North Korea has been sending GPS jamming signals since April 28, wreaking havoc with civilian aviation and fishing fleets. Over the last 12 days, 624 passenger planes operated by Korean Air and Asiana Airlines, and 49 foreign carriers were affected by GPS jamming and one U.S. military aircraft on the way from Beijing to Yokohama also experienced disruption. There were four close calls where passenger jets approaching Incheon and Gimpo airports abruptly shifted course when their GPS malfunctioned and landed only after circling the airports.
One wrong move by the pilot during a GPS malfunction could lead to a major accident. Sending GPS jamming signals aimed at civilian passenger planes and ships is clearly an act of terrorism.
But the government here has yet to explain to the public just how dangerous GPS jamming signals are, and the ministries of Defense and of Land, Transport and Maritime Affairs and the Korea Communications Commission are unable to come up with a concerted response.
The KCC said it has evidence to prove that the jamming signals originate from Kaesong. But the only thing the government has done is to issue a warning to passenger jets and civilian ships to watch out for GPS jamming signals. It was not until Wednesday, 11 days after the GPS jamming signals began, that South Korea sent North Korea a letter of protest through the border truce village of Panmumjom. North Korea simply refused to accept the letter.
Civilian aircraft use distance-measuring equipment (DME) which is different to inertial navigation systems (INS). GPS augments DME, so it can be switched off if it malfunctions and a plane can still manage to fly safely. But human error is always a possibility, and alarmed pilots can make the wrong decisions when their GPS malfunction, leading to disastrous consequences.
Ships are far more vulnerable than planes to GPS jamming. Large vessels can rely on effective radar systems if their GPS fails to work, but smaller boats either have no such radars or weak ones. That means seamen have to rely on compasses should their GPS equipment fail and may end up drifting off course. Last Wednesday, the GPS on 10 trawlers in the West Sea was jammed by North Korean signals, and one of them almost ended up crossing over the Northern Limit Line into North Korean waters.
Experts say South Korea lacks the technology to block North Korean GPS jamming signals. The only thing it can do is to gain the cooperation of the international community and pressure the North to halt its terror attacks. The government must waste no time in seeking the assistance of the U.S., Japan, China and other countries.