Why safety fears over Hong Kong’s new air traffic control system are groundless
P. F. Wong says given the stringent testing that has been carried out, the more technologically advanced system is good to go, marking a new chapter in the city’s aviation history
I am thrilled to learn that the government has set a clear timetable to launch the new air traffic control system in phases, starting this month. This will mark a new chapter in Hong Kong aviation history. Nevertheless, when attending a recent Legislative Council subcommittee meeting on the three-runway project, I noticed that individuals, including some lawmakers, still have doubts over the new air traffic control system, particularly its safety and efficacy. Let me, a 30-year veteran in this profession, try to allay such concerns.
Delayed take-off: Further hold up for HK$1.5 billion Raytheon AutoTrac III air traffic control system
The existing system, known as AutoTrac1, was designed and supplied by Raytheon, an American manufacturer. Since its commissioning in 1998, the system has performed very satisfactorily, providing a safe and reliable air transport service to the public. The new system, known as AutoTrac3, is the latest model by the same manufacturer, with greatly enhanced capability. In particular, advanced electronics technology is used with the aim of improving and automating various functions. Examples include: enhanced flight information and data processing capacity, advanced conflict alert features, precise aircraft trajectory predictions, and satellite-based technology. All these new features will help improve the efficiency of our frontline air traffic controllers.
It is equally important that the new system is equipped with multiple layers of backup, and the “ultimate fallback” system is now fully independent of the “main” and “standby” systems. This ensures air traffic control operations will not be paralysed even in the unlikely event that both the “main” and “standby” systems are disrupted one after the other. In a nutshell, the new system will be more effective in safeguarding air traffic control operations than the existing one.
Some critics said the contract for AutoTrac3 has been amended twice, and a number of follow-up items were identified during acceptance tests. The inference is that the new system might not be up to scratch. These worries are ungrounded. Given that the International Civil Aviation Organisation updated its air traffic management requirements after the contract was awarded, it was wholly appropriate to modify it to take in the latest international standards.
As regards follow-up items identified during the acceptance tests, it is the norm for large-scale computer systems in all areas, including civil aviation, and highlights the importance of comprehensive testing for a system where safety is critical. Items identified were mainly concerned with optimising the system to adapt to the needs of local air traffic control operations, and had nothing to do with aviation safety. Other civil aviation authorities around the world have faced similar challenges in replacing their air traffic control systems.
Some media reports also claimed that the displayed aircraft position on the radar screen of the new system updated at four-second intervals, which was said to be “slower” than the existing system, which refreshed at a three-second frequency.
As far as I know, the new system allows the user to adjust the update rate and is capable of refreshing as quickly as the existing system. In setting this parameter, the user should take into account a number of factors, including operational needs, the comfort of the air traffic controllers (a too-frequent update rate will make them feel tired due to “data overload”), and so on. I believe all these factors have been carefully assessed by the Civil Aviation Department before determining an appropriate update rate. International guidelines state that the update rate should be no more than five seconds. Therefore, the new system complies with international best practice.
Cathay Pacific, Dragonair, HK Express and Hong Kong Airlines face cuts to flights ahead of much-delayed air traffic control system
With regard to the proposed reduction of air traffic during the transition period, it is considered best international practice for civil aviation authorities to temporarily adjust the maximum number of flights handled. Such a measure ensures the transition can be meticulously planned and executed, and should not be misinterpreted as a confidence issue. Rather, it is an effective and pragmatic safety measure.
AutoTrac1 underwent a series of stringent acceptance tests before it was commissioned. That has helped ensure its smooth operation. Today, AutoTrac3 has undergone similar, if not more, stringent tests. The Transport and Housing Bureau and the Civil Aviation Department have each engaged an independent overseas consultant to carry out comprehensive safety assessments on the new system and make recommendations about the transition, including that it be launched in phases. This is the right call, as it allows frontline air traffic controllers and engineering staff to progressively adapt to the various new features for real-time operation.
Commissioning of the new system is to be welcomed. It will take the development of civil aviation in Hong Kong to new heights.
P. F. Wong is a former assistant director general of civil aviation. A registered professional engineer, he participated in the building of Hong Kong International Airport