Behavior of Unsurfaced Airfields Supporting Operations of C-17 Aircraft

Abstract

The C-17 Globemaster III aircraft was developed by McDonnell Douglas (now Boeing) with the capability of transporting equipment and cargo to small airfields with short runways and minimal ground support equipment. The introduction of the C-17 into the U.S. Air Force’s inventory initiated the requirement to validate existing semiprepared (unsurfaced, aggregate surfaced, and stabilized) airfield design and evaluation criteria for the operation of the C-17 aircraft. The U.S. Army Engineers Waterways Experiment Station was requested by the U.S. Air Force to characterize the structural capacity of selected semiprepared test sites and document each airfield’s behavior under actual C-17 aircraft operations. The results of three live-flight tests indicate that the current U.S. Army Corps of Engineers unsurfaced airfield criteria does not adequately predict the behavior of unsurfaced airfields in arid or semiarid climates subjected to the braking and turning forces of a 226,800-kg (500,000-lb) aircraft. This investigation presents the results of the field tests and includes a regression model that can be used to predict the behavior of unsurfaced airfields in semiarid/arid environments under C-17 aircraft traffic.