What is a simulator and how does it work?

A simulator is software, equipment or a combination of both that reproduces the behaviour of a real system, machine or environment. It works by taking user and environmental inputs, applying mathematical models and rules, updating the simulated state repeatedly, then presenting the result through graphics, sound, instruments, controls or physical motion.

How does a simulator work step by step?

Most computer simulators run a repeating input-process-output loop, often many times per second.

1. Set the initial conditions: The simulator loads the vehicle, location, weather, equipment state and other scenario variables.
2. Read the inputs: These may come from a keyboard, joystick, yoke, throttle, pedals, touchscreen, sensors or an automated test script.
3. Run the model: Mathematical equations and programmed rules calculate what should happen next. A flight model considers forces such as lift, drag, thrust and gravity; a train simulator may calculate traction, braking, adhesion and resistance.
4. Update the state: Position, speed, attitude, system conditions and environmental effects advance by one small time step.
5. Produce the output: The simulator updates the view, instruments, sounds, control forces, motion platform or recorded data before beginning the next cycle.

Interactive simulators usually keep simulation time close to real time. Engineering and research simulations can run faster or slower than real time and may produce charts or datasets instead of a visual scene.

For a cockpit-specific example, our explanation of the calculations behind a flight simulator shows how aircraft physics, systems, weather and visuals interact during this loop.

What does the simulation model include?

A model includes only the details needed for the simulator's intended purpose. It may represent physics, mechanical and electrical systems, human behaviour, traffic, weather, failures or operating rules.

No practical simulator reproduces every part of reality. Developers simplify effects that have little bearing on the intended task while modelling important behaviour more closely. In flight simulation, for example, the aerodynamic model and aircraft systems can have very different levels of detail even when the exterior graphics look convincing.

How accurate is a simulator?

A simulator is accurate only within the areas, conditions and tasks its model was designed to represent.

• Physical fidelity describes how closely movement and forces match the real system.
• Systems fidelity covers switches, instruments, computers, failures and operating logic.
• Environmental fidelity includes terrain, weather, traffic and other external conditions.
• Temporal fidelity concerns timing, update rates and how the model behaves as conditions change.
• Sensory fidelity covers visuals, sound, control forces and motion cues.

A mistake we see constantly is treating visual quality as proof of simulation accuracy. Detailed scenery can coexist with a simplified vehicle model, while a plain-looking engineering simulator may calculate its chosen subject very precisely.

Professional validation or certification also applies to a defined device configuration and training purpose. It should not be assumed that every installation of the same underlying software has the same approved capabilities.

Why can a simulator feel wrong?

Unexpected behaviour often comes from the configuration or controls rather than the core simulation model.

• Bad control calibration: Unwanted dead zones, duplicated assignments, reversed axes and noisy hardware can produce abrupt or constant inputs. Our guide to flight-simulator controls and their roles explains the common input options.
• Incorrect starting conditions: Weight, balance, weather, equipment state or assistance settings may not match the scenario being compared.
• Performance problems: Irregular processing can delay input response or visual feedback. Visual frame rate and physics update rate are not necessarily the same, so low frame rate alone does not prove that the model is calculating slowly.
• Model limitations: The simulator may simplify unusual conditions, damage, tyre behaviour, airflow near the ground or systems that fall outside its main purpose.
• Unrealistic expectations: A desktop monitor cannot reproduce acceleration forces, vibration, peripheral vision or physical risk without specialised hardware.

Is a simulator the same as a game?

A simulator describes how something is modelled, while a game describes an experience built around rules, objectives, challenge or progression.

One product can be both. A flight simulator may provide realistic aircraft operation alongside missions, scoring and multiplayer activities. Other simulations run automatically for engineering, forecasting or training and have no game structure at all. We cover that overlap in our explanation of how simulator games differ from conventional games.

What is the difference between a simulator and an emulator?

A simulator recreates the behaviour or results of a system, whereas an emulator reproduces another system's operating environment closely enough to run software or behave like that original system. The terms sometimes overlap, but an emulator normally focuses on compatibility; a simulator focuses on representative behaviour.

Does every simulator need special hardware?

No; many simulators work with an ordinary computer, console or mobile device, although dedicated controls can make the interaction more natural.

Home flight and train simulators commonly add throttles, yokes, joysticks, pedals, instrument panels or multiple displays. Full-size training installations may also use replica controls, enclosed cockpits, projected visuals and motion systems. Those additions improve the interface and sensory cues, but they do not automatically make the underlying model more accurate.

How should you judge a simulator?

Choose a simulator by the task it must perform, not by its screenshots or the number of features advertised.

• For learning procedures, prioritise correct controls, instruments and systems logic.
• For practising vehicle handling, prioritise the physics model, input response and suitable control hardware.
• For route or location familiarisation, prioritise accurate terrain, navigation data and environmental representation.
• For entertainment, balance realism against accessibility, available content and computer performance.
• For formal training or engineering work, require evidence that the complete configured system is validated for that specific use.