On Friday, February 10, the NTSB (National Transportation Safety Board) of USA published the preliminary report of the incident that took place on January 13 of this year and Boeing 777-200 de American Airlines and a Boeing 737-900ER de Deltawhen the first crossed active runway 4L on which the Delta 737 was making its takeoff roll.
According to what is indicated in said preliminary reportAmerican 777-200, operating flight AA106, had instructions to taxi to runway 4L via B Street and hold position before crossing K Street.
Subsequently, it was cleared by apron control to cross runway 31L at K street. When AA106 reached the intersection of B and K streets, it continued straight to J street, crossing runway 4L without traffic control clearance. .
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The reports indicate that at the time of entering runway 4L, the Delta 737-900, with flight identifier DAL1943, had begun its takeoff run with increasing speed and then close to 80 knots, some 900 meters from the intersection. from taxiway J, in use by AA106.
The ADSE-X system, key to avoiding the tragedy
The preliminary report confirms that the system came into play ADSE-X, Airport Surface Detection System — Model Xwhich alerted the airport control tower of the conflict.
The ADSE-X system is a radar, multilateration and satellite surveillance system that allows air traffic controllers to follow the surface movements of aircraft and vehicles.
The system alerts air traffic controllers to potential runway conflicts by providing detailed coverage of runway and taxiway movement. It was designed to reduce category A and B runway incursions.
By collecting data from various sensors, the ASDE-X system is capable of tracking transponder-equipped and non-transponder-equipped vehicles and aircraft in the airport movement area.
According to the FAAcontrollers receive the information on a color display that shows aircraft and vehicle positions as an icon overlay on a map of the airport’s runways and approach corridors.
The system continually updates the airport movement area map that controllers can use to improve their situational awareness.
The system is especially beneficial at night or during adverse weather conditions, when visibility is poor. The ASDE-X is also equipped with visual and audible alarms that will alert controllers to potential runway incursions or incidents.
Currently, 38 airports in the United States have the ADSE-X system installed, including Boston Logan, Chicago O’Hare, Dallas-Fort Worth, Atlanta Hartsfield-Jackson, JFK, Newark and La Guardia, Seattle-Tacoma, Phoenix Sky Harbor and Miami International, among others.
Alarm and Aborted Takeoff
The tower, following instructions from the ADSE-X system, ordered DAL1943 to immediately abort its takeoff, which proceeded to cancel it when it had already reached 100 knots of speed and stopped 500 feet -about 150 meters- from the street of filming j.
According to the report, the shortest distance between the two planes was about 1,500 feet, when the Delta 737 was already slowing down and the AA106 was just finishing crossing the runway at J Street.
Research faces problems
The NTSB indicates in the report that it formed four groups to investigate the incident: Operational Factors, Human Factors, Air Traffic Control and Flight Data Recorders. Likewise, the Federal Aviation Administration (FAA), Boeing, Delta, American Airlines and the Allied Pilots Association (APA), a union that brings together American Airlines pilots, were identified as interested parties.
The investigative agency says that on February 1 it conducted interviews with Air Traffic Control personnel, which were recorded for later transcription. The Data Recorders investigation group observed that both cockpit voice recorders (CVR – Cockpit Voice Recorder) had been overwritten, losing information from the time of the incident.
Although the crews submitted written statements, the NTSB indicated that it wanted to conduct interviews with the American Airlines crew involved in the incident, requesting meetings on three occasions.
The company released the crew members to ensure their availability, but they refused to be interviewed because they would be recorded for later transcription. An APA representative, acting on behalf of the crew, informed the NTSB that the crew would not consent to participate in taped interviews in any way.
The NTSB determined that the investigation “requires that interviews with crew members be recorded and transcribed by a commissioned agent to ensure a high degree of accuracy, completeness, and efficiency.”
The Board of Inquiry closes the preliminary report stating that “as a result of the crew’s failure to cooperate in proceeding with a recorded interview, subpoenas were issued to obtain their testimony.”
The pilots’ union, on alert
In a statement also issued on February 10,Allied Pilots Alliance indicated that “as professional aviators, we support the vital role of the NTSB in the investigation of accidents and incidents to promote aviation safety” and that “they have a clear interest in the work that the NTSB does” and a “long history of cooperative work with the agency.”
The union notes that previously, when the NTSB conducted interviews, “note-taking by the parties” or the intervention of a stenographer was sufficient to produce accurate records “and allowed the Board to make detailed reports and findings.”
However, for APA “the introduction of electronic recording devices has more possibilities of altering an investigative process than of improving it”, since “not only the recording of interviews can lead to less sincere answers”, but also “the existence and potential availability of interview records when investigations are complete may induce crews willing to be interviewed to choose not to participate in the process.”
“None of the possible consequences will serve the objective of conducting effective investigations to promote operational safety,” adds the pilots’ union.
APA closes its statement by saying that “NTSB investigations are intended to be fact-finding processes without affected parties. Implementing changes to established practices, especially those with a demonstrated track record of success, in a manner that discourages cooperative witnesses from participating in such process is contrary to the purpose and objective of the NTSB.”
According to the citations issued by the NTSB, the crew members involved have seven days to respond to the Board.
