What is an airport EMAS?

EMAS stands for "Engineering Materials Arresting System." Such systems consist of materials designed or engineered to collapse or crush in a controlled manner in order to absorb the energy of an aircraft that has overrun the end of a runway, thus preventing a catastrophic accident. These systems have been successfully deployed and used at a number of airports around the world, including New York's Kennedy International. See the articles at the following link: http://www.4jda.aero/pdfs/ROR-December07.pdf.