An aircraft overrun occurs when an aircraft is unable to stop within the runway design length. Although the airline industry has an impressive safety record, overruns occur. Consequently, commercial airports are required to have a 305m (1000-ft) runway safety area (RSA) at each runway end to avail an aircraft adequate length for stoppage during an overrun. At airports where this space is unavailable, the FAA allows for an airport to use an Engineered Materials Arrestor System (EMAS). An EMAS is positioned within the RSA and is comprised of an energy absorbing material that brings the aircraft to stoppage through drag forces developed at the tire-EMAS interface. EMAS are constructed using low-density 1.21m x 1.21m (4-ft x 4-ft) variable thickness cementitious blocks. The blocks are aligned adjacent to one another to form a rectangular EMAS bed within the RSA.
Idea No. 168