The pilots in command of an SA Airlink passenger aircraft that broadcast a false hijacking alert on Monday are adamant that they did not type in the code used to declare the emergency.
The aircraft‚ carrying 72 passengers and four crew‚ transmitted an eight-second-long alert about 10 minutes prior to landing at Wonderboom Airport in Pretoria.
Under normal circumstances‚ the alert can only be triggered by the pilots although a radar fault could also be responsible. The cause is still under investigation.
SA Airlink CEO Rodger Foster told
Cape Talk radio‚ in an interview on Tuesday: “The two pilots maintain‚ adamantly‚ that there was no intervention inside the cockpit that would have dialled in the very special code that would have depicted a hijack event.”
“Approximately 10 minutes before landing … we had a report at head office through our flight operations department that there was a hijack alert being transponded from the aircraft. This alert had manifested over a very short period‚ approximately eight seconds‚” he said.
Air traffic control responded as if it were a real event‚ as per protocol. News of the “hijacking” spread rapidly on social media until the airline took to Twitter to reassure the public that the passengers and crew were safe – although police had to thoroughly check the aircraft before they could disembark.
“Notwithstanding the false hijack alert‚ which lasted a few seconds‚ the mandatory hijack response procedures were activated‚” said the South African Civil Aviation Authority.
“When the aircraft landed at Wonderboom Airport‚ the police’s hijack response team conducted the necessary checks to ascertain that indeed the aircraft was not hijacked.”
Foster said: “We consider that there is some kind of an anomaly. We don’t believe the anomaly comes from the on board equipment of the aircraft‚ however that remains to be proved. But there is an anomaly in the system somewhere.”
Air Traffic and Navigation Services COO Peter Marais‚ told the Cape Town radio station that it was possible‚ although unlikely‚ for part of a signal transmitted by an aircraft not being properly received or processed by equipment on the ground‚ resulting in a false code being interpreted as valid.
Explaining how the signals work‚ he said various codes were transmitted from aircraft as specific radio frequency pulses. These were received‚ processed and decoded on the ground.
“In this instance‚ the radar system received the transponder signal from the aircraft‚ processed it and decoded it and indicated that there was a valid code related to this emergency‚” he said.
Asked if there had been false codes picked up by ground radar systems in the past‚ he said: “It has occurred previously‚ this was probably two or three years ago.”