:** An aircraft rotates about three principal axes passing through the centre of gravity: the longitudinal axis (nose to tail -- roll), the lateral axis (wingtip to wingtip -- pitch), and the vertical axis (top to bottom -- yaw). Option B uses mathematical labels but omits aviation-specific names. Options A and D fabricate a non-existent fourth axis. ### Q15: Rotation around the longitudinal axis is primarily produced by the... ^t20q15 - A) Rudder. - B) Trim tab. - C) Elevator. - D) Ailerons. **Correct: D)** > **Explanation:** Ailerons control roll -- rotation around the longitudinal axis. When one aileron deflects up and the other down, differential lift rolls the aircraft. Option A (rudder) controls yaw around the vertical axis. Option C (elevator) controls pitch around the lateral axis. Option B (trim tab) modifies control forces but is not a primary roll initiator. ### Q16: On a small single-engine piston aircraft, how are the flight controls typically operated and connected? ^t20q16 - A) Electrically via fly-by-wire systems. - B) Power-assisted via hydraulic pumps or electric motors. - C) Manually via rods and control cables. - D) Hydraulically via pumps and actuators. **Correct: C)** > **Explanation:** Small piston aircraft and gliders use direct mechanical linkages -- push-pull rods and steel control cables -- to transmit pilot input directly to control surfaces. This is simple, lightweight, and reliable with no power source required. Option A (fly-by-wire) is used on modern airliners and military aircraft. Options B and D (hydraulic systems) are used on larger aircraft requiring greater control forces. ### Q17: When left rudder is applied, what are the primary and secondary effects? ^t20q17 - A) Primary: yaw to the left; Secondary: roll to the left. - B) Primary: yaw to the right; Secondary: roll to the right. - C) Primary: yaw to the left; Secondary: roll to the right. - D) Primary: yaw to the right; Secondary: roll to the left. **Correct: A)** > **Explanation:** Left rudder primarily yaws the nose left around the vertical axis. The secondary effect is roll to the left: as the nose yaws left, the outer (right) wing moves faster and generates more lift while the inner (left) wing slows and generates less, creating a bank to the left. Options B and D have incorrect yaw direction. Option C has correct yaw but incorrect secondary roll direction. ### Q18: What happens when the control stick or yoke is pulled rearward? ^t20q18 - A) The tail produces an increased downward force, causing the nose to rise. - B) The tail produces an increased upward force, causing the nose to rise. - C) The tail produces a decreased upward force, causing the nose to drop. - D) The tail produces an increased downward force, causing the nose to drop. **Correct: A)** > **Explanation:** Pulling back on the stick deflects the elevator upward, increasing the downward aerodynamic force on the tail. With the tail pushed down, the nose pivots up around the lateral axis through the centre of gravity. This seems counterintuitive but is correct: tail goes down, nose goes up. Option B incorrectly states the tail force is upward. Option C describes a forward stick input. Option D has the correct force but wrong nose direction. ### Q19: Which of these lists contains all primary flight controls of an aircraft? ^t20q19 - A) Flaps, slats, and speedbrakes. - B) All movable components on an aircraft that help control its flight. - C) Elevator, rudder, and aileron. - D) Elevator, rudder, aileron, trim tabs, high-lift devices, and power controls. **Correct: C)** > **Explanation:** The three primary flight controls are elevator (pitch), rudder (yaw), and aileron (roll). These directly control rotation about the aircraft's three axes. Option A lists secondary/high-lift devices only. Option B is too vague and includes secondary controls. Option D mixes primary with secondary controls (trim tabs, high-lift devices, power controls). ### Q20: What function do secondary flight controls serve? ^t20q20 - A) They serve as a backup system for the primary flight controls. - B) They enable the pilot to control the aircraft about its three axes. - C) They enhance performance characteristics and relieve the pilot of excessive control forces. - D) They improve turning characteristics at low speed during approach and landing. **Correct: C)** > **Explanation:** Secondary flight controls (trim tabs, flaps, speedbrakes, slats) enhance aircraft performance and reduce pilot workload. Trim neutralises stick forces; flaps increase low-speed lift; speedbrakes manage descent rate. Option A is incorrect -- they are not backup systems. Option B describes primary controls. Option D is too narrow, covering only one aspect of flap function. ### Q21: If the pilot moves the trim wheel or lever aft, what happens to the trim tab and the elevator? ^t20q21 - A) The trim tab moves up, the elevator moves down. - B) The trim tab moves down, the elevator moves down. - C) The trim tab moves up, the elevator moves up. - D) The trim tab moves down, the elevator moves up. **Correct: D)** > **Explanation:** Moving trim aft commands nose-up trim. The trim tab deflects downward, generating an aerodynamic force that pushes the elevator trailing edge upward. The raised elevator pushes the tail down and raises the nose. Trim tabs always move opposite to the elevator: tab down causes elevator up. Options A and C have the tab moving up (nose-down trim). Option B has both moving down, which is mechanically impossible in a normal trim system. ### Q22: In which direction does the trim tab deflect when trimming for nose-up? ^t20q22 - A) It depends on the CG position. - B) It deflects upward. - C) In the direction of rudder deflection. - D) It deflects downward. **Correct: D)** > **Explanation:** For nose-up trim, the trim tab deflects downward. The downward tab creates an aerodynamic force pushing the elevator trailing edge up, which holds the elevator in a nose-up position without pilot input. Option A (CG position) affects how much trim is needed but not the direction. Option B (upward) would produce nose-down trim. Option C (rudder direction) is unrelated to elevator trim operation. ### Q23: The purpose of the trim system is to... ^t20q23 - A) Lock the control surfaces in position. - B) Shift the centre of gravity. - C) Adjust the control force. - D) Increase adverse yaw. **Correct: C)** > **Explanation:** Trim adjusts control forces so the pilot can fly hands-off at the trimmed speed and attitude. It neutralises the stick force to zero at the desired condition. Option A (lock surfaces) is incorrect -- trim holds an aerodynamic equilibrium, not a mechanical lock. Option B (shift CG) is wrong -- only physically moving mass changes CG. Option D (adverse yaw) is a roll-yaw coupling unrelated to trim. ### Q24: The Pitot-static system is designed to... ^t20q24 - A) Correct the airspeed indicator to show zero when the aircraft is stationary on the ground. - B) Prevent static electricity accumulation on the airframe. - C) Prevent ice formation on the Pitot tube. - D) Measure total air pressure and static air pressure. **Correct: D)** > **Explanation:** The Pitot-static system measures total pressure (from the Pitot tube facing the airflow) and static pressure (from flush static ports on the fuselage). These feed the ASI, altimeter, and variometer. Option A describes a consequence, not the purpose. Option B (static electricity) is an unrelated electrical phenomenon. Option C (ice prevention) is handled by optional Pitot heating, not the system's design purpose. ### Q25: What type of pressure does the Pitot tube sense? ^t20q25 - A) Static air pressure. - B) Total air pressure. - C) Cabin air pressure. - D) Dynamic air pressure. **Correct: B)** > **Explanation:** The Pitot tube faces into the airflow and senses total pressure (stagnation pressure), which equals static pressure plus dynamic pressure (q = 1/2 rho v-squared). Option A (static pressure) is measured by separate static ports. Option C (cabin pressure) is unrelated. Option D (dynamic pressure) is not measured directly by the Pitot tube -- it is derived by subtracting static from total pressure inside the ASI. ### Q26: QFE refers to the... ^t20q26 - A) Barometric pressure corrected to sea level using the international standard atmosphere (ISA). - B) Altitude referenced to the 1013.25 hPa pressure level. - C) Barometric pressure at a reference datum, typically the runway threshold of an airfield. - D) Magnetic bearing to a station. **Correct: C)** > **Explanation:** QFE is the atmospheric pressure at a specific reference point, typically the runway threshold. Setting QFE on the altimeter causes it to read zero on the ground at the aerodrome, showing height above the field during flight. Option A describes QNH (sea level corrected pressure). Option B describes the flight level datum (1013.25 hPa). Option D describes QDM/QDR radio navigation terminology. ### Q27: What is the function of the altimeter subscale? ^t20q27 - A) To correct the altimeter for instrument system errors. - B) To set the reference datum for the transponder altitude encoder. - C) To reference the altimeter reading to a chosen level such as mean sea level, aerodrome elevation, or the 1013.25 hPa pressure surface. - D) To compensate the altimeter reading for non-standard temperatures. **Correct: C)** > **Explanation:** The altimeter subscale (Kollsman window) lets the pilot set a reference pressure: QNH for altitude above sea level, QFE for height above the airfield, or 1013.25 hPa for flight levels. Option A (system errors) requires calibration, not subscale adjustment. Option B (transponder encoder) operates on standard pressure independently. Option D (temperature correction) requires a separate mathematical calculation. ### Q28: How can an altimeter subscale set to an incorrect QNH lead to a dangerous altimeter error? ^t20q28 - A) Setting a lower pressure than actual causes the reading to be too low, meaning greater height above ground than intended. - B) Setting a lower pressure than actual causes the reading to be too high, bringing the aircraft closer to the ground than indicated. - C) Setting a higher pressure than actual causes the reading to be too high, bringing the aircraft closer to the ground than indicated. - D) Setting a higher pressure than actual causes the reading to be too low, meaning greater height above ground than intended. **Correct: C)** > **Explanation:** Setting a higher pressure than actual QNH causes the altimeter to over-read -- it shows a higher altitude than the aircraft's true position. The aircraft is actually closer to the ground than indicated, creating a dangerous terrain clearance illusion. The memory aid: "High to Low, look out below." Options A and B incorrectly describe the effect of a low pressure setting. Option D reverses the consequence of a high setting. ### Q29: A temperature lower than the ISA standard may cause... ^t20q29 - A) An altitude reading that is too high. - B) A correct altitude reading provided the subscale is set for non-standard temperature. - C) An altitude reading that is too low. - D) Pitot tube icing that freezes the altimeter at its current value. **Correct: A)** > **Explanation:** In colder-than-standard air, the atmosphere is denser and pressure drops faster with altitude than ISA assumes. The altimeter over-reads, indicating a higher altitude than the aircraft's actual position -- the pilot is lower than they think. "Cold air = lower than you think." Option B is wrong because altimeter subscales cannot correct for temperature. Option C reverses the error. Option D describes an icing issue separate from temperature-induced altimeter error. ### Q30: A flight level is a... ^t20q30 - A) True altitude. - B) Pressure altitude. - C) Density altitude. - D) Altitude above the ground. **Correct: B)** > **Explanation:** A flight level is a pressure altitude expressed in hundreds of feet with the altimeter set to 1013.25 hPa (standard pressure). FL100 = 10,000 ft on standard setting. All aircraft above the transition altitude use this common datum for vertical separation regardless of local pressure variations. Option A (true altitude) is actual MSL height. Option C (density altitude) is a performance calculation parameter. Option D (above ground) is height AGL. ### Q31: True altitude is defined as... ^t20q31 - A) A height above ground level corrected for non-standard pressure. - B) A pressure altitude corrected for non-standard temperature. - C) An altitude above mean sea level corrected for non-standard temperature. - D) A height above ground level corrected for non-standard temperature. **Correct: C)** > **Explanation:** True altitude is the actual geometric height of the aircraft above mean sea level (MSL), obtained by correcting indicated altitude for deviations from the ISA temperature profile. The altimeter assumes standard ISA conditions; when actual temperature differs, the indicated reading diverges from the real MSL height. A and D are wrong because true altitude is referenced to MSL, not above ground level (AGL). B mentions temperature correction but is imprecise — true altitude is the actual MSL height, not merely a pressure altitude with a temperature factor applied. Only C correctly defines true altitude. --- ### Q32: When flying in air colder than ISA, the indicated altitude is... ^t20q32 - A) Equal to the standard altitude. - B) Lower than the true altitude. - C) Equal to the true altitude. - D) Higher than the true altitude. **Correct: D)** > **Explanation:** In colder-than-ISA air the atmosphere is denser, so pressure decreases more rapidly with altitude than the altimeter assumes. The altimeter therefore over-reads and shows a higher value than the aircraft's actual MSL height — the aircraft is physically lower than the instrument indicates. This is a serious terrain clearance hazard, summarized by the memory aid "High to low (temperature), look out below." B states the opposite of what occurs. A and C only apply under exact ISA conditions. Only D is correct. --- ### Q33: When flying in an air mass at ISA temperature with the correct QNH set, the indicated altitude is... ^t20q33 - A) Lower than the true altitude. - B) Higher than the true altitude. - C) Equal to the true altitude. - D) Equal to the standard atmosphere. **Correct: C)** > **Explanation:** The altimeter is calibrated to the ISA standard temperature lapse rate. When the actual temperature exactly matches ISA and the correct QNH is set, all instrument assumptions are perfectly met and no error exists — indicated altitude equals true altitude. This is the ideal baseline condition from which deviations introduce errors. A and B describe situations with non-standard temperature or pressure. D is vague and not a meaningful statement about the altimeter reading. Only C is correct. --- ### Q34: Which instrument is susceptible to hysteresis error? ^t20q34 - A) Vertical speed indicator. - B) Direct reading compass. - C) Altimeter. - D) Tachometer. **Correct: C)** > **Explanation:** Hysteresis error affects the altimeter because its aneroid capsules — thin elastic bellows that expand and contract with pressure changes — do not return to exactly the same position when pressure is restored to a previously experienced value. This mechanical lag means the altimeter may show slightly different readings at the same altitude when climbing versus descending. A (VSI), B (compass), and D (tachometer) do not rely on elastic aneroid capsules for their primary measurement and are therefore not subject to this specific error. Only C is correct. --- ### Q35: Altitude measurement relies on changes in which type of pressure? ^t20q35 - A) Total pressure. - B) Differential pressure. - C) Static pressure. - D) Dynamic pressure. **Correct: C)** > **Explanation:** Static pressure is the ambient atmospheric pressure that decreases predictably with altitude according to the ISA model. The altimeter senses this pressure via the static port and converts it to an altitude reading using calibrated aneroid capsules. A (total pressure) equals static plus dynamic and is measured by the Pitot tube for airspeed. B (differential pressure) is the difference between total and static, which drives the ASI. D (dynamic pressure) depends on airspeed and has no role in altitude measurement. Only C is correct. --- ### Q36: How does a vertical speed indicator work? ^t20q36 - A) It measures total air pressure and compares it to static pressure. - B) It compares the current static air pressure against the static pressure stored in a reservoir. - C) It measures vertical acceleration using a gimbal-mounted mass. - D) It measures static air pressure and compares it against a vacuum. **Correct: B)** > **Explanation:** The VSI detects rate of climb or descent by comparing current static pressure (from the static port) against a reference pressure stored in an internal reservoir that communicates via a calibrated leak. When climbing, static pressure drops faster than the reservoir can equalize, creating a pressure difference that deflects the pointer proportional to climb rate. A describes the ASI operating principle (total minus static = dynamic). C describes an accelerometer. D describes a barometer, which cannot indicate a rate of change. Only B correctly explains VSI operation. --- ### Q37: The vertical speed indicator compares the pressure difference between... ^t20q37 - A) The current dynamic pressure and the dynamic pressure from a moment earlier. - B) The current static pressure and the static pressure from a moment earlier. - C) The current total pressure and the total pressure from a moment earlier. - D) The current dynamic pressure and the static pressure from a moment earlier. **Correct: B)** > **Explanation:** The VSI senses only static pressure, which changes as altitude changes. It compares the instantaneous static pressure arriving through the static port with the slightly delayed static pressure stored in the metering reservoir behind the calibrated restriction. The rate of pressure change indicates the rate of altitude change. A, C, and D all involve dynamic or total pressure, which are Pitot-tube quantities used for airspeed measurement and play no role in the VSI. Only B is correct. --- ### Q38: An aircraft flies on a heading of 180° at 100 kt TAS. The wind blows from 180° at 30 kt. Ignoring instrument and position errors, what will the airspeed indicator approximately show? ^t20q38 - A) 70 kt - B) 130 kt - C) 30 kt - D) 100 kt **Correct: D)** > **Explanation:** The ASI measures the aircraft's speed relative to the surrounding air mass, not relative to the ground. The aircraft moves through the air at 100 kt TAS, so the ASI shows 100 kt regardless of wind. A wind from 180° on a heading of 180° is a headwind, reducing ground speed to 70 kt — that is A, but ground speed is not what the ASI reads. B (130 kt) would only apply with a 30 kt tailwind. C (30 kt) is merely the wind speed, irrelevant to the ASI. Only D is correct. --- ### Q39: What principle does the airspeed indicator use to determine speed? ^t20q39 - A) Static air pressure is measured and compared against a vacuum. - B) Dynamic air pressure is sensed by the Pitot tube and converted directly into a speed reading. - C) Total air pressure is sensed by the static ports and converted into speed. - D) Total air pressure is compared against static air pressure. **Correct: D)** > **Explanation:** The ASI compares total pressure from the Pitot tube (which captures all air pressure including the motion component) against static pressure from the static port (ambient pressure only). The difference is dynamic pressure (q = ½ρv²), proportional to airspeed squared — the expanding capsule converts this into an IAS reading. A describes a simple barometer. B is incorrect because the Pitot tube measures total pressure, not pure dynamic pressure. C wrongly attributes total pressure measurement to the static ports. Only D correctly describes ASI operation. --- ### Q40: Red lines on instrument displays typically mark which values? ^t20q40 - A) Recommended operating ranges. - B) Caution areas. - C) Operational limits. - D) Normal operating areas. **Correct: C)** > **Explanation:** Red radial marks on aircraft instruments indicate absolute operational limits that must never be exceeded — such as VNE (never-exceed speed) on the ASI. These represent structural or aerodynamic boundaries beyond which catastrophic failure or loss of control may occur. B (caution areas) are indicated by yellow arcs, covering the speed range between maneuvering speed and VNE where smooth air is required. D (normal operating range) is shown by a green arc. A ("recommended operating ranges") is not a standard instrument marking. Only C correctly defines the red line. --- ### Q41: To determine indicated airspeed (IAS), the airspeed indicator requires... ^t20q41 - A) The difference between total pressure and dynamic pressure. - B) The difference between total pressure and static pressure. - C) The difference between standard pressure and total pressure. - D) The difference between dynamic pressure and static pressure. **Correct: B)** > **Explanation:** IAS is derived from dynamic pressure, which equals total pressure (Pitot tube) minus static pressure (static port). The ASI capsule deflects in proportion to this pressure difference and the needle indicates IAS. A (total minus dynamic) would yield static pressure alone — not useful for airspeed. C (standard minus total) has no aerodynamic significance for airspeed. D (dynamic minus static) is not a meaningful Pitot-static quantity since dynamic pressure is not independently measured at a single port. Only B is correct. --- ### Q42: What does the red line on an airspeed indicator represent? ^t20q42 - A) A speed limit in turbulent conditions. - B) The maximum speed with flaps deployed. - C) A speed that must never be exceeded under any circumstances. - D) The maximum speed in turns exceeding 45° bank. **Correct: C)** > **Explanation:** The red line marks VNE — Velocity Never Exceed — the absolute structural speed limit that must not be exceeded under any circumstances, including smooth air. Beyond VNE, the risk of aeroelastic flutter or catastrophic structural failure is unacceptable. A describes the upper boundary of the yellow arc (caution range), where turbulence must be avoided. B describes VFE (flap extension speed), marked by the top of the white arc. D does not correspond to any standard ASI color marking. Only C is correct. --- ### Q43: The compass error produced by the aircraft's own magnetic field is known as... ^t20q43 - A) Variation. - B) Deviation. - C) Declination. - D) Inclination. **Correct: B)** > **Explanation:** Deviation is the compass error caused by the aircraft's own magnetic fields — from steel structures, electrical wiring, and electronic equipment on board. It varies with the aircraft's heading and is tabulated on the compass deviation card after a compass swing. A (variation) and C (declination) are two names for the same geographic phenomenon: the angle between true north and magnetic north at any given location on Earth — this is not caused by the aircraft. D (inclination) refers to the vertical dip angle of Earth's magnetic field, which causes turning and acceleration errors. Only B is correct. --- ### Q44: What errors cause a magnetic compass to deviate from magnetic north? ^t20q44 - A) Variation, turning errors, and acceleration errors. - B) Gravity and magnetism. - C) Inclination and declination of the earth's magnetic field. - D) Deviation, turning errors, and acceleration errors. **Correct: D)** > **Explanation:** Three instrument errors cause the magnetic compass to deviate from magnetic north: deviation (from the aircraft's own magnetic fields), turning errors (the compass card tilts due to magnetic dip during turns, especially on northerly/southerly headings), and acceleration errors (speed changes on easterly/westerly headings produce false readings due to the same dip effect). A incorrectly includes variation, which is a geographic property of Earth, not an instrument error. B is too vague. C lists physical properties of Earth's field rather than specific instrument errors. Only D correctly names all three. --- ### Q45: Which cockpit instrument receives input from the Pitot tube? ^t20q45 - A) Altimeter. - B) Direct-reading compass. - C) Airspeed indicator. - D) Vertical speed indicator. **Correct: C)** > **Explanation:** Only the airspeed indicator is connected to the Pitot tube, which supplies total pressure as one of the two inputs needed to compute IAS. A (altimeter) and D (VSI) are connected only to the static port — they measure changes in static pressure for altitude and climb/descent rate. B (direct-reading compass) is a self-contained magnetic instrument with no connection to the Pitot-static system. Only C is correct. --- ### Q46: An aircraft in the northern hemisphere turns from 270° to 360° via the shortest route. At roughly what compass indication should the pilot stop the turn? ^t20q46 - A) 360° - B) 030° - C) 330° - D) 270° **Correct: C)** > **Explanation:** The shortest turn from 270° to 360° is a right turn through northwest toward north. In the northern hemisphere, magnetic dip causes the compass to lead (read ahead of the actual heading) when turning toward north, so the pilot must stop early — before the compass reaches 360°. The rule of thumb is to stop approximately 30° before the target when turning to north: 360° − 30° = 330°. Waiting until the compass shows 360° (A) results in overshooting to approximately 030° (B). D (270°) is the starting heading. Only C is correct. --- ### Q47: Which instruments receive static pressure from the static port? ^t20q47 - A) Altimeter, vertical speed indicator, and airspeed indicator. - B) Airspeed indicator, direct-reading compass, and slip indicator. - C) Altimeter, slip indicator, and navigational computer. - D) Airspeed indicator, altimeter, and direct-reading compass. **Correct: A)** > **Explanation:** All three Pitot-static instruments receive static pressure: the altimeter (converts static pressure to altitude), the vertical speed indicator (compares current and stored static pressure to show climb/descent rate), and the airspeed indicator (uses static pressure alongside Pitot total pressure). The direct-reading compass in B and D is a self-contained magnetic instrument with no pneumatic input. The slip indicator in B and C is an inertial/gravity instrument (a ball in liquid) that requires no connection to the static port. Only A lists the correct three instruments. --- ### Q48: An aircraft in the northern hemisphere turns from 360° to 270° via the shortest route. At approximately what compass reading should the turn be stopped? ^t20q48 - A) 300° - B) 240° - C) 360° - D) 270° **Correct: D)** > **Explanation:** The shortest turn from 360° (north) to 270° (west) is a left turn passing through northwest and west. On westerly headings in the northern hemisphere, the magnetic dip-induced turning error is minimal because the compass card tilts most significantly near north and south, not near east and west. At 270° the compass reads with acceptable accuracy, so the pilot should stop the turn when the compass shows 270°. A (300°) stops too early. B (240°) overshoots significantly. C (360°) is the starting heading. Only D is correct. --- ### Q49: Static pressure is defined as the pressure... ^t20q49 - A) Sensed by the Pitot tube. - B) Inside the aircraft cabin. - C) Of undisturbed airflow. - D) Produced by orderly movement of air particles. **Correct: C)** > **Explanation:** Static pressure is the ambient atmospheric pressure of undisturbed air, exerted equally in all directions at a given altitude regardless of airflow velocity. It is measured by flush static ports positioned on the fuselage where local aerodynamic disturbance is minimized. A is wrong: the Pitot tube senses total pressure (static plus dynamic). B (cabin pressure) is a separately regulated quantity inside the aircraft. D more closely describes dynamic pressure, which arises from organized directed air motion. Only C correctly defines static pressure. --- ### Q50: An aircraft in the northern hemisphere turns from 030° to 180° via the shortest route. At approximately what compass heading should the turn be ended? ^t20q50 - A) 180° - B) 210° - C) 360° - D) 150° **Correct: B)** > **Explanation:** The shortest turn from 030° to 180° is a right turn through east and south. When turning toward southerly headings in the northern hemisphere, the compass lags — it under-reads the actual heading and shows a smaller value than the aircraft has actually turned through. The pilot must therefore overshoot: continue turning until the compass reads approximately 180° + 30° = 210°, at which point the actual heading is approximately 180°. Stopping at 180° on the compass (A) means the aircraft has not yet reached 180° in reality. D (150°) is far too early. C (360°) is irrelevant. Only B is correct. ---