Full-Flight Simulator

Overview

A full-flight simulator is the only machine in which an airline pilot can legally complete an entire type rating, first landing in the real aircraft happens with passengers aboard. To earn that authority, a Level D device must reproduce one specific aircraft type so faithfully that regulators accept simulator hours as flight hours: a Replica Cockpit built from the same part numbers as the aircraft, a six-axis Motion Platform, a collimated Visual System, and a flight model validated point-by-point against flight-test data. The complete machine weighs about 12 tonnes on the moving side, costs US$10–15 million, and runs up to 20 hours a day.

Motion: the washout trick

The cabin sits on a Stewart platform, six Electric Motion Actuator legs between a Base Frame on the foundation and an Upper Frame under the cabin, each leg swinging on two Gimbal Joint universals. Coordinating six leg lengths produces any combination of pitch, roll, yaw, surge, sway and heave within roughly ±34 degrees and ±1.4 m. Modern platforms are electric: each leg pairs a 30 kW Servo Motor with a Ball Screw, replacing the hydraulic rams (and their pump rooms, accumulators and oil) that dominated the type until the 2010s.

A platform with 1.5 m of stroke obviously cannot reproduce a 3,000 m takeoff roll. The Motion Controller therefore runs washout algorithms: it renders the onset of each acceleration faithfully, then bleeds the platform back to neutral below the vestibular threshold of about 0.05 g, where the inner ear cannot detect the cheat. Sustained longitudinal acceleration is faked by tilting the cabin backward so gravity supplies the push, with the visual scene held level, the brain reads the tilt as thrust. Motion cueing is psychophysics as much as mechanics, and the Vibration Shaker units under the floor fill in everything too high-frequency for the legs: runway rumble, buffet, the thump of gear into wells.

Vision at infinity

The visual problem is that two pilots sit a metre apart but must both see the runway in the correct direction. A direct screen a few metres away would give each pilot a different parallax. The solution is collimation: three Projector units throw an edge-blended 200 × 40 degree scene onto a Back-Projection Screen above the cockpit, and the crew views its reflection in a Collimating Mirror, a vacuum-tensioned aluminised mylar membrane curved to about a 3 m radius. The mirror places the image at optical infinity, so both seats see the scene in the same direction with relaxed focus, exactly as out a real windscreen. The Image Generator renders airport databases at 60 Hz; regulators cap total transport delay, control input to correlated visual and motion response, at 100 ms, since latency between cue systems is what makes simulators induce nausea and negative training.

The cockpit and its forces

Inside, fidelity is literal: the Glareshield, Centre Pedestal and Overhead Panel are aircraft parts or exact replicas, the displays are real LCD Panel units driven through the Avionics Interface Unit on ARINC 429 buses, and crews strap into aircraft Seat Assembly hardware. What the pilot's hands feel comes from Control Loading Unit units on the column, wheel and pedals: a Servo Motor and Force Transducer close a force loop at 2 kHz, reproducing the measured force-versus-displacement curves of the real aircraft, including breakout friction, trim shifts and the heavying of controls with airspeed. Control feel is among the most heavily checked items in certification because pilots transfer motor memory directly from this hardware to the aircraft.

The Host Computer System runs the aerodynamic, engine and systems models, supplied as a validated data package by the airframe manufacturer, on redundant Host Computer servers, synchronised with motion, visual and sound over deterministic Network Switch Ethernet. The Sound and Vibration System reproduces engine spool, airflow and precipitation noise through eight Speaker channels to certification tolerances measured in decibels.

Training and certification

Behind the pilots, the instructor works from the Instructor Operating Station: two Touch Digitizer consoles from which they reposition the aircraft to short final at Innsbruck, set 200 m RVR fog, fail an engine at V1, or freeze the simulation for debrief. This is the point of the machine, the failures rehearsed here (windshear escapes, dual hydraulic loss, rejected takeoffs) are exactly those that cannot be practised in an aircraft.

Certification is continuous, not one-time. A Qualification Test Guide defines hundreds of automated test points, control sweeps, takeoff rotations, engine-out climbs, each compared against flight-test data within tolerances of a few percent, re-run quarterly and witnessed annually by the regulator. Crews board across the Boarding Ramp, whose interlock Relay chain must prove the drawbridge retracted before the platform will move: a 12-tonne cabin sweeping through its envelope shares the hall with nothing.