Different landing rates in flight simulators (like MSFS 2020/2024, X-Plane) for seemingly similar landings are caused by a combination of software polling inconsistencies, aircraft weight, atmospheric conditions, and the specific methodology of third-party tracking tools.
Here are the primary reasons for these discrepancies:
1. Inconsistent “Polling Intervals” (Data Measurement)
Landing rate tracking tools do not usually measure the exact instant the tires touch the ground. Instead, they use a polling interval (checking simulation data every few milliseconds).
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The Issue: The simulator might register the landing at -100 fpm in one frame, but in the next frame, the plane settles, causing the tracker to record -250 fpm.
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Result: A “buttered” landing can often show a higher, firmer, or lower rate depending on when the app takes its data snapshot.
2. Variable Aircraft Weight and Balance
The landing rate is highly dependent on the aircraft’s current weight.
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Weight Sensitivity: An aircraft nearing its maximum landing weight requires a firmer touchdown (higher landing rate) to ensure positive ground contact, while a light aircraft can land much more softly.
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Momentum: Higher weight means higher momentum, which often results in a higher FPM (feet per minute) reading if the flare is not perfect.
3. Atmospheric Conditions (Wind and Turbulence)
Simulators often introduce variable wind gusts, which make consistent landing rates difficult.
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Wind/Gusts: A sudden drop in wind during the flare can cause the aircraft to settle faster, leading to a higher landing rate.
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Real-world vs. Sim: While real-world winds are often steady with a directional feel, simulator winds can sometimes feel unnaturally turbulent, causing inconsistency.
4. Approach Speed and Power Settings
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Insufficient Power: If power is reduced too early, the aircraft loses too much speed and stalls earlier than expected, causing a “harder” (higher FPM) landing.
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Speed Management: Maintaining the correct, consistent approach speed (roughly 5 times your ground speed in FPM) is crucial for a consistent, moderate rate.
5. Third-Party Monitoring Tools Differences
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Different Algorithms: Different monitoring tools (e.g., FSUIPC-based tools, Volanta, internal landing checkers) may calculate the touchdown moment or interpret FPM vs. G-force differently.
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“Hard Landing” Definition: Different Virtual Airlines (VAs) or tools have different thresholds for what they consider “firm” or “hard”.
6. Runway Slope and Surface
- Sloped Runways: If the runway has a significant incline or decline, the vertical speed, when referenced to sea level rather than the surface of the runway, will differ, leading to misleading landing rate readings.
7. Simulation Frame Rate (Sim Rate)
- Sim Rate Speed: Using a higher frame multiplier (speeding up the simulation) causes the physics engine to skip frames, which can lead to erratic landing data.