Stick the Landing - Performance, Handling, and Motion Tests for Landing in Your Helicopter Simulator

Landing a helicopter smoothly and safely takes skill, precision, and a solid understanding of the aircraft's behavior. For those involved in rotary wing simulator training and seeking EASA qualification, demonstrating the simulator's ability to accurately represent the complexities of landing is essential. This involves a range of rigorous tests, both objective and subjective, as detailed in EASA CS-FSTD(H). Let's take a look at some of the key areas and tests that focus on the landing phase.

Interestingly, the very definition of a less-than-perfect landing can vary. Following a recent helicopter incident involving Iranian President Raisi, former helicopter pilot Ash Alexander-Cooper explained that a "hard landing" can range from a minor bump causing slight damage to a much more serious, even "catastrophic incident." This highlights the spectrum of landing scenarios that a comprehensive simulator should be capable of representing.

EASA Qualification Tests for Helicopter Landing Simulation

To get an EASA stamp of approval for a rotary wing simulator that includes landing scenarios, several tests come into play, varying by the Flight Simulation Training Device (FSTD) level (FFS, FTD, or FNPT).

Measuring Against the Data (Objective Tests)

These tests involve precise measurements compared to real helicopter data. When it comes to landing, several performance and handling tests are particularly important.

Performance Tests, Including Landings

These tests check how well the simulator mimics the helicopter's performance during different landing scenarios.

• Normal Landing (All Engines Operating): This test looks at things like airspeed, the helicopter's nose angle (pitch), the angle of the blades to the oncoming air (angle of attack), height above the ground, the position of the controls, and how fast the helicopter is descending (vertical speed) during a typical landing. Accurate readings here are key to judging how realistic any landing feels, even one with a higher impact.

• Landing (One Engine Inoperative - OEI): For helicopters with more than one engine, this test assesses how the simulator behaves when landing with a single engine not working. Correct simulation of control and performance in this challenging situation is vital, as it could lead to a hard landing. The standards for this test apply at airspeeds above a certain lift threshold for more advanced simulators.

• Auto-rotational Landing: This test examines how the simulator slows down during an emergency landing where the rotors are driven by airflow, not engine power. The simulator's response during this critical procedure is very important.

Handling Qualities, Including Control Response

These tests evaluate how the simulator reacts to a pilot's actions on the controls during different parts of flight, including hovering and landing.

• Control Response (Longitudinal, Lateral, Directional): These tests measure the rates and changes in pitch, roll, and yaw in response to sudden control inputs, often while hovering. Accurate control response is fundamental for all flight phases, especially the final moments of landing where poor control could cause a heavy impact. The simulator should also show the correct related movements (off-axis responses) when no automatic systems are assisting the pilot.

Ground Effect

A specific test should confirm the accuracy of how the simulator models the changes in airflow and lift that happen when the helicopter is close to the ground. Proper simulation of ground effect is crucial during landing and for showing the dynamics that could affect the force of touchdown. Suitable tests involve scenarios very near the ground.

Motion System Tests

If the simulator has a motion platform, its performance and the sensations it provides during landing are checked.

• Motion Cues: These tests should show that the initial sensations of movement in each direction (pitch, roll, yaw, vertical, lateral, longitudinal) are correctly timed with the pilot's control inputs and the simulated helicopter's response. This includes the feeling of touchdown being related to the simulated rate of descent.

• Specific tests for the range of motion (how far it can move), speed, and acceleration in each direction are defined based on the simulator's level. How realistic these sensations feel to the pilot during landing is important.

• Touchdown Bump: For higher-level simulators (FFS), the motion system should provide sensations that represent touchdown, although specific objective measurements might be less common here.

Visual System Response

• Visual Cues: The visual system must provide cues that allow the pilot to judge their rate of descent, sideways and forward/backward movement, and speeds during takeoff and landing. These visual cues are essential for the pilot's perception during approach and touchdown, influencing their control inputs that can lead to a normal or hard landing.

• Visual Response Time (Transport Delay): Tests measure the time delay between a control input and when the visual system shows the result. Too much delay can negatively affect the simulation of quick events like a hard landing.

Pilot Assessment (Functions and Subjective Tests)

These tests involve a qualified and experienced pilot evaluating the overall behavior and realism of the simulator.

• Landing: This includes assessing normal landings. The pilot will judge the overall feel and how realistic the landing seems, which would naturally include the simulation of different touchdown forces.

• Abnormal/Emergency Procedures: Several emergency scenarios are listed, such as failures of hydraulic or stability systems. Simulating these failures leading to a landing is critical, and how realistic the resulting touchdown feels (which could be heavy) will be judged by the pilot.

• Balked Landing (Go-Around): Procedures for stopping a landing approach and going around again, both with all engines working and with one or more not working, are evaluated. The transition from being close to landing to a go-around, especially after a potentially unstable approach, is relevant.

• Motion Effects: The pilot will subjectively assess the motion cues during various flight phases, including those related to ground contact, such as the feeling of rolling on a runway (or the helicopter equivalent). This contributes to the overall impression of the landing.

• Visual System: How accurately the visual environment matches the simulator's attitude and position is crucial during the landing phase. Visual scenes that show realistic situations known to cause landing illusions, like sloping landing areas, are also important, as these could lead to pilot actions that result in a heavy landing.

• Sound System: Realistic engine and rotor sounds are important, as are other cockpit sounds that might change during a hard landing.

Qualification Levels and Details

The specific tests and the level of detail required in the simulation depend on the desired qualification level of the FSTD. Higher levels generally demand more thorough objective and subjective testing with tighter limits and a more accurate representation of the helicopter's behavior and systems.

In short, achieving EASA qualification for a rotary wing simulator capable of representing heavy landings means ensuring the simulator meets the objective test requirements for normal and potentially abnormal landings, handling, ground effect, motion, and visual systems, as outlined in CS-FSTD(H). Furthermore, a qualified pilot's subjective assessment will evaluate the overall realism and how well these systems work together during landing scenarios, including those where a hard touchdown might occur due to pilot actions or simulated failures. The Master Qualification Test Guide (MQTG) will provide the specific test procedures and acceptance standards for the chosen qualification level.

This detailed look at the EASA qualification process underscores the importance of accurately simulating all aspects of helicopter flight, especially the critical and complex maneuver of landing.