Flight Control Systems & FBW
This type of flight control system uses mechanical cables, pulleys, and push-pull rods directly connected between pilot controls and control surfaces without hydraulic or electronic assistance
What is a Manual Flight Control System?
Manual systems rely entirely on the pilot's muscle power to overcome aerodynamic hinge moments acting on control surfaces
Located directly above the pilots' heads, this cockpit panel houses switches for electrical power generation, fuel management, engine starting, and environmental control
What is the Overhead Panel?
The overhead panel organizes system control units (such as APU, hydraulics, fuel pumps, and lighting) within easy reach of both crew members
This international Very High Frequency (VHF) carrier frequency is reserved globally for aviation emergency and distress monitoring
What is 121.5 MHz? (Military UHF distress is 243.0 MHz)
Standard civil aviation voice communications operate within the 118.000 to 135.975 MHz VHF air band.
The minimum number of satellite pseudorange measurements required by a GPS receiver to solve for a 3D position (latitude, longitude, altitude) and receiver clock bias
What is Four (4) satellites?
Four simultaneous equations are needed to solve for four unknown variables: x, y, z space coordinates and receiver clock bias offset Delta t.
The standard electromechanical grouping of six primary flight instruments arranged in a standardized layout on the main instrument panel
What is the Basic 'T' (or Basic Six) layout?
The "Basic T" centers the Attitude Indicator, flanked by Airspeed Indicator (left), Altimeter (right), and Heading Indicator (bottom)
Unlike an Autopilot which controls full flight path trajectories, this lower-level control system automatically dampens short-period aircraft oscillations (like Dutch roll) without moving cockpit controls
What is a Stability Augmentation System (SAS)?
SAS uses rate gyros and feedback actuators to enhance inherent aerodynamic damping, stabilizing pitch, roll, or yaw rates
This modern flight deck display concept replaces individual electromechanical "clockwork" round dials with multi-function Electronic Flight Instrument System (EFIS) CRT or Active Matrix LCD screens
What is a Glass Cockpit?
Glass cockpits centralize flight, navigation, and engine data on customizable Primary Flight Displays (PFD) and Navigation Displays (ND), reducing pilot scan workload
This ground-based radio navigation aid operates in the 108.00–117.95 MHz band and provides 360-degree radial magnetic bearing information to an aircraft
What is VOR (VHF Omnidirectional Range)?
VOR compares the phase angle between a non-directional reference signal and a rotating directional signal to compute magnetic bearing
An autonomous onboard navigation system that uses a combination of accelerometers and gyroscopes to calculate position by continuous dead reckoning without external ground signals
What is an Inertial Navigation System (INS) / Inertial Reference System (IRS)?
INS double-integrates measured linear accelerations over time. Because it is self-contained, it is completely immune to external jamming, but suffers from integration drift over long flights
This central computing unit processes raw total stagnation pressure (p_0) and ambient static pressure (p) from pitot-static probes to calculate Indicated Airspeed, Mach number, and Pressure Altitude
What is an Air Data Computer (ADC)?
The ADC eliminates mechanical leverage linkages by using solid-state pressure transducers and sending digital air data across ARINC 429 databuses
In an Airbus A320 Fly-By-Wire system, if the primary computer (FCPC) fails, control automatically degrades to this secondary computer to handle ailerons, elevators, and yaw damping
What is the Flight Control Secondary Computer (FCSC)?
Airbus FBW architecture features three Flight Control Primary Computers (FCPC) for normal control laws and two Flight Control Secondary Computers (FCSC) for backup reconfiguration
A pilot needs to enter a new flight plan route, execute performance calculations, or set waypoints on an integrated airliner flight deck. This center console unit serves as the tactile keyboard/display interface
What is the Multifunction Control and Display Unit (MCDU / CDU)?
The MCDU located on the pedestal panel allows pilots to interface directly with the Flight Management System (FMS) computers
If an ILS approach localizer carrier operates on 110.3 MHz, calculate the free-space signal wavelength lambda (assume speed of light c = 3 times 10^8 m/s)
What is 2.72 meters?
Using lambda = c/f:
lambda = 3 times 10^8 m/s //110.3 times 10^6 Hz
approx 2.7198 m
An airborne GPS software feature that uses redundant satellite signals (minimum 5 satellites) to independently detect and isolate a faulty satellite signal without ground assistance
What is RAIM (Receiver Autonomous Integrity Monitoring)?
RAIM compares pseudorange solutions from overlapping satellite subsets. 5 satellites enable fault detection, while 6 satellites allow fault detection and exclusion (FDE)
An uncompressed pitot tube measures a total pressure p_0 = 103,825 N/m^2 and static pressure p = 101,325 N/m^2. If sea-level air density rho = 1.225 { kg/m^3, calculate the indicated airspeed V
What is 63.89 m/s (or ~124.2 knots)?
q = 103,825 - 101,325 = 2,500 N/m^2
Compare Boeing 777 and Airbus A330/A340 FBW architectures: Boeing uses three Primary Flight Computers (PFC) interfaced via ARINC 629 data buses to drive four of these intermediate units that directly interface with hydraulic actuators
What are Actuator Control Electronics (ACE) units?
On the Boeing 777, PFCs process digital control laws and send commands across A629 buses to 4 ACEs, which convert digital signals to analog hydraulic actuator drive commands
Analyze the display architecture of a dual EFIS suite: If the Captain's primary Symbol Generator (SG) fails in flight, how does the system maintain display redundancy on the Captain's PFD/ND?
What is switching to a third (Center / Hot Spare) Symbol Generator (SG)?
Civil EFIS installations include a third Center SG connected via electromechanical relays. The pilot uses an instrument source selector switch to reroute drive signals instantly
Differentiate the Instrument Landing System (ILS) frequency pairings: The Localizer (lateral guidance) operates in VHF (108–112 MHz), while the Glide Slope (vertical guidance) operates in this higher frequency band
What is the UHF (Ultra High Frequency) band (329.00–335.00 MHz)?
ILS pairing rules automatically tune the corresponding UHF Glide Slope receiver channel when the pilot selects the VHF Localizer frequency
Analyze multi-sensor integration in modern Flight Management Systems (FMS): Why does an FMS continuously combine GPS position updates with INS measurements using a Kalman Filter?
What is to combine the high short-term dynamic accuracy of INS with the long-term drift-free accuracy of GPS?
INS provides instant response without signal dropouts but drifts over time. GPS corrects INS integration drift, while INS provides smooth navigation data if GPS signals are temporarily obstructed
Differentiate between EICAS (Boeing) and ECAM (Airbus) engine/system monitoring displays regarding their presentation philosophy during system failures
What is ECAM provides step-by-step corrective action checklists on-screen, whereas EICAS displays parameter warnings/cautions with manual checklist procedures?
ECAM (Electronic Centralized Aircraft Monitor) actively displays affected system synoptics alongside remediation steps. EICAS (Engine Indication and Crew Alerting System) focuses on primary engine metrics and message alerts
Evaluate the safety trade-off between Airbus "Hard Limits" and Boeing "Soft Limits" in Fly-By-Wire flight envelope protection philosophy.
What is: Airbus hard limits prevent the pilot from ever exceeding pitch/roll/G-limits regardless of stick force, whereas Boeing soft limits allow the pilot to override protections by applying extra yoke force in extreme emergencies?
Airbus prioritizes structural/stall prevention by enforcing absolute flight envelope limits. Boeing maintains final pilot authority, allowing envelope boundary overrides via tactile feedback resistance
Evaluate the human factors advantage of using Active Matrix Liquid Crystal Displays (AMLCD) over older Cathode Ray Tube (CRT) displays in modern transport cockpits
What is higher brightness/contrast in direct sunlight, significantly lower weight and power consumption, lower depth, and higher thermal reliability?
AMLCDs eliminated high-voltage CRT power supplies and heavy glass envelopes while providing glare-free visibility under direct cabin sunlight
Evaluate why civil aviation transitioned from 25 kHz to 8.33 kHz channel spacing in the VHF air band across European airspace
What is to triple the number of available voice channels in congested airspace and prevent frequency saturation?
Splitting each 25 kHz channel into three 8.33 kHz sub-channels expanded the available spectrum capacity without requiring additional radio frequency allocations
Evaluate the operational distinction between Satellite-Based Augmentation (WAAS) and Ground-Based Augmentation (LAAS/GBAS) for Category III precision autoland approaches
What is LAAS provides localized VHF differential corrections with sub-meter accuracy (~1 m) required for Cat III autoland, whereas WAAS provides regional geostationary corrections (~7 m) suitable for Cat I approaches?
LAAS places reference receivers directly at the airfield, broadcasting ultra-high precision corrections to meet stringent Category III vertical guidance integrity limits
Evaluate the safety critical risk of a blocked pitot tube drain hole during a high-altitude climb, and describe how the Airspeed Indicator (ASI) will erroneously behave
What is the ASI will act like an altimeter, falsely indicating an increase in airspeed as altitude increases?
If the pitot probe tip and drain hole freeze shut, trapped pressure p_0 remains constant inside the diaphragm. As the aircraft climbs, ambient static pressure $p$ drops, causing q = p_0 - p to expand the diaphragm and register false speed increases.