page_title: Engineered materials arrestor system
section_title: United States installations
hierarchical_section_title: Engineered materials arrestor system / United States installations
caption_attribution_description: English: An Engineered Materials Arrestor System (EMAS) bed under construction. The slope part on the left is the blast shield. The EMAS blocks are on the right.
context_page_description: An engineered materials arrestor system, engineered materials arresting system, or arrester bed is a bed of engineered materials built at the end of a runway to reduce the severity of the consequences of a runway excursion. 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". While the current technology involves lightweight, crushable concrete blocks, any material that has been approved to meet the FAA Advisory Circular can be used for an EMAS. The purpose of an EMAS is to stop an aircraft overrun with no human injury and minimal aircraft damage. The aircraft is slowed by the loss of energy required to crush the EMAS material. An EMAS is similar in concept to the runaway truck ramp or race circuit gravel trap, made of gravel or sand. It is intended to stop an aircraft that has overshot a runway when there is an insufficient free space for a standard runway safety area. Multiple patents have been issued on the construction and design on the materials and process.
context_section_description: The FAA's design criteria for new airports designate Runway Safety Areas (RSAs) to increase the margin of safety if an overrun occurs and to provide additional access room for response vehicles. A United States federal law required that the length of RSAs in airports was to be 1,000 feet (300 m) by the end of 2015, in a response to a runway overrun into a highway at Teterboro Airport in New Jersey. At airports built before these standards were put into effect, the FAA has funded the installation of EMAS at the ends of main runways. The minimum recommended overall length of an EMAS installation is 600 feet (180 m), of which at least 400 feet (120 m) is to consist of the frangible material.
  As of April 2019, ESCO's EMAS is installed at 112 runway ends at 68 airports in the United States, with plans to install 3 EMAS systems at 2 additional U.S. airports and Runway Safe EMAS is installed at 4 runway ends at 1 airport in the U.S.
  The FAA found that pilots are trying to avoid the EMAS and steer to the grass sides in 30–40 kn (56–74 km/h; 35–46 mph) low-energy events in order not to make the news.
caption: EMAS under construction. The slope part on the left is a blast shield.[4]
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