The police have been accused of jamming airport traffic control radio channels during the Indonesian president’s visit to Hong Kong.
An anti-explosive van was deployed when Joko Widodo arrived in the city on Sunday. It is able to remotely block signals which could ignite a bomb.
But on Sunday, a Facebook post on a page where civil servants can leave anonymous messages, claimed that the van jammed air traffic control frequencies, with noise from the interference “deafening” controllers.
One commenter said: “If there is a plane crash, and several hundred died, we can’t sue the police for manslaughter, right?”
The Civil Aviation Department (CAD) confirmed on Monday that its facilities received “intermittent temporary radio interference” on Sunday, but air traffic control officers provided services as normal, and flight operations had not been affected. It said it reported the incident to the Communication Authority.
The Communication Authority said it has received the CAD’s notice about facilities at Victoria Peak being intermittently jammed. It sent workers to the site for inspection, but the work was halted as the interference, and its origin, could not be detected.
The Authority also said it was not unusual for the CAD to report jamming at its facilities.
A government source cited by Ming Pao said Widodo was scheduled to visit Madame Tussauds Hong Kong at Victoria Peak on Monday, therefore the anti-explosive van was discharged to the area on Sunday evening to detect suspicious items.
The source said it was suspected that during the detection mission, the radio signal it emitted jammed the air traffic control channel of the CAD.
According to a clip obtained by HKFP through LiveATC.net, a website which broadcasts air traffic control conversations, there was also loud rustling sound at around 2pm on Sunday, when Widodo’s plane arrived in Hong Kong.
The police had not directly responded as to whether the signal jamming was related to the van, saying that operational details cannot be disclosed. It also said it would communicate with other departments when making security arrangements.
Civic Party lawmaker Jeremy Tam Man-ho, a former commercial flight pilot, said it was an offence to interfere with air traffic control frequencies.
“The Communication Authority must investigate as to whether the police failed to notify the CAD, or whether the police were even unaware that they would jam the air traffic control system,” he said.
He said in foreign countries, there were several ways to deal with such arrangement so that air traffic control officers will be prepared.
“Normally the civil aviation department and airlines would be notified beforehand. Either suspend flights for a short time, or say there could be delays of around 15 minutes throughout the day,” he said.
William Cheung Sing-wai, associate professor at the Department of Electrical and Electronic Engineering of University of Hong Kong, told Ming Pao that normal explosive devices would be triggered by phones or Wi-Fi signals, and it was rare for explosives to use air traffic control channels.
He said the anti-explosive van should have targeted the former frequencies and questioned whether police had made a mistake.