Soft Ground Arresting System for Airports

Aircraft can and do overrun the ends of the runway, sometimes with disastrous consequences. Safety overrun areas are designed to provide an additional 1,000 feet of length for stopping overrunning aircraft. At many airports, however, the additional 1,000-foot safety area is not available. At these locations, soft ground arresting systems can be employed to decelerate or stop an overrunning aircraft. A mathematical model representing the interface between the aircraft and the soft ground was developed. This model was used to predict aircraft gear loads, deceleration, and stopping distance within the soft ground system. The validity of the mathematical model was confirmed by eight tests with use of an instrumented Boeing 727 aircraft. A phenolic foam bed 680 feet long by 48 feet wide and 18 inches deep was used to demonstrate the effectiveness of safely stopping a Boeing 727 aircraft entering the bed at 50 knots and 60 knots; at 50 knots the aircraft came to a complete stop in 420 feet and at 60 knots in 540 feet. The aircraft was successfully extracted from the bed, the foam was successfully repaired, and airport rescue and fire fighting equipment and personnel were able to maneuver without difficulty on the foam.