AMASS is Inadequate - NTSB


iAirport safety. Warning of an impending runway incursion needs to go to pilots as well as air traffic controllers, according to National Transportation Safety Board (NTSB) Acting Chairman Mark Rosenker. Speaking Sept. 13 before the runway and airport safety summit of the American Association of Airport Executives at Dulles, Va., Rosenker pointed out that the Federal Aviation Administration’s Airport Movement Area Safety System (AMASS) is “not adequate” to prevent serious runway collisions because of its operational limitations and the fact that it provides warnings, when it does work, to controllers but not to pilots.

            Citing several recent near-collisions where AMASS did not perform, Rosenker noted that the situations were instead resolved by flight crew actions sometimes bordering on the heroic, and luck. “That is not good enough, he said. (The full text of his speech is at

            The Dreadle system outlined in this publication provides a direct warning to pilots and controllers, and it is not vulnerable to rain or affected by converging runways (see ASW, July 16, 2001, p. 6).


Remarks of Mark V. Rosenker
Acting Chairman, National Transportation Safety Board
before the
American Association of Airport Executives
Runway and Airport Safety Summit
Dulles, Virginia
September 13, 2005

Good morning. Thank you for inviting me to speak to you today about runway safety, a topic that is high on the National Transportation Safety Board’s list of concerns. Since the people in this room own and operate a lot of runways, this seems like an excellent place to spend some time discussing our mutual interest in accident prevention.

As you know passengers who have concerns about flying tend to worry most about the part of their trip that involves being unnaturally separated from the ground. Life seems pretty good until takeoff, and landing is clearly a positive relief; no one is known as a “white-knuckle-taxier.” Yet few members of the general public know that the worst accident in aviation history was a runway collision.

Those of us who work in the aviation safety business know that surface operations present some of the most challenging situations for pilots and controllers, and in many cases leave the least room for error. In the air, we try to maintain miles of space between aircraft. But, on the airport, the tolerances are comparatively tiny; the difference between being in a safe place and an unsafe place is measured in feet, not miles. Caution and vigilance are gate-to-gate necessities for pilots and controllers – and as you know occasionally things even go wrong at the gate.

The hazards of airport surface operations have been a concern of the Safety Board for over 30 years. Since 1973, we have issued some 100 safety recommendations related to runway incursions. These recommendations addressed the need for improvements in air traffic control operations, training and hardware; pilot training; airport signs, lighting and markings, aircraft conspicuity and incident reporting.

The runway incursion issue has been on the Board’s Most Wanted List since its inception in 1990. In the late 1980s, an inordinate number of runway incursions/ground collision accidents resulted in substantial loss of life and the Safety Board issued numerous safety recommendations addressing the issue. The FAA completed action on a number of important objectives to make the ground operation of aircraft safer. However, these incidents continue to occur with alarming frequency. The FAA indicates that during fiscal year 2003 (FY-03), there were 323 incursion incidents, and that during FY-04 (ending September 30, 2004), there were 326 occurrences. As of the end of August, this year’s total was 296. Assuming that September is a “normal” month for incursions if there is such a thing, it looks like FY-05 will end up slightly better than last year.

While the numbers are interesting, we also must focus on severity. Runway incursions are categorized from A through D according to collision risk, with category A and B incursions presenting the highest likelihood of collision. Over the last 5 years the trend has been encouraging, with A and B events decreasing by half. However, we seem to have hit a plateau, with the FY-04 and FY-05 numbers being essentially identical. We’ve had about two of these most serious incidents every month for the past two years. Any one of these events has the potential to be a very significant accident.

We’re not alone; runway safety is a worldwide issue. On October 8, 2001, 118 people died when an SAS MD-87 airliner taking off for Copenhagen, Denmark, hit a Cessna private jet that wandered across the runway Milan, Italy. The airliner then careened into an airport building in a fiery crash that killed all 114 people on both planes and four people on the ground. It was Italy's worst aviation disaster. Italy’s Agenzia Nazionale per la Sicurezza del Volo’s 2004 report listed numerous causes including: low visibility; high traffic volume; lack of adequate visual aids; the Citation crew’s use of the wrong runway and entry without specific clearance; failure to check the Citation crew’s qualifications; pressure on the Citation crew to commence flight despite prevailing weather conditions; air traffic control did not realize the Citation’s location; instructions, training and prevailing environmental situation prevented air traffic control personnel from having full control over aircraft movements on the ground; and deficient signs, marking, and lighting diminished the Citation crew’s situational awareness.

On October 31, 2000, 83 people died when a Singapore Airlines 747 struck a concrete barrier and hit a construction site as it mistakenly took off from a closed runway during a storm at Taipei’s Chiang Kai-shek International Airport, Taiwan. There were 179 on board the flight to Los Angeles. The Taiwan Aviation Safety Council’s 2002 report listed various findings that contributed to the accident, including: heavy rains and strong winds from a typhoon at the time of the accident; the second and third officers did not question the captain’s decision to take off even though the crew had information about the closed runway; the flight crew did not adequately review their taxi route, and pressure to take off influenced the flight crew’s decision making ability. Consequently, the flight crew lost situational awareness and commenced takeoff from the wrong runway.

European ATC authorities have reported that they experience about one incursion every day, with a serious incursion occurring about every 14 days. Following their own internal analysis of surface incidents, the Australian Transport Safety Bureau noted that, while the vast majority of incursions are classified as “low risk” and unlikely to cause an accident, the consequences of a ground collision are potentially catastrophic, warranting “…constant vigilance and the implementation of all practicable measures for reducing runway incursions.”

Here in the US, we have recently experienced some very close calls. On June 9 of this year at Boston’s Logan International Airport, an Aer Lingus Airbus 330 and a US Airways Boeing 737 nearly collided at the intersection of runway 9 and runway 15R. Because of an air traffic control coordination error, both pilots were issued nearly simultaneous takeoff clearances. The aircraft passed through the intersection at flying speed with about 170 feet of lateral separation. The Aer Lingus flight was airborne, and only a quick decision by the US Airways crew to delay liftoff and pass beneath the Airbus prevented what could easily have been a terrible accident.

The air traffic control tower at Logan is equipped with the FAA’s Aircraft Movement Area Safety System (AMASS), which is intended to warn of potential surface collisions. However, the system did not alert the tower controllers of their mistake. Investigation revealed that because of nuisance alert problems identified during system development, the AMASS software is not configured to detect conflicts between aircraft operating on converging runways at Logan or any other airport.

On July 6, 2005 at John F. Kennedy airport in New York, a pilot deviation occurred when Israel Air flight 102, a Boeing 767 was instructed to taxi to runway 22R via taxiway H, and then turn left onto taxiway B. ISR102 did not turn left onto taxiway B and crossed runway 22R without authorization. Airborne Express 50, a DC8 freighter, had been cleared for take off on the same runway.

Preliminary information indicated ABX50 may have overflown ISR102 on the runway. The two aircraft’s closest proximity was initially estimated at 100 feet (vertical). According to the pilot of ABX50, his aircraft did overfly the B767 with clearance of less than 75 feet at the nose and as little as 45 feet at the tail.

AMASS did not alert the controllers to the mistake that was made by the pilot because it was raining heavily at the time. Under such conditions, the radar that supplies surveillance data to the AMASS processor generates excessive amounts of false targets because of the precipitation. To compensate for this, AMASS is placed into “limited mode,” which disables much of its conflict detection and warning capability in order to prevent nuisance alarms. As a result, the system was of little use when it was needed most.

In November 2004, an accident occurred at Philadelphia International Airport when a Mitsubishi MU-2 collided with an aircraft tug during takeoff. The tug had been cleared to cross the runway by the tower at the same time as the MU-2 was taking off. AMASS alerted, but not in time to prevent the collision. The MU-2 pilot attempted to avoid the tug, but was unable to do so.

On August 19, 2004, an Asiana Airlines Boeing 747 and a Southwest Airlines Boeing 737 nearly collided on runway 24L at Los Angeles International Airport (LAX) after the tower controller mistakenly instructed the Southwest flight to taxi onto the runway in front of the landing 747. While on very short final, the Asiana crew saw the conflict and initiated a go-around, making a low pass directly over the 737. The AMASS system at LAX activated a warning in the tower about 10 seconds before the two aircraft would have collided, likely too late for effective ATC intervention. Had the Asiana crew not seen the Southwest aircraft and taken action on their own, a major accident could have occurred.

I have animations of the Asiana incident and another near collision that occurred at O’Hare International Airport in 1999 that I’d like to show you in order to illustrate the situation we’re trying to prevent.

In the first animation, the Asiana 747 is on final approach to runway 24L at LAX when the Southwest aircraft is cleared onto the runway. The tower controller thought Asiana had been cleared to land on runway 24R, leading to the conflict.

Safety Board aircraft performance analysis strongly suggested that if Asiana had delayed their go-around until after AMASS alerted the tower controller, the 747 would likely have struck at least the vertical stabilizer of the 737 on the runway.

In the next animation, an Air China 747 has just landed at ORD, is turning off the runway, and being issued taxi instructions to the cargo area. The crew becomes disoriented, and instead of following the parallel taxiway as cleared instead turns back out onto the runway just after a Korean Airlines 747 begins its takeoff roll. The controller sees the problem and reacts, but too late for effective intervention.

AMASS was not installed at the airport when this incident occurred, but the recorded flight data was supplied to the FAA for use in an AMASS simulator. The simulation indicated that the system would have alerted about 8 to 9 seconds before collision, again too late for effective intervention.

These incidents and others continue to be of serious concern to the Safety Board. Despite the efforts of pilots, controllers, FAA management, and airport operators to mitigate the risks of surface operations, the continuing occurrence of hazardous incidents shows that we still have work to do.

The runway safety recommendation included on the Most Wanted List asks the FAA to:

Require, at all airports with scheduled passenger service, a ground movement safety system that will prevent runway incursions. The system should provide a direct warning capability to flight crews. In addition, demonstrate through computer simulations or other means that the system will prevent incursions.

Analysis of several near-collisions has shown that AMASS performance is not adequate to prevent serious accidents. As evidenced by the Boston incident, in some cases the system does not provide an alert at all, and when it does alert in critical situations such as the Asiana incident, the warning may come so late as to be of little use. In addition to the incidents I just described, the Board is aware of several near-collisions occurring at AMASS-equipped airports that were prevented not by virtue of a timely warning from the system, but instead were resolved through flight crew actions sometimes bordering on the heroic – along with a lot of luck. That is not good enough.

In order to ensure that all commercial passengers receive effective protection against the dangers of runway incursions, the Board has urged the FAA to develop and demonstrate the effectiveness of ground movement safety systems appropriate for use at a variety of airport types ranging from large international airports to the smaller regional airports served only by commuter airlines. We do not expect that the answer will be a “one size fits all” system, but will instead require creative use of different combinations of sensors, processors, and warning methods tailored to the requirements of each situation. At small and uncomplicated airports, simple methods of aircraft detection and warning may be sufficient, while at complex and busy airports a more elaborate approach may be needed.

Delivering technological solutions takes time, but the hazards are here now. Consequently, over the past few years the Safety Board has made other recommendations that we believe will improve runway safety without requiring lengthy development periods. For example, we have recommended that the FAA promote more rigorous standards for the marking of temporarily closed runways, in order to minimize the chances of an inadvertent takeoff or landing. Our intent is that the effort put into preventing access to closed areas is commensurate with the hazard of inadvertent use. For example, if a runway is closed briefly to allow paint to dry or because of other benign conditions unlikely to threaten safety in the event of a pilot or controller error, minimal effort would be required. In contrast, if the condition of the surface or the presence of men and heavy equipment renders a serious accident virtually certain in the event of an inadvertent takeoff or landing, the Board believes that substantial prevention efforts are needed. This may require physical access barriers, lighted “X” markings, or other methods for sending pilots an unmistakable message that a runway is not available for use.

Other recommendations have addressed the use of air traffic procedures such as holding aircraft on runways, communications techniques used by controllers, implementation of ICAO standards within the US ATC system instead of US-only procedures, and revision of Federal Air Regulations regarding the need for specific clearance to cross a runway rather than the implied crossing permission that currently comes with certain types of taxi clearances. Our European counterparts have made similar recommendations in response to accidents and incidents occurring within their own area of responsibility.

Operational procedures must take into account the inevitability of human error and, whenever possible, be designed to provide redundancy in order to eliminate the possibility that a single human or equipment failure will lead to a catastrophic accident.

Our recommendations are often intended to improve the awareness of pilots and controllers, so that if one makes a mistake, the other has an opportunity to notice and react. In some cases, this objective suggests that the use of procedures such as “position and hold” (where an aircraft waits on the runway for departure clearance rather than waiting on the taxiway) be limited to circumstances where the runway environment is visible to the crews of landing aircraft in time to execute a go-around if necessary to avoid a ground conflict.

We have also asked the FAA to require that controllers issue traffic advisories when aircraft are landing on converging runways, so that the pilots are aware of the potential conflicting traffic and can respond in a timely manner if spacing is less than needed for a safe landing.

Such recommendations often meet resistance in the form of assertions that redundancy is not needed if everything goes the way it’s supposed to. Unfortunately, virtually all of the Safety Board’s workload comes from situations where everything doesn’t go the way it’s supposed to, and often only a minor change in the sequence of events would have turned the accident or incident into a non-event. We’ll do whatever it takes to increase the number of non-events in the system – that’s one of our main criteria for “having a good year,” and I’m sure you all share that goal.

I thank you for allowing me to talk with you today, and I’d like to further thank the leadership of AAAE for sponsoring the numerous classes, seminars, and other training opportunities that help improve safety at airports all across the country. I would be pleased to answer any questions you may have about our efforts in runway safety or other aspects of the Board’s work.


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