In Focus

Arresting air disasters

Airports worldwide are bracing themselves for disasters that may arise from unforeseen circumstances by adopting suitable technologies. Does India have its systems in place?

The recent TAM Airlines crash in Brazil is just one more of the flight mishaps that the world has been witnessing of late. The aircraft careened off the runway upon landing at Sao Paulo's Congonhas airport in heavy rain killing all 186 passengers and crew aboard the Airbus 320, along with a number of people on the ground.

According to the Montreal-based International Federation of Air Traffic Controllers Associations, air safety is currently compromised and is a danger to the travelling public. Brazil has come under heavy criticism over air safety after the TAM Airlines revealed that the jetliner in the country's worst air disaster had part of its braking equipment switched off at the time of the accident.

Eye-opener

Whatever the case may be, this should serve as an eye-opener for airports in India. The reason is simple; none of the runways in the country's airports are equipped to prevent major aircraft mishaps.

Technology is the only means of countering such disasters - a technology that acts as a buffer to slow down aircraft that overrun the length of the runway. The EMAS technology or the Engineered Material Arresting Systems developed jointly by the Federal Aviation Administration (FAA) and ESCO (Engineered Arresting Systems Corporation) in 1998 after numerous real time aircraft tests is made up of a bed of cellular cement material that crushes under the weight of an aircraft, resulting in guaranteed deceleration of the aircraft.

A standard EMAS arrestor bed extends around 600 feet from the end of the runway. At most commercial airports the RSA (Runway Safety Area) is 500 feet wide and extends 1,000 feet beyond each end of the runway. Such technology is useful in cases where there is a shortage of land and it is not possible to have the standard 1,000 feet overrun.

The most dangerous of these incidents are overruns, but since many airports were built before the 1,000-foot RSA length was adopted some 20 years ago, the area beyond the end of the runway is where many airports cannot achieve the full standard RSA. During the monsoons, landing distance is increased by more than 20 per cent, but no runway in India is that long. This only increases the chances of an accident, although the Airports Authority of India (AAI) has claimed that all runways in India meet international standards.

Concrete solutions

In July 1998, when the technology was set in place, Jane Garvey, the FAA administrator, was quoted as saying, "FAA engineers helped develop a new technology (EMAS) that will increase airport runway safety, protecting people and aircraft during overrun accidents."

The front of the EAMS includes a grade-break that transitions the aircraft into the concrete material. The arrestor bed set-back is increased on long runway safety areas and the system is sized for 70-knot performance. Beyond the runway width, the sides of the EMAS are stepped to provide emergency vehicle access and passenger egress. EMAS length, depth and strength are varied to provide optimum performance. As the aircraft traverses the bed, the wheels crush the EMAS material creating a tire/material interface that provides the resistive loads to decelerate the aircraft. The load is placed on the aircraft landing gear and support structure. The level of performance depends primarily on the landing gear strength and the runway safety area available. While snow and winter weather conditions do not affect EMAS performance, snow is easily removed with equipment designed for use on the bed.

EMAS arrestments

There have been four incidents in the US where the technology has worked successfully to keep aircraft from overrunning the runway:

• May 1999: A Saab 340 commuter aircraft overran the runway at JFK
• May 2003: Gemini Cargo MD-11 was safely decelerated at JFK
• January 2005: A Boeing 747 overran the runway at JFK
• July 2006: Mystere Falcon 900 airplane ran off the runway at the Greenville Downtown Airport in South Carolina

Presently, the EMAS system developed by ESCO using crushable concrete is the only system that meets the FAA standard. FAA is currently in the process of conducting research through the Airport Cooperative Research Program (project number 07-03) that will examine alternatives to the existing approved system, the results of which are expected in 2009.