It could have been the most expensive ball bearing the Marines had ever bought. A team of 50 Marines, moving in slow, shoulder-to-shoulder search patterns for more than an hour, had located seven of a set of eight half-inch-diameter ball bearings that fell from a vehicle at the Marine Corps Air Station in Yuma, Ariz. The eighth was proving elusive. It was somewhere on the parking area used by Yuma’s four AV-8B V/STOL Harrier squadrons, and it had to be found, because the AV-8B’s voracious appetite for air sucked through the large intake of its Pegasus engine makes the airplane especially vulnerable to foreign object debris (FOD) during vertical operations. Sucked into the Harrier’s engine intake during a full-power vertical climb, the small, hardened-steel bearing could destroy the jet’s $4 million Pegasus in seconds.

That day, the Marines were lucky. Undergoing testing at Yuma was a truck-mounted, radar-sensing FOD detection and collection unit. Within 30 minutes the errant bearing was recovered. But the incident clearly illustrated the potentially enormous cost disparity between the cause of a FOD event and its economic effect. In this case, a $1 item could have had a $4 million impact. The estimated $30 titanium strip deemed to be responsible for bringing down the Air France Concorde 12 years ago may have caused losses exceeding $1 billion. Indeed, average civil aviation losses from FOD, including bird strikes (recall the US Airways ditching), have been estimated at nearly $14 billion a year in the U.S. and European Union. As air travel increases that figure will likely increase accordingly.

These facts, plus the shock of the Concorde loss, triggered the need to develop technologies and recommended FOD reduction practices across the international civil aviation community.

The FAA Program

In June the U.S., the major user of civil air transport, became the first nation to launch a program of airport runway automatic FOD detection systems. After conducting a multi-year program of investigation, analysis, technical evaluation and demanding, all-weather testing at commercial airports under a wide range of actual operating conditions, the FAA is moving into a limited implementation program under which candidate systems will be installed at an initial three major airports, and placed under the control of airport staff, with the eventual aim of integrating FOD reports and associated data into the airport’s safety management system. The program will receive 50 percent Airport Improvement Program support. At press time the FAA was reviewing cost proposals from airports interested in participating, including the applicant’s FOD system preference. The decision on which airports have been selected is expected to be announced at month end or early September. {{Underwood asked to update this sentence.}}

FOD Detection Options

All four systems available meet or exceed FAA detection standards, but they differ from each other in their technology, required location, size, number of units per runway and other factors. All provide automatic alerting when FOD is detected, as well as zoom visual augmentation to determine the nature of the FOD (for example a windblown shopping bag or a broken piece of pavement?). Each system also includes a comprehensive central control, alerting and system monitoring console with selectable slew controls for individual zoom cameras, all of which would be located in the tower itself or with the ground movements controller. In addition, each system offers unique secondary features that could play a deciding role.

QinetiQ’s Tarsier uses a fairly powerful scanning radar, generally requiring two separate radars set back from the runway and overlapping to cover an 11,000-foot runway, as well as a slewable, military-grade camera for close target inspection. Recently, the UK company announced the integration of Tarsier with a runway and taxiway acoustic sensing system to warn of potential runway incursions.

The iFerret system from Singapore-based Stratech Systems typically uses eight non-radar “intelligent vision” electro-optic sensors alongside, but set back from, the runway. The sensors capture images in full HD quality, with a 70X zoom capability that allows swift visual assessment of FOD. The system’s software-controlled optics also compensate for changing ambient light levels to maintain daylight-like images in darkness.

The mobile FOD Finder, the system employed at Yuma, incorporates into one pallet a radar, radome, electronics, wireless data transfer and 360-degree zoom cameras, and is operable while moving in a half-ton truck. Surface-mounted FOD Finders can be rapidly linked to create a temporary or permanent fixed array along a runway. When the system is mobile, a powerful vacuum system can recover FOD while moving. The device is offered by San Diego-based Trex Industries.

The FOD detection system from Tel Aviv-based Xsight uses existing runway-edge light fixtures as mounting bases. A weatherproof above-ground unit holds scanning radar and zoom camera. Watertight electronic units, power and communication equipment contained in an underground chest support the mounting base. Runway cameras are individually slewed via consoles in the control tower. The system is deployed on dual runways at Bangkok Suvarnabhumi International.