Aircraft Vibration Responses to Terrain-Induced Boundary-Layer Flow Variability during Low-Altitude Flights

General aviation (GA) and emerging urban air mobility (UAM) operations are primarily conducted at low altitudes within the atmospheric boundary layer (ABL), where aircraft are directly exposed to turbulence generated by complex terrain. Despite its operational importance, the physical mechanisms linking boundary-layer flow structures to observed aircraft vibration and response characteristics remain insufficiently understood. This limitation is particularly critical in terrain-influenced ABL environments, where flow variability is dominant and conventional turbulence metrics, such as the eddy dissipation rate (EDR), may provide limited insight into aircraft response characteristics.

In this study, aircraft vibration responses observed during low-altitude flights within the ABL over Jeju Island are analyzed using high-frequency (100 Hz) three-axis acceleration data collected from a Cessna aircraft operating at altitudes of 1,000–2,000 ft AGL. Flight segments near mountainous terrain exhibit relatively enhanced aircraft vibration responses compared to surrounding regions. Root-mean-square (RMS) acceleration and power spectral density (PSD) analyses are employed to examine the directional dependence and anisotropic characteristics of aircraft responses under low-altitude turbulent conditions.

To interpret the observed aircraft responses from an ABL physics perspective, numerical simulations are conducted using a high-resolution atmospheric flow model capable of resolving terrain-induced boundary-layer flow structures. These simulations are intended to analyze the spatial and temporal relationships between terrain-modified ABL flow variability and the locations and times at which enhanced aircraft vibration responses are observed.

Rather than treating aircraft acceleration as a direct measure of atmospheric turbulence intensity, this study interprets it as a manifestation of aircraft response to localized ABL flow variability shaped by complex terrain. Through this approach, the study explores the potential of terrain-resolving numerical simulations as an interpretative tool for linking boundary-layer flow structures with low-altitude aircraft responses. The findings of this work are expected to provide meaningful implications for low-altitude flight safety assessment, UAM corridor design, and the applied extension of ABL research.