What is it? The new air traffic control system – the US-made Raytheon Auto Trac III – has not been working smoothly. The expensive upgrade was supposed to replace the old system – Raytheon’s Auto Trac I – that has been in use since the opening of the airport on Chek Lap Kok in 1998. But is has been dogged by bugs and malfunctions. Suppose you bought a brand new car in 2011 for HK$156,000, to replace the one you bought in 1998. But today, that new car hasn’t even been used, and you’ve had to fork out thousands on repairs on it. Meanwhile, you’re still driving the old car and have to spend HK$2,000 every year to keep it running. Replace the car in this story with a new air traffic control system – and multiply the amounts by a million – and you have a better idea of the problems for the Civil Aviation Department (CAD). When will they make the switch? The new system was expected to start working in 2012. The current system became outdated that year, and has been kept on life support since then. Aviation officials have gone to great lengths to keep the creaking system from breaking under the strain. Sometimes staff have to blast cold air directly into machines to avert breakdowns. The government had been keen to see the final phase of the new system go live on Sunday, October 30 2016. How much does the new system cost? HK$1.56 billion And why is it controversial? When the CAD bought the new system in 2011, the technology had only been used at a handful of airports in India and later in the United Arab Emirates, but only after the tender in Hong Kong had closed. Lawmakers were up in arms with officials over why they chose a system with no proven track record. So, what happens next? The government had said the plan was on track for October 30. But the probe revealed on Friday could extend testing and delay the final commissioning of the new system. Even the airport, and airlines which had to cut flight schedules to accommodate final testing, are unclear on whether they will need to axe more flights.