Nov. 10--Midway Airport is the first airport in the world to install a bed of lightweight glass rocks beyond the end of a runway that in an emergency crumbles to bring a landing jet traveling at 80 mph to a halt, according to aviation officials.
The technology is replacing a first-generation aircraft-arresting system built at Midway in 2006 and 2007 for more than $24 million. The old system is being removed because it is too brittle under regular operating conditions and costs the Chicago Department of Aviation millions of dollars in repairs and inspections, officials said.
Runway overruns during landing by commercial airliners account for roughly 10 incidents or accidents every year worldwide, with many resulting in deaths, according to the National Transportation Safety Board.
A fatal overrun occurred at Midway nine years ago. It happened at a time Midway lacked arrester beds, which the Federal Aviation Administration accepts as a substitute for safety standards that require a 1,000-foot margin at the end of runways free and clear of obstacles.
Since arrester beds were first installed in the U.S. in the 1990s, there have been nine incidents in which planes overrunning runways were safely stopped, according to the FAA, which said the nine aircraft carried a total of 243 passengers and crew members.
The arresting beds are in place at 51 U.S. airports, and 10 additional airports are planning to deploy the system, the FAA said.
Midway officials are banking on the new emergency stopping system's ability to last at least 20 years. The system is set to be installed on four runway corners through 2015, at a cost of $15 million.
The first of the four installations is being completed this week on the northeast corner of the airport, at the end of runway 22 Left, near 55th Street and Cicero Avenue. It is manufactured by Runway Safe, based in Austin, Texas , and Stockholm.
Your Getting Around reporter was shown the materials and installation last week at Midway. The foam glass rocks are extremely lightweight and look similar to lava rocks that are used in barbecue grills.
The layer of foam glass increases in thickness from basically zero at the front of the arrester bed to about 16 inches deep at the back, in order to smoothly decelerate a plane, said Marc Klein, site manager for Care Plus, Chicago's construction manager at Midway and O'Hare International Airport.
Above the foam glass is a thin concrete layer, followed by a polymer topcoat that is similar to the sealant used on bridge decks, Klein said.
The exact composition was based on the types of aircraft operating at Midway, said Kirk Marchand, chief executive officer at Runway Safe.
He said the company is talking to other airports about its new, federally approved arrester beds, the thickness of which would be customized to match the airplane fleet mix at each airport.
"The system is essentially about 90 percent silica foam, or recycled glass bottles," Marchand said. "It is environmentally sustainable. We view this installation at Midway as the poster child."
Midway's original system, made by Engineered Arresting Systems Corp., was installed after a Southwest Airlines plane skidded off a snowy runway Dec. 8, 2005, and plowed through the airport fence onto Central Avenue and 55th Street. The Boeing 737 hit a car, killing a 6-year-old Indiana boy inside.
Federal investigators determined that the Southwest plane would have remained on airport property if the arresting system were in place then. Only three months before the accident, the FAA had approved rules governing the arrester beds that were later installed at Midway.
"The accident was horribly coincidental to the process," said Erin O'Donnell, managing deputy commissioner for Midway.
Both the old and new systems are designed with the same aim -- to safely stop a plane traveling up to 70 knots, or about 80 mph. The pavement collapses when airplane wheels punch through the thin surface. The crushing action of the materials underneath absorbs the plane's energy to gradually stop the wheels.
Until now, Engineered Arresting Systems was the only FAA-approved manufacturer of arresting-bed technology.
"They effectively had a monopoly," O'Donnell said.
Midway's original crushable concrete beds, made up of lightweight blocks that are held in place by construction tape, have been blown away by jet blast from the engine thrust of planes taking off, officials said.
"We have been maintaining the heck out of them," O'Donnell said, adding that the old system came with a one-year warranty.
The city has spent $1.4 million on maintenance and repairs and $1.1 million on inspections since 2009, the aviation department said.
"I always joke that I go to Target to buy a coffeepot, and I get a five-year warranty. I spend $24 million on arrester beds, and I get a one-year warranty," O'Donnell said.
In 2011, Engineered Arresting Systems did replace at its expense more than half of the arresting system blocks on runway 31 Center at Midway due to "block failures," said Karen Pride, an aviation department spokeswoman.
In addition to the maintenance costs, the need to keep repairing the individual blocks on the old system means closing the affected runways during the work, which can lead to flight delays, Pride said.
The Runway Safe system carries a five-year warranty.
Most runways at O'Hare have a federally required 1,000-foot runway safety zone and don't need arrester beds, but there are two, made by Engineered Arresting Systems, officials said.
Those beds have not had severe deterioration because O'Hare's runways are longer than Midway's and planes departing O'Hare generally do not start engine runups close to the beds.
"Pilots at Midway like to use all of the runway, starting at the very end, to make sure they have enough runway to get up and over the fence," Klein said.
Midway, which occupies only one square mile, is outfitted with arrester beds because the airport lacks enough land to construct the minimum 1,000-foot runway safety zone that is required beyond the end of runways to provide extra stopping protection in emergencies, according to the FAA.
Midway also doesn't have room for the standard 600-foot-long aircraft arresting system. The FAA granted a variance for shorter beds at the landlocked Southwest Side airport. The arrester bed on the end of runway 22 Left is 245 feet long, officials said.
The FAA has set a Dec. 31, 2015, deadline for all U.S. airports to comply with runway safety standards that require either the 1,000-foot setback or arrester beds. Chicago's two airports were built before the standards were adopted about 20 years ago, but they both comply, either directly or via approved variances, officials said.
Contact Getting Around at jhilkevitch@tribune.com or c/o the Chicago Tribune, 435 N. Michigan Ave., Chicago, IL 60611; on Twitter @jhilkevitch; and at facebook.com/jhilkevitch. Read recent columns at chicagotribune.com/gettingaround.
