Learn how automatic spoilers deploy after landing, which touchdown signals trigger them, and what to check when they stay retracted in a simulator.
In real-world aviation and accurately modelled flight simulators, automatic ground spoilers deploy when the system is armed and touchdown is confirmed by main-wheel spin-up, landing-gear weight-on-wheels sensing, or both, normally with thrust at idle. The raised panels dump lift, putting more aircraft weight on the tyres for effective braking.
How does the aircraft know it has landed?
The aircraft declares itself on the ground only when the required combination of arming, thrust and touchdown signals is satisfied. Touching the runway is not necessarily enough; the exact logic varies between aircraft types.
| Input | What it tells the system | Common caveat |
|---|---|---|
| Spoiler lever armed | Automatic deployment is permitted | ARM is a standby position, not a command to raise the panels |
| Thrust levers at idle | Landing is intended and spoiler deployment is safe | A miscalibrated simulator throttle may remain slightly above idle |
| Main-wheel spin-up | The wheels have contacted a moving runway surface | Only aircraft designs using wheel-speed logic require this signal |
| Weight-on-wheels or air/ground signal | The landing-gear strut has compressed under aircraft weight | A one-wheel crosswind touchdown may delay the required signal |
| Reverse selection | Provides an additional landing confirmation on some aircraft | This is type-specific and should not replace normal arming |
Weight-on-wheels does not usually mean a literal weighing device. It is an air/ground signal produced by compressed shock struts, proximity sensors or related landing-gear components. Our explanation of landing-gear load transfer and ground sensing covers that mechanism in more detail.
Some jets stage the sequence: selected flight-spoiler panels rise after wheel spin-up, followed by additional ground-spoiler panels when the landing gear compresses. Other aircraft use a different combination or deploy the panels together. Automatic deployment works after either a manual landing or an autoland; it is not dependent on the autopilot.
What physically raises the spoiler panels?
Once the deployment conditions are valid, the spoiler control system commands the actuators that raise the selected panels. Transport jets normally use hydraulic actuators controlled through valves and electronic or mechanical logic, although the arrangement differs by aircraft.
The result is primarily lift dump, not just extra aerodynamic drag. Removing wing lift places more weight on the main wheels, improving tyre grip, wheel-brake effectiveness and directional control. Some panels also serve as in-flight speed brakes or roll-control surfaces; see how the different spoiler panels control lift, drag and roll.
Depending on the cockpit design, the speedbrake lever may move automatically to an extended position, remain in its armed detent, or be accompanied by a dedicated indication. Autobrakes and reverse thrust are separate systems, even though they work alongside the spoilers and may use related ground signals.
Do all aircraft have automatic ground spoilers?
No. Automatic ground-spoiler systems are common on airliners and many business jets, but the exact deployment logic is aircraft-specific. Light aeroplanes often have no spoilers, while gliders and some other aircraft normally use manually controlled airbrakes or lift-dump devices.
Always use the checklist and indications for the aircraft being flown. Boeing and Airbus logic should not be assumed to be interchangeable, and simplified simulator aircraft may reproduce only the visible animation rather than the complete system.
Why do spoilers sometimes fail to deploy after touchdown?
Most apparent failures result from an unarmed lever, thrust not reaching idle, incomplete touchdown sensing or a conflicting simulator control assignment.
- The lever was not armed: selecting ARM before landing is normally required. Do not select full extension in the flare unless the aircraft's approved procedure explicitly calls for it.
- The throttles are not truly idle: hardware noise, an incorrect detent or poor axis calibration can leave a small amount of commanded thrust and inhibit deployment.
- Only one main gear is down: during a crosswind landing or bounce, the logic may wait for another wheel-speed or strut-compression signal.
- A binding keeps commanding retract: duplicate keyboard, joystick and throttle-quadrant assignments can fight the automatic command.
- The aircraft model is simplified: some simulator aircraft omit automatic logic or tie the animation to conditions different from the real aeroplane.
- A system failure is active: hydraulic, electrical, sensor or spoiler-control failures may prevent some or all panels from rising.
On a Boeing 737, the speedbrake lever, thrust settings and touchdown signals have model-specific roles. Our 737-specific speedbrake arming and deployment guidance explains the normal cockpit procedure.
What should I do if the spoilers stay down in a simulator?
Once the aircraft is firmly on the runway with thrust at idle, manually deploy the ground spoilers if the simulated aircraft's procedure permits it. Do not look down and troubleshoot during an uncertain bounce or while directional control demands your attention.
- Confirm touchdown: make sure the main gear is settled on the runway rather than briefly skipping or bouncing.
- Set idle thrust: bring the thrust levers fully into their idle detent and check that the simulator registers idle.
- Check the indication: look for the spoiler annunciation, synoptic display or lever movement appropriate to that aircraft.
- Deploy manually if required: select the speedbrake or ground-spoiler lever to its landing position only after positive ground contact.
- Continue the landing roll: maintain centreline control and use wheel braking and reverse thrust as applicable. Our complete simulator landing-roll sequence covers how these systems work together.
- Troubleshoot after clearing: inspect spoiler bindings, throttle calibration, failure settings and the aircraft documentation once safely off the runway.
In a real aircraft, pilots must follow the aircraft's approved checklist rather than substitute a generic manual-deployment technique.
What happens during a bounced landing or go-around?
A one-main-wheel touchdown or brief bounce can delay deployment, produce only partial deployment, or cause the spoilers to retract again as the ground signals change. That behaviour may be normal for the particular system rather than a fault.
Advancing the thrust levers for a go-around normally retracts or inhibits automatic ground spoilers on transport aircraft, but the exact logic remains type-specific. If spoilers deploy during a bounce, the sudden loss of lift can produce a firm second contact, so avoid moving the lever manually until the aircraft is unquestionably on the ground or committed to the go-around.