Latest Runway Innovations Help Pilots Avoid Ground Collisions

Feb. 22, 2006
Two new runway technologies still in the testing phases will help pilots avoid collisions with other aircraft and airport vehicles during both takeoffs and arrivals.

Two new runway technologies still in the testing phases will help pilots avoid collisions with other aircraft and airport vehicles during both takeoffs and arrivals.

On the arrival side, the Federal Aviation Administration (FAA) is about to begin a demonstration of the nation's first automated system for detecting aircraft and vehicles on runways and then alerting incoming pilots with flashing runway lights.

For enhanced safety during takeoffs, engineers with the FAA's William J. Hughes Technical Center are developing a distinctively low-tech response. Their solution would help avoid confusion for pilots who are just about to begin their takeoff roll, and who spot another aircraft far down the runway, but can't tell whether the other craft is actually on the runway or just on an "end-around taxiway." In such cases, the pilot has to get final clearance from air traffic control. Hughes Center technicians would simply to hide those aircraft behind large screens.

The Hughes Center, which is near Atlantic City, N.J., calls itself "the nation's premier aviation research and development, and test and evaluation facility" and "the national scientific test base for the FAA."

Reducing the number of runway incursions--consisting of collisions or near collisions between aircraft and other craft, ground vehicles, or other objects--is a top priority of both the FAA and the National Transportation Safety Board (NTSB). Of the 257 million aircraft arrivals and takeoffs from 2001 to 2004, there were 1,395 runway incursions--an average of nearly one per day during the four-year period, FAA says. The issue of runway incursions also has been on the NTSB's "most wanted" list of safety recommendations since 1990.

Furthermore, in three recent incidents from 2005 (at Boston in June, New York in July, and Las Vegas in September), the airport movement area safety system (AMASS) alerted air traffic control (ATC) without enough time to do much good, NTSB explains. AMASS simulations using data from actual incursions show that alerts may occur as little as 8 to 11 seconds before a potential collision. This type of situation cries out for a better system that provides direct information or warnings to pilots.

Meanwhile, for large airports with enough real estate to build them, end- around taxiways can be a great way to improve efficiency and enhance safety, says the Hughes Center's Jim Patterson. Instead of having a taxiway cutting across the middle of two or more parallel runways, it's built just beyond the runway's end.

Two airports that do have enough land beyond their runways and which have recently built end-around taxiways are Detroit Metropolitan Wayne County Airport (DTW) and Hartsfield-Jackson Atlanta Int'l (ATL). In Atlanta, the end-around taxiway happens to be on land that is quite a bit lower in elevation than the runway itself, so when looking down the runway, all one sees of an aircraft on the taxiway is the top of its tail, Patterson tells Air Safety Week.

But at Dallas-Fort Worth Int'l (DFW), everything is pretty flat. Looking down one of its 14,000-foot runways at the end-around taxiway beyond the runway's end, an airplane on the taxiway is fairly visible. So Dallas is set to become the first customer for the large screens that the Hughes Center is developing.

That will happen a few months after Patterson and his colleagues finish testing the screens at Atlantic City Int'l (ACY), which is adjacent to the center. Testing there is expected to end in April. Installation at DFW should begin early next fall.

The Atlantic City screens are 112-foot long, 13-foot high plastic cardboard sheets. For a permanent installation (like at Dallas), the dimensions will be similar, but the backing structure will be concrete. But for the purposes of testing at ACY, the screens have been mounted on truck trailers so they can be quickly moved around, says Patterson, who is the projector director for the screens at Hughes.

Recently, the screens were set up at the end of a 10,000-foot runway at ACY, with a speeding airport vehicle simulating an aircraft on a takeoff roll. Videotaping allowed the Hughes Center technicians to see how well the screens blocked the pilots' view of the area just off the end of the runway.

Moreover, the screens' mobility at ACY is allowing Patterson and his colleagues to experiment with different screen colors and varying types of visual patterns. So far, alternating patterns of red and white do well because at least one of those colors contrasts with 99 percent of the aircraft in use. Upcoming tests will determine if the colors should be arranged in a large "chevron" pattern (of stripes) or in large blocks as on a checkerboard, or in some other pattern. Checkerboard has an advantage because it's already mentally associated with other obstruction markings.

Size, of course, is a major design factor. The screens have to be large enough to hide a commercial jet, but not so large that they themselves became obtrusive. They also have to be visible day or night.

The bottom line, though, is that the screens have to be usable through the entire takeoff sequence, Patterson emphasizes. This would start at the point just before takeoff, when pilots position the craft "on the numbers," then continuing all the way through the takeoff roll to the point where pilots decide whether to lift off or abort the takeoff.

Patterson emphasizes that the screens will only be practical at airports like Dallas that have enough land, and not at many eastern airports.

So, while Patterson and his colleagues continue fine-tuning their screens to make takeoffs safer, across the country at Long Beach Airport (LGB), airport officials in partnership with the FAA are preparing a months-long, real-world demonstration of the Final Approach Runway Occupancy Signal (FAROS). This system will warn pilots on an approach that there's something on the runway.

When and if FAROS becomes generally available, airports wishing to replicate the system would only need to buy some software and install some inductive loop sensors just beneath the surfaces of their runways. The glide slope indicator lights, also known as the precision approach path indicator (PAPI) lights, normally used to help pilots correctly line up their approach, would flash when an aircraft or vehicle is detected on the runway.

Long Beach already had the inductive loop sensors installed for a previous test, so all it needed to test FAROS was the software, Airport Operations Superintendant Fred Pena tells Air Safety Week. Testing is set to begin as early as March.

Inductive loop sensors have already been in use for years by local highway departments to detect the presence of automobiles in the turn lane of an intersection, for example, to activate the turn signal in the next traffic-light cycle. Embedded beneath the roadway are coils of wire that set up an electromagnetic field. Small pieces of iron, like a small iron rod, or very large pieces of iron, like automobiles and aircraft, greatly increase the inductance of the electromagnetic field. The level of inductance can then be read and used to trigger another part of the system, like warning lights.

Long Beach Airport will have three inductive loop sensors embedded under Runway 30, in areas that are being called the FAROS activation zones. "Zone 1" is under the standard full-length departure position at the end of the runway, "zone 2" is at the common departure position where the runway intersects with one of the taxiways, while the third zone is farther up at an intersection with another taxiway.

It was the FAA's Joint Safety Implementation Team that first proposed devising such a method for reducing runway incursions, and the Air Safety Foundation, which is part of that team, suggested making use of the PAPI lights, FAA says. In 2001, the FAA successfully completed a FAROS "proof-of-concept" testing phase, to see if the system would work as planned.

The next round of testing at Long Beach would gauge how well the system does on a day-to-day basis. Pilots coming into LGB and taking advantage of the system will be asked to fill out an evaluation. In the meantime, educational materials and seminars are familiarizing pilots with the system.

Pilots on an approach to LGB when FAROS is in its fully operational testing phase will be asked to follow certain sequential guidelines:

1. If the PAPI lights are flashing while on final approach above the contact height of 500 feet above ground level, continue the approach with heightened awareness of conflicting traffic on the runway.

2. If the PAPI lights are flashing as the aircraft reaches the contact height, contact ATC about the flashing lights, and prepare for a possible go- around.

3. If there is no response from ATC, or if a response is given that does not give assurance that the runway will be clear, execute a go-around procedure as per the aircraft flight manual or company procedures, advise ATC of the situation and request further instructions. If ATC indicates that the runway will be clear, continue a normal approach and landing.

The FAA makes a couple more side notes. A steady (non-flashing) PAPI signal will not guarantee that the runway is clear, and it will remain the pilot's responsibility to make sure there are no obstructions. The system will also be activated, of course, when aircraft use the runway for takeoffs. Unless there are other safety concerns, departing pilots who see the flashing PAPI lights should continue their takeoff procedures, and should not contact ATC. The lights will stop flashing once the aircraft takes off and is beyond the FAROS activation zones.

More information on FAROS, including a survey form for pilots who land at Long Beach during the evaluation, is at ?CFID=20229207&CFTOKEN=28106384.

>>Contacts: Jim Patterson, Hughes Center, (609) 485-4989, [email protected]; Fred Pena, Long Beach Airport, (562) 570-2632, [email protected]<<

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