Comment by 4ndrewl

I wouldn't rule out a mass panic-type event. A similar event which closed London's Gatwick airport (one of Europe's busiest) garnered no evidence and no serious lines of enquiry.

https://www.theguardian.com/uk-news/2020/dec/01/the-mystery-...

See also the recent closure of Heathrow Terminal 4 https://www.bbc.co.uk/news/live/c5ypl5grg24t