How it works: Stopping power

At a small airport and at a low speed, the outcome is usually just embarrassing. At a large commercial airport with hundreds of passengers and thousands of tons of jet, racing off the end can be disastrous.

Knowing the potential for damage, the FAA began a process more than 20 years ago to attach long overrun areas to the end of as many runways as possible. However, in many places a lack of land, the topography, or other factors made this impossible. For that, there’s EMAS, or Engineered Material Arresting System. EMAS is a layered surface of cement and other materials that can stop even the biggest jets in a relatively short distance.

According to Runway Safe, the owner of the proprietary technology, each installation is unique, although each uses a similar process and materials. In general, the bottom of the company’s traditional product consists of a layer of nylon mesh. Like building a cake, they layer on a thick block of crushable cellular cement, then a foam sheet, and finally a plastic cover. A green version uses recycled glass as the primary crushing structure.

Typically, EMAS is the same width as the runway, and extends maybe a few hundred feet. The construction is modular. The concrete blocks are manufactured at the company’s facility and then shipped in pallet-sized squares that are then placed down and held together with caulk or tape. The finished top is resistant to jet blast. Each block is single use only. If an airplane goes through the EMAS, the damaged blocks can be taken out and replaced, negating the need to fix the entire area.

To date EMAS products have been installed at the end of 115 runways in the United States and have helped to slow down 15 aircraft with 406 passengers and crew. The system can be found at airports as big as John F. Kennedy International in New York and as small as in Rutland, Vermont.

[email protected]