Runway Safety Work Could Cause Delays at SFO

Officials at San Francisco International Airport are alerting the public that their flights might be delayed — for about four months later this year.

A pair of the airport's shorter runways will be shut down from May to September to allow installation of new pavement designed to, in the airport's words, "safely capture an aircraft’s landing gear should it overshoot the airstrip."

In an advisory, the airport says that all arriving and departing traffic will use Runways 10R-28L and 10L-28R. During good weather, minor delays might occur during peak periods of traffic demand, such as 9 a.m. to noon. More significant delays will occur during bad weather — say, during very foggy or windy conditions.

The work on Runways 1R and 1L is being done under a Federal Aviation Administration program to improve what the agency calls runway safety areas at the nation's commercial airports. The safety areas are essentially emergency-stop zones for planes that approach the end of runways on landings or aborted takeoffs.

Since SFO doesn't have enough room for the full 1,000-foot runway safety area extension mandated in the FAA rules, the airport is installing an "engineered material arresting system" designed to slow down and stop planes that overrun the end of a runway.

The material's manufacturer, Engineered Arresting Systems Corp., describes what it is and how it's supposed to work: "EMAS is consisted of a bed of cellular cement material manufactured in the form of engineered block components that are strategically placed at the overrun end of a runway. The EMAS predictably and reliably crushes under the weight of an aircraft, providing deceleration and a safe stop."

The company also says the material can be installed around "high-value public and private buildings" to stop "threat vehicles." A truck carrying explosives, say.

The arresting systems already have saved some planes, including a couple of commercial flights full of passengers: a Mexicana Airlines Airbus A320 at Chicago's O'Hare International Airport in 2008; a PSA Airlines Bombardier CJR200 in West Virginia in 2010; and, perhaps most spectacularly, a 747 cargo jet at JFK in New York City in 2005.

Aspiring EMAS nerds need to watch the video below from the manufacturer. It actually does a great job explaining how the system works, complete with video from a live test with a real airliner.