AAHK right now: Normal operations using Centre and South runways. RIP security guys in the car.
Too early to speculate but the AAHK spokesman stated "North runway was operating normally at the time of the incident."
"the car was on the perimeter road north of the runway when the aircraft impacted it" "the car was stationary on the perimeter road at the time of the incident" "control tower tried to ask the aircraft why they are turning thru radio but no answer was received"
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This is an old map of the perimeter road when we still only had two runways
https://www.cad.gov.hk/reports/r1app1/app1-12.pdf .
Assuming the perimeter road was rebuilt the same way for the third (North) runway [does anyone have the updated Airport Grid Map?], then AAHK is asserting the aircraft swerve [for unknown reason] and hit the car.
Map of aircraft path. Vehicle location at time of impact not shown, I think the vehicle icon is where it is now: