‘Crushable concrete’ arresting beds still saving aircraft, preventing injury

On a rainy Oct. 1, a G-4 Gulfstream aircraft overran its runway on landing at Teterboro Airport, New Jersey. But its crew and passengers were uninjured when the aircraft came to a safe stop amid a pile of crushed concrete. The successful stop marked the seventh aircraft save by Engineered Material Arresting Systems (EMAS), informally labeled “crushable concrete” in the aviation industry.

The material – a lightweight concrete mixed with a foaming agent that creates air pockets within the mix as it cures, making it crushable – was developed by Engineered Arresting Systems Corp. of Logan Twp., N.J. (now Zodiac Arresting Systems of America), in partnership with the FAA, the Port Authority of New York and New Jersey, and the University of Dayton Research Institute. It’s currently installed at the end of 51 runways at 35 U.S. airports as a failsafe if a plane overshoots on landing. When an aircraft’s tires hit the engineered concrete, the material collapses and provides enough drag to safely decelerate the plane.

UDRI researchers Bob Cook (retired), Mike Bouchard, Geoffrey Frank, Michael Craft, James Higgins and Scott Stouffer made a number of contributions toward the development of runway arresting systems during a 15-year period that began in the late 1980s. Contributions include materials and structures development and testing, design recommendations and an analytical model to predict how aircraft would behave when running over the arresting beds.

Frank, a research engineer in structures and mechanical systems, recalls making occasional trips to LaGuardia airport in New York City, where he and colleagues had set instrumentation at the end of a runway to measure jet blast speeds and acoustic and ground-vibration levels created by aircraft at takeoff. “The first generation beds worked well at stopping aircraft, but didn’t fare as well under the conditions created by jets taking off over them,” Frank said. “So we sat in a van near the end of the runway and recorded jet blast speeds and vibrations created by a number of different aircraft, so the manufacturer would know what conditions the material would need to withstand.” Other researchers in UDRI tested the material for heat and cold tolerance and moisture permeability, Frank said.

The FAA requires that commercial airports have a runway safety area where feasible. But many airports cannot meet the required safety extension of 1,000 feet beyond the end of a runway because of obstacles such as highways, railroads, severe drop-offs in terrain or bodies of water. In those cases, arresting beds – at a standard length of only 600 feet – can provide effective stopping power; shorter beds can also be installed if lack of land precludes a standard bed.

The first EMAS bed was installed at John F. Kennedy International Airport in 1996. Since then the arresting beds have been successful at stopping all seven overruns on runways where the material is installed. In a Nov. 1 Aviation Week & Space Technology magazine story by James Ott, FAA manager Rick Marinelli says that none of the arrested planes suffered serious damage, and passengers and crew have sustained only minor injuries when there were injuries at all. “Every aircraft that’s been arrested has flown away,” Marinelli said in the story.

Bouchard, who served as UDRI’s principal investigator for a program to improve the system’s durability, said EMAS is a great safeguard, especially when it sits between a runway end and a sharp land drop, a body of water or residential area. “The material has proven not only to save aircraft, but it’s also very likely to have saved lives,” he said.

On Jan.19, a Bombadier CRJ-200 carrying 34 passengers and crew aborted takeoff at Yeager Airport in Charleston, W. Va., coming to a safe stop short of a steep drop into a valley after it was arrested by EMAS (see photos at right). Other overrun arrests include: an Airbus 320 at Chicago O’Hare International in July 2008, a Mystere Falcon 900 at Greenville Downtown Airport in July 2006 and, at John F. Kennedy International, a Boeing 747 in January 2005, a Gemini Cargo MD-11 in May 2003, and a Saab 340 commuter in May 1999.

Each year, sponsored research programs at the University of Dayton provide real-world research opportunities to nearly 300 undergraduate and graduate students working with more than 500 professional and faculty researchers from the Research Institute, the School of Engineering and the College of Arts and Sciences.