Hong Kong air traffic system fix to come ‘in two weeks’ after latest glitch
Recent fault caused by amount of user preference settings being saved exceeding limit of 5,500
The contractor of Hong Kong airport’s new air traffic control system has pledged to provide a software fix in two weeks for testing after some information on eight flights went missing on radar screens last week in a worrying system glitch.
Raytheon, which developed the HK$1.56 billion air traffic control technology, made the promise on Saturday – a week after the incident – along with the submission of an investigation report to the Civil Aviation Department.
Referring to the recent system fault, the department said only “a few” flights were affected. The backup system was activated and clearance for departure flights was delayed for 15 minutes.
Raytheon’s latest report confirmed that the problem was caused by an accumulation of user preference settings, which exceeded the system limit. The flight data processors therefore could not function properly.
The current system can store up to 5,500 preferences, which allowed some 400 traffic controllers to individually customise settings such as text size and brightness of radar screens to their liking.
But on the morning of April 8, one extra setting beyond the limit sent the system into an alert mode and the first server was shut down. The staff member involved, who was unaware of the problem, saved the preference again, leading to a shutdown of a second server.
The developer said the root cause was not related to system performance.
A software fix, which can be implemented in May, will be prepared by Raytheon. Enhancements include alerts to controllers when the amount of user preference settings saved reached a threshold before hitting the limit. Any extra setting created above the limit will also be rejected without affecting normal operations. The amount of preferences the system can store will also be increased.
Before the fix, the department said staff members would be asked to stop setting new preferences. Obsolete or unwanted preferences would also be removed, and hourly checks would be conducted to monitor trends of users and take any early preventive measures.
The department also said it would monitor closely the progress of the fix and request all relevant work to be completed as soon as possible.
Civic Party lawmaker and qualified pilot Jeremy Tam Man-ho said the software fix should be able to prevent similar issues in the future.
“The causes were low-level but the consequences were unexpectedly serious,” said Tam, who has been a harsh critic of the new system.
But he said the report did not explain why the system’s “emergency” operation – which was designed to allow staff to fix problems under limited flight information for a certain period of time – failed to work.
“Staff members should be able to clear the exceeded preference settings in the collapsed servers during the emergency state, instead of having the system jump straight to a backup mode,” he said.
While deputy director general of civil aviation Kevin Choi earlier said the department would take the latest incident into account before deciding whether to retire the old system next month, Tam said it should be kept until the new one had been tested fully.