ATM Modernization, Business & GA, Commercial

Runway Incursions: The Threat on the Ground

By Adrian Gerold | April 1, 2001
Send Feedback

The world’s worst aviation accident occurred in 1977, almost a quarter of a century ago, at Tenerife, the largest of the Canary Islands. Five hundred and eighty-three persons were killed when a fully laden Boeing 747 collided during its takeoff run with another fully laden 747, which had strayed on the active runway in low visibility. Poor communications and misinterpretation of the tower’s clearance instructions were subsequently cited as major contributors to the accident.

Just Bad Luck?

At the time, most observers regarded the tragedy as incredibly bad luck. The catastrophe, they say, would have been avoided by just a few seconds either way. Coupled with this was the then-common perception that the odds against such an accident occurring again would be astronomical, and that the safety procedures in place at the time were more than adequate to prevent a recurrence.

Fast forward to January 2001, and the Providence, R.I., airport. Snow is falling. Visibility is dwindling. A USAirways Airbus 319 commences its takeoff roll. But as it accelerates to lift-off speed, its crew sees a Southwest Airlines Boeing 737 taxiing across the runway ahead. The takeoff is immediately aborted, and a smaller version of the Tenerife collision is avoided. Possibly, out of the 102 passengers and crew aboard the A319 and 142 aboard the B737, only the USAirways pilots knew how close a call this had been.

Unfortunately, this was not an isolated incident. Since 1977, there have been a disturbingly large number of situations in which only the skill and alertness of pilots and air traffic controllers–plus a good measure of luck–have averted major tragedies. But on five occasions in the United States since 1990, pilot and controller vigilance, and luck, ran out, and many lives were lost in runway accidents.

For this reason, U.S. Federal Aviation Administration (FAA) Administrator Jane Garvey, speaking at the agency’s Runway Safety National Summit conference last year, emphasized that "Taxiing on the airport surface is the most hazardous phase of flight." At the time, this surprised many pilots, who traditionally considered the approach and landing phase as being the most hazardous. Yet when accident statistics–including those of "near misses"–were analyzed, today’s airport surface was found to have the greatest potential for major catastrophes.

And, at first sight, the outlook is not encouraging. In November 2000, the Massachusetts Institute of Technology estimated that up to 800 airline passengers could die in airport surface accidents over the next 20 years due to "too much traffic, poor visibility and other problems." As well, U.S. runway incursion incidents have been increasing every year, with close to 430 reported in 2000 versus 321 in 1999, a 33% increase.

This major escalation created both consternation and acute disappointment within the FAA. Consternation because the aggressive effort launched at the FAA Runway Summit was aimed at substantially lowering the accident rate over the balance of the year. Acute disappointment because the summit generated such a positive commitment among attendees that the target set at the time–248 runway incursions by Dec. 31, 2000–seemed well within the realm of possibility.

Victim of a Catch-22

So what went wrong?

Certainly, the traffic volume increased in 2000, but by nowhere near 33%. And it seemed highly improbable that there could have been such a dramatic deterioration of vigilance by pilots, controllers, vehicle drivers and others on airport surfaces. The FAA’s own analysis had not been completed by press time, but informed observers suggest that the agency fell victim to a Catch-22 of its own making. That is, in placing the highest priority on runway incursion awareness among all participants, it also placed increased emphasis on the reporting of every incident, however minor.

At a Runway Incursion Workshop sponsored by the American Association of Airport Executives (AAAE), held in Arlington, Va., in December, one official informally put it this way: "At the [Runway Safety] summit, we established regional runway incursion action teams [RIATs]. We redefined what a runway incursion was. We laid down strict reporting guidelines, and we then chose 248 runway incursions as our goal for 2000. The fact that we missed the target by so much shows that the bigger runway incursion numbers were always there, but we somehow hadn’t been logging them all."

The FAA’s new definition of a runway incursion is all-inclusive: "Any occurrence at an airport involving an aircraft, vehicle, person or object on the ground that creates a collision hazard or results in loss of separation with an aircraft taking off, intending to take off, landing or intending to land." At the same time, FAA analysis shows that some elements appear to have been common to most runway incursion events in the past, as listed below:

  • In 89% of cases, weather was not a factor.

  • In 69% of cases, general aviation aircraft were involved.

  • In 62% of cases, pilots taxied onto runways or taxiways without clearances.

  • In 32% of cases, low-time pilots with less than 100 hours flying experience were involved.

  • In 22% of cases, pilots were unfamiliar with air traffic control procedures or language.

The preponderance of the general aviation element is significant here. But it is also a delicate topic among FAA officials, because it underlines an important reason for the difference between the runway incursion rate in the United States, where it is a major problem, and in Europe, where runway incursions occur much less frequently. Commercial traffic densities in both regions are comparable, but general aviation traffic in Europe is insignificant compared to that in the United States.

At the AAAE Workshop, John Mayrhofer, director of FAA’s Runway Safety Program, reviewed the agency’s list of top 10 actions to reduce runway incursions. These are:

  • Enhance tower controller training.

  • Develop a strategic plan for foreign air carrier pilot training, education and awareness.

  • Issue an airport surface operations advisory circular.

  • Improve airport surface markings.

  • Improve education, training and awareness for pilots, controllers and vehicle operators.

  • Provide memory enhancement training for tower controllers.

  • Review pilot/controller communications phraseology.

  • Improve pilot evaluation and testing.

  • Develop air traffic teamwork enhancement training for tower controllers.

  • And assess new technologies.

FAA regions already are implementing the first nine items of the list. And Washington headquarters was expected in February to issue development contracts for several new, previously untried, concepts, while continuing to support several technologies that either suggest or have already demonstrated their potential abilities to reduce incursions. Notable among these are:

  • UPS Airborne Technologies’ airport surface map, which shows active runways, taxiways and other aircraft. Based on Automatic Dependent Surveillance-Broadcast (ADS-B) signals, this system was installed in two of five cargo jets for a complex, NASA-monitored, night taxiing exercise at the Louisville, Ky., airport in October. Both equipped aircraft completed the exercise easily, while the three non-equipped aircraft had varying degrees of difficulty in following the required route from the runway back to the ramp.

  • Rockwell Collins Flight Dynamics’ Surface Guidance System (SGS), which uses a head-up display (HUD) to show a cockpit perspective of the cleared taxi route from runway to terminal, or vice versa, via a tower-to-aircraft data link to the on-board flight management system (FMS) and then to the HUD. Directions include taxiway centerline guidance, distance to the next turn and its direction, plus unmistakable stop bars and other advisories. A major advantage of this concept is that it eliminates voice instructions from the airport tower, which are all too often delivered in machine gun-like rapidity and frequently misunderstood, especially by non-English speaking pilots. Jeppesen Sanderson and Smiths Industries are working with Flight Dynamics on the SGS.

  • NASA’s Runway Incursion Prevention System (RIPS), which uses ADS-B to drive a cockpit head-down surface map with an associated head-up perspective display.

  • NASA/Rannoch Corp.’s terminal area/airport surface Traffic Information System (TIS). This will provide general aviation pilots with a low cost cockpit display of traffic information (CDTI), showing all local traffic and using multilateration techniques, i.e., tracking aircraft in the area by triangulating on their individual ATCRBS (radar beacon system), TCAS (traffic alert collision avoidance system), ADS-B, IFF (identification friend or foe) and other transmissions.

  • FAA Airport Surveillance Detection Equipment, version 3 (ASDE-3). Currently operational at the nation’s top 34 airports, ASDE-3 installations will be upgraded, under a $142-million development program, by Airport Movement Area Safety Systems (AMASS), to provide automated alerts and warnings to controllers.

  • Raytheon/Sensis Corp.’s ASDE-X, an advanced, X-Band ASDE radar incorporating multilateration aircraft monitoring, which is to be installed at 25 of the nation’s busiest airports, next to the top 34 above.

Unquestionably, and correctly, FAA regards the increasing numbers of runway incursions as a very serious safety issue. So has the U.S. Congress, which has increased funding in this area from $18.6 million in FY99 to $33.4 million in FY00, and to $43.3 million in FY01.

But while additional funding will go a long way towards ameliorating the problem, money alone will not eliminate it. As a long time FAA observer of the scene stated, "No matter how much money you throw at it, the runway incursion situation will never be entirely resolved as long as you have human beings in the loop. In the end, education and strict discipline are the only ways to truly bring things back under control."

Receive the latest avionics news right to your inbox