Stress Analysis of the Phoenix Compacted Snow Runway to Support Wheeled Aircraft

Landing wheeled aircraft on snow runways is uncommon and minimally documented. This report describes the modeling used to evaluate design and construction of the new compacted-snow Phoenix runway in Antarctica for the first wheeled C17 aircraft landing. Snow density from the target design and snow density of the as-built Phoenix runway structure were used to determine basic elastic parameters for use in layered elastic analysis formulation (LEAF). LEAF is part of a software package developed by the Federal Aviation Administration (FAA) that allows for forward calculation of runway stress, strain, displacement, and associated principal stress and strain based on design aircraft loading. Stress responses for the Phoenix runway were modeled for the C17, A319, and B757 aircraft. Two construction vehicles were also modeled for comparison. Results show the comparison of the stress profiles and effect of subgrade stiffness on stresses in the layers just above the subgrade. This is the first time the model was used for a snow runway and it provided valuable insight for design, construction and runway performance for the first landing of the C17 on compacted snow. The model is flexible enough for simulating additional aircraft that might use the runway in the future. The successful construction and use of the new compacted-snow Phoenix runway is significant and demonstrates the heaviest wheeled aircraft (C17) operating on a compacted snow runway, ever.