CHRIS KJELGAARD / WASHINGTON DC
The US Federal Aviation Administration appears to be making progress in its efforts to make airports safer as the number of runway incursions continues to fall
If the incursion rate at US commercial airports so far this year proves to be a reliable long-term guide, the Federal Aviation Administration's runway safety programme is beginning to show signs of success.
New figures from the FAA show that, in the first four months of this year, the rate of runway incursions at the 450 US commercial airports with towers had decreased by 32% year-on-year. This is good news for the FAA, considering that 2001 was already showing an encouraging reduction in the incursion rate even before the attacks of 11 September curtailed US civil aviation traffic.
By May, this year's incursion rate was showing every sign of a slowdown. At 119, the number of incursions at monitored US airports since the start of 2002 suggested that, if the FAA's prevention efforts continue to make headway, it could emerge this year with fewer than 350 incursion incidents. This would be an improvement of nearly 10% on the figure of 381 recorded in 2001, itself far better than the 431 incursions that were experienced in 2000.
Since last year was also the first in around five years to show a drop in incursion rate, improvement in 2002 would be welcome evidence to the FAA that its runway safety measures are working.
Incursion rates tell only a small part of the runway safety story, however. An aircraft that stops with its nose-wheel 0.5m (1.6ft) over the runway hold-line is classed as committing an incursion, but so is an incident in which two aircraft narrowly miss each other in the middle third of a runway where their momentum is highest and the potential for a disastrous accident is greatest. The severity of incursion incidents in terms of the degree of collision danger they create must therefore be weighed when citing statistics.
Breakdowns of the relative severity rates of 2002 incursions are not yet available from the FAA, but its data from last year give every sign that relative frequencies of the most dangerous incursions - those classed as categories "A" and "B" by the FAA - could be on the wane. Not only did the numbers of these incursions fall year-on-year in 2001 from 68 to 50, but the proportion of the most dangerous incursions within the overall incident tally declined to 11% from 13% in 2000.
Pressed throughout the 1990s by the US National Transportation Safety Board to take strong action on runway incursions, the several FAA airport-based technology programmes aimed at improving air traffic controller and pilot awareness of incursion risks are now well under way.
The FAA's flagship is the Airport Movement Area Safety System (AMASS), a software package that takes data from the ASDE-3 airport surface movement detection radars installed at 40 major US airports and processes it to provide controllers with aural and visual warnings of potential collision risks.
False starts
After many false development starts, which resulted in a seven-year programme delay, AMASS is now fully operational at 12 major US airports, with controllers at another seven performing operational reliability trials with the system to ensure its readiness before the FAA commissions it at each airport. The agency plans to provide controllers at the 34 busiest US commercial airports with 37 AMASS systems (some multi-runway airports, such as Los Angeles, will get two) and expects to have the system in operation at all of them except security-sensitive Washington National Airport by July next year.
In addition, the FAA has contracted to purchase X-band airport surface movement radars, known as ASDE-X, to equip 25 more US commercial airports where traffic levels are not as high as at the ASDE-3/AMASS-equipped airports - but high enough to create significant risks of incursions. Milwaukee Airport is due to receive the first ASDE-X radar, designed to also receive and process automatic dependent surveillance - broadcast signals from aircraft to help derive target position. All 25 airports should be equipped by 2007.
The FAA also continues to experiment with other technologies to help reduce the danger posed by runway incursion incidents. For instance, it plans to test anti-blocking devices for cockpit radios to prevent pilots missing critical instructions from air traffic controllers and so unwittingly causing incursions.
Another is a "virtual tripwire" cable loop system laid in an airport's taxiways to detect magnetic field anomalies created by the presence of an aircraft, and to generate information for controllers about each aircraft's location. A third, offered by a UK company, is a complementary system that broadcasts an aircraft's position to its marker-beacon receiver by means of short-range VHF radios that would receive aircraft-location information from motion sensors such as the cable-loop system.
Airport-based multilateration systems, capable of locating and tracking aircraft transponder emissions and infrared signatures, are under consideration. The FAA is also planning to test programmable runway and taxiway intersection light-diode signs to let controllers create messages and indications tailored to specific situations. Another approach the FAA plans to test is the use of Bluetooth wireless communications datalink technology to create an aircraft and ground vehicle tracking system on the airport.
Positive effects
But despite all the longer-term technological possibilities for reducing runway incursion rates, the FAA is encouraged most of all by the positive effects its less high-tech efforts appear to be having. The organisation strongly believes the detailed review and adjustment of operational processes and airport geography is at least as vital to reducing risk as any advanced-technology programme.
As a prerequisite for this effort, the FAA's Office of Runway Safety has sought to expand the upgraded data-collection effort begun in 1997 to try to better understand causal chains that create incursions.
Office of Runway Safety director Bill Davis says detailed data on incursion causal chains is needed so the FAA can take pre-emptive action to break each incursion-event chain before it can lead to an accident. As new incursion incidents take place in the USA, the runway safety office's database grows and Davis's team learns more about why they happen.
As well as its data collection, the office is involved in several parallel lines of work aimed at ensuring operational processes do not increase the risk of incursions. It is conducting reviews of pilot and controller phraseology to try to generate a standard set of instructions and wording to prevent misunderstandings, particularly where foreign pilots and non-professional general aviation pilots are concerned.
In addition, on-site airport reviews carried out by special teams look at each US airport's signage, topography, geography, taxiway and runway markings, and lighting. In almost every case, the FAA feels, the airport's unique operational conditions contribute to the causal chain that leads to an incursion - as is evidenced by the fact that some airports have far more incursions than others that are much busier. As a result, most if not all airports require site-specific solutions, an FAA official says.
The agency is also increasingly working with NASA's Ames Research Center in California to find ways to change airport layouts to minimise the risk of incursions. Ames's "Future Flight Central" facility, a simulator that models airport ground movement environments, has given major US airports such as Los Angeles a way to experiment with changes to the configuration of their taxiways and runways to maximise traffic flow while minimising incursions and delays, without affecting operations.
With enough effort, each airport's idiosyncrasies can be addressed and safety improved. So too can human error, "the common denominator" in every incursion, and a class of causal event that, in the FAA's view, nearly always involves "a failure of situational awareness".
Aware the human link is potentially the weakest in the incursion causal chain, the FAA is conducting a massive educational and training effort to make people operating on or involved in US airport movement areas more aware of the incursion problem and how it happens.
Film star help
Last year, the Office of Runway Safety distributed 250,000 items of programme materials. These included aide-memoire cards on runway and taxiway signage and markings, training videotapes in English and Spanish, and posters - the last two items featuring film star Harrison Ford, an experienced pilot and the FAA's celebrity advocate for the runway safety programme.
Now the FAA is launching a new effort to ensure all 450 FAA-operated control towers at US commercial airports publish diagrams for pilots, to ensure they do not stray into incursions because they do not know the basic geography of the airports at which they are operating.
In its bid to improve runway safety, a fight the FAA might just be starting to think it can win, the agency wants to hear more success stories such as that of Dallas/Fort Worth Airport, one of the USA's busiest.
"The air traffic controllers at Dallas/Fort Worth tower are as pleased as punch that they've worked a record nine months without any incursions," an FAA official says. The Dallas/Fort Worth controllers have achieved this feat despite the fact that every day they have to handle 2,400 take-offs and landings, and another 1,800 runway crossings by taxiing aircraft.
Source: Flight International
