Elevators
The main braking system uses Green hydraulics for normal operation and includes anti-skid. The alternate braking system uses Yellow hydraulics and typically has reduced anti-skid or no anti-skid functionality, and may also be activated by the accumulator if Yellow pressure is lost.
To transfer hydraulic power from the Green system to the Yellow system without transferring fluid.
APU FIRE PUSH
Cargo door operation
To automatically control the outflow valve and regulate cabin pressure and climb/descent rates.
To determine which ELAC is active and which is in standby, ensuring only one controls surfaces.
Load factor protection
ENGINE page
The CVR records audio from the cockpit (pilot voices, radio transmissions, ambient sounds) for accident investigation. The FDR records various flight parameters (speed, altitude, control surface positions, engine data) to reconstruct the flight path and aircraft state prior to an incident.
Blue
Landing Gear Control Interface Unit (LGCIU)
Blue
Slats and flaps extension
Each engine has fire detection loops connected to the FWC. Upon fire detection, a warning is issued. The system includes two fire extinguisher bottles, which can be discharged into either engine bay via a discharge button in the cockpit, cutting off fuel and hydraulics.
The APU provides electrical power and bleed air on the ground and electrical power in flight (up to specific altitudes). It has a maximum operating altitude for bleed air extraction and a higher one for electrical generation. It is designed for unattended operation but has start limits.
To increase drag, decrease lift, and assist with roll control.
Two
8.6 PSI
Green, Yellow, Blue
The APU bleed valve is open.
Automatically by the flight control computers
The fuel system consists of two wing tanks and one center tank, with fuel pumps to transfer fuel, jettison systems (on some variants), and a cross-feed system. Its primary function is to store fuel, supply engines and APU, and manage fuel distribution for balance.
The FMS integrates navigation, performance, and flight planning data. It allows pilots to input flight plans, calculate performance parameters, optimize routes, and guides the autopilot and autothrust systems throughout the flight.
The AFS includes the Autopilot (AP) and Autothrust (AT). AP modes control the aircraft's flight path (e.g., ALT HOLD, HDG SEL, NAV, V/S). AT modes control engine thrust (e.g., SPD, THR CLB, IDLE). Both work together to manage the aircraft's flight profile according to FMS programming or pilot inputs.
AC Essential
Ram Air Turbine
Normal braking uses Green hydraulics and has full anti-skid protection. Alternate braking uses Yellow hydraulics and typically has degraded anti-skid protection or none, and it is activated if normal braking fails, using accumulated hydraulic pressure if necessary.
Dedicated battery packs
Brake and Steering Control Unit
A category of ILS approach allowing for very low visibility landings (e.g., CAT IIIb with RVR as low as 50m).
ELAC (Elevator Aileron Computer)
Upon selection of the GEAR DOWN lever, the gear bay doors open, the main and nose landing gear extend, and then the doors close (or remain open depending on the specific door) once the gear is locked down. This sequence is hydraulically powered by the Green system.
Engine starting, thrust, and monitoring
To adjust the amount of air supplied to the cabin
Blue system powered by the RAT
Ground spoilers deploy automatically upon main landing gear compression after touchdown. Their purpose is to increase aerodynamic drag, destroy lift (dumping the wing's lift), and thereby maximize the effectiveness of the wheel brakes, ensuring a shorter stopping distance.
The A320 has a tricycle landing gear configuration with two main gear legs and a steerable nose gear. It is hydraulically actuated (Green system for normal operation) and electrically controlled. An alternate gravity extension system is available in case of hydraulic or electrical failure.
The pressurization system maintains a comfortable cabin altitude by regulating the outflow of cabin air using an outflow valve, controlled by two cabin pressure controllers (CPCs). It relies on bleed air for cabin air supply and operates automatically in normal flight.
The bleed air system taps hot, compressed air from the engine compressors or APU. This air is used for air conditioning, pressurization, engine starting, wing anti-icing, and hydraulic reservoir pressurization.
ADIRU (Air Data Inertial Reference Unit)
Direct Current
ELAC, SEC, FAC
The anti-icing system uses hot bleed air for the wings (outboard sections) and engine nacelles, and electrically heated windscreens, probes (pitot, static, AOA), and drain masts. Rain protection includes windshield wipers and rain repellent for the cockpit windows.
Power transfer unit
Maximum flap extended speed.
To cool, condition, and regulate the temperature and flow of bleed air for the cabin and cockpit.
The A320 has NORMAL, ALTERNATE, DIRECT, and MECHANICAL laws. NORMAL law provides full protections and flight path stability. ALTERNATE law engages after certain failures, offering reduced protections. DIRECT law means direct control surface movement from side stick input with no protections. MECHANICAL law is for severe failures, using rudder and THS via mechanical linkage.
The auto-brake system assists pilots during landing and rejected takeoffs by automatically applying wheel braking at a pre-selected deceleration rate or maximum effort. This reduces pilot workload and ensures consistent, optimized braking performance.
Circuit breakers protect against overcurrent due to short circuits by tripping, opening the circuit. Protection against open circuits (loss of connection) is not actively 'protected' in the same way, but system monitoring detects such failures and triggers appropriate warnings and redundancy activations.
Engine 1 driven pump
To suppress a fire in the APU compartment
The ECAM 'Auto Call' system automatically generates verbal callouts for certain flight phases (e.g., '1000 feet', 'RETARD', 'MINIMUMS') or specific warnings/cautions, ensuring critical information is audibly delivered to the crew, reducing workload and improving situational awareness.
It represents the FMS computed flight plan route.
APU generator
Auxiliary Power Unit
To control rudder, rudder trim, yaw damper, windshear detection, and provide speed and characteristic speeds computation.
In FADEC Normal mode, the FADEC automatically manages all engine parameters based on pilot thrust lever commands. In FADEC Manual mode (rarely used, usually for maintenance), the pilot has more direct control over specific engine parameters, bypassing some FADEC protections and automatic functions, primarily for engine starting and troubleshooting.
Engine driven generators
FADEC (Full Authority Digital Engine Control)
Flap surfaces
The ECAM system provides pilots with clear, concise information regarding system failures, presents checklists, outlines appropriate actions, and monitors system performance during abnormal operations, ensuring an organized response to malfunctions.
To provide trim air for temperature regulation in zones and anti-icing for water/waste pipes.
Accumulator
Center tank
FLEX thrust is a reduced thrust setting used for takeoff when runway and aircraft performance allow, prolonging engine life. TOGA (Take-Off Go-Around) thrust is maximum available takeoff thrust, used for maximum performance takeoffs or go-arounds in emergencies.
The emergency lighting system is battery-powered and consists of exit signs, floor path marking, and cabin lights. It can be armed (AUTO) from the cockpit and will automatically activate upon loss of normal aircraft power or severe deceleration. It can also be manually turned ON.
41,000 feet
To provide electrical power and bleed air on the ground or in flight (as backup).
24 quarts
The A320's electrical system automatically sheds non-essential loads (e.g., AC SHED bus, Galley bus) in the event of generator failure or reduced power availability to ensure essential systems remain powered. This prioritization maintains critical functions during abnormal electrical configurations.
Generate additional lift
To increase drag and reduce lift during landing to enhance braking.
DOOR/OXY
38 knots (for typical operations, check FCOM for specific values)
Flight Management System
In Normal Law, the flight control computers (ELACs, SECs, FACs) interpret pilot inputs from the side stick as demands for a specific flight path, attitude, or load factor, rather than direct control surface deflection. The computers then command the control surfaces to achieve these demands while providing protections like angle-of-attack, pitch, roll, and overspeed limits.
To control spoilers and provide backup control for elevators.
ECAM displays warnings (red, level 3, immediate action), cautions (amber, level 2, attention), and advisories (amber, level 1, monitoring). Warnings involve a Master Warning light, aural alert, and red message. Cautions involve a Master Caution light, single chime, and amber message.
The RAT is an emergency power source that deploys automatically in specific electrical or hydraulic failures (e.g., loss of both AC bus bars). It uses airflow to drive a hydraulic pump (for the Blue system) and an emergency generator, providing essential power to critical systems.
3000 PSI
ALPHA FLOOR is an autothrust protection that engages automatically when the aircraft approaches a critical angle of attack, commanding TOGA thrust regardless of thrust lever position. It aims to prevent a stall by increasing engine power, and remains active until a safe angle of attack is recovered.
GPS signal
To manually control the emergency generator and DC Essential Feed in case of power loss.
Aircraft batteries
AC SHED Bus
The crew oxygen system uses a high-pressure cylinder with individual masks for continuous flow. The passenger oxygen system uses chemical oxygen generators located above passenger seats, which activate automatically when cabin altitude exceeds approximately 14,000 feet, providing oxygen via drop-down masks for a limited duration.
TCAS is an airborne system that monitors the airspace around the aircraft for other transponder-equipped aircraft. It provides pilots with traffic advisories (TAs) and resolution advisories (RAs) to help prevent mid-air collisions, instructing pilots on vertical maneuvers.
Fuel-to-hydraulic heat exchangers
Minimum safe speed with slats extended and flaps retracted.
Three
Outboard wing leading edge
Autobrake 'MAX' applies maximum braking effort immediately upon touchdown or brake pedal release after a rejected takeoff. It is used for shortest stopping distances, typically in emergency situations or on contaminated runways.
A manual start is initiated by selecting the IGN/START mode, followed by opening the engine master lever when N2 reaches a specified percentage (e.g., 22%). The pilot monitors engine parameters for a normal light-off and acceleration. This bypasses some FADEC automatic sequencing.
To measure static air pressure for altitude and vertical speed indications.
The fuel jettison system allows for the rapid dumping of fuel to reduce the aircraft's weight to below its maximum landing weight. It involves dedicated jettison pumps and valves, typically in the outer wing, to discharge fuel overboard, usually controlled from the cockpit.
To control elevators, ailerons, and the horizontal stabilizer (THS).
The nose wheel steering system is hydraulically powered (Yellow system) and electrically controlled. It allows steering via a tiller in the cockpit and provides limited steering authority via rudder pedals. Its function is to maneuver the aircraft on the ground during taxi, takeoff, and landing.
Bleed air supply
Rudder
