Unit 2 - Practice Quiz

The fuselage is the central body of an aircraft, designed to accommodate the crew, passengers, and cargo.

The wings are airfoils designed to create the aerodynamic force known as lift, which counteracts gravity and allows the aircraft to fly.

The engine (or engines) generates thrust, pushing the aircraft through the air, by either turning a propeller or expelling hot gases.

The altimeter is a barometric instrument that measures static air pressure and displays it as altitude.

The ASI works by measuring the difference between the total pressure captured by the pitot tube and the static pressure from the static port. This difference is the dynamic pressure, which relates to airspeed.

The VSI, also known as a variometer, indicates how quickly the aircraft is climbing or descending, typically in feet per minute.

The ailerons (for roll), elevator (for pitch), and rudder (for yaw) are the primary control surfaces that allow the pilot to control the aircraft's movement around its three principal axes.

Flaps are secondary control surfaces that increase the wing's lift and drag, allowing the aircraft to fly safely at lower speeds, which is essential for takeoff and landing.

The ailerons are located on the trailing edge of the wings and move in opposite directions to create a differential lift, causing the aircraft to roll or bank.

Conventional systems use a physical connection, typically a series of cables, pulleys, and pushrods, to directly transmit the pilot's input to the flight control surfaces.

Hydraulic systems work because liquids are nearly incompressible, allowing them to transmit force efficiently from one point to another, as described by Pascal's law.

Pneumatic systems use a compressible gas, such as air, under pressure to move components and perform work.

A fly-by-wire system uses computers to process the pilot's inputs and sends corresponding electrical signals to actuators that move the flight control surfaces.

Fly-by-light systems replace the electrical wires of a fly-by-wire system with fiber optic cables, which transmit signals as pulses of light. This offers advantages like immunity to electromagnetic interference.

At high altitudes, the outside air is too thin to breathe. Pressurization maintains a higher air pressure and density inside the cabin, ensuring passengers and crew have enough oxygen.

Hot, high-pressure air is "bled" from the compressor section of the jet engines. This bleed air is then cooled, conditioned, and routed into the cabin for pressurization and climate control.

The stall warning system provides an audible or tactile warning (like a stick shaker) to alert the pilot that the wing's angle of attack is approaching the critical point where it can no longer produce sufficient lift.

An ILS is a ground-based precision approach system that uses radio signals to provide pilots with precise horizontal and vertical guidance for landing on a runway, especially in poor weather.

The localizer provides lateral (left/right) guidance to align the aircraft with the runway centerline, while the glideslope provides vertical (up/down) guidance for the correct descent path.

Anti-icing systems are proactive and are used to prevent ice from accumulating in the first place, often by heating surfaces like wing leading edges and engine inlets.

When an aircraft rolls, the upward-deflected aileron creates more drag than the downward-deflected one, causing the nose to yaw away from the turn (adverse yaw). The rudder is used to apply a corrective yawing moment, keeping the nose of the aircraft aligned with the flight path for a coordinated turn.

An altimeter is a barometer that interprets lower pressure as higher altitude. When flying into an area of lower pressure, the altimeter senses the pressure drop and indicates a climb, even if the true altitude is constant or decreasing. Therefore, the aircraft's true altitude will be lower than the 10,000 feet indicated on the instrument. The mnemonic is: "From high to low, look out below!"

Deploying spoilers (or speed brakes) symmetrically on both wings disrupts the airflow over the wing, which reduces lift and significantly increases drag. This allows the aircraft to achieve a steeper descent path without accelerating, which is very useful for managing energy during the approach phase.

An accumulator is a pressure storage reservoir. Its key functions are to supply peak demands for fluid that may exceed the pump's capacity, dampen pressure fluctuations (like a shock absorber), and provide a temporary source of hydraulic power if the main pump fails.

A key safety feature of advanced fly-by-wire systems is flight envelope protection. The flight control computers (FCCs) are programmed with the aircraft's safe operating limits. If a pilot's input would cause the aircraft to exceed these limits (e.g., stall or over-stress the airframe), the FCCs will not command the control surfaces to perform the unsafe maneuver.

The system works by continuously pumping a relatively constant volume of conditioned air into the cabin. The desired cabin pressure is then precisely maintained by controlling the rate at which this air is allowed to escape through one or more outflow valves. Opening the valve decreases cabin pressure (increases cabin altitude), while closing it increases pressure (decreases cabin altitude).

The ILS instrument display shows the position of the desired path relative to the aircraft. A localizer needle deflected to the right means the runway centerline is to the aircraft's right, so the aircraft must be to the left of the centerline. A glideslope needle deflected downwards means the ideal glide path is below the aircraft, so the aircraft is too high. The pilot needs to fly right and down to re-intercept the path.

The core difference is their philosophy. Anti-icing systems are preventative; they are activated before or upon entering icing conditions to keep surfaces warm enough that ice cannot accrete. De-icing systems are corrective; they allow some ice to build up and then activate periodically to break it off.

A 'TRAFFIC, TRAFFIC' alert is a Traffic Advisory (TA). It is an early warning that another aircraft is nearby and could become a collision threat. The correct procedure is for the pilots to attempt to visually acquire the traffic and be prepared for a potential avoidance maneuver, but not to maneuver based on the TA alone. A maneuver is only commanded during a Resolution Advisory (RA), such as 'CLIMB, CLIMB'.

Fly-by-Light systems transmit control signals as pulses of light through fiber-optic cables. Unlike the electrical signals in copper wires used by FBW systems, these light signals are completely unaffected by external electromagnetic fields. This immunity to EMI, RFI, and lightning-induced electrical surges is a major safety and design advantage.

An aircraft's metal structure expands and contracts significantly with the large temperature variations experienced during flight. Without a tension regulator, control cables would become slack at cold high altitudes or overly tight on a hot ramp. The regulator is a spring-loaded device that automatically adjusts to maintain the designed tension, ensuring consistent control response.

The ASI is a differential pressure gauge. It measures the difference between the total pressure captured by the forward-facing pitot tube and the ambient static pressure from the static ports. This difference is known as dynamic pressure (), which is directly proportional to the square of the airspeed.

Flaperons combine the function of flaps and ailerons. When flaps are commanded (e.g., for landing), both flaperons lower together to increase lift. When a roll command is given, they then move differentially (one up, one down) from their current flap setting. This provides roll control while still benefiting from the high-lift characteristic of flaps.

The main drawback of using air (a gas) as a working fluid is its compressibility. When force is applied, the air must be compressed before the actuator moves, resulting in a delayed and non-rigid response. Hydraulic fluid is virtually incompressible, providing an immediate and stiff transfer of force, which is essential for precise control of large aerodynamic surfaces on high-speed aircraft.

The FCCs are the 'brains' of the FBW system. They receive the electrical signals from the pilot's controls, process these signals along with data from numerous other sensors (airspeed, attitude, etc.), and then calculate and send the precise electrical commands to the actuators to move the control surfaces in the most efficient and stable manner.

The most efficient source of high-pressure air on a jet aircraft is the compressor section of its own engines. This air is 'bled' from one or more compressor stages, where it is already at very high pressure and temperature. This bleed air is then cooled, regulated, and routed to the cabin for pressurization and air conditioning.

The Outer Marker is located several miles from the runway threshold. When the aircraft flies over it, a blue light illuminates in the cockpit and a specific Morse code tone is heard. This provides the pilot with a positive position fix, allowing them to verify they are established on the localizer and at the correct altitude to begin the final descent on the glideslope.

Dihedral provides roll stability. If an external force (like a gust) causes a wing to drop, the aircraft will sideslip toward the lower wing. Due to the dihedral angle, the lower wing meets the relative wind at a higher angle of attack than the higher wing. This generates more lift on the low wing, creating a restoring moment that tends to roll the aircraft back to a wings-level attitude.

This specific alert is characteristic of an Enhanced GPWS (EGPWS) or Terrain Awareness and Warning System (TAWS). The system uses a worldwide terrain database and GPS positioning to look ahead of the aircraft's flight path. The "TERRAIN, PULL UP!" warning is the most urgent alert, indicating an imminent risk of controlled flight into terrain (CFIT).

The concept of fly-by-acoustic control involves using the aircraft's physical structure as a data bus. Instead of sending signals through wires or fiber optics, coded acoustic or ultrasonic waves would be propagated through the airframe from the control computer to the actuators. This research aims to reduce wiring, weight, and complexity.

Vortex generators are small vanes that create tiny vortices. These vortices mix the high-energy air from outside the boundary layer with the lower-energy air inside, delaying flow separation. This is crucial for maintaining control surface effectiveness in the adverse pressure gradient behind a shock wave.

In a deep stall, the aircraft is at a very high angle of attack. For a T-tail, the wake from the stalled main wing flows directly over the horizontal stabilizer. This 'blanketing' effect reduces airflow over the elevator, making it impossible to generate the necessary pitch-down moment to lower the nose and recover from the stall.

Compressibility error causes the ASI to read higher than the equivalent airspeed because air compresses in the pitot tube at high speeds. The correction formula is fundamentally a function of the measured impact pressure (which is related to CAS) and the static pressure (related to Pressure Altitude). Air data computers use these inputs to calculate and correct for the error.

A mechanical HI is subject to apparent drift due to Earth's rotation and precession from bearing friction. In the Northern Hemisphere, these combined errors typically cause the HI to 'lag' the actual heading during turns. When turning right from a northerly heading, the gyro will not indicate a full 360° rotation by the time the aircraft has aerodynamically completed the turn, resulting in a reading slightly less than 360°.

Flaperons combine the functions of ailerons and flaps. For roll control (the turn), they move differentially. For increasing lift (to climb), they act as flaps and move symmetrically downwards. To achieve both maneuvers simultaneously, the system superimposes these commands. The existing differential for the turn is maintained, and an equal downward deflection is added to both surfaces.

At high airspeeds, deflecting a large outboard aileron creates a force that can physically twist the flexible wing. This twisting can change the wing's angle of attack in the opposite direction of what's desired, leading to a roll in the wrong direction (control reversal). Using inboard ailerons and spoilers, which are closer to the rigid wing root, prevents this dangerous aeroelastic effect.

An anti-servo tab moves in the same direction as the main control surface. This increases the aerodynamic force resisting the pilot's input. Its purpose is to provide artificial 'feel' and resistance, preventing the pilot from over-controlling the powerful stabilator. A servo tab, in contrast, moves in the opposite direction to help the pilot move the main surface, thus reducing control forces.

A hydraulic fuse is a flow-sensing safety device. When it detects a flow rate that exceeds a pre-set limit (indicating a ruptured line), an internal valve snaps shut, isolating the leaking component. This preserves hydraulic fluid and pressure for the remaining essential systems.

The vacuum system actively holds the de-icing boots down. Without it, the low static air pressure at high altitudes will cause the flexible boots to lift away from the wing surface and billow. This creates a significant aerodynamic disturbance that can disrupt lift and increase drag, even without any ice present.

Normal Law provides comprehensive stall prevention via High Angle of Attack (AoA) protection. This protection relies heavily on accurate air data. In Alternate Law, triggered by multiple ADR failures, this critical protection is lost. The system reverts to a conventional stall warning, and the pilot is solely responsible for preventing and recovering from a stall.

In a g-command system, the pilot's stick input commands a desired load factor, not a direct elevator position or pitch rate. A neutral stick commands 1g. A sustained aft input commands a load factor greater than 1g. The flight control computer manipulates the control surfaces to achieve and maintain this commanded load factor, regardless of changes in airspeed.

The most critical advantage of FBL is its immunity to EMI and HIRF. Strong external radio and radar signals can induce currents in the copper wires of FBW systems, potentially corrupting control signals. Fiber optic cables, used in FBL, transmit data as light pulses and are inherently immune to this interference, offering a much higher level of system integrity.

An aircraft structure is an incredibly noisy environment, filled with vibrations from engines and aerodynamic forces. The core challenge is designing a signal processing system that can reliably isolate the faint, encoded acoustic command signal from this massive amount of background noise to maintain signal integrity.

The system maintains pressure by balancing a constant inflow of air with a modulated outflow. A leak is an additional, uncontrolled outflow. To compensate and keep the total outflow equal to the inflow (thus maintaining pressure), the automatic controller must command the primary outflow valve to move towards the closed position.

The most significant temperature drop in an ACM occurs when the hot, compressed air expands through a turbine. This expansion forces the turbine to spin at high speed, performing work. According to the first law of thermodynamics, if a gas does work during expansion, its internal energy must decrease, which manifests as a dramatic drop in temperature.

The mandated procedure is unambiguous: the pilot must always follow the TCAS RA over a contradictory ATC instruction. TCAS provides a real-time, immediate threat resolution based on direct communication with the other aircraft. The pilot's immediate responsibility is collision avoidance by following the RA, then informing ATC as soon as possible.

ILS categories are defined by their minimums. CAT IIIB allows for landing with a decision height below 50 feet (or no DH) and a runway visual range (RVR) as low as 150 feet, meaning the pilot may not see the runway until after touchdown. CAT IIIC is the theoretical 'zero-zero' category, with no DH and no RVR requirement, implying a fully automated landing and rollout in complete blindness (CAT IIIC is not in operational use).

The ILS signal pattern is sensitive to obstructions. The ILS critical area on the ground is a zone where vehicles are prohibited during low-visibility operations precisely because their presence can reflect or block the radio signals. This multi-path interference distorts the signal received by the approaching aircraft, causing the needle oscillations known as scalloping.

This is an energy-resource trade-off. The large surface area of a wing requires a massive amount of thermal energy. Tapping hot bleed air is an efficient way to provide this heat. An aircraft's electrical generators have finite capacity; generating enough electricity to heat the entire wing would require prohibitively large generators. Therefore, limited electrical power is reserved for smaller, critical components where compact heating elements are effective.

The TKS system works in two ways. First, the glycol lowers the freezing point of water. Second, the fluid flows back over the wing, creating a thin liquid film. Any ice that begins to form does so on this unstable liquid layer, not on the wing skin. Aerodynamic forces then easily shear off this poorly bonded ice before it can accrete into a dangerous shape.