【明報專訊】SOME flight information, including the call letters and flight speeds of some aircraft, was missing for 26 seconds in the new air traffic control system yesterday afternoon, forcing the Air Traffic Control Centre to stop handling outbound flights for 15 minutes so as to prepare for all possible contingencies.
The new air traffic control system in question, namely the Autotrac 3, was acquired from Raytheon Company, based in the United States, by the Civil Aviation Department (CAD) for $1.5 billion. However, the new system has run into a number of issues since it went into full operation in the middle of this month. Whistle-blowers from inside the CAD raised doubts about the safety of the new system, citing a number of cases in which a flight went "missing" for 12 seconds, a so-called "doppelganger" of an aircraft appeared on the radar screen, and double images appeared. Lawmaker Jeremy Tam, citing a whistle-blower, even claimed that after the full implementation of the new system, there was once a private jet flying close to the sea surface at an altitude significantly lower than normal. Another incident involved two passenger airplanes which were flying very close to each other, which, fortunately, did not result in an accident.
As answered by the CAD, issues like double images, "doppelganger" and "vanishing" airplanes happened every now and then in the old system, and are common in the air traffic control systems of other places as well. Related to factors like the topography, weather and temperature, such issues are all "foreseeable", which air traffic controllers are fully capable of dealing with. As for the cases of a private jet flying at an inappropriately low altitude and two planes flying too close to each other, they might not have been related to the system itself. They might have been due to the fact that air traffic controllers were not fully familiar with the new system, and did not notice that an airplane had started flying at a low altitude suddenly and that two planes were flying too close to each other. According to the CAD, in these two incidents, the positions, altitudes and distances of flights were displayed correctly in the new system, which raised an alert when two planes were flying too close.
But yesterday afternoon, the new system was unable to fully display flight information for 26 seconds, which was different from the "foreseeable situations" mentioned above. What happened yesterday was without doubt a "non-foreseeable" situation that was completely different in nature. Simon Li, the Director-General of Civil Aviation, said that the incident might have resulted from failures of the flight data processor while it was backing up flight data automatically. In other words, it was a fault of the system, and there is no evidence that it was caused by mishandling or misjudgement on the part of air traffic controllers. The CAD has demanded that senior officers of the contractor explain the matter in person in Hong Kong, submit a report within 48 hours, and put forward a solution to prevent similar incidents from happening. Such a demand is necessary.
There are different views concerning the new air traffic control system within the CAD, with some frontline staff arguing that the new system is not well-designed or convenient to handle. However, according to NATS, an overseas independent consultancy commissioned by the government to provide an evaluation, the new system is safe. Air traffic control requires a high degree of professionalism, and should be founded on professional advice. It should be determined by the professionals whether the incident is sufficient proof that the new air traffic control system contains serious safety risks. Since aviation safety allows no margin of error, it is important to maintain transparency. The CAD has set up an expert group and invited people including representatives of air traffic controllers to provide opinion when the new system is being assimilated. This is a step in the right direction that encourages the free airing of views. Furthermore, the Transport and Housing Bureau should contact NATS in order to understand why it failed to discover the related problems when the new system was being tested and address the matter appropriately as soon as possible.
Presented by lecturers of Hong Kong Community College, PolyU and The Hong Kong Polytechnic University