Industry rumours surrounding the movements of North Korean leader Kim Jong-un are circulating that the arrival of an Air Koryo IL-76 cargo aircraft in Vladivostok (pictured) may suggest a visit to Russia is imminent.

On Sunday, Swedish-based global flight tracking service Flightradar24 recorded the aircraft’s approach to the city from North Korean capital Pyongyang. It was unable to confirm the exact destination of the Soviet-era aircraft, as its MLAT coverage of the area is weak, though few other airports suggested themselves.

MLAT was developed by Flightradar24 and requires four or more receivers in a region to receive a signal from the same aircraft. Flightrader24 then measure the Time Difference of Arrival (TDOA)—or the time it takes the signal from the aircraft to reach the receiver. By comparing how long it takes the signal from the aircraft to reach each of our receivers it is able to determine the aircraft’s position and speed. MLAT position accuracy is near that of ADS-B. Through testing accuracy to within 10-20m has been achieved. Speed is also calculated when tracking with MLAT, but errors are common in speed data, especially when an aircraft is circling or making turns.

The significance of the use of the aircraft, which was flying on a day when North Korean carrier Air Koryo does not operate the Pyongyang to Vladivostok route, is that it was used in June to carry Kim’s limousine and freight to Singapore ahead of the summit with US president Donald Trump.