Engineered materials arrestor system

An engineered materials arrestor system, engineered materials arresting system (EMAS), or arrester bed is a bed of engineered materials built at the end of a runway to reduce the severity of the consequences of an aircraft running off the end of a runway. Engineered materials are defined in FAA Advisory Circular No 150/5220-22B as "high energy absorbing materials of selected strength, which will reliably and predictably crush under the weight of an aircraft".

Source: Wikipedia — Engineered materials arrestor system (CC BY-SA 4.0)