ACSS targets runway incursion dangers

 - September 12, 2006, 12:54 PM

Runway incursions this summer nearly wrecked the flawless accident record major U.S. airlines have achieved since the crash of American Airlines Flight 587 in New York almost five years ago.

On July 23 a departing United Airlines Boeing 737 came within 300 feet of colliding with a Boeing 747 freighter on an intersecting runway at Chicago O’Hare Airport. The incident was blamed on controller error.

Less than a week later, two regional airliners nearly collided at Los Angeles International Airport (LAX) when an America West regional jet strayed onto an active runway into the path of a departing SkyWest Embraer Brasilia. A warning by the tower controller and the quick reaction by the SkyWest pilot averted disaster as the airplanes missed each other by an estimated 150 feet.

Both incidents were attributed to problems with the airport movement area safety system (AMASS) equipment at the airports on the days the near collisions occurred. The incident at LAX has prompted a review of operating procedures that could include a restriction on intersection departures. Both episodes also should serve as a reminder to pilots and controllers that airport surface operations remain near the top of the list of safety dangers.

Business jet manufacturers have been exploring a number of technologies that could help curb or even prevent incursions. Aviation Communication & Surveillance Systems (ACSS), the Phoenix company that makes TCAS, TAWS and automatic dependent surveillance-broadcast (ADS-B) avionics, has held discussions recently with at least two OEMs about bringing a version of the company’s developmental surface area movement management (SAMM) system to new airplanes. The concept as described would use ADS-B technology to give pilots aural and visual warnings of other aircraft on the ground. SAMM’s software would judge which targets pose a potential danger.

“From our discussions with the OEMs, their feeling is that the surface area movement management function for runway incursion and enhanced situational awareness on the ground is the first thing that they want to roll out,” said ACSS chief technologist Cyro Stone. “That is what they think their customers will want as far as ADS-B is concerned.”

The SAMM concept consists of an element of a product and software suite from ACSS called SafeRoute. FAA Administrator Marion Blakey touted SafeRoute at July’s Farnborough International Air Show not merely for its safety benefits but
also for the efficiency gains it could provide. UPS, in conjunction with ACSS and Boeing, is adding a Safe-Route feature that would help UPS pilots merge at cruising altitudes before flying continuous descent approaches at fixed intervals “like beads on a string,” in the words of Capt. Karen Lee, director of flight operations for the cargo airline.

The merging and spacing application is anticipated to improve the efficiency of flight operations, saving the carrier $1 million in fuel each year. The elimination of low-altitude maneuvering associated with “drive and dive” approaches will reduce noise and emissions near the ground. And the procedure will reduce controller workload, leaving them to manage a predictable flow of traffic and intervene only when needed. The major benefit of the concept is that it will give UPS pilots a clear picture of other UPS airplanes on approach, allowing them to self-separate even at night or in IMC.

UPS also plans to use SAMM at its Louisville, Ky. hub by adding the application to the Boeing Class-3 electronic flight bags it has ordered for its Boeing 757s and 767s. SAMM shows a map of the airport surface and other airplanes. The active runway turns yellow and then red as an airplane approaches. It can also alert pilots to other airplanes equipped with ADS-B avionics and some transponders.

ADS-B Mandates Coming

The FAA is currently considering ADS-B-related avionics mandates after formally launching its nationwide ADS-B program in May. The plan is to take advantage of mode-S transponders in airliners and other aircraft–including some business jets–since many of these already emit the “extended squitter” signal bursts used in ADS-B. But because general mandatory equipage is still thought to be many years away, the full benefits of concepts like SAMM could be a long time coming.

But as the airlines begin signing on for ADS-B-related equipment that is designed to improve efficiency and by extension save them money on fuel, voluntary equipage could start to become the norm, even for business jet operators who are less conscious of fuel costs, Stone said.

“We had an engineer at one business aircraft OEM tell us that the first time the CEO asks why the delay and the pilots say, ‘Well, we were in a longer holding pattern because everybody else is doing merging and spacing and we’re not,’ he’s going to want to get that technology on the aircraft,” Stone recounted. “It’s going to take some time to reach that point, but I really think this engineer was dead-on in his assessment. But definitely SAMM will make its way to business aviation much sooner.”

Business jet crews flying ADS-B-equipped aircraft will be able to “see” only other ADS-B-equipped aircraft on the cockpit traffic displays. Equipped aircraft constantly broadcast their current position and altitude, category of aircraft, airspeed, identification and other data, such as whether the aircraft is turning, climbing or descending. The transmission is made over a dedicated radio datalink and is known as “ADS-B out.” This is the basic level of ADS-B functionality.

ADS-B transmissions are received by ATC and all other ADS-B-equipped aircraft within reception range, typically about 200 nm. Reception by aircraft of ADS-B data is known as “ADS-B in.” This is the classification for airplanes fitted with SafeRoute avionics and software applications. And the same way merging and spacing reduces controller workload in the terminal environment, concepts such as SAMM could reduce the potential for errors on the ground, where–as recent incidents have shown– the dangers remain as real as ever.