In Airbus fly-by-wire aircraft, ELAC is one of the most important control computers responsible for pitch, roll, and speed-brake management. Together with SEC and FAC computers, ELAC ensures smooth, stable, and safe aircraft control in all flight phases.
ELAC
What Does ELAC Mean in Airbus?
ELAC stands for Elevator and Aileron Computer.
Airbus aircraft such as the A320, A330, and A340 use multiple ELAC computers to control:
Elevators
Ailerons
Trimmable Horizontal Stabilizer (THS) trimming commands)
Speed brakes
Ground spoiler arming
Pitch and roll logic
ELAC is a critical component of the Airbus Fly-By-Wire (FBW) system.
How Many ELAC Computers Are on Airbus Aircraft?
Most Airbus models have two ELAC computers:
ELAC 1 – Primary control
ELAC 2 – Redundant backup
If ELAC 1 fails, ELAC 2 automatically takes over to maintain flight safety.
Core Functions of ELAC
ELAC handles several essential flight-control tasks. These tasks vary slightly by Airbus model, but generally include:
1. Pitch Control
ELAC uses elevator surfaces to maintain aircraft pitch.
It receives input from:
Pilot sidesticks
Auto-pilot
Flight control laws
Flight computers
It then converts these inputs into precise elevator movements.
2. Roll Control
ELAC commands ailerons to control roll, especially at low speeds, where aileron authority is greater than spoiler authority.
At higher speeds, roll control is shared with SEC-controlled spoilers.
3. THS Trim Commands
Although the Flight Control Computers generate the trimming orders, ELAC often sends commands to the Trimmable Horizontal Stabilizer (THS) for pitch trimming.
4. Speed Brake Control
ELAC manages speed brake deployment during:
Approach
Landing
Descent
Spoiler arming on the ground
This ensures correct drag and descent control.
5. Ground Spoilers on Touchdown
ELAC controls the automatic deployment of ground spoilers when the aircraft:
Has weight on wheels
Thrust levers are at idle
Speed brake lever is armed
This increases braking efficiency on landing.
ELAC and Airbus Flight Control Laws
ELAC plays a major role in implementing Airbus flight control laws, including:
• Normal Law
Provides full protections:
Pitch stability
Roll protection
Load factor limitation
High and low speed protections
• Alternate Law
Used when system components fail. Fewer protections are available.
• Direct Law
Sidestick inputs are transmitted directly to control surfaces, with no flight-law protections.
ELAC helps determine which law the aircraft is operating in based on system health.
What Happens If an ELAC Fails?
Airbus aircraft are designed with redundancy, so a single ELAC failure is not critical.
If ELAC 1 fails:
ELAC 2 automatically takes over
Some advanced protections may downgrade
Flight crew sees alerts on the ECAM
If both ELAC computers fail:
SEC computers take over elevator & roll control
Some protections drop to alternate or direct law
Automatic spoiler deployment may be affected
Autopilot disconnects
Despite this, the aircraft remains fully controllable.
Common ECAM Messages Related to ELAC
Pilots may see alerts like:
ELAC 1 FAULT
ELAC 2 FAULT
ELAC PITCH FAULT
ELAC ROLL FAULT
ELAC MONITORING
These alerts let the crew know which functions have been degraded.
Why ELAC Is Essential in Airbus Fly-By-Wire
ELAC brings major advantages:
✔ Increased aircraft safety
Redundant computers ensure control even during failures.
✔ Precision flight control
Digital systems provide smooth, accurate surface movement.
✔ Reduced pilot workload
Automatic trimming, spoiler management, and roll authority reduce manual tasks.
✔ Enhanced efficiency
Better control logic improves fuel efficiency and performance.
✔ Integration with protections
ELAC helps enforce Airbus’ famous flight envelope protections.
Future of ELAC in Next-Generation Airbus Aircraft
Airbus continues to enhance control computers with:
Smarter algorithms
AI-based failure prediction
Improved redundancy
Faster data processing
Enhanced flight envelope protection
Future aircraft may integrate ELAC into unified flight management systems.
Conclusion
What Is ELAC in Airbus?
ELAC is one of the core brains of Airbus flight control, managing elevator and aileron movement, pitch and roll control, and speed brake functions. Without ELAC, the aircraft would lose major flight capabilities.
Its redundancy, precision, and integration with fly-by-wire laws make it one of the most critical systems in Airbus aircraft.
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