CAD responds to media enquiries on new ATMS

     In response to media enquiries today (November 19) on the new Air Traffic Management System (ATMS), a spokesman for the Civil Aviation Department (CAD) said:

     The operation of the new ATMS has been smooth in general since its full commissioning on November 14. On November 15 afternoon, the position of an departing aircraft was not displayed temporarily on the radar screen of one workstation in the new Air Traffic Control (ATC) Centre and there was a brief occurrence of split tracks (showing two flight tracks of the same aircraft on the screen). Through radar screen updates, the aircraft position was shown again automatically within 12 seconds. The allegation made by a source in a Chinese-language newspaper today that the position of an aircraft "resurfaced after some 20 to 30 seconds" was not factually correct. During the process, radar screen display of all other workstations were operating normally in the new ATC Centre.

     As a matter of fact, the phenomenon of aircraft positions temporarily not displayed on the radar screens was also observed occasionally in the ATMS elsewhere. It is a common practice for the ATMS developers to address the issue in their system design. In Hong Kong, no matter the air traffic controllers (ATCOs) use the old or the new ATMS, they can retrieve the position of an aircraft immediately or avoid split tracks by choosing an appropriate radar signal through the main system in accordance with established operation procedures. This procedure is called switching to the "bypass mode" (in case of the old ATMS) or "local mode" (in case of the new ATMS). There are long established guidelines on how to tackle relevant scenarios for all ATCOs to follow. The allegations quoted by the newspaper that "ATCO could not get hold of the aircraft position" or that "the phenomenon will have profoundly impacted on the daily operations" were unfounded. Moreover, the same set of aircraft information are available to the workstations operating in the "bypass mode" or "local mode". There is no question of putting extra pressure on the ATCOs.

     The CAD has been in close communications with the President of the Hong Kong Air Traffic Control Association and the Chairman of the Civil Aviation Department Electronics Engineers Branch of Hong Kong Chinese Civil Servants' Association. They both understood the situation on November 15 and supported the management of the CAD. They acknowledged that there is a set of clear guidelines for frontline officers to follow. They considered it reasonable for the CAD management to remind the ATCOs to switch to "local mode" in order to address the issue in case of recurrence. They believed that the ATCOs who have all undergone professional training are capable to handle this kind of known phenomenon.

     The new ATMS, with sophisticated design, adopted multi-radar tracking system to enhance the precision of aircraft position. It may take a bit longer occasionally for synchronisation. Sometimes, radar signals may be affected by different external factors (for instance aircraft transponder is busy or has radio communication problems, the reception of radar signals is interfered by external factors, terrain or obstacles etc.). Even if the aircraft is following a standard flight path, there is still a possibility that its position cannot be displayed temporarily or there are split tracks on the radar screen.

     According to the guidelines issued by the International Civil Aviation Organisation (ICAO) and the European Organisation for the Safety of Air Navigation (EUROCONTROL), the position of an aircraft displayed on the radar screen should be updated at an interval of not more than five seconds. The CAD has adopted an update rate of four seconds. On November 15, the position of the aircraft concerned appeared after two to three updates (within 12 seconds), even without the need to switch to "local mode".

     In conclusion, the phenomenon mentioned above is a relatively minor occurrence, in relation to local external factors, that requires further optimisation of the ATMS in the light of operational experience. The overseas independent consultant of the Transport and Housing Bureau from the United Kingdom, National Air Traffic Services (NATS), has confirmed that the CAD's new ATMS is safe, stable and reliable, and that the CAD is ready for the full commissioning of the new ATMS. According to the experience of NATS, given the complexity of an ATMS, even with all reasonable efforts and endeavours, there could still be possibilities to have setā€backs during introduction of a new system. To safeguard aviation safety, the CAD has laid down procedures for trained and professional ATCOs to handle different situations. It is normal and in accordance with international practice that the new ATMS needs some time to optimise its performance and suit the local operating environment. The CAD will continue to closely monitor the operations of the new ATMS with a view to bringing further improvements to it.

Ends/Saturday, November 19, 2016
Issued at HKT 20:04